Performance Analysis of UV Solar Dryer

CONTENTS

Abstract

Contents

List of Figures

List of Tables

Abbreviations

Nomenclature

CHAPTER 1: INTRODUCTION
1.1 INTRODUCTION
1.2 SOURCES OF ENERGY
1.2.1 Conventional Sources of Energy
1.2.2 Non-conventional Sources of Energy
1.3 SOLAR ENERGY AND ITS AVAILABILITY
1.4 APPLICATIONS OF SOLAR ENERGY
1.5 SOLAR DRYER AND HISTORICAL OVERVIEW
1.6 OPEN SUN DRYING
1.7 SOLAR DRYER
1.7.1 The Concept of solar dryer
1.7.2 Drying process
1.8 SOLAR DRYER CONSTRUCTION DETAIL
1.9 APPLICATION OF SOLAR DRYER
1.10 CLASSIFICATION OF SOLAR DRYER
1.11 ADVANTAGES AND DISADVANTAGES OF THE TYPES OF SOLAR DRYERS
1.12 PARAMETERS AFFECTING SOLAR DRYER PERFORMANCE
1.13 PERFORMANCE ENHANCEMENT OF SOLAR DRYER
1.14 OBJECTIVES OF PRESENT INVESTIGATION
1.15 ORGANIZATIONS OF THE THESIS

CHAPTER 2: LITERATURE REVIEW
2.1 INTRODUCTION
2.2 LITERATURE REVIEWS OF VARIOUS TYPES OF SOLAR DRYER
2.3 RESEARCH GAP

CHAPTER 3: PERFORMANCE EVALUATION PARAMETERS
3.1 INTRODUCTION
3.2 DRYING KINETICS OF SOLAR DRYERS
3.2.1 Moisture Content
3.2.2 Moisture Ratio
3.2.3 Drying Rate
3.2.4 Drying Efficiency
3.2.5 Drying Period
3.2.6 Useful Heat Gain
3.2.7 Collector Efficiency
3.3 GENERAL PARAMETERS CONSIDERED FOR PERFORMANCE EVALUATION OF SOLAR DRYERS

CHAPTER 4: EXPERIMENTAL SET-UP AND DATA COLLECTION
4.1 INTRODUCTION
4.2 EXPERIMENTAL SET-UP DESCRIPTION
4.3 MATERIAL
4.4 MEASUREMENT OF OPERATING PARAMETERS
4.5 EXPERIMENTAL PROCEDURE AND DATA COLLECTION
4.6 UNCERTAINTY ANALYSIS

CHAPTER 5: RESULT AND DISCUSSION
5.1 INTRODUCTION
5.2 METEOROLOGICAL PARAMETERS PERFORMANCE RESULT
5.3 OPERATING PARAMETERS PERFORMANCE RESULT
5.4 EVALUATING PARAMETERS PERFORMANCE RESULT
5.4.1 Moisture Content
5.4.2 Moisture Ratio
5.4.3 Drying Rate
5.4.4 Drying Efficiency
5.5 QUALITY ANALYSIS OF PRODUCT

CHAPTER 6: CONCLUSIONS AND FUTURE SCOPE OF WORK
6.1 CONCLUSIONS
6.2 SCOPE FOR FUTURE WORK

REFERENCES

Abstract

A mixed mode natural convection ultraviolet (UV) tent house solar dryer is designed and installed at University Teaching Department, Chhattisgarh Swami Vivekanand Technical University, Bhilai, Chhattisgarh (21°27'N, 81°43' E) India for drying potato slices. This solar dryer is equipped with a solar flat plate collector (area 1.12 m[2]), covered with 5.0 mm thick glass and consist of two trays of the same sized (0.57m X 1.11m) in a drying chamber on which the equal quantities of potato slices were placed. The local atmospheric conditions including relative humidity, atmospheric temperatures, solar intensity and wind velocity have been recorded for analyzing various parameters. The initial moisture content value of 85.25% reaches to 14.75 % for 2.5 mm thick potato slices and for 5.0 mm thickness the initial & final moisture content values are 85.10% & 14.90% respectively. The open sun drying took 6 hours of longer than the natural convection drying. Moisture ratio for 2.5 mm thickness and 5.0 mm thickness lies 0.475-0.001 and 0.650-0.003 respectively. The maximum dryer efficiency is 26.62% and 21.61% for 2.5 mm and 5.0 mm thick potato slices respectively. All the drying kinetics is superior in 2.5 mm thickness of potato in process of drying using natural convection.

Keywords: Solar dryer, solar collector, ultraviolet tent house, natural convection drying, drying efficiency.

LIST OF FIGURES

Abbildung in dieser Leseprobe nicht enthalten

LIST OF TABLES

Abbildung in dieser Leseprobe nicht enthalten

ABBREVIATIONS

Abbildung in dieser Leseprobe nicht enthalten

NOMENCLATURE

Abbildung in dieser Leseprobe nicht enthalten

CHAPTER 1 INTRODUCTION

1.1 INTRODUCTION

Energy is essential for improving quality of life because it serves as the main input for practically all activities. Due to its widespread use in industries including telecommunications, industry, transport, commerce, a wide range of agriculture, and domestic services, we must pay close attention to its supply in order to satisfy our always growing needs. ¹.

Energy is the key input in economic growth and there is a close link between the availability of energy and the growth of a nation. Since energy is essential to conduct the process of Production, the process of economic development requires the use of higher levels of energy consumption.

The main factor influencing economic growth is energy, and the development of a country is closely related to the energy supply. Economic development necessitates increased levels of energy consumption since energy is required to carry out the industrial process.

At the beginning of the 20thcentury, the energy demand was half of the present scenario. Nowadays the population of the world is increasing day by day, which causes the high energy demand, our need for coal and additional fossil fuels like petroleum oil, gas, etc. is increasing day by day which causes different environmental hazards, but fossil fuels are very limited and their depletion rate is very high, that energy demand causes the price hike of non- renewable energy sources ².Recent analyses predict that during the next few decades, there will be a noticeable decrease in the stock of widely utilized fossil fuels ³⁴. The superiority of using renewable energy (RE) has several advantages, including lowering greenhouse gas emissions (GHE) and pollution emissions into the atmosphere ⁵⁶, it is necessary to move us toward RE sources such as solar energy, hydro, geothermal, wave, tidal energy, and wind energy ⁷⁸. Out of these energy sources, the most plentiful source of energy is solar energy among all the RE sources.

1.2 SOURCES OF ENERGY

The sources of energy (fig. 1.1) are of following types:

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.1 Sources of energy [1]

1.2.1 Conventional Sources of Energy:

These energy sources are also known as non-renewable sources. There is a finite supply of these sources of energy. [1, 9, 10].

The following are further divided into commercial and non-commercial energy:

(a) Commercial Energy Sources:

Coal, oil, and electricity fall under this category. These are referred to as commercial energy because the consumer must pay a fee to buy them.

(i) Coal:

The main energy source is coal. India has 14438.22 million tonnes of coal reserves. India's coal reserves are thought to be sufficient for 130 years. India is currently the second-largest producer of coal in the world. The primary coal-producing states are Orissa, Jharkhand, Bengal, and Madhya Pradesh. 7 lakh employees are employed by it.

(ii) Oil and Natural Gas:

Oil is currently regarded as the most significant source of energy in both India and the rest of the globe. It is frequently utilized in vehicles including as cars, trains, planes, and ships. It can be found in Gujarat, Mumbai High, and upper Assam in India. Oil is a scarce resource in India. Not with standing a sharp rise in oil production. Still, 85% of India's oil needs are imported.

13 public sector refineries with a 604 lakh tonnes per year capacity were built after independence. Private refineries are also involved in oil refining with the advent of economic reforms.

Since the last two decades, natural gas has been the most significant source of energy. There are two ways to create it:

(i) Using petroleum products as an associated gas.
(ii) Free gas sourced from gas fields in Gujarat, Andhra Pradesh, and Assam.

It is utilized in petrochemical, gas-powered thermal power plants, and fertilizer manufacturing facilities.

(iii) Electricity:

The most common and widely used form of energy is electricity. Both domestic and commercial uses are made of it. It is utilized for air conditioning, cooking, lighting, and the operation of electrical appliances like TVs, refrigerators, and washing machines.

There are three main sources of power generation (fig. 1.2):

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.2 Sources of power generation

(b) Non-Commercial energy Sources:

These materials include dried dung, straw, and fuel wood. In rural India, these are frequently utilized. There were only 50 million tonnes of fuel wood available annually in India, according to an estimate. It is less than half of what is needed. There would be a lack of firewood in the upcoming years.

Straw is one agricultural waste that is utilized as fuel for cooking. One estimate puts the amount of agricultural waste utilized as fuel at 65 million tonnes. When dried, animal excrement is also utilized in cooking. A total of 324 million tonnes of animal dung are produced annually, of which 73 million tonnes are utilized as fuel for cooking. The soil's fertility and hence productivity can be increased by using the straw and dung as useful organic manure.

1.2.2 Non-conventional Sources of Energy:

Non-conventional sources of energy exist in addition to traditional ones. These are also referred to as renewable energy sources. Bio energy, tidal energy, wind energy, and solar energy are a few examples. To effectively harness non-conventional energy, the Indian government has created a special department inside the Ministry of Energy named the Department of Non-conventional Energy Sources. ⁹.

1.3 SOLAR ENERGY AND ITS AVAILABILITY

Solar energy could be only source to fulfill energy requirements of entire human population if even 1 % of it could be collected on earth surface [1, 9-11]. The availability of solar radiation on earth surface is very less as compared to outside of the earth atmosphere. While entering the atmosphere solar radiations get reduced by the occurrence of losses of approximately 25- 50 % outside the earth's outer atmosphere. The water vapor and greenhouse gases absorb much of the solar radiation. The major drawback with this energy source is its dependency on weather conditions and low intensity. Despite of all the limitations solar energy is the most reliable source of renewable energy and is capable to meet the energy requirements if its proper accumulation and utilization is assured. The solar energy comes from the Sun. The largest member of the solar system and the source of solar energy is the Sun, which is surrounded by smaller planets. It is a sphere of extremely hot gaseous stuff with a 1.39 x 10[9] m diameter that is, on average, 1.5 x 10[11] m away from the earth. In the central region, the temperature is estimated to vary from 8 x 10[6] to 40 x 10[6] K. The surface temperature of the sun can be estimated as 5762 K.¹⁰¹¹

The solar radiation (fig. 1.3) that reaches the earth's surface consists of [1, 9].

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.3 Types of solar radiation

i. Direct or beam radiation : This radiation comes on the earth surface without any change in its direction.

ii. Diffuse radiation : The solar radiation that has been scattered by molecules and particles in the atmosphere but that has still made it down to the surface of the earth. On days with a clear sky, the diffuse component makes up between 10 % and 20 % of the total radiation; however, on days with a cloudy sky, it can reach up to 100 % of the total radiation that reaches the surface of the planet.

iii. Reflected Radiation : The radiation which strikes non-atmospheric body such asground and reflected back, are termed as reflected radiation.

Abbildung in dieser Leseprobe nicht enthalten

1.4 APPLICATIONS OF SOLAR ENERGY

A few of the significant uses of solar energy (fig. 1.5) are shown below ¹²:

Abbildung in dieser Leseprobe nicht enthalten

Solar energy must be efficiently collected and stored in order for its use to be economically viable. As the world's population rises and food demand increased but the agricultural land has decreased so the land demand also increased for survival. For survival, food preservation is necessary and post-harvest losses must be avoided, so this food demand is to be fulfilled by solar techniques i.e solar drying system.

1.5 SOLAR DRYING AND HISTORICAL OVERVIEW

Drying with sun radiation is one of the first uses of solar energy. Since the beginning of time, it has been used mostly to preserve food, however it has also been used to dry other important items like textiles and building supplies. The first solar-powered drying device was discovered in South France and dates to around 8000 BC. It was a stone-paved area where harvests were dried. The age of numerous other installations discovered worldwide ranges from 7000 to 3000 BC. There were a number of integrated installations, including sun radiation and natural airflow, used mostly for food drying. The first crop drying system that used only air was discovered in the Hindu River Valley and dates to around 2600 BC.

Aristotle, a famous Greek philosopher and physician (384-322 BC), provided the first theoretical justifications for drying when he described the phenomenon in detail ¹³.

For agricultural products, especially those produced in medium to small quantities, solar energy drying is a fairly cost-effective method for preserving extra output. It is environmentally friendly. It is still used to dry crops, agricultural products, and foodstuffs including fruits, vegetables, aromatic herbs, wood, etc. on a domestic up to small commercial scale, making a substantial economic contribution to small agricultural communities and farms.

1.6 OPEN SUN DRYING

In open sun drying, the materials being dried are exposed to sunlight radiation directly in order to lower their moisture content. The movement of air is caused by the variation in atmospheric air density. In order to expose the product to solar radiation, a thin coating of drying product must be spread out across a sizable area. The items must be processed for a considerable amount of time before they are sufficiently dry. Concrete or a certain type of soil that is suitable for outdoor direct sun drying makes up the surface floor. When it comes to drying grains, this kind of drying method is crucial. The product that needs to be dried is left on the outdoor floor for a lengthy time, typically 10 to 30 days.

The main drawbacks of this procedure include bird pecking, bug and microbe destruction, and dust contamination of the products. Additionally, a certain amount will typically be lost or destroyed during handling; it is labor-intensive, results in the loss of nutrients like vitamin A, and takes time. Finally, the technique is entirely dependent on favorable weather. ¹⁴

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.6 Open Sun Drying.

1.7 SOLAR DRYER

A solar dryer is a device that dries items, particularly food, using solar energy. The basic concept of solar dryers is to use solar radiation to heat air, which is used to remove moisture of food. This device also improves the quality, texture, hygiene and color of the crop and vegetables as compared to open sun drying.

1.7.1 The conceptof solar dryer:

- Energy change: The initial stage is to capture any light that strikes it and transform it into heat.
- The heat trap: The heat must then be contained in order to be used later. Because of this, the air inside the dryer is insulated from the air outside. To ensure that light that enters the space cannot escape, a plastic bag or a glass cover is utilized. Due to this process, the solar dryer can reach certain temperatures regardless of the outside weather and temperature.
- Transfer of heat: The next stage is to apply warm air in the convection form over the food or other item that has to be dried using this trapped heat.

1.7.2 Dying process:

Abbildung in dieser Leseprobe nicht enthalten

(1) Through the air inlet, cold, dry air enters the drying chamber.
(2) Through the transparent cover material, the sun's rays enter the cabinet where they are transformed into heat energy, raising the temperature inside. Food that has been heated releases water vapor and dries out.
(3) Through the air outlet at the dryer's high end, hot, moist air gradually rises and exits the drying chamber.

1.8 SOLAR DRYER CONSTRUCTION DETAIL

The detailed diagram of the solar dryer is shown in Fig. 1.8. Below is a description of the solar dryer's operation and construction. ¹⁵¹⁶¹⁷:

Frame - The frame is constructed with wood.

Drying chamber - Woods are used for construction of chamber, under which the trays are kept to dry the product.

Solar air collector - The collector is made to be airtight from two sides and to allow air to move between the bottom and top of the collector. It has a rectangular shape, with a black insulated lower layer, an air passage medium in the middle layer, and transparent glass on top.

Black Interior - The inner surfaces are painted with black paint to absorb more solar energy. Absorber plate - The absorber plate, which collects solar radiation and transfers the heat energy to the air moving through the duct, plays a important function.

Inlet /outlet section - Air intake and exhaust are provided with an inlet and outlet segment. Glazing - The top side of the glass has glazing to help it collect more solar rays. For glazing, materials including acrylic, tempered glass, and polycarbonate are typically utilized.

Insulation - To prevent heat loss via the walls, insulation is included in the bottom and side walls of ducts.

Trays - The drying chamber, which is built of mild steel or stainless steel and fine wire mesh with a relatively open structure to allow drying air to move through the items, is where the trays are kept.

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.8 Schematic diagram of solar dryer

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.9 Schematic diagram of flat plate collector

1.9 APPLICATION OF SOLAR DRYER

- Textiles industries.
- Fruit and food processing industries.
- Agro industries.
- Pharmaceutical industries.
- Paper industries.
- Drying timber.
- Fish drying.

1.10 CLASSIFICATION OF SOLAR DRYER

Solar dryers can be categorized into a variety of groups, as shown in Fig. 1.10. This graphic shows how different types of solar dryers are categorized according to their modes of operation and designs.

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.10 Classifications of solar dryer

On the basis of air flow, solar dryers are categorized i.e natural (passive) and forced (active) type of dryer. In passive type solar dryer, the air flow for drying product due to normal or lightness because of the density difference between environment air & hot air. Further, depending on the technique of solar heat application & the characteristic design of structural components the passive dryer is classified in three subcategories ¹⁸

1) Integral (Direct) type solar dryer
2) Indirect type solar dryer
3) Hybrid (Mixed) type solar dryer

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.11 Types of solar dryer ¹⁹

1) Integral (Direct) type solar dryer:

The traditional method of drying the items is through direct solar radiation. In this technique, the products are exposed to sunlight directly, which lowers their moisture content when in contact with ambient air. The air movement is caused by a difference in density. It can be broadly divided into two groups:

(1) solar drying outdoors in the open air.

(2) Using a translucent cover that partially shields the food from rain and other natural occurrences, such as a passive solar drying technique [20].

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.12 Outdoor open air solar drying

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.13 Working Principle of direct solar drying through a transparent cover

2) Indirect type solar dryer:

In Indirect solar dryer, the dryer consists of two elements i.e., solar collector and drying chamber in solar collector, the solar energy is collected in the form of heat energy then it is connected to the drying chamber, heated air is passed through it and extraction of moisture is takes place finally the product is to be dried. Indirect solar dryer either passive or active type ²⁰

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.14 Working Principle of Indirect solar drying

3) Hybrid (Mixed) type solar dryer:

Mixed mode solar dryer is a dryer that uses the direct as well as indirect solar radiations by the use of a solar air collector. It consists of a reflector, solar collector, and heat exchanger and drying chamber units. In Mixed mode solar dryer the solar energy collection occurs in solar collector and drying chamber both and drying the food product is carried out in only drying chamber. Mixed mode solar dryer is the best option for cloudy days comparing to other dryers. It is also called Hybrid solar dryer.

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.15 Working Principle of Mixed mode solar drying

1.11 ADVANTAGES AND LIMITATIONS OF THE TYPES OF SOLAR DRYERS

Abbildung in dieser Leseprobe nicht enthalten

1.12 PARAMETERS AFFECTING SOLAR DRYERPERFORMANCE

A solar dryer's performance is influenced by a number of factors (fig. 1 . 16),which can be characterized as under,

Abbildung in dieser Leseprobe nicht enthalten

Fig.1.16 Parameters affecting dryer's performance

1.13 PERFORMANCE ENHANCEMENT OF SOLAR DRYER

a. Increasing the heat storage capability of the drying chamber by using phase changing material (PCM). It provides extra time for drying, after sunset.

b. In order to maintain a higher air flow velocity, the chimney built into the solar dryer enhances the buoyant force that is applied to the air stream.

c. The use of concentrators, which raise the temperature within the dryer, has been found to speed up drying.

d. The thermal efficiency of the system can be increased by applying extended surfaces of higher thermal conductivity materials to the collector.

e. Flat type absorber plate can be replaced by wavy type absorber plate to get the higher air temperature for drying chamber.

f. Optimum air flow rate may increase the thermal performances of the drying system

1.14 OBJECTIVES OF PRESENT INVESTIGATION

The present work has been conducted on the performance analysis of UV sheet mixed­mode tent house solar dryer under natural convection mode at different thickness of product. The prime objective of the current work; consequently:

- Design and developing a mixed-mode UV house solar dryer made with polycarbonate sheet.
- Assessment of drying parameters of potato.
- Different thicknesses are used for drying potatoes.
- Performance comparison of drying using OSD and natural convection.

1.15 ORGANIZATIONS OF THE THESIS

Chapter-1 - This chapter provides a brief description on energy, sources of energy, solar energy and its availability, application of solar energy, solar dryer, constructions detail of solar dryer, classification of solar dryer and performance enhancement of solar dryer. The end of the first chapter reveals the objectives of present work.

Chapter-2 - This chapter presents the literature survey of solar dryer. A table that consist the summary of literature work. On the basis of literature review, research gap has been found.

Chapter-3 - This chapter discusses about the performance of solar dryer. Different parameters such as moisture content, equilibrium moisture content, moisture ratio, drying rate, drying period, drying efficiency, collector efficiency, useful heat gain and their equations are presented.

Chapter-4 - This chapter discusses about the experimental study, experimental set-up description and data collection with measuring instruments of solar dryer. The schematic diagram, photographic view, data sample and parameters are also presented.

Chapter-5 - This chapter presents the details of results and discussion. The meteorological parameters, solar collector performance, tray temperatures, outlet temperature, and dryer performance are discussed in brief with appropriate graph.

Chapter-6 - This chapter discusses the Conclusions and Future scope of work.

References - It contains the details of Research Papers and Books used as reference in the present work.

CHAPTER 2 LITERATURE REVIEW

2.1 INTRODUCTION

For the drying process, several types of solar dryers have been created, which was more efficient and cost effective. The process of drying can be done by using electrical, freeze, or solar drying. On the basis of air flow, solar dryers are categorized i.e. natural (passive) and forced (active) type of dryer. In this chapter the various types of solar dryer along with parameters, performance and experimental investigation have been described.

2.2 LITERATURE REVIEWS OF VARIOUS TYPES OF SOLAR DRYER

The performance of solar dryers of the direct, indirect, and hybrid types have been examined by various researchers. The experimental studies of different types of solar dryers are described asbelow:

Abdullah and Mursalim ²¹ designed and evaluated the greenhouse effect (GHE) solar dryer's performance for drying vanilla pods. The GHE solar dryer consists of four coal stoves using a 0.005 kg/min combustion rate throughout the experiment within the drying chamber. In this paper, two experiments were performed. In the first experiment, 46.6 kg of vanilla pods were dried for 49 hours from an initial moisture level of 82.6 % (wb) to a final moisture level of 37.9 % (wb). The drying chamber temperatures and average relative humidity were recorded 43.3oC and 34.95 % respectively. The second experiment used 52.4 kg of vanilla pods with a moisture level of 80.9 % (wb) at the beginning to 37.8 % (wb) at the end within 53.5 hours. The average relative humidity and drying chamber temperatures were 34.2 % and 44.4°C respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.1 Green house solar drying system

K. Abdullah et al. ²² designed a prototype of a greenhouse solar dryer and tested its technical performance for drying tropical products (seaweeds, smelt fish, coffee berries, and fermented cocoa beans). 70 kg of seaweeds dried to a final weight of 12 kg within two days and under 51°C drying temperature 65 kg smelt fish dried in 7 hours. The best specific energy achieved was 6.2 MJ/Kg of water vapor and 5.2 MJ/Kg of water vapor for fermented Mathematical models were developed by Jain and Tiwari ²³ to investigate the thermal behavior of crops (peas and cabbages) for open-air sun dryer and greenhouse-type solar dryers (natural and forced convection). MATLAB software was used to predict crop temperature, room air temperature of green house, as well as the moisture evaporation rate based on sun intensity and atmospheric temperature. For the comparison of predicted and experimental values, coefficients of correlation and the root mean square of present deviation were used respectively. It was found that the predicted values and experimental data with correlation coefficients were in good agreement varying between 0.77 for the crop and greenhouse air temperature to 0.97 and 0.98-0.99 for the crop mass while drying.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.2 GHE Solar Dryer

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.3 Solar Crop Drying under Greenhouse effect

Kumar and Tiwari ²⁴ studied the mass transfer coefficient for drying onion flakes in a greenhouse and OSD. The drying time of the product was 33 hours for both drying processes and the experiment was done in 3 sets with different quantities of product (i.e 300 g, 600 g, and 900 g).With the increase in the quantity of product convective mass transfer values were raised by 30-135 %.It was found that the moisture evaporation rate is high in greenhouse drying than in OSD.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.4 Onion drying under open sun, NC mode and FC mode in greenhouse

Barnwal and Tiwari ²⁵ designed and constructed a hybrid PV greenhouse solar dryer that was used to dry thompson seedless grapes. For experiment purposes, 8 kg of grapes were dried. The grapes were stored in two grades, GR-1 and GR-2. A comparison had been made between OSD and forced convection drying. Experiment resulted heat transfer coefficient for GR-1 grapes lies between 0.34-0.40 W/m[2]k for OSD and 0.26 - 0.31 W/m[2]k for greenhouse dryer, similarly for GR-2 grapes it lies between 0.46-0.97 W/m[2]k for OSD and 0.45-1.21 W/m[2]k for greenhouse, respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.5 Hybrid photovoltaic-thermal (PV/T) integrated greenhouse dryer.

Olokorand Omojowo ²⁶ compared two tent-type solar dryers. Kainji Solar Tent Dryer was an improvement of Deo's Solar Tent Dryer for fish drying. Kainji Solar Tent consists of black igneous rocks for heat generation and Deo's tent consists of PVC black polythene on the base of the tent. Kainji Solar Tent was found to be based on the quality of the product and dry faster than Deo's tent. The experiment also showed that an average of 14 flies was counted in Deo's Tent and an average of 3 flies was counted in the Kainji Solar tent.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.6 Kainji solar tent dryer

To dry osmotically dehydrated tomatoes, Janjai ²⁷ developed a greenhouse solar dryer for small-scale food companies. On a concrete floor, a parabolic-shaped frame enveloped with PV sheet and nine 50W DC fans were connected for ventilation which is powered with the help of 50W PV modules. About 1000 kg of product can be dried at once and for the continuous drying of the product 100 kW, an LPG burner was connected with a dryer to supply warm air on rainy and cloudy days. The drying time was reduced by about 2-3 days to OSD and the temperature inside the dryer varies between 35°C -65°C. The payback period of the dryer was 0.65 years.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.7 Green house solar dryer

Almuhanna ²⁸ analyzed the thermal performance of gable- even span greenhouse solar dryer for drying dates. The drying time of the dates was 5 days and the overall thermal efficiency was 57.2 %. The solar energy available was 12.335 kWh during the drying and about 7.414 kWh of energy can be used as useful heat. The Dryer reduced the relative humidity from 35.3 % to 9.6 % during the drying inside the drying chamber.

Abbildung in dieser Leseprobe nicht enthalten

Kumar et al. ²⁹ analyzed the thermal performance of passive and active type green-house type solar dryers in no-load conditions. The optimum inside temperatures in forced and natural convection dryers were 41.4°C and 40.6°C, respectively. The maximum relative humidity observed for forced and natural convection drying was 42.8 % and 62.6 %, respectively. The relative humidity was less in forced convection drying and found 31% more efficient than natural convection. In comparison of natural convection 2% more efficiency was obtained in forced convection.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.9 Greenhouse-type solar dryer at no load condition. (a) Natural

(b) Forced convection mode

Prakash and Kumar ³⁰ designed natural convection greenhouse-type solar dryer for drying jaggery. An Artificial Neural Network (ANN) was used for predicting the mass on an hourly basis. For the prediction of the jaggery mass in the ANN model, different input parameters were taken as relative humidity solar radiation, and ambient temperature. For comparison between different predicted and experimental values, a mean square method and correlation coefficient (R[2]) was used. Four neurons and a log sig transfer function with a trainlm back propagation technique were determined to be the most effective approach for drying jaggery.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.10 Greenhouse type solar dryer

Prakash, Kumar, and Laguri ³¹ analyzed the annual performance, energy, and exergy analysis of the novel greenhouse solar dryer under natural and forced convection mode. Three kinds of thermal storage i.e.barren floor, black PVC sheet, and black coated are applied on the floor of the dryer. The black PVC sheet was more conducive for drying purposes other than two ways. Tomatoes and capsicums dried more quickly using forced convection than they did using natural convection, and for the potato chips, both modes work similarly. The payback period of the natural and forced convection mode was found to be 1.11 years and 1.89 years respectively. The exergy efficiency range for NC and FC modes is 29 %-86 % and 30 %-78 % respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.11 Modified greenhouse solar dryer under natural and forced convection mode

Fudholi et al. ³² analyzed a performance of greenhouse-type solar dryer for salted catfish drying. System consisted with the ETSC, heat pipe, electric heaters, water tank and blower pumps. 200 kg of salted catfish was dried which reduced the moisture content from 73 % to 30 % (wb) in 18 hours. The exergy efficiency varied between 29 % and 82 %. The specific moisture extraction rate (SMER) and moisture extraction rate (MER) were 0.385 kg/KWh and 6.3 kg/h respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.12 Greenhouse solar dryer with heat exchanger.

Tiwari and Tiwari ³³ constructed a hybrid mixed-mode type solar dryer connected with a solar air collector which was partially covered with a number of PV thermal and evaluated performance parameters. Using the different number of PV thermal air collector, the outlet temperature and greenhouse inside temperature was increased from 29°C-122.78°C and 22.44°C- 87.42°C, respectively. For the different mass flow rates, the value of electrical energy, thermal energy, and equivalent thermal energy varies between 0.23-20, 2.63-7.70, and 3.24-8.24 kWh/day respectively. It was found that by increasing the number of PVT and mass flow rate the equivalent exergy efficiency and exergy efficiency were decreased.

Mehta et al. ³⁴ designed and developed a mixed-mode tent-type solar dryer consisting of a drying chamber and a solar collector for drying fish. For solar drying, the original moisture content of 89 % was reduced to 10 % in 18 hours, whereas OSD requires 38 hours to obtain the same moisture content. During the experiment, under no-load conditions, the maximum outlet temperature and dryer efficiency were found at 86°C and 25.42 %. The author concluded after the experiment that the Lewis model of drying is the best suited model for the current experiment.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.13 Mixed mode tent type solar dryer

Eltawil et al. ³⁵ constructed a mixed-mode tunnel solar dryer for drying potato slices. The dryer was integrated with FPC and axial DC fan for maintaining the optimum temperature inside the drying chamber. Pre-treatments were done before drying and different air flow rates (2.1, 3.12, and 4.18 m[3]/min) were used for drying. It was found that the highest value of drying efficiency as 34.29 % at the 0.0786 kg/s of air flow rate when thermal curtain was applied.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.14 An upgraded tunnel drier for potato chips driven by solar PV is set up for testing.a) Without shading the potato chips, b) with shading the potato chips

Purusothaman and Valarmathi ³⁶ analyzed the performance of greenhouse solar dryer under computational fluid dynamics simulation. For the simulation different thicknesses of the sheet (100-200 micrometer) and different mass flow rates (0.025 kg/s, 0.05 kg/s, 0.075 kg/s) of air were used. The dryer was operated in both modes active and passive; it was found that the temperature obtained in the active mode was 41 % higher than the temperature obtained in passive mode. For 0.025 kg/s mass flow rate, the maximum temperature was obtained in an active mode of drying which was 71°C.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.15 Greenhouse solar dryer under CFD simulation

Badaoui et al. ³⁷ designed a greenhouse solar dryer for drying tomato waste. It was found that the inside temperature of the dryer varies between 40-58oC and the drying time was five hours. Five different drying models were used while model 2 was best for the tomato pomace waste. The activation energy was 75.6 KJ/mol and effective diffusivity ranged between 3.2x10-[9]- 4.7x10-[10] respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.16 Greenhouse solar dryer for drying tomato waste

Chiwaula et al. ³⁸ successfully designed and considered the economic viability of a tent­type solar dryer for fish drying. A probabilistic Net Present Value (NPV) study was performed on an 850 Kg tent-type solar dryer. 58 % efficiency was obtained by a positive NPV assessment. It was observed that NPV is extremely sensitive to total cost and total income and that investing in massive solar tent dryers is financially viable.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.17 Tent type solar dryer for fish drying

Lithi et al. ³⁹ evaluated the quality of mola which dried in the open rack and tent solar dryer for 3 days. It was found that the overall quality of mola was higher in solar tent drying compared to open rack drying. Further research revealed that sun tent drying contained less moisture than open rack drying. The microbial load was higher in open rack drying.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.18 Open rack and tent solar dryer

Kushwah et al. ⁴⁰ investigated the drying performance of mushrooms using a greenhouse solar dryer coupled with an evacuated tube collector. It was found that for the day- 1 and day- 2 the maximum temperature was 51.25°C and 49.95°C while the temperature difference during the experiment was 14.35°C and 13.95°C respectively. The maximum thermal efficiency of the evacuated tube collector was 18.9 %.

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.19 Schematic view of greenhouse setup

Bekkioui ⁴¹ designed three different types of green-house dryers and semi-green-house dryers for drying wood. Three different types of materials (transparent cover, double glazing, and Plexiglas) were used for comparison and economic analysis. It was found that the use of a transparent cover was more prominent because it increased the drying time by 5 % and 10 % for greenhouse dryers and semi greenhouse dryers respectively. According to the economic study of the three experimented designs, double glazing decreased drying time, but also raised the cover's cost by more than 130 %. The drying time was reduced by 25 % and the cost increased only by 57 % when a Plexiglas cover was placed over the glass cover.

Mellalou et al. ⁴² reconstructed a dissimilar-span greenhouse solar dryer evaluated under free convection mode in no load condition. To envision the air temperature distribution inside the greenhouse drier, CFD analysis was done. The highest internal air temperatures on days 1 and 2 were 56°C and 52°C, respectively, while the lowest internal relative humidity values were 17 % and 12 %, respectively. The result of the simulation was that covering the dryer floor with asphalt was good in heating the inside air at less solar radiation was available.

Ahmad and Prakash ⁴³ designed and developed a greenhouse solar dryer that uses natural convection to dry potato chips and tomato flakes. The new drying model was proposed and compared with 6 types of mathematical models. As a result, proposed model had the maximum coefficient of determination for both products. Compared to other models the ability of curve fitting of the proposed model was best for both products.

Abbildung in dieser Leseprobe nicht enthalten

Table 2.1: The summary of literature work

Abbildung in dieser Leseprobe nicht enthalten

2.3 RESEARCH GAP

Numerous performance analyses and designs have been observed for green-house solar dryers such as even span greenhouse dryers, parabolic roof greenhouse dryers, and tent with different covering materials. This survey showed that glass cover was used to cover the greenhouse drying chamber [21-43]. The polycarbonate sheet (UV sheet) covering the greenhouse dryer has not yet been used. Utilizing polycarbonate sheet covers is a novel concept for the green-house dryer and also, mixed-mode dryer collectors are not directly connected to the tent in the above literature. After evaluating several studies, it was found that relatively few analyses for potato drying had been conducted.

Therefore, it seems appropriate to go for a performance of the mixed-mode UV tent house solar dryer is being detail investigated. by conducting experiments in actual outdoor conditions .

CHAPTER 3 PERFORMANCE EVALUATION PARAMETERS

3.1 INTRODUCTION

The effectiveness of solar dryers is influenced by a number of variables, including moisture content, drying time, dryer efficiency, etc. There are various parameters that affect the performance of the various types of solar dryers. The following discussion covers the numerous elements that are crucial for assessing the effectiveness of various solar dryers.

3.2 DRYING KINETICS OF SOLAR DRYER

Solar drying system performance investigated using many parameters such as moisture content, moisture ratio, drying rate, drying efficiency, useful heat gain, and collector efficiency may be assessed by using the following equations as given below [35] ;

3.2.1 Moisture Content

The product's initial and final masses are used to calculate the quantity of moisture eliminated. Almost all agricultural and industrial products, with very few exceptions, have moisture content. Both a percentage and a decimal ratio can be used to represent this moisture content. There are two ways to represent how much moisture is present in a product. They are wet basis (% w.b) and dry basis (% d.b) [19].

Wet moisture content:

The mass of moisture content per unit mass of the product in the wet basis method. The calculation for the moisture content on a wet basis is [13]:

Abbildung in dieser Leseprobe nicht enthalten

Dry moisture content:

The following formula is used to calculate the mass of moisture content per unit mass of dry product on a dry basis:

Abbildung in dieser Leseprobe nicht enthalten

Obtaining the percent moisture content requires multiplying the decimal moisture content by 100. Although it is convenient to represent the moisture content of any item on a dry basis, agricultural products show their moisture content on a wet basis. The difference between moisture content on a wet basis and dry basis is depicted in Figure 3.1.

Abbildung in dieser Leseprobe nicht enthalten

Fig.3.1 Variation of moisture content on dry basis with wet basis [44]

Equilibrium Moisture Content:

A material will reach an equilibrium moisture content with the surrounding air when exposed to air at a constant temperature and relative humidity. Water in the product has a vapour pressure equal to the atmospheric partial pressure. The desorption of moisture from the product is currently equal to the air's environmental air's absorption of moisture. It denotes that there is no net moisture exchange between the substance and the air. The solids are said to either gain or lose moisture to the surrounding air, to put it another way. Equilibrium moisture content is the term used for this moisture level (EMC). By lowering the relative humidity of the surrounding air and by removing extra free moisture, the EMC can be lowered. With an increase in temperature and a certain relative humidity, a product's equilibrium moisture content falls. ⁴⁴.

3.2.2 Moisture Ratio

The moisture ratio is the ratio of the product's initial moisture content to its moisture content at time t. The following is the relationship between the moisture ratio:

Abbildung in dieser Leseprobe nicht enthalten

3.2.3 Drying Rate

Both the characteristics of the air and the characteristics of the wet product affect how quickly a thing dries. The amount of moisture that evaporates over time is referred to as the drying rate. It measures how quickly moisture from plants or vegetables evaporates into the atmosphere. It is determined by the moisture content at any subsequent time interval in relation to time.

Abbildung in dieser Leseprobe nicht enthalten

3.2.4 Drying Efficiency

Drying efficiency is defined as the ratio of energy or heat given for the evaporation of moisture from the sample to the total energy acquired during the experimental method. It demonstrates how efficiently the energy used to dry the food product is used. Both active and passive convection can be examined for drying effectiveness.

Abbildung in dieser Leseprobe nicht enthalten

3.2.5 Drying Period

It is the amount of time that the food product is dried within the dryer. It is the most crucial factor taken into account when evaluating dryers. From the time the food product is retained in the dryer until it dries to a specific moisture content level, the drying time is estimated. Estimates of the drying time are given in hours or days.

3.2.6 Useful Heat Gain

Amount of heat gain by the supplied inlet air.

The air's intake and output temperatures are used to compute the amount of heat that the air gains. The following equations provide the rate of heat transfer inside a solar air heat collector:

Abbildung in dieser Leseprobe nicht enthalten

3.2.7 Collector Efficiency

It is defined as the ratio of useful heat gain by the air through the absorber to the input energy of the collector.

The conversion of solar energy into useable heat gain and loss is a measure of collector efficiency. Thermal analysis is used to calculate the heat gain and loss. In this analysis, the top flow (between the absorber plate and the glass cover) and bottom flow (between the absorber plate and the bottom insulation) heat gains and losses are computed.⁴⁵. The relation for collector efficiency is as follows:

Abbildung in dieser Leseprobe nicht enthalten

3.3 GENERAL PARAMETERS CONSIDERD FOR PERFORMANCE EVALUATION OF SOLAR DRYERS

Different general characteristics that are taken into account for solar dryer performance evaluation were given by Leon et al. in 2002. The following are the frequently measured variables ⁴⁶:

- Dryer's physical characteristics
- Type, size, and shape of dryer,
- The dryer's drying capacity and loading density,
- Size and quantity of trays (as per dryer).

- Heat transfer characteristics
- Drying rate,
- Air temperature for drying,
- Flow of air,
- Dryer efficiency.

- The dried product's quality
- Sensory quality (taste, color, aroma, etc.),
- Nutritional characteristics,
- Rehydration potential.

- Payback time and dryer price

CHAPTER 4 EXPERIMENTAL SET-UP AND DATA COLLECTION

4.1 INTRODUCTION

In this chapter, the details of experimental setup have been discussed and also the diagrammatic and photographic view of experimental setup of solar dryer has been given. All elements of the set-up and measuring instruments are described along with experimental procedure and data collection. Data sample and parameters used are also presented through appropriate tables.

4.2 EXPERIMENTAL SET-UP DESCRIPTION

The mixed-mode UV house solar dryer is shown in fig.4.1 and fig.4.2 and the specification of the elements are shown in Table 4.1. The frame of the mixed mode tent type solar dryer is made of wood and fully covered by an ultraviolet sheet (polycarbonate sheet), which makes the structure light weight and portable, and maintains the higher temperature range of the tent. The transmissivity of the polycarbonate sheet is 0.80-0.85. A hole of 15 cm is provided on top of the back wall of the tent, which is used for moisture outlet. At the inlet of the tent, a duct is placed through which the heated air coming from it, is sent inside the dryer and this heated air is used to increase the temperature of the trays in which the product (which is to be dried) is placed. Two equal-sized tray dimensions 0.57 m x 1.11 m, are placed on the inner side of the tent at a distance of 18 cm. The tray is made up of a wooden frame and meshed with stainless steel wire, which dimension is 1.10 m x 0.57 m. The side wall of the tent is used for opening purposes to the product can be placed inner side the tent and dried product carry out from it. The measurement of the solar duct is 1.50 m x 0.64 m x0.20 m. The structure of the passive type duct is prepared with plywood of 18 mm thick. The entry side of this duct is divided into two parts. The lower part is filled with glass wool (Thermal conductivity 0.03 W/m-k) and packed with the help of wood avoiding the air leakage. The upper part of this duct is open, which allows air to pass through it. A 1.2 mm galvanized Iron (G.I.) sheet is placed on the upper side of the duct, which is painted in black color and increases the temperature of the inlet air, and this sheet is covered by the glass (5 mm thick). The gap between the black painted absorber plate and glass cover is 6 cm. The duct is attached to the tent with an inclination of 15 degrees from the horizontal surface.

Abbildung in dieser Leseprobe nicht enthalten

Fig.4.1 Schematic design of a mixed-mode UV tent house solar dryer.

Abbildung in dieser Leseprobe nicht enthalten

Fig.4.2 (a), (b) and, (c) represents the photographic view of a Mixed-mode UV tent house solar dryer.

Table 4.1: Element and specification of mixed-mode UV house solar dryer

Abbildung in dieser Leseprobe nicht enthalten

4.3 MATERIAL

In the whole world, potatoes are the fourth major vegetable for nutrients. India ranked 2nd position for the production of potatoes all over the world ⁴⁷. The scientific name of potato is Solanumtuberosum which is also known as yam, murphy, earth apple, tuber, tater, and aloo. Potato is rich in carbs, fiber, and nutrients like vitamin C, vitamin B6, potassium, phosphorus, magnesium, manganese, niacin, and folate. It helps to improve digestive health and keep blood sugar under control.

4.4 MEASUREMENT OF OPERATING PARAMERTERS

The temperature at different parts of the dryer was measured through a digital thermocouple with an accuracy of ±1°C. A hygrometer, also called a humidity meter could measure the relative humidity with an accuracy of ±1%. An anemometer was used to measure the speed of the wind with an accuracy of ±0.5°C and ±0.5 m/s respectively. The solar power meter (accuracy of ±10 W/m ) measured solar intensity which strikes on the surface of the collector and dryer. An electronic weighing machine (SF-400A model) with an accuracy of ±1g was used to measure the weight of potato slices. The specifications of all the instruments used in the experiments are listed in Table 4.2.

Table 4.2: Specification of Instruments

Abbildung in dieser Leseprobe nicht enthalten

4.5 EXPERIMENTAL PROCEDURE AND DATA COLLECTION

Table 4.3 shows the location and orientation details of the experiments. The product (potato) was purchased from the local market in Bhilai (Chhattisgarh). It is peeled and then cleaned with water, after cleaning these potatoes have been sliced to equal thickness i.e 2.5 mm and 5.0 mm through a vegetable slicer for 1st and 2nd experiments respectively. The sliced potatoes were boiled with water (which contained 0.5 % of sodium chloride) and potash alum [K 2 SO 4 (Al 2 SO 4) 3.24H 2 O] solution for 10 min. 2 kg of potato slices were weighed using an electronic weighing machine and put on the two trays in equal quantities and placed inside the drying chamber. During the experiment, it should be careful that the side wall of the tent which is provided for the opening purpose to the product placed inner side of the drying chamber should be closed properly. A similar quantity of potato slices was kept for both the experiments (1stand 2nd) inside the dryer and for the OSD process also. The incident rays of the sun strike the collector the temperature of the sheet is increased gradually as the glass cover traps heat, due to this phenomenon the temperature of the sheet increases. This heat is utilized to increase the inlet air temperature. When inlet air passes through the duct, its temperature increases. The heated air is sent to the drying chamber, which helps in raising the temperature of the trays on which the product is placed for drying. In the same way, the tent which comprises of polycarbonate sheet also takes up heat from the sun. This increased temperature provides for heating of the tent in both direct type and indirect type i.e., mixed-mode type, which helps for drying the products in less time. Before the experiment, the setup was run for 1 hour to reach equilibrium (steady state) conditions in the dryer. The experiments were performed from 09:00 AM to 05:00 PM, for 8 hours every day until the weight of the dried sample turns into constant. At the end of 8 hours of drying the dried potato slices (both tent dryer and OSD) were stored in airtight packets. Different parameters were measured during the experiment i.e., Relative humidity (RH), outlet and inlet temperature of solar collector, tray temperature, absorber plate and glass cover temperature, solar intensity (SI), wind speed (WS), and ambient temperature (AT). All parameters were taken at half-hour intervals, potato slices were weighted and mass was recorded every couple of hours. This mass has been used for the evaluation of various drying kinetics.

Table 4.3 Location and orientation details of the experiments

Abbildung in dieser Leseprobe nicht enthalten

Experimental data were taken in outdoor condition on the roof of building on clear sky days between 09.00 to 17.00 Hours during the months of May-June, 2022. The data were collected at interval of 30 minutes. The detailed of data sample collection has been shown in Table 4.4. The parameters measured during experimentation were:

(a) Wind speed
(b) Ambient temperature
(c) Inlet air temperature.
(d) Outlet air temperature.
(e) Temperature of glass cover (T GC )
(f) Temperature of absorber plate (T AP )
(g) Temperature of trays
(h) Solar intensity
(i) Inlet humidity
(j) Outlet humidity

Table 4.4: A sample data, collected on 28th May, 2022 (for thickness = 2.5mm)

Abbildung in dieser Leseprobe nicht enthalten

4.6 UNCERTAINTY ANALYSIS

Uncertainty analysis is important to point out the inaccuracy in the estimated quantities out of the measured quantities. The aim of uncertainty analysis is to evaluate the fluctuation of the output caused by the flexibility of the input. Observation, wear and tear, environmental causes, calibration, the accuracy of the instruments, legibility, and human errors are parameters, which impact the uncertainty measurement. The dependent parameters are, solar radiation, wind speed, weight of the product, humidity of the air, and temperature, measured during the experiment. The uncertainties present in data are shown in the Table 4.5.

Table 4.5: Uncertainty analysis

Abbildung in dieser Leseprobe nicht enthalten

CHAPTER 5 RESULT AND DISCUSSION

5.1 INTRODUCTION

The mixed mode UV tent house solar dryer was installed at Chhattisgarh Swami Vivekanand Technical University, Bhilai (Chhattisgarh), India. The experiment was conducted in the month of June 2022. The purpose of the experiment was to investigate the different drying parameters of dried potatoes of varying thicknesses (2.5 mm and 5 mm). In this chapter deals with the result of performance of the natural convection drying process differentiates with OSD and also different thicknesses of potato slices in mixed mode ultraviolet tent house solar dryer. The metrological parameters, operating parameters and evaluating parameters have been presented through plots and discussed by using graphical representations.

5.2 METEOROLOGICAL PARAMETERS PERFORMANCE RESULT

Solar intensity (SI) is measured with the help of a solar power meter (TM-207 model). The SI value is relatively low in the morning and gradually increases until 12:00 PM, when it reaches a maximum of 993 W/m[2]. The SI value subsequently decreases until the last value recorded throughout the experiment that is 192 W/m[2], which was taken at 05:00 PM for the 2.5 mm thick slices of potato. For 5 mm thickness, the maximum and minimum SI values were 992 W/m[2] and 178 W/m[2] at 12:00 PM and 05:00 PM respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.1 (b) Variation of wind speed and solar intensity with time at day-2 of drying day.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.1 (d) Variation of wind speed and solar intensity with time at day-2 of drying day.

Abbildung in dieser Leseprobe nicht enthalten

A similar trend was observed during the measurement of AT and its maximum and minimum values are 44.2°C (at 01:00 PM) and 36.3°C (at 09:00 AM) respectively. Fig.5.1 (a) and fig.5.1 (b) for 2.5 mm thickness and fig.5.1 (c) and fig.5.1 (d) for 5.0 mm thickness show the variation of SI and WS with respect to time. The fluctuating nature of WS is observed during the whole period of the experiment and the overall maximum and minimum values are 3.8 m/s and 0.8 m/s respectively. Further, it has been determined that the range of relative humidity lies between 15 %-26 % during the drying time.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.2 (a) Variation of relative humidity and ambient temperature with time at day-1 of drying day.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.2 (b) Variation of relative humidity and ambient temperature with time at day-2 of drying day.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.2 (d) Variation of relative humidity and ambient temperature with time at day-2 of drying day.

5.3 OPERATING PARAMETERS PERFORMANCE RESULT

The solar collector is the main component of the solar dryer. The variation of the temperature of glass cover and absorber plate with respect to time, was measured using a thermocouple (AP -1511A001), is shown in Fig.5.4 (a) and fig.5.3 (a) for 2.5 mm thickness potato slice and fig.5.4 (b) and fig.5.3 (b) for 5.0 mm thickness potato slice, respectively. The absorber plate reached its highest temperature of 84.1°C at 01:00 PM, which corresponded to a sun intensity of 993 W/m[2], and reached its lowest temperature of 47.8°C at 05:00 PM, which was recorded for 2.5 mm thick slices of potato. Whereas the maximum and minimum temperatures for potato slices with a thickness of 5.0 mm were recorded as 94.2°C at 12:30 PM and 35.3°C at 5:00 PM, respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.3 (a) Variation of absorber plate temperature with time for 2.5 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

The maximum temperature of glass cover was recorded as 60.7°C at 01:00 PM corresponding to a solar intensity of 993 W/m[2] and 38.2°C at 09:00 PM was the minimum temperature of glass cover for 2.5 mm thick slice of potato. For 5.0 mm thickness the maximum and minimum temperature values of glass cover was recorded as 64.9°C at 12:30 PM and 32.9°C at 05:00 PM respectively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.4 (a) Variation of glass cover temperature with time for 2.5 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.4 (b) Variation of glass cover temperature with time for 5.0 mm thick potato slice.

During the experiment, it was found that the inlet temperature of the solar collector is similar to the atmospheric temperature. The air flows into the collector, which absorbs heat from the absorber plate and increases the air temperature. The maximum and minimum inlet temperature of the collector was recorded as 44.6°C (at 01:00 PM) and 36.7°C (at 09:00 AM)respectively, for 2.5 mm thick potato slices. For 5.0 mm thickness, the inlet temperature of the collector was 45.0°C at 12:30 PM,which is the maximum value and the minimum value of 38.6°C was recorded at 05:00 PM.Similarly, the minimum and maximum outlet temperatures of the collector for 2.5 mm thickness and 5.0 mm thickness were obtained at 47.2°C (at 01:00 PM) and 38.2°C (at 09:00 AM) and 48.8°C (at 12:30 PM) and 40.8°C (at 05:00 AM) respectively. Fig.5.5 (a), for 2.5 mm thickness and fig.5.5 (b), for 5.0 mm thickness, shows the variation of collector outlet temperature with respect to time .

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.5 (a) Collector outlet temperature variation of solar dryer with time for 2.5 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.5 (b) Collector outlet temperature variation of solar dryer with time for 5.0 mm thick potato slice.

The useful heat gain and collector efficiency has beencalculated by using equations (6) and (7). The maximum value of useful heat gain is 222.3 W for both 2.5 mm and 5.0 mm thick potato slices. The collectorefficiency for a 2.5 mm thick potato slice varies from 6.3 % to 33.9 % and 10.0 % to 63.2 % for a 5.0 mm thickness. For 2.5 mm and 5.0 mm thickness the optimum value of collector efficiency isattained as 33.9 % and 63.2 % respectively. It has beenobserved that the highest value of collector efficiency is recorded around 05:00 PM ( less sunshine hour) because sensible heat stored in the collector is used.

Fig.5.6 (a) and fig.5.6 (b) represents the variation of outlet temperature with respect to time.The maximum and minimum outlet temperatures of the dryer are 52.3°C and 39.4°C for 2.5 mm thickness and 59.0°C and 33.7°C for 5.0 mm thick potato slices respectively. The drying chamber temperature is more than thenearby temperature of the solar dryer.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.6 (a) Variation of outlet temperature of solar dryer with time for 2.5 mm thick potato slices.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.6 (b) Variation of outlet temperature of solar dryer with time for 5.0 mm thick potato slice.

The temperature is measured with the help of a thermocouple. Fig.5.7 (a) and fig.5.7 (b) for 2.5 mm thickness and Fig.5.7 (c), fig.5.7 (d), and fig.5.7 (e) for 5.0 mm thickness, shows the variation in tray temperature on the inner side of the tent (i.e drying chamber) after the loading of potato slices. The temperature was recorded 34.3°C at 09:00 AM for tray-1, which is the minimum temperature among the trays. The potato slices in tray-1 take up thermal energy from hot air and which then flows to tray-2. The tray-2 temperature was found 54.2°C at 01:00 PM, which is the maximum temperature of the trays for 2.5 mm thickness of potato slices. Whereas for a 5.0 mm thick slice of potato the minimum and maximum tray temperature was 33.6°C and 59.7°C for tray-1 (lower tray) and tray-2 (upper tray) respectively. At the beginning of drying process, the trays temperature is less due to the less amount of solar intensity; however, the tray's temperature rises as the solar intensity increases.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.7 (a) Variation of tray temperature with time at day-1 of drying day for 2.5 mm thick potato

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.7 (b) Variation of tray temperature with time at day-2 of drying day for 2.5 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.7 (c) Variation of tray temperature with time at day-1 of drying day for 5.0 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.7 (d) Variation of tray temperature with time at day-2 of drying day for 5.0 mm thick potato slice.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.7 (e) Variation of tray temperature with time at day-3 of drying day for 5.0 mm thick potato slice.

5.4 EVALUATING PARAMETERS PERFORMANCE RESULT

5.4.1 MOISTURE CONTENT

Moisture content (MC) is the word used to describe how much moisture is contained in a sample or product. Fig.5.8 (a) represents the variation in MC for the potato slices at every 2 hours interval. The maximum obtained value of MC was 85.25% (wet basis) at the starting of experiment, during the drying period its value started decreasing continuously. The minimum value of MC reaches 14.75 % for 2.5 mm thick potato slices inside the dryer. For OSD of 2.5 mm thick sliced potato the maximum and minimum value of MC was 85.10 % (wet basis) and 14.90 % (wet basis) respectively. It was also noticed that the 6 hours extra time was taken for reaching its final MC value during OSD. When the thickness of potato slices was increased to 5mm, the initial and final values of MC were recorded as 81.00 % (wet basis) and 19.00 % (wet basis) as shown in fig.5.8 (b) when a dryer was used, whereas for the same thickness when the potato slices were exposed to the sun directly the initial MC was 80.80 % (wet basis) and 19.20 % (wet basis) with 6 hours of extra time. Fig.5.9 (a) and fig.5.9 (b) shows the potato slices before and after drying correlatively.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.8 (a) Variation in moisture content for the potato slices at every 2 hour interval.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.8 (b) Variation in moisture content for the potato slices at every 2 hours interval.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.9 Photographic view of the potato slices (a) before drying (b) after drying.

5.4.2 MOISTURE RATIO

The ratio of moisture availability at any given time relative to the initial moisture content is known as the moisture ratio (MR). From fig.5.10 (a) and fig.5.10 (b) it can be observed that the MR shows its falling rate during the whole experimental period. At the start of the experiment, the evaporation of moisture from potato slices is faster. Significant reduction of moisture evaporation is seen with respect to time when sufficient moisture was available in the product, but after some time when the moisture inside the product was reduced, the MR was also decreased. For 2 kg of potato slices of 2.5 mm thickness, the MR varies from 0.475 to 0.001 at 12 hours of drying inside the dryer and the variation of MR took from 0.739 to 0.001 during OSD at 18 hours of drying. The same trend of the graph is seen for 5 mm thick sliced potato during tent drying, the MR varies from 0.650 to 0.003 at 14 hours of drying whereas for the same thickness the variation of MR is from 0.679 to 0.002 at 22 hours of drying.

Fig.5.10 (a) Variation in moisture ratio for the 2.5 thick potato slices at every 2 hours interval.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.10 (b) Variation in moisture ratio for the 5.0 thick potato slices at every 2 hours interval.

5.4.3 DRYING RATE

Drying rate (DR) indicates the frequency of moisture evaporation. Fig.5.11 (a) for 2.5 mm thickness and fig.5.11 (b) for 5.0 mm thickness shows the variation in drying rate at every 2 hours interval. At the initial stages of drying, the rate of falling is observed due to the higher moisture availability in the product, and higher values of drying rate are seen. The moisture coming out to the atmosphere from the upper surfaces of the potato slices is compensated by the MC within the slices; hence, the moisture's thin layer is generally available at the outer surface of the product. During the drying period, the reduction in DR is observed in the dryer and OSD as well. This is due to less moisture availability in the product the maximum value of DR for a 2.5 mm thick potato slice is 0.518 kg/h and for 5 mm thickness, 0.407 kg/h is evaluated. For OSD the lower values of DRs are recorded during the initial stage of drying compared to the dryer, but after some time the DR values are higher comparatively. For the same thick slices, this is due to the higher moisture availability in the product compare to those slices put inside the dryer. The maximum DR during OSD for a 2.5 mm thick potato slice is 0.333 kg/h and for 5mm thickness, 0.390 kg/h is evaluated.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.11 (a) Variation of drying rate for the 2.5 thick potato slices at every 2 hours interval under UV tent house solar dryer and OSD conditions.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.11 (b) Variation of drying rate for the 5.0 thick potato slices at every 2 hours interval under UV house solar dryer and OSD conditions.

5.4.4 DRYING EFFICIENCY

Drying efficiency is the ratio of energy utilization during the heating of the sample for moisture removal to the overall energy consumption during experiment.The drying efficiency has been calculated using equation number (5). The maximum and minimum drying efficiency for both 2.5 mm and 5.0 mm thick potato slices are shown in table 5.1.

Table 5.1: Drying Efficiency

Abbildung in dieser Leseprobe nicht enthalten

5.5 QUALITY ANALYSIS OF PRODUCT

The product's color is an important characteristics and an indicator of the product's inherent high qualities. The Color of the dried product's color potato slices are an essential quality and the most preferred color by the consumer are golden brown fried potato chips. Photographic view of the dried slices of potato is shown in fig.5.12. It is clearly visible that the slices which are directly exposed to the open sun have very poor color quality as compared to those slices which are dried in the experimented dryer (which color quality is superior). It has also been observed that the dryer is useful for keeping the slices free of dust and dirt, which is not possible during OSD, so it is recommended that the product should be dried inside the dryer to achieve better product quality.

Abbildung in dieser Leseprobe nicht enthalten

Fig.5.12 Color differences of potato slices after drying.

CHAPTER 6 CONCLUSIONS AND FUTURE SCOPE

6.1 CONCLUSIONS

A unique designed mixed mode UV tent house solar dryer has been installed for drying potato slices and experimentally evaluated. The experiments were performed from 09:00 AM to 05:00 PM in May-June 2022 and resulted more efficiency compare to OSD. It was noticed that the dried potato slices were free from environmental pollution. The ambient conditions such as solar intensity, atmospheric temperature, wind speed and relative humidity of air ranges between 134­993 W/m[2], 36.2-44.9 °C, 0.8-4.9 m/s, 12-26 % respectively. The sample's weight is calculated at every 2 hours interval and all operating and metrological parameters have been measured in every half an hour. The drying kinetics of potato slices were evaluated and following conclusion have been drawn:

a) The maximum and minimum values of recorded temperature were 59.7°C and 34.2°C for the upper tray whereas the lower tray temperature varies from 33.6 to 57.1°C.

b) The final moisture content of 14.75 % is found in tent house drying and for OSD 14.90 % of moisture content is obtained with 6 hours of extra time for 2.5 mm thickness of potato slices. The same extra hour is taken for 5.0 mm thick slices to reach its equilibrium state in OSD as compared to the tent house drying.

c) The highest value of drying rate is achieved for sliced potatoes with a thickness of 2.5 mm during tent house drying, followed by sliced potatoes with a thickness of 5.0 mm sliced potato dried in tent, and the DR values are least for OSD during end stages of the experiments.

d) The drying efficiency of potato slices with a thickness of 2.5 mm was 18.82 % greater than that of potato slices with a thickness of 5.0 mm.

e) The MR varies from 0.475 to 0.001 for 2.5 mm thick slices and 0.650 to 0.003 for 5.0 mm thickness in tent drying.

f) The significant reduction in drying time is observed with a superior quality product in tent house SD compared to OSD.

6.2 SCOPE FOR FUTURE WORK

The following work can be carried out in future studies:

- Design of the absorber plate can also be change for the better performance.
- Higher thermal conductivity materials for the absorber plate can be used for improving the performances of solar dryer.
- CFD analysis can be implemented for such types of solar dryers.
- Phase change materials can be used to operate the solar dryer after sunset.
- Extended surfaces (fins) can be used to increase the heat transfer rate.

REFERENCES

[...]

---

¹ . S.P. Sukhatme, J.K. Nayak, Solar Energy- Principles of Thermal Collection and Storage, Tata Mc Graw Hill, New Delhi, 1996.

² . Khan, B.H., 2006. Non-conventional energy resources. Tata McGraw-Hill Education.

³ . Jurasz, J.; Canales, F.A.; Kies, A.; Guezgouz, M.; Beluco, A. A review on the complementarity of renewable energy sources: Concept, metrics, application and future research directions. Sol. Energy 2020, 195, 703-724.

⁴ . European Commission. Energy for the Future: RES White Paper for a Community Strategy and Action Plan; Office for Official Publications of the European Communities; European Commission: Luxembourg, 1997; Volume 97, p. 599.

⁵ . Deng, Z.; Cui, S.; Kou, K.; Liang, D.; Shi, X.; Liu, J. Dopant-Free _-Conjugated Hole Transport Materials for Highly Stable and Efficient Perovskite Solar Cells. Front. Chem. 2021, 9, 664504.

⁶ . Li, R.; Liu, M.; Matta, S.K.; Hiltunen, A.; Deng, Z.; Wang, C.; Dai, Z.; Russo, S.P.; Vivo, P.; Zhang, H. Sulfonated Dopant- Free Hole-Transport Material Promotes Interfacial Charge Transfer Dynamics for Highly Stable Perovskite Solar Cells. Adv. Sustain. Syst. 2021, 2100244. Available online: https://onlinelibrary.wiley.com/doi/abs/10.1002/adsu.202100244 (accessed on 23 November 2021).

⁷ . Iqbal, W.; Yumei, H.; Abbas, Q.; Hafeez, M.; Mohsin, M.; Fatima, A.; Jamali, M.A.; Jamali, M. ; Siyal, A.; Sohail, N. Assessment of Wind Energy Potential for the Production of Renewable Hydrogen in Sindh Province of Pakistan. Processes 2019, 7, 196.

⁸ . Hadjiat, M.M.; Mraoui, A.; Ouali, S.; Kuzgunkaya, E.H.; Salhi, K.; Ait Ouali, A.; Benaouda, N. ; Imessad, K. Assessment of geothermal energy use with thermoelectric generator for hydrogen production. Int. J. Hydrog. Energy 2021, 46, 37545-37555.

⁹ . Duffie, J.A., Beckman, W.A. (2006). Solar Engineering of Thermal Processes, third ed. Wiley Interscience, New York.

¹⁰ . Rai, G. D., (2004). Non-Conventional and Energy sources, Khanna Publishers, India.

¹¹ . Garg.H.P, Prakash.J, “Solar energy fundamentals and applications”, Tata McGraw Hill publishing Co. Ltd, 2006.

¹² . Ghritlahre, H.K., Ph.D. Thesis (2019). Performance evaluation of solar air heating systems using artificial neural network. National Institute of Technology Jamshedpur Jharkhand, India.

¹³ . Belessiotis, V. and Delyannis, E., 2011. Solar drying. Solar energy, 85(8), pp.1665-1691.

¹⁴ . Atul Sharma, C.R. Chen, Nguyen Vu Lan, “Solar-energy drying systems: A review”, Renewable and Sustainable Energy Reviews 13 (2009)1185-1210

¹⁵ . Garg.H.P, Prakash.J, “Solar energy fundamentals and applications”, Tata McGraw Hill publishing Co. Ltd, 2006.

¹⁶ . Teja, M.S.K., Rao, K.N. and Pochont, N.R., 2018. Design, development and experimental evaluation of solar dryer. Int. J. Mech. Prod. Eng. Res. Dev, 8(3), pp.949-968.

¹⁷ . Bolaji, B.O. and Olalusi, A.P., 2008. Performance evaluation of a mixed-mode solar dryer.

¹⁸ . Chavan, A., Vitankar, V., Mujumdar, A. and Thorat, B., 2021. Natural convection and direct type (NCDT) solar dryers: a review. Drying Technology, 39(13), pp.1969- 1990.https://doi.org/10.1080/07373937.2020.1753065

¹⁹ . Prakash, Om; Kumar, Anil (2017). [Green Energy and Technology] Solar Drying Technology https://doi.org/10.1007/978-981-10-3833-4

²⁰ . Chaudhari, A.D. and Salve, S.P., 2014. A review of solar dryer technologies. International Journal of Research in Advent Technology, 2(2), pp.218-232.

²¹ . Abdullah, K. and Mursalim, 1997. Drying of vanilla pods using a greenhouse effect solar dryer. Drying technology, 15(2), pp.685-698. https://doi.org/10.1080/07373939708917254

²² . Abdullah, K., Wulandani, D., Nelwan, L.O. and Manalu, L.P., 2001. Recent development of GHE solar drying in Indonesia. Drying Technology, 19(2), pp.245- 256.https://doi.org/10.1081/DRT-100102901

²³ . Jain, D. and Tiwari, G.N., 2004. Effect of greenhouse on crop drying under natural and forced convection II. Thermal modeling and experimental validation. Energy Conversion and management, 45(17), pp.2777-2793. https://doi.org/10.1016/j.enconman.2003.12.011

²⁴ . Kumar, A. and Tiwari, G.N., 2007. Effect of mass on convective mass transfer coefficient during open sun and greenhouse drying of onion flakes. Journal of food engineering, 79(4), pp.1337-1350. https://doi.org/10.1016/j.jfoodeng.2006.04.026

²⁵ . Barnwal, P. and Tiwari, G.N., 2008. Grape drying by using hybrid photovoltaic-thermal (PV/T) greenhouse dryer: an experimental study. Solar energy, 82(12), pp.1131-1144. https://doi.org/10.1016/j.solener.2008.05.012

²⁶ . Olokor, J.O. and Omojowo, F.S., 2009. Adaptation and improvement of a simple solar tent dryer to enhance fish drying. Nature and Science, 7(10), pp.18-24.

²⁷ . Janjai, S., 2012. A greenhouse type solar dryer for small-scale dried food industries: development and dissemination. International journal of energy and environment, 3(3), pp.383­398.

²⁸ . Almuhanna, E.A., 2012. Utilization of a solar greenhouse as a solar dryer for drying dates under the climatic conditions of the eastern province of saudiarabia: Part I: Thermal performance analysis of a solar dryer. Journal of Agricultural Science, 4(3), p.237. http://dx.doi.org/10.5539/jas.v4n3p237

²⁹ . Anil, K., Om, P., Ajay, K. and Abhishek, T., 2013. Experimental analysis of greenhouse dryer in no-load conditions. Journal of Environmental Research and Development, 7(4), p.1399.

³⁰ . Prakash, O. and Kumar, A., 2014. Application of artificial neural network for the prediction of jaggery mass during drying inside the natural convection greenhouse dryer. International Journal of Ambient Energy, 35(4), pp.186-192. https://doi.org/10.1080/01430750.2013.793455

³¹ . Prakash, O., Kumar, A. and Laguri, V., 2016. Performance of modified greenhouse dryer with thermal energy storage. Energy reports, 2, pp.155-162. https://doi.org/10.1016/j.egyr.2016.06.003

³² . Fudholi, A., Mat, S., Basri, D.F., Ruslan, M.H. and Sopian, K., 2016. Performances analysis of greenhouse solar dryer with heat exchanger. Contemporary Engineering Sciences, 9(3), pp.135­144. http://dx.doi.org/10.12988/ces.2016.512322

³³ . Tiwari, S. and Tiwari, G.N., 2017. Energy and exergy analysis of a mixed-mode greenhouse­ type solar dryer, integrated with partially covered N-PVT air collector. Energy, 128, pp.183­195. https://doi.org/10.1016/j.energy.2017.04.022

³⁴ . Mehta, P., Samaddar, S., Patel, P., Markam, B. and Maiti, S., 2018. Design and performance analysis of a mixed mode tent-type solar dryer for fish-drying in coastal areas. Solar Energy, 170, pp.671-681. https://doi.org/10.1016Zj.solener.2018.05.095

³⁵ . Eltawil, M.A., Azam, M.M. and Alghannam, A.O., 2018. Solar PV powered mixed-mode tunnel dryer for drying potato chips. Renewable Energy, 116, pp.594-605. https://doi.org/10.1016/j.renene.2017.10.007

³⁶ . Purusothaman, M. and Valarmathi, T.N., 2019. Computational fluid dynamics analysis of greenhouse solar dryer. International Journal of Ambient Energy, 40(8), pp.894-900. https://doi.org/10.1080/01430750.2018.1437567

³⁷ . Badaoui, O., Hanini, S., Djebli, A., Haddad, B. and Benhamou, A., 2019. Experimental and modelling study of tomato pomace waste drying in a new solar greenhouse: Evaluation of new drying models. Renewable energy, 133, pp.144-155. https://doi.org/10.1016/_j.renene.2018.10.02

³⁸ . Chiwaula, L.S., Kawiya, C. and Kambewa, P.S., 2020. Evaluating economic viability of large fish solar tent dryers. Agricultural Research, 9(2), pp.270-276 https://doi.org/10.1007/s40003- 019-00416-8

³⁹ . Lithi, U.J., Surovi, S., Faridullah, M. and Roy, K.C., 2020. Effects of drying technique on the quality of Mola (Amblypharyngodonmola) dried by solar tent dryer and open sun rack dryer. Research in Agriculture Livestock and Fisheries, 7(1), pp. 121-128. https://doi.org/10.3329/ralf.v7i1.46840

⁴⁰ . Kushwah, A., Kumar, A., Pal, A. and Gaur, M.K., 2021. Experimental analysis and thermal performance of evacuated tube solar collector assisted solar dryer. Materials Today: Proceedings, 47, pp.5846-5851. https://doi.org/10.1016/j.matpr.2021.04.243

⁴¹ . Bekkioui, N., 2021. Performance comparison and economic analysis of three solar dryer designs for wood using a numerical simulation. Renewable Energy, 164, pp.815- 823.https://doi.org/10.1016/j.renene.2020.09.126

⁴² . Mellalou, A., Riad, W., Hnawi, S.K., Tchenka, A., Bacaoui, A. and Outzourhit, A., 2021. Experimental and CFD investigation of a modified uneven-span greenhouse solar dryer in no­load conditions under natural convection mode. International Journal of Photoenergy, 2021.https://doi.org/10.1155/2021/9918166

⁴³ . Ahmad, A. and Prakash, O., 2021. Development of mathematical model for drying of crops under passive greenhouse solar dryer. Materials Today: Proceedings, 47, pp.6227-6230. https://doi.org/10.1016/j.matpr.2021.05.180

⁴⁴ . Ekechukwu OV (1999) Review of solar-energy drying systems I: an overview of drying principles and theory. Energy Convers Manag 40:593-613

⁴⁵ . Hegde VN, Hosur VS, Rathod SK, Harsoor PA, Narayana KB (2015) Design, fabrication and performance evaluation of solar dryer for banana. Energy, Sustain Soc. https://doi.org/10.1186/s13705-015-0052-x

⁴⁶ . Leon MA, Kumar S, Bhattacharya SC (2002) A comprehensive procedure for performance evaluation of solar food dryers. Renew Sustain Energy Rev 6(4):367- 393.https://doi.org/10.1016/S1364-0321(02)00005-9

⁴⁷ . Aghbashlo, M., Kianmehr, M.H. and Arabhosseini, A., 2009. Modeling of thin-layer drying of potato slices in length of continuous band dryer. Energy conversion and management, 50(5), pp.1348-1355. https://doi.org/10.1016/j.enconman.2009.01.004