This work is concerned with the effects of fouling on different fin tubes and exchangers cooled by air.
During operation of heat exchangers layers of deposits or corrosive products may be formed and accumulated on heat exchanger surfaces over time. This leads to additional heat transfer resistance and constriction of fluid flow area. In consequence, the exchanged heat duty is badly affected. The loss of heat duty is extreme if local heat transfer coefficients are high at clean conditions. However, maintaining cooling effectiveness is paramount in most applications. As a remedy, surfaces must be regularly cleaned.
Fin tubes are core elements in air cooled exchangers or condensers to transfer heat. Fin tube exchangers are characterized by a multitude of circular, elliptical or channel type core tubes with air-side finning. Generally, the process medium flows on the tube internal side with air as coolant on the external fin side. The report deals with air cooled heat exchangers and condensers under forced or natural draft in dry cooling applications with the focus on the effect of fin side fouling. Water spray injection into the cooling air flow is excluded.
Consequently, the effect of fin side fouling layers will be assessed as well as the consequence for air flowrate and heat duty at different convection types. Special attention is given to the effect of fouling on the performance of dry air cooled condensers. Also, differences of forced, induced or natural draft dry cooling applications will be covered.
Inhaltsverzeichnis (Table of Contents)
- Abstract
- 1. Introduction
- 2. General Fin Tube Geometry
- 3. Heat Balance
- 4. Pumping Power
- 4.1 Bundle Pressure Drop
- 4.2 Natural Draft Pressure Gain
- 4.3 Air Inlet Pressure Drop
- 4.4 Air Outlet Pressure Drop
- 5. Determination of Air Flow
- 6. Results Discussion
- Glossary
- Bibliography
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This report aims to examine the detrimental effect of fouling on the performance of air-cooled heat exchangers, specifically focusing on the impact of fin side fouling. It explores how fouling layers affect heat transfer resistance, air flow rate, and heat duty in both forced and natural draft applications. Special emphasis is given to dry air-cooled condensers and the consequences of reduced cooling air flow on vacuum pressure and power generation.
- The impact of fouling on heat transfer resistance and air flow in air-cooled exchangers
- The effect of fouling on the performance of dry air-cooled condensers
- The consequences of reduced cooling air flow on vacuum pressure and power generation
- A comprehensive assessment of fin side fouling in different convection types
- The analysis of forced, induced, and natural draft dry cooling applications
Zusammenfassung der Kapitel (Chapter Summaries)
- Abstract: This chapter introduces the problem of fouling in heat exchangers, highlighting its impact on heat transfer resistance and air flow area. It emphasizes the importance of regular cleaning to maintain cooling effectiveness and discusses the various methods for cleaning heat exchanger surfaces. The chapter also focuses on the specific case of air-cooled condensers, where fouling can lead to vacuum pressure increases and reduced power generation.
- 1. Introduction: This chapter delves into the detrimental effects of fouling on heat exchanger performance, particularly in dry air-cooled exchangers. It discusses the two primary factors involved: increased heat transfer resistance and reduced air flow area. The chapter also highlights the importance of air flow resistance in determining the impact of fouling, compared to the relatively minor influence of heat transfer resistance.
- 2. General Fin Tube Geometry: This chapter examines the geometry of fin tubes, which are the core elements of air-cooled heat exchangers. It describes the various types of fin tube arrangements, including circular, elliptical, and channel core tubes with air-side finning. The chapter also discusses the common practice of using compact finning to enhance heat transfer efficiency.
- 3. Heat Balance: This chapter focuses on the heat balance equation, which is essential for analyzing the performance of air-cooled heat exchangers. It discusses the factors that influence heat transfer, including heat transfer coefficients, surface area, and temperature differences. The chapter provides a framework for understanding the role of fouling in the overall heat transfer process.
- 4. Pumping Power: This chapter examines the energy required to move air through the air-cooled heat exchanger. It considers the pressure drop across the heat exchanger, including the bundle pressure drop, natural draft pressure gain, and air inlet and outlet pressure drops. The chapter provides insights into how fouling affects air flow resistance and overall pumping power requirements.
Schlüsselwörter (Keywords)
The text primarily focuses on the impact of fouling on the performance of air-cooled heat exchangers. Key terms and concepts include scaling, fouling, fin tubes, air-cooled condenser (ACC), air cooler, natural draft, vacuum decay, heat duty, and mixed convection. The report utilizes a comprehensive approach, analyzing the effects of fouling under different operating conditions and convection types.
- Quote paper
- Dipl.-Ing. Hans Georg Schrey (Author), 2018, Effect of Fouling on Performance of Exchangers Cooled by Air. Ramifications for Exchanged Heat and Cooling Effectiveness, Munich, GRIN Verlag, https://www.grin.com/document/453957
