Influence of fin thickness and winglet orientation on mass and thermal efficiency of cross-flow heat exchanger

Abstract

Heat exchanger efficiency, its dimensions and weight are ones of the most important constraints to consider in engineering design activity. Despite of different types of heat exchangers, single row or double row heat exchangers are still common device in different industries due to the construction simplicity and the maintenance cost. The size of heat exchanger can be limited by introducing the fins and increasing the heat transfer rate between the surface and the surroundings. Numerous modifications can be applied to the fin surface to increase heat transfer. In the paper, thermal efficiency of single row cross flow heat exchanger is investigated and compared to the fin/tube weight. The fin thickness, the length and orientation of winglet are the main parameters to consider. Numerical analyses are carried out to examine finned tube heat exchanger with and without winglets at the fin surface. The fin thickness influences the mass of the whole heat exchanger and the manufacturing cost, meanwhile the correct winglet orientation can improve heat transfer. The relationship between the heat exchanger weight and obtained heat transfer is computed for different fin configurations. Three-dimensional models are performed to find heat transfer characteristics between a finned tube and the air. The results show that the optimization cannot be performed for one criterion only. More parameters should be considered at the same time to run the process properly and improve the heat exchanger efficiency. All calculations demonstrate that the ratio of heat exchanger mass to the heat transfer is an important parameter that should be taken into account during design process.