Heat transfer and pressure drop of horizontal heat exchangers with different configurations and installations numerically characterized. Three different heat exchangers were used and shaped as linear, wavy, and horizontal slinky, respectively. Installation depth was set from 0.5m to 3.0m and pipe spacing was ranged from 0.3m to 2.1m. The results showed that heat transfer rate and pressure drop were increased with the increase in the installation depth and the pipe spacing. The horizontal slinky heat exchanger carried more heat compared to others due to the greater effective heat transfer surface area per installation area. In terms of a ratio of heat transfer rate to pressure drop indicating the system efficiency, the linear heat exchanger performed better than others. On the other hand, the horizontal slinky heat exchanger was the most effective with respect to a ratio of heat transfer rate to installation cost.

One simple way of increasing the heat transfer for a fin-and-tube heat exchanger is to increase the fin surface area. In this study, a series of tests were conducted on wide slit fin heat exchangers having an increased fin area (Pl/Pt = 0.87), and the results were compared with those of standard slit fin heat exchangers (Pl/Pt = 0.6). Thermal performances of wide silt-finned samples were superior to those of standard slit fin samples. For one row configuration, the j factor of the wide slit fin sample was 11% larger, and the f factor was 33 % smaller than those of the standard slit fin sample. The difference decreased as the number of tube row increased, although wide slit fin sample always yielded superior performance, The reason was attributed to the many narrower slits formed on the wide fin sample. Furthermore, the effect of fin pitch on j and f factor was not significant, and j factor decreased with the increase of the number of tube row.

In this study, a plate heat exchanger was developed for applying to a heat pump system using the heated effluent from a thermal power plant. Since seawater is used as a heat source and a heat sink in this heat pump system, Titanium was chosen as the heat plate material for its high corrosion resistance. One of the purposes of the study was to get an optimized distribution area in the heat plate in order that better thermal performances could be achieved through equal flow rates along the heat transfer area. It was revealed from the performance tests that the mean heat transfer rate and the overall heat transfer coefficient were enhanced by 2.9% and 7.7%, respectively, compared to those measured before the design optimization.

The wavy fins have been widely used on the compact heat exchangers in aero system, automotive, air-conditioner and cooler system. The Special Purpose Vehicle has many oil used system and it need cooling system by air in form of fin-flat tube heat exchanger. The objective of this work is to evaluate the performance of wavy fin by Computational Fluid Dynamics(CFD) analysis. 3 modified models were suggested to change protrude direction or to remove blocked surface bot and top of corrugated fin. The base model shows the lowest performance in pressure drop, and modified model 3 shows the highest performance in heat transfer rate. But, modified model 2 has the highest value in the Area goodness factor results, and modified model 3 has the highest value in the Volume goodness factor results.

In this paper, we study the effect of cooling dehumidification process and wave heat exchanger on the reduction of white smoke and the efficiency by combination of heat exchanger with numerical analysis method. For this purpose, four types of heat exchange systems combined with 5-stage wave heat exchangers were selected to analyze the heat transfer characteristics of the heat exchange system in the winter condition. As the high temperature exhaust air flowed from HX 1 to HX 5, the final outlet temperatures of the four heat exchange systems(Cases 1, 2, 3 and 4) gradually decreased. The heat transfer rate and dehumidification amount were the best in Case 1 and Case 3, respectively. It can be seen that the heat flow in the heat exchanger is different according to the combination of the four kinds of wave heat exchanger and the fluid flow.

The heat transfer characteristics of a louver fin for a radiator are numerically analyzed to investigate the performance of radiator for automotive. The commercial code FLUENT is utilized to simulate a louver fin to analyze both the flow fields of air and the solid region of lover fin. The numerical analysis is performed with the variation of air mass flow rate. The results show that as mass flow rate increases, louver fin efficiency is nearly constant. The correlation of the average Nu is derived. The results of numerical study is useful in louvered fin design.

In this paper, cycle performance characteristics of a cascade refrigeration system with internal heat exchanger for cascade heat exchanger using alternative freon refrigerants is presented to offer the basic design data for the operating parameters of the system. This system considered in this study is consisted of a high temperature cycle using Freon refrigerant R23, R508B and low temperature cycle using Freon refrigerants R22, R507A. The operating parameters of this system include subcooling and superheating degree, evaporating temperature, compressor efficiency, and so on. The main results were summarized as follows : The COP of cascade refrigeration system using R23/R507A is the highest results in this study. The COP of cascade refrigeration system with internal heat exchanger only in high temperature cycle is the highest value among three cycle, such as only low temperature cycle, only high temperature cycle and all the cycle

선박에 사용되는 TEMA 열교환기 전열관의 확관 공정에서 발생되는 탄소성 응력과 변형량의 거동을 유한요소법으로 해석하였다. 열교환기의 관판 구명의 홈 깊이와 롤러 익스팬더의 작용압력을 변화시켜 해석한 결과, 전열관의 관판 구멍의 홈 깊이가 커지면 탄소성 압축응력은 감소하였고, 롤러 익스팬더 압력이 높을수록 관판 구멍의 홈 모서리 부분의 탄소성 응력이 증가되었다.

Heat transfer enhancement of fin-tube heat exchangers with vortex generators is investigated using naphthalene sublimation technique. Experiments are performed for the fin-flat tube and the fin-circular tube heat exchangers with and without vortex generator. Vortex generators are found to enhance heat transfer rate on the fin surface dramatically. Their effect is relatively high in the fin-flat tube heat exchanger compared to fin-circular tube heat exchanger. Performance test is done for the prototype of air-conditioning heat exchanger and gas boiler heat exchanger with and without vortex generators .Fin-flat tube heat exchanger with vortex generator promote local heat transfer coefficient by 75% and increase friction factor, but friction of fin-flat tube heat exchanger with vortex generator is lower than that of fin-circular tube heat exchanger without vortex generator by 45%