외기 온도 변화가 핀-관 열교환기의 공기측 열전달계수와 마찰계수에 미치는 영향에 관한 실험적 연구

다국어 초록 (Multilingual Abstract)

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

목차 (Table of Contents)

• Abstract
• 1. 연구배경 및 목적
• 2. 실험장치 및 방법
• 3. 실험결과 및 고찰
• 4. 결론
• References

참고문헌 (Reference)

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4 Gnielnski, V., "New equations for heat and madd transfer in turbulent pipe and channel flow" 16 : 359-368, 1976

5 Dittus, F. W., "Heat transfer in automobile radiators of the tubular type" 2 (2): 443-461, 1930

6 Schmidt, T. E., "Heat transfer calculations for extended surfaces" 4 : 351-357, 1949

7 Park, B. B., "Experimental study of heat transfer and pressure drop characteristics for flow of water inside circular smooth and micro-fin tubes" 9 (9): 454-461, 1997

8 Wang, C. C., "Effect of waffle height on the air-side performance of wavy fin-and-tube heat exchangers under dehumidifying conditions" 21 : 17-26, 2000

9 "ESDU 98005, Design and performance evaluation of heat exchangers : the effectiveness and NTU method, Engineering and Sciences Data Unit 98005 with Amendment A"

10 Wang, C. C., "Data reduction for air-side performance of fin-and-tube heat exchangers" 21 (21): 218-226, 2000

11 Mills, A. F., "Basic Heat ad Mass Transfer" Irwin Pub 1995

12 "ASHRAE Standard 41.5, Standard Measurement Guide, Engineering Analysis of Experimental Data"

13 "ASHRAE Standard 41.2, Standard Method for Laboratory Air-Flow Measurement"

14 "ASHRAE Standard 41.1, Standard Method for Temperature Measurement"