• 설비공학논문집
• /
• 제10권4호
• /
• pp.423-430
• /
• 1998

Single phase heat transfer coefficients were measured for turbulent water flow in a micro-fin tube by using Wilson plot technique. An experiment for counterflow heat exchange between the micro-fin tube and its outer annulus passage was performed. The annulus side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a micro-fin tube were obtained by Wilson plot technique. Nusselt numbers based on the real heat transfer area and the nominal area were about 35% and 50% larger than those for smooth tube respectively Also, single-phase heat transfer correlations based on real heat transfer area and nominal area have been proposed for a micro-fin tube.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.408-413
• /
• 2008

This study presents comparison of the air side heat transfer and friction characteristics in a heating condition between Louver fin-tube heat exchangers and aluminum heat exchangers. Experiments are performed for the Louver fin-tube heat exchangers and aluminum heat exchangers using a calorimeter, which is designed based on air-enthalpy method described in ASHRAE standards. The air velocities its are varied from 0.7 to 1.6 m/s with 0.3 m/s interval. A study result shows that the heat transfer performances of aluminum heat exchangers are $40{\sim}80%$ higher than those of Louver fin-tube heat exchangers per unit volume, mass and heat transfer area.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.633-638
• /
• 2006

This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers with various fin types. A total of 8 samples of heat exchangers are tested. Fin patterns tested are slit, louver and plate fins. Each fin type has three cases of number of tube rows(N=1, 2, 3) and two different fin pitches. The results are plotted in terms of Colburn j-factor and friction factor f with respect to Reynolds number in the range of 200 to 510.

• 한국자동차공학회논문집
• /
• 제23권6호
• /
• pp.608-614
• /
• 2015

Nitrogen oxide(NOx) emission reductions are required to meet the strict emission regulations for environmental protection. Most of the Exhaust Gas Recirculation(EGR) system applied to a diesel engine can relatively decrease the NOx at a low cost, but it has a disadvantage in that the PM generation is promoted due to the hot intake air temperature. Thus, high heat exchange efficiency of the EGR cooler is required for an effective removal of NOx. In this study, heat exchange efficiency for various types of heat exchangers used in EGR cooler was measured under same conditions, and determined best heat exchange performance shape depending on type of heat exchanger.

• 설비공학논문집
• /
• 제24권3호
• /
• pp.265-270
• /
• 2012

A finned tube type heat exchange module has been proposed for a multi-burner water tube boiler. Fin density and length increase in streamwise direction to equalize the evaporation for each module, which makes it difficult to apply conventional bulk design procedure. The design program has been improved by updating data for every row of tubes along the flow. A numerical simulation has been also conducted to evaluate the effect of inlet conditions and validated with experiment. The heat transfer of the first row has been underpredicted by the conventional Zhukauskas correlation, since the acceleration of the flow due to the blockage is not fully inflected. The fin tip temperature is also underpredicted by Bessel solution, because of the interaction with neighboring fins.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제15권1호
• /
• pp.25-33
• /
• 2007

The investigation has been made into the prediction of heat exchange performance of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and micro-fin tube. Under various heat transfer conditions, mass flux, pressure drop and heat transfer coefficient of the mixed refrigerants were calculated using a prediction method, when the length of condensing tube, total heat transfer rate, mass flux and outlet temperature of coolant were maintained constant. Also, the predicted results were compared with those of HCFC22. The results showed that the mixed refrigerants of Propane/n-Butane or Propane/i-Butane could be substituted for HCFC22, while the pressure drop and overall heat transfer coefficient of the refrigerants were evaluated together.

• 설비공학논문집
• /
• 제17권9호
• /
• pp.816-823
• /
• 2005

This paper deals with the heat exchange performance prediction of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and a micro-fin tube. The local characteristics of heat transfer, mass transfer and pressure drop are calculated using a prediction method developed by the authors. The total pressure drop and the overall heat transfer coefficient are also evaluated on various heat exchange conditions. The calculated results of the natural refrigerant mixtures are compared with HCFC22. In conclusion, natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane are appropriate candidates for alternative refrigerant from the viewpoint of heat transfer characteristics.

• 한국산학기술학회논문지
• /
• 제8권6호
• /
• pp.1337-1342
• /
• 2007

본 연구에서는 동시 냉난방 히트펌프용 열교환기의 성능평가 및 설계해석 기술의 확보를 위해 난방운전 온도조건에서 6종의 루버핀-관 열교환기의 공기측 열전달특성 및 마찰특성을 실험을 통하여 조사하였다. 실험을 위해 공기엔탈피방식의 칼로리미터와 항온수조를 이용하였다. 전열량의 증가는 핀피치보다 열수에 의해 더 크게 나타났고, 핀피치가 작을수록 열전달계수는 더 높았다. 또한 핀피치가 작을수록 열수증가에 의한 열전달계수의 증가폭이 커졌다. 핀피치와 열수변화에 대한 j-계수와 f-계수는 레이놀즈 수가 증가할수록 감소하였고, 레이놀즈 수 400부근의 영역에서 역전현상이 존재하였다.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
• /
• pp.21-27
• /
• 2002

Catalytic combustor with heat exchangers are often employed in process technology where a compact design is required [1]. The use of fin and tube heat exchanger offers the enhanced surface area for heat exchange. The recent progress and performance of the fin-tube heat exchanger, especially airside, has been reviewed extensively by Wang[2].(Omitted)

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2007년도 동계학술발표대회 논문집
• /
• pp.209-215
• /
• 2007

This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers. Variations of heat transfer performance in each row are investigated in the present work. Experiments were performed for the Louver fin-tube heat exchangers using air-enthalpy type calorimeter, which is based on air-enthalpy method described in ASHRAE standards. The air velocity was varied from 0.7 to 2.5 m/s with 0.3 m/s interval. The results are plotted in terms of Colburn j-factor and friction factor of with respect to Reynolds number in the range of 200 to 1100.