• 설비공학논문집
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• 제20권7호
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• pp.447-454
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• 2008

The regenerative evaporative cooler(REC) is to cool a stream of air using evaporative cooling effect without an increase in the humidity ratio. In the regenerative evaporative cooler, the air can be cooled down to a temperature lower than its inlet wet-bulb temperature. Besides the cooling performance, for practical application of the regenerative evaporative cooler, the compactness of the system is also a very important factor to be considered. In this respect, three different configurations, i.e., the flat plate type, the corrugated plate type, and the finned channel type are investigated and compared for the most compact configuration. The optimal structure of each configuration is obtained individually to minimize the volume for a given effectiveness within a limit of the pressure drop. Comparing the three optimal structures, the finned channel type is found to give the most compact structure among the considered configurations. The volume of the regenerative cooler can be reduced to 1/8 by adopting the finned channel type as compared to that of the flat plate type.

• 수산해양교육연구
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• 제9권1호
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• pp.71-82
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• 1997

최근 오징어는 주요 대상어종이 되고 있으므로, 동중국해와 우리 나라 남해에서 어획되는 Short-finned squid와 Long-finned squid에 대해 분석하였다. 조업시험은 실습선 새바다호를 이용하여 다이아몬드형 망목에 의한 조업시험은 망목의 크기가 A(51.2mm), B(70.2mm), C(77.6mm), D(88.0mm), E(111.3mm)인 5종의 끝자루를 제작하여 1991년 6월부터 1992년 12월 중에 행하였으며, 정방형망목에 의한 조업시험은 망목의 크기가 A(51.2mm), B(70.2mm), C(77.6mm), D(88.0mm)인 4종의 끝자루를 제작하여 1992년 7월부터 1994년 6월 중에 행하였다. 다이아몬드형 망목과 정방형 망목의 끝자루에 Cover net를 부착하고 Trouser방식으로 실시하였다. 분석한 결과를 요약하면 다음과 같다. 1. 동장이 201mm 이상 되는 도피율은 D Type가 A type 보다 Short-finned squid는 55%, Long finned squid는 46% 컸다. 2. Short-finned squid의 어획량은 한국남해가 동중국해 보다 2.5배 많았으며, Long-finned squid는 동중국해가 한국남해 보다 14.3배 많았다. 3. 다이아몬드형 망목의 선택성곡선에서 Short-finned squid의 평균 선택동장 49mm, 평균 50% 선택동장 141mm 이었으며, Long-finned squid의 평균 선택동장 48mm, 평균 50% 선택동장 122mm 이었다. 정방형 망목의 선택성곡선에서 Short-finned squid의 평균 선택동장 67mm, 평균 50% 선택동장 156mm 이었으며, Long-finned squid의 평균선택 동장 60mm, 평균 50% 선택동장 137mm 이었다. 4. Short-finned squid에 대한 Master curve 선택성곡선 에서 다이아몬드형 망목은 기울기 3.01, 선택계수 2.10 이었으며, 정방형 망목은 기울기 1.82, 선택계수 2.37 이었다. Long-finned squid에 대한 Master curve 선택성곡선에서 다이아몬드형 망목은 기울기 3.11, 선택계수 1.81 이었으며, 정방형 망목은 기울기 2.35, 선택계수 2.08 이었다.

• 대한설비공학회지:설비저널
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• 제5권2호
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• pp.91-97
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• 1976

This study was concerned with performance of 2 types of black painted solar air heaters, one is finned type better, the other is mesh type. The performance test of heaters was made under the different operating conditions during winter season of December in Seoul area. It was analized and discussed by comparing the overall efficiency of 2 solar heaters at the same mass flow rate and ambient temperature. Experimental results show that finned type solar heater is better than mesh type from the point of view of design and heat removal efficiency. Finned-type solar air heater supplies hot air up to 30 degree centigrade above ambient temperature with an overall efficiency of 47 percent whilemesh type was 44 percent.

• 대한기계학회논문집B
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• 제20권5호
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• pp.1725-1734
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• 1996

Experimental condensation and evaporation heat transfer coefficients were measured in a horizontal smooth tube and a horizontal micro-finned tube with HFC-134a. The test sections are straight, horizontal tubes with have a 9.52mm outside diameter and about 5000mm long. The micro-finned tube had 60 fins with a height of 0.12mm and a spiral angle of 25.deg.. The condensation test section was a double-pipe type with counter flow configuration. The evaporation test section employed an electic heating method. Enhancement factors which is defined as a ratio of the heat transfer coefficient for micro-finned tube to that for smooth tube, varied from 1.3 to 1.6(mass flux:110~190kg/m$^{2}$s) for condensation and 1.2 to 1.5 (mass flux:70~160kg/m$^{2}$s) for evaporation. The experimental data of condensation and evaporation heat transfer coefficients were compared to several empirical correlations. Based on these comparisons, modified correlations of the condensation and evaporation heat transfer coefficient for both smooth and micro-finned tubes were proposed.

• 설비공학논문집
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• 제20권10호
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• pp.679-688
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• 2008

Air-heating vaporizer usually is used to regasify LNG at satellite areas because of the small demand of natural gas there. The common type of air heating vaporizer which exists in the market is the longitudinally finned type with 8 fins, 55 mm fin length and 2mm fin thickness. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50mm(fin length) with 2 mm(fin thickness) which exist in the market and 4 fins, 75 mm(fin length) with 2 mm(fin thickness), which is proposed, were conducted. Then, both types of vaporizers are compared. The experiments were conducted in one hour by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same temperature, humidity and air velocity with air condition in every season available and the length was varied 4000 mm, 6000 mm and 8000 mm for each type of vaporizer. Additional experiment with longer duration, i.e. In this experiment, the main aspects in analyzing the characteristics of the air heating vaporizer the inlet-outlet enthalpy difference and the outlet temperature of the working fluid. $LN_2$ is used to substitute LNG because of safety reason. The results show that the characteristics of the finned type 4fin75le vaporizer are comparable to finned type 8fin50le vaporizer.

• 설비공학논문집
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• 제14권1호
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• pp.46-54
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• 2002

To investigate the design effects of a heat exchanger on a tube type, a tube circuit and a fin pitch, an experimental study on the heat transfer characteristics of finned- tube evaporators was performed. The refrigerant was R-22. A refrigerant loop was established to measure the heat transfer rate, the air heat transfer coefficient. The experimental results showed that the heat transfer characteristics of the evaporators were affected by the design parameters. And the heat transfer rate of the slit fin was better about 25%, compared to those of the louver fin. In the present experimental range, the heat transfer performance with the straight tube circuit was more remarkable than that of the zigzag tube circuit, as seen from temperature variations of the evaporator exit. $\jmath$-factor on the tube type, the tube circuit and the fin pinch decreased, as increasing Reynolds number.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2321-2326
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• 2007

To return LNG to a gaseous state, it is fed into a regasification plant. For inland area, where pipelines do not exist or difficult to construct, the LNG is delivered to the inland-receiving terminal available at that area, regasified and delivered to consumers. At inland-receiving terminal, air-heating vaporizer type is usually used. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50 mm fin length (8fin50le) and 4 fins, 75 mm fin length (4fin75le) were conducted. The experiments were conducted by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same condition with air condition in every season available. $LN_2$ is used to substitute LNG because of safety reason. The results show that characteristics of the finned type 4fin75le vaporizer are comparable to finned type 8fin50le vaporizer at all season.

• 한국태양에너지학회 논문집
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• 제24권1호
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• pp.39-45
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• 2004

The thermal performance of glass evacuated tube solar collectors with finned tubes is numerically modelled with code and investigated to see the effect of toe inner tube diameter and incidence angle. The solar collector consists of a two-layered glass tube and an inner tube. Finned tubes are used as the inner tube of the collector in order to improve the performance of the solar collector. Two strip-type fins are attached on the opposite sides of the inner tube surface. The fin is wide enough to be tightly fatted inside the glass tube. The results show that if the incidence angle is small, the effect of the tube diameters is not significant on the thermal performance and the outlet air temperature. If the incidence angle is large, however, the outlet air temperature and the performance increases as the inner tube diameter increases.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.359-364
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• 2005

In dehumidification evaporation cooling system. the regeneratie evaporative cooler(REC) makes an important role to reduce the sensible cooling load in the system through evaporative cooling, By this reason, many studies about increasing the cooling capacity of the REC were undertook. In this paper, we analyzed the cooling characteristics of the REC due to the structures of the REC and determined the best structure for the REC's effectiveness and cooling capacity. From the study. we could obtain some important results: at first. corrugated type has the benefit to expand the channel width of the REC, But because the type has some weak points about the size and weight. there is almost no benefit to improve the performance of the REC. Through these reasons. we decided that finned type is the best structure to improve the performance of the REC.

• 설비공학논문집
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• 제8권2호
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• pp.267-278
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• 1996

Steady, laminar, forced convection flow and heat transfer in the entrance region of an internally finned circular duct with a finite thermal conductivity has been analyzed numerically. The problem under investigation is a three-dimensional boundary layer problem, and is solved by employing a marching-type procedure which involves solution of a series of 2-dimensional elliptic problems in the cross-stream plane. Two types of inlet hydrodynamic conditions are considered : (a) uniform velocity flow and (b) fully developed flow. From the above inlet conditions, the effects of the fin height(h), fin number(N) and conductivity ratio($k_r$) on the flow and thermal characteristics are investigated. The numerical results show that the height and number of fins, and ratio of the solid to fluid thermal conductivity have pronounced effect on the solution. Considering pressure drop, optimized dimensionless fin height is 0.4.