• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.599-604
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• 2008

An experimental study has been performed to investigate the air-side capacity and pressure drop of the fin-tube heat exchanger for a fan coil unit under a cooling condition. The experimental data of five kinds of slit fin-tube heat exchangers were measured using an air-enthalpy calorimeter and a constant temperature water bath. Cooling capacities at the air and water rating flow rates were larger at the lower inlet water temperature. With increasing the water flow rate, the cooling capacity increased at the constant rate. Under the lower inlet water temperature, since the condensate was generated more on the fin-tube surface, the air-side pressure drop of the heat exchanger was larger.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.893-896
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• 2009

본 연구에서는 공조용 실외기의 고효율화 및 소형화를 위해 응축기로 사용되고 있는 핀-관 열교환기를 동일한 전면면적의 PF 열교환기로 변경하여 성능변화 및 특성을 조사하였다. 이를 위해 3종의 PF 열교환기를 적용하여 공조기의 성능을 비교평가 하였다. 실험은 공기 엔탈피식 칼로리미터에서 공조기의 냉방능력과 소비전력을 측정하여 COP를 계산하였다. PF 열교환기를 적용한 경우에 핀-관 열교환기보다 냉방능력은 증가하고 소비전력은 감소하여 COP가 향상되었다. PF 열교환기의 핀 피치가 클수록 냉방능력과 COP는 감소하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1325-1331
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• 2007

In order to investigate the cooling capacity of an air-conditioner applying a variable capacity compressor and the temperature characteristics on a condenser and an evaporator, the experiment on the operation characteristics of the air-conditioner was performed along a compressor operation ratio and an indoor/outdoor temperatures, under a cooling operation mode. The system characteristics were measured by the psychrometric calorimeter. The cooling capacity increased with decreasing the outdoor temperature and increasing the indoor temperature. Also, it increased with increasing the compressor operation ratio. The temperature of the condenser was more sensitive for the variation of the outdoor temperature and the temperature of the evaporator was more sensitive for the variation of the indoor temperature. The operation characteristics of the cycle used in this present were also analyzed by a pressure-enthalpy chart.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1789-1794
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• 2009

In the present study, the cooling performance characteristics on environment changes of A/C applied fin-tube and PF heat exchangers were experimentally investigated. Capacity and COP on an air velocity, an indoor/outdoor temperature and an indoor/outdoor relative humidity were obtained. Fin types of PF heat exchanger were a triangler and squarer form. The experimental data for the three kinds of heat exchangers were measured using the air-enthalpy calorimeter. Performance of PF A/C was more excellent than that of a fin-tube A/C. Also, the performance of PF-2 A/C with the squarer fin was more excellent than that of PF-1 A/C with the triangler fin. As the air velocity, the indoor temperature and the indoor relative humidity increase, capacity and COP increase. And as outdoor temperature increases, capacity and COP decrease. But, the performance change on the outdoor relative humidity was insignificant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1487-1493
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• 2008

In order to investigate the cooling capacity of multi-heat pump applying an inverter compressor, the experiment on the cooling performance characteristics of heat pump with 3 indoor units was performed under the cooling standard and cooling low-temperature conditions. The system data were measured by the psychrometric calorimeter. The operation characteristics and the behavior of the cooling cycle of the heat pump with 3 indoor units were understood from the cooling capacity, COP, and P-h diagram by indoor-unit combination. The operating load and performance of the multi-heat pump depends on the indoor-unit combination. The cooling capacity and COP of the low temperature condition were larger than those of the standard one. Also the cycle was analyzed by using P-h diagram.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.470-475
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• 2009

In the present study, the heat transfer characteristics of the fin-tube and PF heat exchangers and the performances of the air-conditioner are experimentally investigated. Also, Cooling Seasonal Performance Factor(CSPF) of the air-conditioner is evaluated. For the heat exchanger experiment, the heat transfer and pressure drop are obtained. For the air-conditioner experiment, the cooling capacity, input power and COP are obtained. The air-enthalpy calorimeter and the constant temperature water bath are used. As the inlet air velocity increases, the heat transfer rate and pressure drop of the heat exchanger increased. PF heat exchanger has smaller refrigerant weight and larger capacity and COP than the fin-tube heat exchanger. The performance of PF-2 heat exchanger with the squarer fin is more excellent than that of PF-1 heat exchanger with the triangler fin. Also, CSPF of the fm -tube and PF heat exchanger is evaluated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.7
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• pp.571-579
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• 2014

A series of field tests on hybrid desiccant cooling systems were conducted in July-August, 2013. The temperature and humidity of the supply and return air, power, and heat consumption were monitored and transferred in real time through the Internet. The performance parameters of the cooling system, namely, cooling capacity and COP (coefficient of performance), were evaluated from the measured data and their variations under outdoor conditions was analyzed. It was found that with increase in the outdoor temperature, the total energy decreases and cooling capacity increases whereas the latter decreases with increase in the outdoor humidity. The COP was also found to increase with the increase in outdoor temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.288-296
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• 2019

Radiation cooling has used ceilings or floors as cooling surfaces. In such cases, to avoid moisture condensation on the surface, the surface temperature needs be higher than the dew point temperature or an additional dehumidifier is added. In this study, with a goal for residential application, intentional moisture condensation on the cooling surface was attempted, which increased the cooling capacity and improved the indoor comfortness. This method included two separate refrigeration cycles - convection-type dehumidifying cycle and the panel cooling cycle. Test results on the panel cooling cycle showed that, at the standard outdoor ($35^{\circ}C/24^{\circ}C$) and indoor ($27^{\circ}C/19.5^{\circ}C$) condition, the refrigerant flow rate was 8.8 kg/h, condensation temperature was $51^{\circ}C$, evaporation temperature was $8.8^{\circ}C$, cooling capacity was 376 W and COP was 1.75. Furthermore, the panel temperature was uniform within $1^{\circ}C$ (between $13^{\circ}C$ and $14^{\circ}C$). As the relative humidity decreased, the cooling capacity decreased. However, the power consumption remained approximately constant. In the convection-type dehumidification cycle, the refrigerant flow rate was 21.1 kg/h, condensation temperature was $61^{\circ}C$, evaporation temperature was $5.0^{\circ}C$, cooling capacity was 949 W and COP was 2.11 at the standard air condition. When both the radiation panel cooling and the dehumidification cycle operated simultaneously, the cooling capacity of the radiation panel cycle was 333 W and that of the dehumidification cycle was 894 W, and the COP was 1.89. As the fan flow rate decreased, both the cooling capacity of the radiation panel and the dehumidification cycle decreased, with that of the dehumidification cycle decreasing at a higher rate. Finally, a possible control logic depending on the change of the cooling load was proposed based on the results of the present study.

• Journal of Energy Engineering
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• v.10 no.4
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• pp.357-362
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• 2001

A bench type ammonia-water absorber heat exchange cycle was tested by varying the system charging concentration, refrigerating valve opening and weak solution flow rate. It was observed that the cooling capacity was increased as the system charging concentration was increased. Optimum system charging concentration was found for the coolong capacity of the system. The opening rate of refrigerant expansion valve had a direct influence on the refrigerant sub-cooling at the condenser outlet. Optimum sub-cooling was found to be 0~4$^{\circ}C$. As the weak solution flow rate increased the concentration of strong solution and the evaporating pressure decreased. There existed a optimum weak solution flow rate which maximized the cooling capacity and COP.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1997.10a
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• pp.85-92
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• 1997

R22 대체냉매로 R410A를 사용하는 가정용 분리형 에어컨의 성능을 향상시키기 위한 연구를 실험적으로 수행하였다. R22 시스템에서 냉매와 압축기의 오일만 교체할 경우 기본시스템에 비해 냉방능력은 17% 증가하였고 에너지 소비효율은 29% 감소하였다. 이를 해결하기 위해 고압냉매 R410A에 적합한 압축기와 시스템의 효율을 향상시키기 위한 고효율 응축기를 개발하였다. R410A 압축기와 고효율 응축기를 R410A 시스템에 적용할 경우 냉방능력과 효율이 R22 시스템에 비해 각각 1.8% 와 2.2% 증가하였으며, 소음도 R22 시스템과 동등한 수준을 나타내었다.