• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.4
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• pp.312-317
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• 2003

This paper describes an experimental study on small-scale sorption refrigerator. Silica gel (type A) as an adsorbent, HFC-l34a as a refrigerant were selected for a sorption refrigerator The focus of the design was to reduce the cycle time of the sorption refrigerator. Through the experiment, pressure and temperature variations in the adsorber were measured and the performance of refrigerator was predicted. In this paper, the small-scale sorption refrigerator operates with the cycle time of 4805. Its predicted cooling capacity is 25 W at -15$^{\circ}C$ and COP is 0.23.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.54-61
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• 2004

The purpose of this study is to improve of energy performance in school buildings. Many building renovations have mainly focused on commercial buildings and houses, but school buildings have no attention in this field although there are many buildings that show degraded energy performance and there are many old fashioned buildings which need renovation. This study was carried out through the survey, field study, energy simulation and life cycle cost analysis. The results of this study can be summarized as follows: In model building, large amount of heat were lost at the building envelope, such as non-insulated skins, window-sills and window-frame joints. According to the simulation result, about 15％ of heating energy is saved by the insulating works compared to pre-renovation condition. Also, LCC analysis revealed to be more effective to select a exteria wall insulation such as a dryvit system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.2
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• pp.142-154
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• 1990

A theoretical cycle analysis has been performed for a basic heat pump, charged with non-azeotropic refrigerant mixtures, R22/R114 and R13B1/R152a. At first, a procedure is introduced to calculate thermodynamic properties simply and correctly, and the advantages of using refrigerant mixtures are discussed through the cycle analysis. It is shown that by using refrigerant mixtures in the heat pump, several improvements can be made. In comparison with conventional pure refrigerants, the application of refrigerant mixtures results in high reliabilities caused by the extension of the application limit, energetic improvements, and a continuous capacity control. From generalizing various results, the optimum compositions in refrigerant mixtures are also determined. The 30%/70% and 40%/60% compositions are selected for R22/R114 and R13B1/R152a, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.3
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• pp.97-102
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• 2014

For an analysis of the horizontal-type geothermal heat exchanger system, an understanding of the ground temperature distributions is required in order to predict system performance. Because it is difficult to decide on the underground temperature due to the adjustment of its temperature cycle, numerous calculations are required in order to decide on the temperature cycle. In this paper, Buggs formula is utilized to decide a phase shift for outdoor temperature and ground surface temperature, which are obtained from Korea Meteorological Administration. Overall, the underground temperature distribution in the Changwon region is predicted as $10.5^{\circ}C{\sim}20.3^{\circ}C$ at a depth of 3 m.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.2
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• pp.1-7
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• 2013

Most researches done on heat pumps have been on heat pumps for refrigeration, cooling and heating. There is therefore the need for more research on hot water heat pumps, especially for high temperature. Even though the cascade heat pump cycle has a great potential more efficient hot water generation even at low evaporating temperatures, it has been researched least for this purpose. In this study, the heating performance of a variable speed cascade heat pump was investigated by varying operating conditions. For the same heating capacity values, it was found that increasing the low stage compressor speed was more suitable for enhancing the performance of the system to get a higher temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.854-862
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• 2002

In the previous research, a simplified correlation method was developed as an easy prediction tool for comparing energy use of cooling plants. The purpose of this paper is to test the applicability of this method for economic evaluation with two zones of a 20-story commercial building in Seoul. The results of this method were compared with the DOE-2 simulation and actual measured data. Then, Comparisons of life cycle cost were carried out for three types of cooling plants. Testing of one zone showed good agreement of within 10% error in cooling energy use and within 2% error in LCC. But testing of the other zone indicated that the use of this method were invalid when input variables were used beyond its valid range.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.73-81
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• 1997

In this experimental study, the air cooling radial shape heat exchanger which influences on the COP and the cooling capacity by heat and mass transfer rate in the adsorbent bed was designed and applied to test its performance for adsorption heat pump(AHP). Zeolite-water was used for the adsorbent-adsorbat pair. As a result, the cooling COP and a cycle period of this adsorption heat pump are 0.28 and 2 hours, respectively, on the condition of none heat recovery from the adsorption reactor(absorber). The other results and recommendations are mainly related to improving the heat and mass transfer inside the absorber to reduce a cycle period.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.536-544
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• 1997

This study presents test results of a residential window system air-conditioner using R22 and two potential alternative refrigerants, R407C and R410B. A series of performance tests was performed for the basic and liquid-suction heat exchange cycle in a psychrometric calorimeter test facility. For R407C, the same rotary compressor was used as in the R22 system. However, compressor for the R410B system was modified to provide the similar cooling capacity. The evaporator circuit was changed to get a counter-cross flow heat exchanger to take advantage of zeotropic mixture's temperature glide, and liquid-line suction-line heat exchange cycle was also considered to improve the performance of the system. Test results were compared to those for the basic R22 system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.7
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• pp.604-610
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• 2003

Cycle test for developed phase change material (PCM) is necessary in order to analyze the variation of latent heat, which decreases with time by deterioration. 7-history method and measurement using heat flux meter are appropriate for the cycle test in a tube filled with PCM because they do not need an extraction of sample in measuring the heat of fusion. In the present study, these methods were applied to a PCM having a melting point below a room temperature, different from the past studies for PCMs melting above a room temperature. As a result of experiment using pure water as specimen, we can obtain reason-able values for heat of fusion by both methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.662-668
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• 2008

The objectives of the present work are to investigate the influence of the solution cooled absorber(SCA), refrigerant drain heat exchanger(RSX), exhaust gas/solution heat exchanger(ESX) and high efficiency solution heat exchanger on COP for a double-effect series-flow absorption chiller. A simulation program has been prepared for the cycle analysis of absorption chillers. As a result, solution heat exchangers(LSX, HSX) are the most effective element for the COP than the others. In spite of the poor contribution to COP, SCA plays an important role to reduce the crystallization phenomena of LiBr solution at solution heat exchanger. And the optimum solution split ratio varies with the relative size of RSX and LSX.