• 한국자동차공학회논문집
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• 제23권4호
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• pp.428-435
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• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.45-50
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• 2020

In this research, the variation of round-trip efficiency in a liquid air energy storage system (LAES) is calculated and an optimal configuration is found. The multiple stages of cold energy storage are simulated with several materials that process latent heat at different temperature ranges. The effectiveness in the charging and discharging processes of LAES is newly defined, and its relationship with the round-trip efficiency is examined. According to defined correlation, the effectiveness of the discharging process significantly affects the overall system performance. The round-trip efficiency is calculated for the combined cold energy storage materials of aqueous dimethyl sulfoxide (DMSO) solution, ethanol, and pentane theoretically. The performance of LAES varies depending on the freezing point of the cold storage materials. In particular, when the LAES uses several cold storage materials, those materials whose freezing points are close to room temperature and liquid air temperature should be included in the cold storage materials. In this paper, it is assumed that only latent heat is used for cold energy storage, but for more realistic analyzes, the additional consideration of the transient thermal situation to utilize sensible heat is required. In the case of such a dynamic system, since there is certainly more increased heat capacity of the entire storage system, the volume of the cold energy storage system will be greatly reduced.

• 설비공학논문집
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• 제28권1호
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• pp.7-14
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• 2016

This study explores the feasibility of a cold storage system to provide thermal comfort for idle stop and go (ISG) vehicles. ISG function is the most valuable and environmental friendly technology in the current automobile industry. However, when an ISG vehicle stops, meaning when the engine standstill, the air-conditioning system does not work, because the compressor also stops. Therefore, passenger thermal comfort is not maintained, as cold air is not provided in the cabin. Consequently, many automakers have studied electric air-conditioning systems based on electrically-driven compressors or cold storage systems using phase-change materials. The experiments herein were conducted for the feasibility testing of different types of cold storage heat-exchangers, cold storage mediums, and thermo-expansion valves with current air-conditioners. The auxiliary cold storage system, filled with phase-change materials, was located behind the evaporator and almost stacked on top of it. In the experimental results, the air discharge temperature rate of increase was better than the conventional air-conditioning system when the compressor stopped and thermal comfort was maintained with $1.9{\sim}4.3^{\circ}C$ decreases within 60 seconds. The #1 cold storage heat-exchanger (CSH), #2 thermo-expansion valve (TXV) and #2 phase change material (PCM) were chosen because of the best temperature rise delay. It was concluded that a cold storage system is an effective solution for ISG vehicles to maintain thermal comfort during short engine stops.

• 설비공학논문집
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• 제6권3호
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• pp.247-258
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• 1994

In this study, experimental investigations to find cold energy storage performance have been made for two different temperatures at condenser. Temperatures at inlet and outlet of condenser were measured to calculate global heat transfer coefficient of direct contact method in our cold energy storage system. Also storage performance by direct contact method was compared with that of Ice-On-Coil type ice storage which was calculated by analytic solution. Results show that, in the case of $-8.0^{\circ}C$ at condenser inlet, heat transfer coefficient of direct contact method is 3.25 times higher than that of conventional method and COP of system is improved by using R141b as refrigerant which produces gas hydrate and has higher phase change temperature than $0.0^{\circ}C$.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.22-28
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• 2012

The purpose of this study was to show how tomaintain high efficiency and to use reasonably when being applied the cold-heat storage systems to the showcase. An experimental study was performed to manufacture the showcase system in a laboratory. Comparing the result at general operation condition with that of the new condition using ice storage system, this study showed the effects of the refrigerant sub-cooling, and with using inverter. Using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using the stored cold-heat after being discharged from the air cooling condenser during the day time. Through the experiments, the load transfer rate for the showcase using inverter and ice storage was estimated about 30.0%. And showed that the total power consumption of the showcase with inverter could be reduced about 37% than that of the showcase without inverter.

• 설비공학논문집
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• 제11권2호
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• pp.205-214
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• 1999

The objective of this paper is to investigate the thermal properties of TMA clathrate compound applicable to cold storage system for building air-conditioning. Especially, the test tube experiments are performed by comparing and analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of density, temperature of heat source and charging quantity in TMA clathrate compound. The results are summarized as follows:1) $-15^{\circ}C$ is not proper as the temperature of heat source because the temperature of subcooling is above $8.3^{\circ}C$ 2) temperature of phase change is dropped as the temperature of heat source is lower, 3) the effect of subcooling suppression with about 8$^{\circ}C$ is confirmed when the temperature of heat source is $-10^{\circ}C$ in case of 26, 27, and 30wt%, while the temperature of subcooling is about $0^{\circ}C$ when the temperature of heat source is $-15^{\circ}C$ in case of 25, 26 and 30wt%. Thus, the effect of subcooling suppression is greater as the temperature of heat source is lower. Additionally, the concentrative study is needed on mass concentration causing the phase change without subcooling phenomenon when the temperature of heat source is $-15^{\circ}C$. Thus, it is concluded that TMA clathrate compound has enough thermal properties as the cold storage medium for building air-conditioning.

• 설비공학논문집
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• 제12권8호
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• pp.725-734
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• 2000

The objective of this paper is to investigate the thermal properties of TMA clathrate applicable to cold storage system for building air-conditioning. Especially, the test tube experiments are peformed by comparing and analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of concentrations and temperature of heat source in TMA clathrate. The results are summarized as follows; 1) temperature of phase change is dropped as the temperature of heat source is lower, 2) the effect of subcooling suppression with about $9.3^{\circ}C$ is confirmed when the temperature of heat source is $-10^{\circ}C$ in case of 30wt%, while the temperature of subcooling is about $0^{\circ}C$ when the temperature of heat source is $-15^{\circ}C$ in case of 25, 29wt% and 30wt% . Thus, the effect of subcooling suppression is greater as the temperature of heat source is lower. Additionally, the concentrative study is needed on mass concentration causing the phase change without subcooling phenomenon when the temperature of heat source is $-15^{\circ}C$ Thus, it is concluded that TMA clathrate has proper properties as the cold storage medium for building air-conditioning.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1111-1116
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• 2008

The purpose of this study is to maintain high efficiency and reasonable use of cold-heat storage systems operated the showcase. An experimental study is carried out to manufacture the showcase system in a laboratory. Comparing the result at general operation condition with that at the new condition using ice storage system, this study showed the effects of the refrigerant sub-cooling, and with using inverter. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1261-1266
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• 2008

Experimental study was performed to understand the operations of a showcase working in a discount store. Temperatures of evaporation, condenser were measured and also electric power consumption of compressor were measured. The purpose of this study is to application use of cold-heat storage systems operated the showcase. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling. So the operating characteristics of the showcase system under various working conditions were analyzed and discussed.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.990-995
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• 2009

Experimental basic study was performed to understand the characteristics of sub-cooled refrigerant using a cold heat storage system. This system was made up general vapor-compression refrigeration cycle added sub-cooler and ice storage tank. The purpose of this study are to application use of cold-heat storage systems multiplicity of fields and to understand of sub-cooling system. At the condition using ice storage system, the ice making process was operated during night time by electric power. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. Comparing the result at general operation with the operation using sub-cooling system. This study showed the effects of the sub-cooled degree. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, and the compressor consume power was a little decreased. Thus the COP was also increased owing to the sub-cooling of refrigerant.