• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.12
• /
• pp.984-991
• /
• 2006

The applications of multi air-conditioners into multiplex and high-rise buildings have been increased by replacing central air-conditioning systems. The pipe length and altitude difference between the indoor and outdoor units can be increased based on installation conditions, which may increase the possibility of flash gas generation at the expansion device inlet. The flash gas generation causes rapid reduction of refrigerant flow rate passing through the expansion device, yielding lower system efficiency. Accumulator heat exchangers have been widely used in multi air-conditioners in order to minimize flash gas generation and obtain system reliability. However, the studies on the heat transfer characteristics and pressure drops of accumulator heat exchangers are very limited in open literature. In this study, the heat transfer rates and pressure drops of accumulator heat exchangers were measured with refrigerant flow rate and operating conditions by using R-22. The heat transfer rate increased with the increase of refrigerant flow rate, while subcooling decreased. The heat transfer rate enhanced with the reduction of inlet superheat and subcooling due to the increased temperature difference between the accumulator and inner heat exchanger.

• Journal of the Korean Society of Safety
• /
• v.29 no.5
• /
• pp.166-171
• /
• 2014

This study is conducted to compare three methods of hazard analyses and to propose the control for the accidents arising under construction of heat accumulator of group energy projects(co-generation plants). The analysis of fatal accidents and the Analytic Hierarchical Process(AHP) using by the questionnaire survey for the workers engaged in the construction of heat accumulator and the quantitative questionnaire survey of expert group has been carried out. In order to analyze the fatal accidents, the 115 cases of accidents from 2001 to 2012 published by Korean Occupational Safety and Health Agency(KOSHA) and workers suffered from industrial accidents are collected and analyzed. The AHP is applied and analyzed for 66 persons of the construction site managers, safety engineers and construction engineers and the questionnaire survey of expert group is carried out and analyzed for the 51 persons of contractors and construction inspectors. The analyses of the types of accidents and the jobs of the suffered workers and the hazardous construction processes which are occurred accidents frequently are shown. The results of the analysis of fatal accidents and the AHP as well as the questionnaire of expert group are shown similar results.

• Proceedings of the SAREK Conference
• /
• 2005.11a
• /
• pp.433-438
• /
• 2005

An AHX(Accumulator Heat eXchanger) consists of a commercial accumulator and an inner heat exchanger located inside of the accumulator. The AHX is used in multi air-conditioners to assure the liquid-phase refrigerant entering into the expansion device. This purpose is achieved by heat transfer between the refrigerant leaving the evaporator and the refrigerant leaving the condenser. In this study, the effects of AHX on the performance of a refrigeration system using H-22 were measured and the test results were analyzed. The operating characteristics of the refrigeration system with the installation of AHX were quite different from those without the installation of AHX. Therefore, it is required to find an optimum refrigerant charging amount and optimum operating conditions, when AHX is installed in the refrigeration system with an fixed area expansion device such as a capillary tube.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.5
• /
• pp.418-425
• /
• 2006

An AHX (Accumulator Heat exchanger) consists of a commercial accumulator and an inner heat exchanger located inside of the accumulator. The AHX is used in multi air-conditioners to assure that liquid-phase refrigerant enters into the expansion device. This purpose is achieved by heat transfer between the refrigerant leaving the evaporator and the refrigerant leaving the condenser. In this study, the effects of AHX on the performance of a refrigeration system using R-22 were measured and the test results were analyzed. The operating characteristics of the refrigeration system with the AHX are considerably different from those without the AHX. Therefore, it is required to determine optimum refrigerant charge and optimum operating conditions when the AHX is used in the refrigeration system having a constant flow-area expansion device such as capillary tube.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.32.2-32.2
• /
• 2005

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.2
• /
• pp.61-70
• /
• 2012

Recently due to the increasing of the importance on the green energy is getting higher by implementing EERS(Energy Efficiency Resource Standards) and NA(Negotiated Agreement) such as lacks of natural resources and The United Nations Framework Convention on Climate Change. And the most practical solution is CHP(Combined Heat and Power) which performs the best energy efficiency. This paper developed optimal operation mechanism of CES(Community Energy System) for enhancement of energy efficiency using CHP(Combined Heat and Power), PLB(Peak Load Boiler) and ACC(ACCumulator) capacities. This method optimally operated these capacities calculated the maximum profits by Dynamic Programing. Through the case studies, it is verified that the proposed algorithm of can evaluate availability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.11
• /
• pp.53-58
• /
• 2015

Systemic heating and cooling air conditioning systems are popular in various industrial fields and even home. Recently, the rate of supply of this kind of multi-heat pump has been increased under ESCO financing supporting system. Generally the heat pumping system has a structural simplicity and easy installation benefits. and has good running efficiency under normal designed condition. But under extreme climate condition (over $+30^{\circ}C$, under $-10^{\circ}C$), this system exposes abnormal power consumption. It causes high progressive electric power rates and resultant peak power capacity of power plant. In this paper, a novel system concept of buffering refrigerant accumulator and constant pressure control system to relieve peak power load is proposed and this system's utility is verified with an prototype experimental system.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.522-523
• /
• 2008

This paper develops optimal operation mechanism of CHP(Combine Heat and Power) for enhancement of energy efficiency. It verify optimal operation of Accumulator using Economic Heat Load Dispatch and Dynamic Programing through case study.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1264-1269
• /
• 2004

This research describes the application of hydrocarbon refrigerants for heat pump system which is needed for fish farm. Tested refrigerants are HCFC-22 and hydrocarbon refrigerants(CARE 50 and ASR-20). CARE 50 is mixture of R-290 and R-170, and ASR-20 is mixture of R-152a, R-290 and other additives. Heat pump consist of shell and tube heat exchanger, scroll compressor, expansion valve and accumulator. Manual expansion valve is used for testing of wide range evaporating temperature. Hydrocarbon refrigerants show a good performance as an alternative for HCFC-22 in the range of evaporating temperature from $-6^{\circ}C$ to $6^{\circ}C$.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2033-2038
• /
• 2008

The CPLs(capillary pumped loops) are two phase heat transfer devices which enable active control of operating temperature of heat absorbing elements(or evaporators). Although the CPLs gain increasing interests as promising heat transfer devices for future missions such as spacecraft and commercial applications, their intrinsic complexity in operating principles makes the widespread use of these devices difficult. The key element and main cause of this complexity in operating principles is the two phase hydrodynamic accumulator or reservoir which controls the saturation state of the remaining loop and, particularly for the CPLs, it is separated from the evaporator. Thus, in this study, the operating characteristics of the CPL is investigated experimentally and theoretically. Mainly focusing on the role of reservoir the thermodynamic operating principle is examined first and the experimentally obtained steady state and transient state operating characteristics are discussed in detail.