• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.271-278
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• 2005

In this paper, the performance of Kim-chi refrigerator with three evaporator and one compressor was investigated in employing $55\%$ propane and $45\%$ isobutane (R290/R600a) refrigerant mixture as an alternative refrigerant of R134a. The drop-in test was performed by varying both refrigerant charge and capillary tube length in order to find both the performance and reliability of a small multi-refrigeration system. Results show that the power consumption is decreased by about $15\%$ and COP is increased by about $10\%$, respectively as compared to the baseline system using R-134a. In addition, the propane/isobutane refrigerant mixture system took advantage of the minimization of modification and redesigning of system components because thermodynamic properties such as saturation pressure, temperature, normal boiling point(NBP) characteristics are similar to those of R134a. The reduction of sales cost is caused by the decrease of refrigerant cost per unit mass and refrigerant charge amount necessary for the refrigeration system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.868-875
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• 2007

In this paper, performance characteristics of a domestic kim-chi refrigerator are predicted by using the theoretical calculation and experimental method. The objective of this study is to find out the best design points of the refrigeration system and to calculate an adiabatic characteristic with variation to outdoor temperatures. The best design points such as refrigerant charge amount and capillary length were experimentally investigated. And the theoretical calculation is conducted as a function of calculation parameters and outdoor temperatures. According to this study results, the best design points of a refrigeration system with 2 rooms are 95 g of a refrigerant charge amount and 3500 / 3500 mm of capillary lengths and the best design points of a refrigeration system with 3 rooms are 100 g of a refrigerant charge amount and 3000/3000/6000mm of capillary lengths. And the power consumptions of both systems are 13.57 and 18.2 kWh/month. The worst part of heat loss is a front side of a domestic kim-chi refrigerator body.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1945-1950
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• 2004

In this paper, The performance of Kim-Chi refrigerator with three evaporator and one compressor was investigated in employing 55% propane and 45% isobutane (R290/R600a) refrigerant mixture as an alternative refrigerant of R134a. The drop in test was performed by varying both refrigerant charge amount and capillary tube length in order to find both the performance and reliability of a small multi-refrigeration system. As a result, Both the power consumption and COP is increased by about 15% and 10%, respectively as compared to the baseline R134a system. In addition, the propane/isobutene refrigerant mixture system took advantage of the minimization of modification and redesigning of system components because of similar thermodynamic properties with R134a such as saturation pressure, temperature, normal boiling point(NBP) characteristics

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.769-774
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• 2003

In this paper, the performance of a domestic Kim-Chi refrigerator is predicted by using a calculation model & experiment. The objectives of this study are to find out the best design points of a refrigeration system and calculate an adiabatic characteristic to change outdoor temperature. The best design points such as refrigerant charge and capillary length were experimentally investigated. And the calculation model is conducted as a function of calculation parameters and outdoor temperature. According to this study results, the best design points of a refrigeration system are each 95g of a refrigerant charge and 3500/3500mm of capillary lengths. And the power consumption is 13.578 Kwh/month. And a part of the worst heat loss is a front side of a domestic Kim-Chi refrigerator body.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.360-363
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• 2012

A solar air heating has low efficiency compared with the solar water heating because the heat capacity of the air is small. The heat received by solar collector plate is not fully transferred to the air and then a part of them became the losses to the environment through conduction and convection process. This research is focusing on a design of better combined multi-purposed system suggested by us and aims to secure the more efficient solar energy utilization by combining the hot water and air heating system. The result in this paper has shown that the proposed design has better thermal performance than that of the common design. Furthermore, it was found that the performance of the combined air - water heating system increases the efficiency from 30% to 35%-40%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.8
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• pp.580-586
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• 2011

In this study, 3 cooling systems of apartment which are air-cooled air conditioner with indoor unit, water-cooled air conditioner with indoor unit and small capacity absorption chiller-heater with FCU have been evaluated by Multi-Criteria Decision Making Analysis. Weights of 7 selected factors which are economics, space, billing, constructability, human comfort, visibility and reliability are determined by expert group of 30 system designers and 30 construction engineers. Final weights were derived for 101 and 166 $m^2$ apartments. Analysis shows that small capacity absorption chiller-heater with FCU is the most favorable system for apartment cooling system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.398-405
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• 2013

Small and medium-size buildings employ a multi-distributed individual air-conditioning system that utilizes package air conditioners instead of centralized cooling systems, which can allow easier building management and maintenance, along with a diversification of facility use. Inverter driven system heat pumps have been developed to achieve not only an easy distribution control, allowing free combination of indoor units with different models and different capacities, but also wide applications to intelligent air conditioning. However, the control algorithms of the system heat pump are limited in the open literature, due to complicated operating conditions. In this paper, an inverter-driven system heat pump having two indoor units with electronic expansion valves (EEV) was simulated in the cooling mode. An integral optimum regulating controller employing the state space control method was also simulated, and applied to the system-heat pump system, to obtain efficient control of the MIMO (multi input multi output) system. The simulation model for the controller yielded satisfactory prediction results. The new control model can be successfully utilized as a basic tool in controller design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.6
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• pp.317-323
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• 2013

A multi-perforated tube indicates the existence of multiple holes of various shapes on the surface of a long cylinder-type or rectangular tube, and a hole installed on the surface is called an orifice, as it is relatively small in size, compared with the surface area of the tube. In this study, the flow characteristics of a circular multi-perforated tube with many orifices on the surface were investigated experimentally and numerically. The volume flowrate issuing from each orifice, discharge angle, effective flow area ratio, and the flow fields around the orifices were measured and visualized, with the variation of the orifice area ratio, at the same blockage ratio. The volume flowrate distributions along the flow direction of the multi-perforated tube tends to be more uniform, as larger orifices were positioned at the inlet side of the multi-perforated tube, compared with no orifice area change along the flow direction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1005-1012
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• 2001

When vortex tubes are applied to enhance the coefficient of performance of refrigeration system, the smaller one is preferable. However, the existing vortex generator with a nozzle hole diameter of 0.5mm was not suitable due to chocking of the nozzle hole. Therefore, experimental investigation was made to find an appropriate geometry of vortex generator, which could give a comparable effect of energy separation to commercial ones without chocking problem. The tested vortex generators were tangential and spiral types, which had single inducing channel with larger cross-sectional area than that of conventional multi-hole ones. The experimental result showed that the performance of the spiral type was better than that of the tangential one. As a small size of spiral one, the diameter of cold-end orifice is proposed to an half of tube diameter for the application to refrigeration system, while cold mass fraction ratio is 0.5∼0.6 for a desirable operation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1598-1603
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• 2004

This paper is an experimental study on the performance characteristic with a variation of capillary diameter and length. The performance characteristic of a refrigeration system is predicted that it is occurring changes of flow pattern and pressure drop in a capillary tube because of reduction of capillary diameter 0.74 to 0.6 mm. The difference between experimental results and analytical results is mainly caused by values of friction factor for using to calculate pressure drop through a small diameter capillary tube under 0.74mm. The experimental equation is derived from capillary tube test data using curve fitting method.