• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.749-755
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• 2002

In order to develop a multi-type heat pump system with two indoor units of non-uniform capacities, the optimum refrigerant circuit was developed using capillary tubes. The refrigerant circuit was composed of four main parts, a heating circuit, a cooling circuit, a by-pass circuit and a balance circuit. The system characteristics of multi-type heat pump was investigated through the rating test and the reliability test, using the multi-type psy-chrometric calorimeter. The results of the rating test showed that the capacity of the multi-type heat pump was about 93% of the design value. In particular, the capacity of cooling single mode was about 13% higher than the design value, and the capacity of heating multi mode was about 5% higher than the design value. The reliability of the multi-type heat pump was verified by various reliability tests (overload, extension tube, freeze up, under/over charging, sweat, flood back). The optimal amount of refrigerant charge and compressor capacity were determined from the present work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4197-4203
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• 2013

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

• Fire Science and Engineering
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• v.25 no.6
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• pp.168-177
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• 2011

The combustion test for real box of AC outdoor unit has been performed in this study in order to estimate the fire hazard in multi-system type of AC outdoor unit which is currently used for commercial use. The result showed that in test, there was explosion inside of AC outdoor unit, and flame erupted and fire spread through upper side grill. And then this fire burnt the combustibles such as wires, electronic control board, heat exchange copper plate and plastics etc inside the unit, refrigerant gas pipe was burst due to fire, and accelerated the explosion and flame eruption to outside while the refrigerant was erupting. It is found in this test that the maximum heat release rate of AC outdoor unit is 5,830 kW, the maximum internal temperature measured with infrared camera and thermocouple is $1,201^{\circ}C$, maximum ambient temperature is $881^{\circ}C$, and flame rose higher than about 5 m. It is concluded that the fire in AC outdoor unit cause fire to combustibles around the unit, and may give big damage by generating the secondary fire. It is expected that the result obtained from the test on the real object may be applied to fire realization of AC outdoor unit and estimation of fire spreading to the combustibles around in the future computer simulation.