• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.21-21
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• 2007

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.591-596
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• 2008

The present study has been conducted to study the performance of dedicated outdoor air handling unit in central and personal air-conditioning. With conventional central and personal air-conditioning systems which are designed according to the maximum load, humidity increase above comfort level can not be avoided as the cooling load decreases. The adoption of dedicated outdoor air handling unit, however, can solve this problem. Moreover, the dedicated outdoor air handling unit has the characteristics of anti-bacteria due to dry coil, energy saving and good indoor air quality. During cooling seasons, dedicated outdoor air handling unit can save energy up to 30% than the conventional cooling+reheating system for controlling both temperature and humidity.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.248-248
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• 2003

• Journal of Power Electronics
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• v.6 no.1
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• pp.29-37
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• 2006

A sensorless control for an IPM (Interior Permanent Magnet) synchronous motor in a single piston rotary compressor is presented in this study. The rotor position is estimated from the d-axis and q-axis current errors between the real system and a motor model of the position estimator. The torque pulsation of the single piston rotary compressor is compensated to reduce speed ripples, as well as, mechanical noise and vibration. The proposed sensorless drive enables the compressor to operate at a lower speed which increases energy savings and reduces mechanical noise. It also gives high speed operations by a flux weakening control for rapid air-cooling and heating of the heat pump air-conditioners.

• Journal of Energy Engineering
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• v.4 no.1
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• pp.67-75
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• 1995

50 kW 냉방용 화학열펌프에 관한 전산설계를 하기 위하여 반응기 모사용 부프로그램을 작성하였으며 전체 시스템을 위하여 상용모사기인 ASPEN PLUS를 이용하였다. 반응물로 각각 SrCl2-8/1 NH3 그리고 MnCl2-6/2 NH3를 사용하는 두 시스템에 대하여 비교 연구하였으며, 조작조건에 따라 시스템 설계치의 변화를 관찰하였다. 이로부터 향후 실용화될 화학열펌프 시스템에 대한 기본 설계자료를 제시할 수 있었다. SrCl2-8/1 NH3를 반응물로 한 경우 반응기의 UA는 6,868.2 J/(s·K), 출력은 95.2 kW이었고, 제한 성능 계수는 0.40이었다. MnCl2-6/2 NH3의 경우 UA는 1,569.7 J/(s·K), 출력은 109.0 kW이었으며 제한 성능계수는 0.34이었다. 이로부터 SrCl2-8/1 NH3을 반응물로 한 시스템이 MnCl2-6/2 NH3를 사용한 시스템보다 유리함을 알 수 있었다.

• Applied Science and Convergence Technology
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• v.25 no.3
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• pp.47-50
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• 2016

Low temperature test for half-wave resonator (HWR) cryomodule is performed at the superfluid helium temperature of 2 K. The effective temperature is defined for non-uniform temperature distribution. Helium leak detection techniques are introduced for cryogenic system. Experimental set up is shown to make the low temperature test for the HWR cryomodule. The cooldown procedure of the HWR cryomodule is shown from room temperature to 2 K. The cryomodules is precooled with liquid nitrogen and then liquid helium is supplied to the helium reservoirs and cavities. The pressure of cavity and chamber are monitored as a function of time. The vacuum pressure of the cryomodule is not increased at 2 K, which shows leak-tight in the superfluid helium environment. Static heat load is also measured for the cryomodule at 2.5 K.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1238-1243
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• 2006

최근 열펌프 시스템 설치가 해마다 평균 10-30% 정도 꾸준히 증가하고 있다. IEA HP Annex 28, 29('열펌프 성능평가 기술', '열펌프 시장 현황 현안')등 국제공동연구를 통한 꾸준한 지열원 열펌프 시스템 응용분야의 발전은 기존의 지열원 시스템에 비해 비용과 더불어 보다 많은 에너지 절감효과를 가져왔다. 지열기술의 성공적 사용여부는 기술의 견실함, 설계기술의 개발, 기반시설설치, 히트펌프와 부품제조업자의 반응에 기인한다. 최근 주요 연구동향은 토양열전도 측정, 지열히트펌프 시스템 전주기 성능평가, 하이브리드 시스템의 초기비용 절감과 이러한 열펌프 시스템 설계방법분야 개발에 대해 초점이 맞춰지고 있다. 본 기술현안 보고서는 최근 국내외 연구동향을 정리하여 본다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.3 no.3
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• pp.180-184
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• 1974

From the point of view of the second law of thermodynamics, house heating and cooling systems were analysed for saving energy. The analysis provides a theoretical basis for the heat-pump application. Also the efficiency of energy use is defined more rigorously by comparing the thermodynamic availability actually consumed in heating and cooling with the minimum thermodynamic availability required to do the same heating and cooling. It was found that the present 'Ondol' heating system has a heating efficiency of around $8\%$ according to the definition described here. Several schemes to inprove the efficiency are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.32-38
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• 2020

This study summarizes test methods and evaluation methods for examining the thermal characteristics of Jeju-type ground heat exchangers (GHXs) installed on Jeju Island, and analyzes the ground temperature and thermal characteristics of ground heat exchangers installed in various regions by using thermal response tests (TRT). Jeju Island is composed of volcanic rock layers, and the groundwater flow is well developed. A Jeju-type GHX can be installed up to 30 m from groundwater level after drilling a borehole. The ground heat exchanger has a structure in which several pipes are inserted into the borehole. In order to examine the characteristics of the Jeju-type GHX, tests were conducted on ground heat exchangers installed in four places on Jeju Island (Pyoseon, Jeju, Namwon, and Hallym). As a result of the analysis of the Jeju-type ground heat exchanger, the ground circulating water temperature stabilized according to the heat injection, depending on the installed location, and was formed within one to three hours. The ground heat exchanger capacity in Hallym was highest at 73.4 kW (cooling) and 82.8 kW (heating), and the Jeju-type calculation was lowest at 34.1 kW (cooling) and 23.3 kW (heating).

• The KSFM Journal of Fluid Machinery
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• v.10 no.2 s.41
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• pp.16-21
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• 2007

Potential advantages of using vapor injection in a two stage rotary compressor for a $CO_2$ heat pump water heater system were addressed in this paper by numerical simulation. Vapor separated from a flash tank in the middle of the expansion process can be used for injection into the second stage suction plenum of the compressor to improve the system performance. Vapor injection increases the intermediate pressure between the two stages, thus increasing the first stage compressor work and reducing that of the second stage. As a whole, however, the compressor input power increases due to injected mass flow rate for the second stage. Computer simulation showed that increment of the cooling capacity by vapor injection exceeded that of the compressor work, thus improving the system performance. COP improvement by vapor injection was calculated to be about 5-14% for normal operating conditions. With vapor injection, a maximum COP was found when the displacement volume of the second stage becomes 90-95% of that of the first stage of the compressor.