• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.4 no.2
• /
• pp.1-7
• /
• 2008

GSHP(Ground Source Heat Pump) has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the system reliability has been key issues and barriers to insure a better system performance as designed originally in ISO (international standard organization) standard. This paper introduces a systematic method to verify its intended design target so called as ISO performance data based commissioning technology for a water to air GSHP system. The commissioning technology starts from are to the international standard ISO performance data of a GSHP model and to compare its installed operation data and to calibrate and tune to the target optimum operation parameters. Results indicated that cooling capacity could be raised up to 76.6% from 46.6% from this proposed commissioning technology.

• Nuclear Engineering and Technology
• /
• v.24 no.3
• /
• pp.311-318
• /
• 1992

During mid-loop operation of Nuclear Power Plant, to prevent the Decay Heat Removal System (DHRS) from failure due to air entrainment of free surface vortex in the piping system, a set of simulating experiments was performed. Through these experiments, a relation between the non-dimensionalized numbers, such as H/d, Froude number, Reynolds number, was found. It was also found that the perturbation of the system by the disturbance such as pump start, valve operation, etc., has a strong effect on the free surface vortex. Furthermore, from viewpoint of reactor safety, a modified inlet device which is reducer type is strongly recommended for the prevention of air entrainment into DHRS.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2000.11a
• /
• pp.199-204
• /
• 2000

산업과 과학발달에 의해 더욱 물질적으로 풍요로워진 인류에게 에너지와 환경문제는 새로운 당면문제로 부각되고 있다. 특히 1992년 몬트리올 협정에서는 CFC 및 HCFC의 사용을 각각 1997과 2002년부터 전면 금지시키기로 하였고, 1997년에는 2008-2012년까지 전세계 온실가스 배출량을 5.2% 줄이는 것을 골자로 하는 교토 선언이 합의되었다. 이러한 상황을 타개하기 위한 많은 연구 중 흡수식 열펌프는 환경친화적인 자연냉매를 사용하는 열구동 시스템으로 다시 주목을 받고 있다. 특히 흡수식 열펌프의 구성요소 중 흡수에 의하여 고온의 열을 얻을 수 있는 흡수기에 효율적인 열·물질전달 모드를 적용함으로써 제품의 소형화와 에너지 손실 감소를 이루고 있다. 이에 본 연구에서는 새로운 흡수기 모드로 연구되고 있는 기포타입모드를 원통형 흡수기에 적용해 보고, 그 특성을 고찰해 보고자 하였다. 흡수기로 유입되는 ammonia gas와 용액을 cocurrnet 및 countercurrent로 흘려주었고, 높이에 따른 농도, 온도 및 압력을 측정·비교해 보았다.(중략)

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.258-259
• /
• 2011

This paper shows the load characteristics of IH (Induction Heating) Cookers which are those of essential appliances for electrifying residential buildings in smart places. Load experiments are carried out in the same manner as like previous two studies. The results will be used to develop new load models for smart places including heat pump loads for analyzing changed power system environments by the smart grid.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.10
• /
• pp.1812-1817
• /
• 2008

A cooling system for microelectronics is becoming more important as its surface heat density is projected to reach that of the sun surface. The existing technologies using natural and forced convection are limited to solve the problems. Recently, an electrohydrodynamic driven flow is studied as one of the means to cope with this problems. A new method, utilizing a needle-centered nozzle electrode, has been proposed and investigated. The I-V characteristics of the nozzle electrode for deionized water and silicone oil were significantly different from that of without liquid, which might be due to the liquid drop covered on the nozzle tip by the EHD force acting near the needle tip. Results showed that the liquid pumping rate and flow efficiency of the nozzle electrode were very high, especially for the silicone oil. Theoretical analysis also showed the effectiveness of the needle electrode centered in the ceramic nozzle, which, however, can be a means as a liquid pump.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.5
• /
• pp.20-27
• /
• 2009

The effect of borehole thermal resistance on the borehole length is studied. In performing this work a new concept BLRR(borehole length reduction rate) is developed based on the line source model. The solution of line source model is shown to be valid through the comparison with the data of thermal response test. It is shown that BLRR is a function of soil thermal conductivity(k) and borehole thermal resistance($R_b$). The value of BLRR increases with increasing k, which means reducing $R_b$ is more effective when k is high. The reduction of borehole length with change of $R_b$ is easily estimated with BLRR. The validity of BLRR is also examined with EED analysis.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.07a
• /
• pp.261-266
• /
• 2002

1992년 이후 우리나라 원예시설 면적은 매년 크게 증가하여 2000년 말 현재 48,853㏊에 이르고 있으며(농림부, 2001), 그중 양액재배 면적은 '92년에는 13.2㏊에 불과하였으나 연평균 64%씩 증가하여 2000년에는 700㏊에 이르렀다. 이들 양액재배 면적 중 채소류가 70%, 화훼류가 30%를 차지하고 있으며, 작물별로는 토마토가 37%로써 가장 많은 면적이 재배되고 있고, 그 다음으로 장미가 25%를 차지하고 있다. 또한 사용하는 배지별 양액재배 비율은 펄라이트 배지가 319㏊로 전체면적의 46%를 차지하고 있으며, 암면배지가 26%, 혼합배지가 17%를 차지하고 있다(농촌진흥청, 2001). (중략)

• Journal of Energy Engineering
• /
• v.16 no.1 s.49
• /
• pp.1-6
• /
• 2007

The purpose of this study was to investigate the reduction of exhaust gas temperature in a LPG engine that had been converted from a diesel engine. A conventional diesel engine was modified to a LPG (Liquefied Petroleum Gas) engine by replacing the diesel fuel injection pump with a LPG fuel system. The research was performed by measuring the exhaust gas temperature upon varying spark ignition timing, airfuel ratio, compression ratio, and different compositions of butane and propane. Engine power and exhaust temperature were not influenced by various butane/propane fuel compositions. Finally, among the parameters studied in this investigation, spark ignition timing is one of the most important in reducing exhaust gas temperature.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.11 no.1
• /
• pp.1-6
• /
• 2015

This study presents analysis of the experimental data meeting conditions of several applications in real time. The results of this experimental study are as follows: Respectively in cooling and heating performance, a refrigerant charge tank can take automatic control of variation of the refrigerant quantity by controling pressure and temperature of system and outlet water temperature. The COP shows 3.5 in cooling operation and 3.2 in heating operation. The refrigerant quantity increases 0.69 kJ/h. When the outdoor temperature decreases $1^{\circ}C$, Therefore if the temperature become lower from $25^{\circ}C$ to $-16^{\circ}C$, the refrigerant quantity increases about 9.5%. Compared to the normal state experiment results, the COP in automatic control of the refrigerant quantity rises roughly 10%.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.5 no.2
• /
• pp.1-6
• /
• 2009

In this paper, RETScreen program model has been investigated to predict the economic analysis for greenhouse and livestock facility. Load calculation result was 35.2[kW] of greenhouse and the calculation result of livestock facility was 35.5[kW]. Also, a case study of the RETScreen program indicated that the equity payback is 6.9 years for a greenhouse facility and the equity payback is 9.5 years for a livestock facility.