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부하변동에 의한 지중유효열전도도와 보어홀 전열저항 해석
노정근(Ro,Jeong-Geun),연광석(Yon,Kwang-seok),송헌(Song,Heon) 한국태양에너지학회 2011 한국태양에너지학회 논문집 Vol.31 No.4
Investigation of the effective soil thermal conductivity(κ) is the first step in designing the ground loop heat exchanger(borehole) of a geothermal heat pump system. Another important factor is the borehole thermal resistance(R<SUB>b</SUB>). Thermal response tests offer a good method to determine the ground thermal properties for the total heat transport in the ground. This is done by supplying a constant heat power into a borehole heat exchanger. There are two methods to supply a constant heat power. One is to employ the electricity provided by Korea Electric Power Corporation(KEPCO). The other is to use electricity generated by a generator. In this study, the power supply regulation was found to reduce when the electricity generated by the generator was used. This is because the generator evaluated with the power supply characteristically reduces the power supply regulation between an overload and a complex using. But it sometimes occurs a power supply regulation in In-situ thermal response test. In this case getting of κ, R<SUB>b</SUB> requires delay times and restored normal state. However, the effect of the delay times and restored normal state on the soil thermal conductivity and borehole thermal resistance is very small. Therefore it is possible to use a generally accepted delay times and restored normal state in the analysis. In this work, it is also shown that an acceptable range Δκ, ΔRb, for normal state and regulation state might be approximately 0.01-0.16 W/m · k, and -0.004-0.007m · K/ W, respectively. Thus, restored normal state of power supply regulation is valuable to recommend.
지중 열전도율이 보어홀 길이에 미치는 영향에 관한 연구
이세균 ( Se Kyoun Lee ),노정근 ( Jeong Geun Ro ) 충북대학교 산업과학기술연구소 2009 산업과학기술연구 논문집 Vol.23 No.2
The effect of soil thermal conductivity on the borehole length is studied. In performing this work the solution of line source model is used. A new concept, (L/Q)r , borehole length per unitgeothermal load ratio, is developed to compare the effect of soil thermal conductivity on the borehole length. It is shown that (L/Q)r is a function of soil thermal conductivity(k)and only very weak function of borehole thermal resistance(R(b)). There is no functional dependency of the (L/Q)r on the temperature( T(fe). Thus it is easy to estimate the effect of on the borehole length with (L/Q)r . The result of this study is also examined with EED analysis.
Song Heon(송헌),Ro Jeong-Geun(노정근) 한국태양에너지학회 2011 한국태양에너지학회 논문집 Vol.31 No.5
생활공간 냉난방용 열펌프의 성능향상을 위해 R22의 대체 냉매로서 새로운 혼합냉매22/R23/R152a(RM-1)을 개발하고 U.S.A.의 NIST사의 REFPROP program을 이용해 이 혼합냉매의 P-hdiagram을 구성하여 실용화에 이용할 수 있도록 하였다. 본 연구는 실험을 통해 R22와 RM-1의 열펌프 성능효과를 분석하였다. 입·출구 물의 온도와 제 2의 전열매체로서 물의 질량유량 압축기의 소요 에너지 그리고 열펌프의 기타 열적 특성을 다양한 조건하에서 측정하였다. 이 실험 데이터를 통해 공기-물 열펌프 시스템에서의 RM-1과 R22의 성능계수(COP)를 비교하였다. 이를 통해 혼합냉매 RM-1을 사용하는 열펌프 시스템은 외기온 -17℃에서도 2.2의 성능계수로 작동하는 결과를 본 연구에서 보여주었다.
이세균(李世均) 교수(敎授) 정년퇴임기념특집(停年退任紀念特輯) : 지중 열전도율이 보어홀 길이에 미치는 영향에 관한 연구
이세균 ( Se Kyoun Lee ),노정근 ( Jeong Geun Ro ) 충북대학교 산업과학기술연구소 2010 산업과학기술연구 논문집 Vol.24 No.2
The effect of soil thermal conductivity on the borehole length is studied. In performing this work the solution of line source model is used. A new concept, (L/Q) , borehole length per unit geothermal load ratio, is developed to compare the effect of soil thermal conductivity on the borehole length. It is shown that (L/Q) is a function of soil thermal conductivity(K) and onlyvery weak function of borehole thermal resistance(R(b)). There is no functional dependency of the (L/Q) on the temperature(L/Q). Thus it is easy to estimate the effect of K on the borehole length with (L/Q) . The result of this study is also examined with EED analysis.
선형열원법에 의한 지중유효열전도도와 보어홀 전열저항 해석
이세균(Lee Se-Kyoun),우정선(Woo Joung-Son),노정근(Ro Jeong-Geun) 한국태양에너지학회 2010 한국태양에너지학회 논문집 Vol.30 No.4
Investigation of the effective soil thermal conductivity(κ) is the first step in designing the ground loop heat exchanger(borehole) of a geothermal heat pump system. The line source method is required by New and Renewable Energy Center of Korea Energy Management Corporation in analyzing data obtained from thermal response tests. Another important factor in designing the ground loop heat exchanger is the borehole thermal resistance(R<SUB>b</SUB>). There are two methods to evaluate R<SUB>b</SUB> : one is to use a line source method, and the other is to use a shape factor of the borehole. In this study, we demonstrated that the line source method produces better results than the shape factor method in evaluating R<SUB>b</SUB>. This is because the borehole thermal resistance evaluated with the line source method characteristically reduces the temperature differences between an actual and a theoretical thermal behaviors of the borehole. Evaluation of R<SUB>b</SUB> requires soil volumetric heat capacity. However, the effect of the soil volumetric heat capacity on the borehole thermal resistance is very small. Therefore, it is possible to use a generally accepted average value of soil volumetric heat capacity(=2MJ/㎥·K) in the analysis. In this work, it is also shown that an acceptable range of the initial ignoring time should be in the range of 8∼16 hrs. Thus, a mean value of 12 hrs is recommended.
물-물 열펌프시스템에 관한 열역학 제1 및 제2 법칙 해석
이세균(Lee Se-Kyoun),우정선(Woo Joung-Son),노정근(Ro Jeong-Geun) 한국태양에너지학회 2007 한국태양에너지학회 논문집 Vol.27 No.4
Thermodynamic analysis of water-to-water heat pump system based on the first and second law of thermodynamics is carried out in this study. This analysis shows the distribution of irreversibilities throughout the system components and informs us of a potential improvements with the temperature condition changes. Source water temperature( T A ), utilization water temperature( T D ) and temperature differences( ΔT AB’ ΔT CD) are important factors to affect system performances such as component irreversibilities, exergetic efficiency and COPH. Advantages and disadvantages with these factors are discussed. Second law optimization phenomena with T A and ΔT AB are also indicated.
이세균(Lee Se-Kyoun),우정선(Woo Joung-Son),노정근(Ro Jeong-Geun) 한국태양에너지학회 2006 한국태양에너지학회 논문집 Vol.26 No.3
Thermodynamic irreversibility analysis of an air-to-water heat pump system is analyzed in this study. This analysis shows the distribution of irreversibilities(true losses in thermodynamic sense) through the system components and informs us of a potential improvements with the irreversibility factor decreases. The results show that the largest irreversibilities occur in the motor-compressor unit. The remaining irreversibilities are distributed relatively uniformly through the other parts including utilization system. The increase of performance can be attained through either the improvement of adiabatic efficiency of motor-compressor unit(ηmc) or the reduction of temperature difference(ΔT). With the decrease of utilization temperature(Tu) COPH also increases but the exergetic efficiency decreases. The increase of COPH of about 0.05 can be accomplished with 1K decrease of ΔT or T u.