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부준홍(Boo, Joon-Hong),정의국(Jung, Eui-Guk) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.06
A numerical study was conducted on a simplified model of a high-temperature solar receiver which incorporates liquid-metal heat pipe. The objective of this paper is to compare the isothermal characteristics of the heat pipe receiver with the conventional receiver utilizing convection of molten salt as heat carrier. The solar receiver was assumed to be subject to a concentration ratio between 50 and 1,000 to supply high-temperature heat to a stirling engine for electric power generation. For simplicity of the analysis, a cylindrical geometry was assumed and typical dimensions were used based on available literature. The heat pipe had a shape of double-walled cavity and the working fluid was a sodium. The analysis was performed assuming that the radiation heat flux on the inner walls of the receiver was uniform, since the focus of this study was laid on the comparison of the conventional type and heat pipe type receiver. The results showed that the heat pipe type exhibited superior performance when the operating temperature becomes higher. In addition, to explore the advantage of the heat pipe receiver, the channel shape and dimensions should be adjusted to increase the heat transfer area between the wall and the heat trnasfer medium.
소결금속 윅과 메탄올을 사용하며 바이패스라인이 부착된 루프히트파이프의 작동 특성
부준홍(Joon Hong Boo),정의국(Eui Guk Jung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Operating characteristics of a loop heat pipe (LHP) having a bypass line was investigated experimentally. The LHP had a sintered metal wick as a capillary structure and methanol as a working fluid. The sintered metal wick was made of stainless steel of which the average pore size was 5㎛ and porosity of 47%. A bypass line of a small diameter was attached between the vapor escape passage and the liquid reservoir. The dimension of the flat evaporator was 50(L)×40(W)×30(H) ㎜ and that of the condenser was 50(L)×40(W)×11(H) ㎜. Wall and pipe material of the LHP was stainless steel and heating area was 35(W) ㎜×35(L) ㎜. The inner diameters of vapor and liquid transport lines were 4.0 ㎜ and 2.0 ㎜, and the lengths of the two lines were both 0.5 m. The LHP was tested for three different tilt angles of horizontal, favorite tilt, and adverse tilt. The thermal load range was up to 290 W at the condenser above evaporation position. Furthermore, the effect of a bypass line on the start-up transient as well as steady-state operation was presented and discussed.
가변열전도성능 히트파이프(VCHP)의 온도제어 성능에 관한 실험
부준홍(Joon Hong Boo),박철민(Cheol Min Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A VCHP was fabricated and tested for its thermal performance. The container was made of copper, and the working fluid was water. STS-316 screen of mesh number 100 was inserted as a capillary structure. As a baseline performance, a normal heat pipe of the same dimensions was tested in advance to compare with VCHP, where an inert gas container was attached. The outer diameter of the heat pipe was 12.8 ㎜ and the total length was 600 ㎜. The evaporator and the condenser lengths were both 200 ㎜. The thermal load ranged from 20 to 300W. Typical result revealed that the operating temperature of the VCHP stayed almost constant, while that of the normal heat pipe varied as much as 40℃. Therefore, it was demonstrated that the VCHP is very effective for temperature control of heatdissipating devices.
부준홍(Boo Joon Hong),정의국(Jung Eui Guk) 한국태양에너지학회 2006 한국태양에너지학회 학술대회논문집 Vol.- No.-
For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply. Based on fluid dynamic and heat transfer theories, a series of modeling and simulation was conducted to achieve practical design requirements. An experimental setup was built and tested and the results were compared with theoretical simulation model. The storage tank capacity was 240 L and the outer diameter of piping was 15 ㎜. Number of tube turns tested were 5, 10, and 15. Starting with initial storage tank temperature of 80℃, the temperature variation of the supply hot water was investigated against time, while maintaining minimum flow rate of 10 LPM. Typical result showed that the hot water supply of minimum 30℃ could be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincided well within 10% in general.
태양열 반응로용 나트륨 히트파이프의 열이송 특성에 관한 실험적 연구
부준홍(Boo, Joon-Hong),박철민(Park, Cheol-Min),김진수(Kim, Jin-Soo),강용혁(Kang, Yong-Heack) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05
Cylindrical stainless-steel/sodium heat pipe for a high-temperature application was manufactured and tested for transient and steady-state operations. The container material was made of stainless-steel 316, and the working fluid was sodium. Stainless-steel 316 mesh screen was inserted as a capillary structure. The working fluid fill charge ratio was approximately 64 sim 181% based on the pore space of the wick. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The evaporator part was 150 mm and the condenser 80 mm. The performance test of the heat pipe has been conducted in the furnace with up to 800 W. The variation of the average heat transfer coefficient was investigated as a function of heat flux and vapor temperature. As input thermal load increased, it was showed that difference of temperatures in evaporator and condenser decreased and that operating section and heat transfer characteristics at the heat pipe increased.
중온 작동 범위에서의 슬랩윅 히트파이프 성능에 관한 실험 연구
정복원,부준홍,곽희열,Chung, Won-Bok,Boo, Joon-Hong,Kwak, Hee-Youl 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.11
A slab-wick heat pipe was fabricated and tested for applications where the condenser temperature is in a range of 80 to 12$0^{\circ}C$. The pipe material was 9.53 mm O.D. copper tube and the working fluids were ethanol and water. The total length of the heat pipe was 1.6 m, in which evaporator section was 1.4 m and the condenser was 0.10 m. The slab was a composite wick structure fabricated with STS316 wire screens. Thermal load was varied for a specified fill charge ratio and inclined angle. The optimum fill charge ratio was identified to be 110% based on a theoretical calculation of the pore space in the slab wick of the heat pipe. The maximum thermal load was 120W for ethanol and the same was 200W for water with the condenser temperature of 8$0^{\circ}C$. The thermal performance of the slab wick heat pipe is analysed in terms of temperature characteristics and thermal resistance against thermal load, tilt angle and fill charge ratio.