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정평석(P.S Jung),원민영(M.Y.Won),김수연(S.Y.Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
A low temperature difference model Stirling engine is a small stirling engine running with several degree of temperaature difference without power output. In this study, the design parameters to give maximum power are discussed. As results, the phase angle is about 100 degree, and compression ratio is 15% of the ratio of heat source temperatures at maximum power condition.
신기열,정평석,김수연,이상천,Shin, K.Y.,Jung, P.S.,Kim, S.Y.,Lee, S.C. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.1
The present paper investigated irreversibilities and energy flow of a vapor compression refrigerator. The entropy generation and the available energy dissipation in components of the system were analyzed by using experimental data. It was shown that the dissipated available energy in the compressor including electric motor was much more than those in other components. The effects of the pressure drop and heat loss on irreversibilities in the condenser and the evaporator were small in comparison with heat transfer.
강동진,류제욱,정평석,Kang, D.J.,Ryu, J.W.,Jung, P.S. 대한기계학회 1993 대한기계학회논문집 Vol.17 No.7
A procedure for the prediction of the off-design performance of a gas turbine engine is proposed. The system performance at off-design speed is predicted by coupling the thermodynamic models of a compressor and a turbine. The off-design performance of a compressor is obtained using the stage-stackimg method, while the Ainlay-Mathieson method is used for a turbine. The procedure is applied to a single-shaft gas turbine and its predictability is found satisfactory. The results also show that the net work output increases with the increase of the turbine inlet temperature, while the thermal efficiency is marginal. The maximum thermal efficiency at design point is obtained between the highest pressure ratio and design pressure ratio.
이상원,김수연,정평석,Lee, S.W.,Kim, S.Y.,Jung, P.S. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.3
The Collins cryocooler is numerically analysed with the optimization technique, and the optimum operating and design conditions are searched. This paper shows that liquefied helium quantity has an external maximum w.r.t. the total mass flow rate, the mass flow rates through expander and the capacities of heat exchangers. The liquefied helium quantity increases as the compressor exit pressure of the cryocooler does. The maximum quantity of liquefied helium and the maximum coefficient of performance have been found to exist in extremum, depending on the ratios of each heat exchanger capicities to the total one. At the optimum condition, the capacity of heat exchanger in high temperature region is larger than that in low temperature region.
주기적 맥동류가 흐르는 극저온 냉동기의 재생기에서 압력강하
정평석,윤성호,장일효,김수연 嶺南大學校 工業技術硏究所 1996 工業技術硏究所論文集 Vol.24 No.1
The characteristics of the periodic pulsatile flow in a regenerator was experimentally studied with flow periods and mesh numbers of regenerator packing materials. The regenerator test system which can generate periodic pulsatile flows with various periods was constructed. The pressure drop and the volume flowrate of the pulsatile flow in the regenerator significantly depends on the periods and the porosities of the materials. The pressure drop are decreased as the period of the pulsatile flow and the porosity of the packing material increase.
김수연,조경철,정평석 嶺南大學校 工業技術硏究所 1997 工業技術硏究所論文集 Vol.25 No.2
A regenerative type cryocooler with free piston and 4 solenoid valves was manufactured and the performance was tested. The valve timing to operate the system had been decided by trial-error method, which was very difficult and exhaustive. But this time, the value timing was designed to be controlled automatically by measuring two characteristic pressures. As results, the control system operates with satisfaction. And the performance test of the cryocooler was carried out with this control system to search the optimal operating conditions. The test results showed that the potential of application of the present cryocooler and control system was very high although its structure is simple and operating control is easy.