A single stage Stirling pulse tube cryocooler was designed based on REGEN 3.2 and fabricated for testing. The experimental results show that the cooler can provide a cooling capacity of 5.0 W at 79.1 K, and produce a ...A single stage Stirling pulse tube cryocooler was designed based on REGEN 3.2 and fabricated for testing. The experimental results show that the cooler can provide a cooling capacity of 5.0 W at 79.1 K, and produce a no-load temperature of 57.0 K, operating with an average pressure of 2.50 MPa and a frequency of 60 Hz, performance results that are very close to the calculated values. The cryocooler can be cooled from room temperature to 80 K in 8.5 min. The fast cooldown time is a result of the small regenerator.展开更多
An inter-phasing pulse tube cooler (IPPTC) consists of two pulse tube units, which are connected to each other at hot ends of the pulse tubes through a needle valve. This paper presents the computational fluid dynamic...An inter-phasing pulse tube cooler (IPPTC) consists of two pulse tube units, which are connected to each other at hot ends of the pulse tubes through a needle valve. This paper presents the computational fluid dynamic (CFD) results of an IPPTC using a 2D axis-symmetrical model. General results such as the phase difference between pressure and velocity at cold end and hot end, the temperature profiles along the wall, the available lowest temperature as well as its oscillations and the coefficient of performance (COP) for IPPTC are presented. The formation of DC flow and its effects on the performance of the cooler are investigated and analyzed in detail. Turbulence, which is partially responsible for the poor overall performance of a single orifice pulse tube cooler (OPTC), is found to be much reduced in IPPTC and its performance is improved significantly compared with the single OPTC.展开更多
Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as w...Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as working fluid was established by Fluent,and thermal effects were specially considered in the simulation.The validity of the LN_(2) cavitation model was verified by the experimental data of hydrofoil LN_(2) cavitation from earlier studies by NASA.Cavitation characteristics of LN2 in the cryogenic globe valve under three typical working conditions were investigated.The average pressure and pressure pulse at different positions of the wall were further studied to reveal cavitation risks from fatigue and vibration.Results show that with similar valve structure and openings,the pressure pulsation frequencies of LN_(2) are lower than those of water,and the shape and location of the cavitation clouds also show significant differences.For LN_(2) cavitation,an extended period of valve opening at 66% should be avoided since its pressure pulse peak is the largest compared to openings of 33% and 100%,and reaches 5×10^(7) Pa.The opening of 33% should also be monitored because of the large torque caused by the pressure difference between the two sides of the valve baffles.To prevent resonance,a critical state for the valve opening and the connecting pipe length is proposed.These predictions of cryogenic cavitation in the globe valve are helpful for the safe and reliable operation of cryogenic fluid transport systems.展开更多
基金the National Natural Science Foundation of China (No. 50676081)the Science and Technology Department of Zhejiang Province (No. 2007C30063), China
文摘A single stage Stirling pulse tube cryocooler was designed based on REGEN 3.2 and fabricated for testing. The experimental results show that the cooler can provide a cooling capacity of 5.0 W at 79.1 K, and produce a no-load temperature of 57.0 K, operating with an average pressure of 2.50 MPa and a frequency of 60 Hz, performance results that are very close to the calculated values. The cryocooler can be cooled from room temperature to 80 K in 8.5 min. The fast cooldown time is a result of the small regenerator.
基金Project supported by the National Natural Science foundation of China (No. 50706042)the Science and Technology Department of Zhejiang Province (No. 2006C24G2010027)the Natural Science Foundation of Zhejiang Province (No. Y105519), China
文摘An inter-phasing pulse tube cooler (IPPTC) consists of two pulse tube units, which are connected to each other at hot ends of the pulse tubes through a needle valve. This paper presents the computational fluid dynamic (CFD) results of an IPPTC using a 2D axis-symmetrical model. General results such as the phase difference between pressure and velocity at cold end and hot end, the temperature profiles along the wall, the available lowest temperature as well as its oscillations and the coefficient of performance (COP) for IPPTC are presented. The formation of DC flow and its effects on the performance of the cooler are investigated and analyzed in detail. Turbulence, which is partially responsible for the poor overall performance of a single orifice pulse tube cooler (OPTC), is found to be much reduced in IPPTC and its performance is improved significantly compared with the single OPTC.
基金Project supported by the National Key R&D Program of China(No.2017YFB0603701)the Key Program of the National Natural Science Foundation of China(No.51636007)partly supported by theèih China Aerodynamics Research and Development Center
基金supported by the National Natural Science Foundation of China(No.50776076)the Doctoral Fund of the Ministry of Education of China(No.20110101110022)the National Funds for Distinguished Young Scientists of China(No.50825601)
基金This work is supported by the Research Fund of State Key Laboratory of Technologies in Space Cryogenic Propellants(No.SKLTSCP1601)the Key Research and Development Program of Zhejiang Province(No.2020C01029)+1 种基金the Key Program of National Natural Science Foundation of China(No.51636007)the Natural Science Foundation of Zhejiang Province(No.LQ21E060011),China.
文摘Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as working fluid was established by Fluent,and thermal effects were specially considered in the simulation.The validity of the LN_(2) cavitation model was verified by the experimental data of hydrofoil LN_(2) cavitation from earlier studies by NASA.Cavitation characteristics of LN2 in the cryogenic globe valve under three typical working conditions were investigated.The average pressure and pressure pulse at different positions of the wall were further studied to reveal cavitation risks from fatigue and vibration.Results show that with similar valve structure and openings,the pressure pulsation frequencies of LN_(2) are lower than those of water,and the shape and location of the cavitation clouds also show significant differences.For LN_(2) cavitation,an extended period of valve opening at 66% should be avoided since its pressure pulse peak is the largest compared to openings of 33% and 100%,and reaches 5×10^(7) Pa.The opening of 33% should also be monitored because of the large torque caused by the pressure difference between the two sides of the valve baffles.To prevent resonance,a critical state for the valve opening and the connecting pipe length is proposed.These predictions of cryogenic cavitation in the globe valve are helpful for the safe and reliable operation of cryogenic fluid transport systems.
基金Project supported by the National Natural Science Foundation of China(No.51106071)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
基金Project supported by the National Natural Science Foundation of China(No.50776076)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20110101110022),China