Recently, it is predicted that the fossil fuels will be sufficient for a few decades at the present extraction rates. So, the performance studies of the internal combustion engines play an important role to achieve th...Recently, it is predicted that the fossil fuels will be sufficient for a few decades at the present extraction rates. So, the performance studies of the internal combustion engines play an important role to achieve the best operating point at different weather temperatures. In the present study, the effects of the inlet air temperatures on the engine performance characteristics were studied at different cooling loads. Several experiments were carried out on a single cylinder diesel engine （SCDI）. The performance characteristics of SCDI included： brake power, specific fuel consumption, brake thermal efficiency and exhaust emissions （carbon dioxide, CO2, carbon monoxide CO, and hydrocarbon HC）. The findings show that the inlet air temperature and cooling conditions have appreciable effect on the performance characteristics of the SCDI especially at low cooling rate. It can be concluded that the high cooling rate leads to the enhancement in the brake thermal efficiency, the b.s.f.c, and the emitted COz, CO, and HC. On the other hand the high cooling rate leads to the decrease in the volumetric efficiency. So, a compromising between the inlet air temperature and the cooling rate should be recommended for the engine best performance.展开更多
Along with the development of space science and technology,miniature liquid helium temperature long life cryocooler is a focus subject in cryogenic study.Since it is the precondition of space detection researches,inst...Along with the development of space science and technology,miniature liquid helium temperature long life cryocooler is a focus subject in cryogenic study.Since it is the precondition of space detection researches,institutions of space in many countries do the research on it.In this article,we designed a compound cooling system.A three-stage high frequency thermal coupled pulse tube cryocooler was used to precool a Joule-Thomson(JT)cryocooler.This system has no moving parts at low temperatures and is hence suitable for space operation.Liquid helium temperature was successfully achieved in both open loop and closed cycle experiments.In the closed cycle experiment,when 473 W electric power was inputted,the cooling system reached a no-load temperature of 4.4 K,and a cooling capacity of 11.6 mW was provided at 4.54 K.It is the first miniature liquid helium temperature JT cryocooler in China and the research achievement paves a way for the space application of ultra-long wave infrared detection and THz technologies.展开更多
文摘Recently, it is predicted that the fossil fuels will be sufficient for a few decades at the present extraction rates. So, the performance studies of the internal combustion engines play an important role to achieve the best operating point at different weather temperatures. In the present study, the effects of the inlet air temperatures on the engine performance characteristics were studied at different cooling loads. Several experiments were carried out on a single cylinder diesel engine （SCDI）. The performance characteristics of SCDI included： brake power, specific fuel consumption, brake thermal efficiency and exhaust emissions （carbon dioxide, CO2, carbon monoxide CO, and hydrocarbon HC）. The findings show that the inlet air temperature and cooling conditions have appreciable effect on the performance characteristics of the SCDI especially at low cooling rate. It can be concluded that the high cooling rate leads to the enhancement in the brake thermal efficiency, the b.s.f.c, and the emitted COz, CO, and HC. On the other hand the high cooling rate leads to the decrease in the volumetric efficiency. So, a compromising between the inlet air temperature and the cooling rate should be recommended for the engine best performance.
基金supported by the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences(Grant No.XDA04074100)the National Natural Science Foundation of China(Grant No.51306196)
文摘Along with the development of space science and technology,miniature liquid helium temperature long life cryocooler is a focus subject in cryogenic study.Since it is the precondition of space detection researches,institutions of space in many countries do the research on it.In this article,we designed a compound cooling system.A three-stage high frequency thermal coupled pulse tube cryocooler was used to precool a Joule-Thomson(JT)cryocooler.This system has no moving parts at low temperatures and is hence suitable for space operation.Liquid helium temperature was successfully achieved in both open loop and closed cycle experiments.In the closed cycle experiment,when 473 W electric power was inputted,the cooling system reached a no-load temperature of 4.4 K,and a cooling capacity of 11.6 mW was provided at 4.54 K.It is the first miniature liquid helium temperature JT cryocooler in China and the research achievement paves a way for the space application of ultra-long wave infrared detection and THz technologies.
