This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the ...This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.展开更多
The analysis and the design of turbojet engines are of great importance to the improvement of the system performance.Many researchers focus on these topics,and many important and interesting results have been obtained...The analysis and the design of turbojet engines are of great importance to the improvement of the system performance.Many researchers focus on these topics,and many important and interesting results have been obtained.In this paper,the thermodynamic cycle in a turbojet engine is analyzed with the entransy theory and the T-Q diagram.The ideal thermodynamic cycle in which there is no inner irreversibility is analyzed,as well as the influences from some inner irreversible factors,such as the heat transfer process,the change of the component of the working fluid and the viscosity of the working fluid.For the discussed cases,it is shown that larger entransy loss rate always results in larger output power,while smaller entropy generation rate does not always.The corresponding T-Q diagrams are also presented,with which the change tendencies of the entransy loss rate and the output power can be shown very intuitively.It is shown that the entransy theory is applicable for analyzing the inner irreversible thermodynamic cycles discussed in this paper.Compared with the concept of entropy generation,the concept of entransy loss and the corresponding T-Q diagram are more suitable for describing the change of the output power of the analyzed turbojet engine no matter if the inner irreversible factors are considered.展开更多
In order to further investigate how much fuel heat sink could be increased and how much power generation could be obtained by using recooling cycle for a regeneratively cooled scramjet,the energy conversion from heat ...In order to further investigate how much fuel heat sink could be increased and how much power generation could be obtained by using recooling cycle for a regeneratively cooled scramjet,the energy conversion from heat to electricity and the fuel heat sink increase in recooling cycle are experimentally investigated for fuel conversion rate and components of gas cracked fuel products at different fuel temperatures.The results indicate that the total fuel heat sink(i.e.,physical+chemical+recooling) of a recooling cycle is obviously higher than the heat sink of fuel itself,and the maximum heat sink increment is as high as 0.4 MJ/kg throughout the recooling cycle.Furthermore,the cracked fuel mixture has a significant capacity of doing work.The thermodynamic power generation scheme,which adopts the cracked fuel gas mixture as the working fluid,is a potential power generation cycle,and the maximum specific power generation is about 500 kW/kg.Turbine-pump scheme using cracked fuel gas mixture is also a potential fuel feeding cycle.展开更多
文摘This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.
基金supported by the National Natural Science Foundation of China(Grant Nos.51376101&51356001)
文摘The analysis and the design of turbojet engines are of great importance to the improvement of the system performance.Many researchers focus on these topics,and many important and interesting results have been obtained.In this paper,the thermodynamic cycle in a turbojet engine is analyzed with the entransy theory and the T-Q diagram.The ideal thermodynamic cycle in which there is no inner irreversibility is analyzed,as well as the influences from some inner irreversible factors,such as the heat transfer process,the change of the component of the working fluid and the viscosity of the working fluid.For the discussed cases,it is shown that larger entransy loss rate always results in larger output power,while smaller entropy generation rate does not always.The corresponding T-Q diagrams are also presented,with which the change tendencies of the entransy loss rate and the output power can be shown very intuitively.It is shown that the entransy theory is applicable for analyzing the inner irreversible thermodynamic cycles discussed in this paper.Compared with the concept of entropy generation,the concept of entransy loss and the corresponding T-Q diagram are more suitable for describing the change of the output power of the analyzed turbojet engine no matter if the inner irreversible factors are considered.
基金supported by the Key Program of the National Natural Science Foundation of China (Grant No. 51076035)
文摘In order to further investigate how much fuel heat sink could be increased and how much power generation could be obtained by using recooling cycle for a regeneratively cooled scramjet,the energy conversion from heat to electricity and the fuel heat sink increase in recooling cycle are experimentally investigated for fuel conversion rate and components of gas cracked fuel products at different fuel temperatures.The results indicate that the total fuel heat sink(i.e.,physical+chemical+recooling) of a recooling cycle is obviously higher than the heat sink of fuel itself,and the maximum heat sink increment is as high as 0.4 MJ/kg throughout the recooling cycle.Furthermore,the cracked fuel mixture has a significant capacity of doing work.The thermodynamic power generation scheme,which adopts the cracked fuel gas mixture as the working fluid,is a potential power generation cycle,and the maximum specific power generation is about 500 kW/kg.Turbine-pump scheme using cracked fuel gas mixture is also a potential fuel feeding cycle.