دانلود رایگان مقاله بهینه سازی و تجزیه و تحلیل ترمودینامیکی چرخه استرلینگ

Abstract

A model for the description of the thermal efficiency of a lunar surface nuclear reactor power system with eight free piston Stirling engines to generate nominal electrical power of 100 kWe was developed. The heat loss of the hot heat pipes, finite rate heat transfer, regenerative heat loss, finite regeneration process time and conductive thermal bridging losses were considered. The results showed that the thermal efficiency increased and then decreased with the hot side temperature increase. The highest thermal efficiency was about 0.29 under the condition of the effectiveness of the regenerator being 0.9 and compression ratio being 2. Higher cold side temperature had bad effect on the thermal efficiency but could reduce the size of the heat rejection system. When the cold side temperature was designed as 500 K, the lowest power system mass of 6.6 ton could be obtained. Enhanced heat transfer of the heat exchangers would increase the thermal efficiency but higher values of the nominal convection heat transfer coefficient of the heat exchangers would lead to a negligible thermal efficiency increase. The results obtained here may provide a new ideal to design lunar surface nuclear powered Stirling cycle.

4. Conclusions

A theoretical model was developed for the thermal efficiency predication of a Stirling cycle applied for lunar surface nuclear power system. It was found that the maximum of the thermal effi- ciency of about 0.29 could be obtained, when the hot side temperature was 1050 K. The radiation heat loss of the hot heat pipes could lead to the decrease of the thermal efficiency if the hot side temperature was higher. A decrease of the cold side temperature could result in an increase of the thermal efficiency. But lower cold side temperature would have bad effect on heat rejection to the outer space by radiation, which could lead to a larger system size and mass. When the cold side temperature was 500 K, the lowest mass of the power system of 6.6 ton can be obtained. Higher nominal convection heat transfer coefficient of the heat exchangers could improve the system thermal efficiency. A compromise between heat exchangers’ mass and system thermal efficiency should be considered, since higher values of nominal convection heat transfer coefficient of the heat exchangers resulted in a negligible increase of the thermal efficiency. In the future, more detailed description about the heat exchangers, Stirling engines and heat rejection system should be revealed.