Thermodynamic power system using binary working fluid

Abstract

A thermodynamic power system has a low-temperature closed bottoming cycle using a first working fluid (first gas) and open or closed modified Brayton topping cycles using a second working fluid (second gas). In the bottoming cycle a mixture of a first gas such as helium or hydrogen and a fine dispersed low-temperature non-freezable lubricating liquid is polytropically compressed in a compressor and then the liquid content is separated from the first gas. The separated first gas is isobarically heated using heat from the second gas and then the heated first gas is adiabatically expanded and cooled while performing useful work and thereafter is fed to the compressor and mixed with the separated liquid to serve as a coolant and facilitate rejection of polytropic heat and to supplement the cool gas/liquid mixture providing polytropic compression of the first gas and thus completing the bottoming cycle. The low-temperature bottoming cycle functions to cool the second working fluids of the open or closed modified Brayton topping cycles before their compression. The power system using a high temperature heat source can generate a large amount of specific power to achieve a high actual thermal efficiency greater than 0.8.