Advances in Defining a Closed Brayton Conversion System for Future ARIANE 5 Space Nuclear Power Applications

Abstract

The present European ARIANE space program will expand into the large ARIANE 5 launch vehicle from 1995. It is assumed that important associated missions would require the generation of 200 kWe or more in space during several years at the very beginning of the next century. For this reason, in 1983, the French C.N.E.S. (Centre National d’Etudes Spatiales) and C.E.A. (Commissariat a` l’Energie Atomique) have initiated preliminary studies of a space nuclear power system. The currently selected conversion system is a closed Brayton cycle. Reasons for this choice are given: high efficiency of a dynamic system; monophasic, inert working fluid; extensive turbomachinery experience, etc. A key aspect of the project is the adaptation to heat rejection conditions, namely to the radiator geometry which depends upon the dimensions of the ARIANE 5 spacecraft. In addition to usual concepts already studied for space applications, another cycle arrangement is being investigated which could offer satisfactory compromises among many considerations, increase the efficiency of the system, and make it more attractive as far as the specific mass (kg/kWe), the specific radiator area (m2/kWe), and various technological aspects are concerned. Comparative details are presented.

Performance Evaluation of Space Solar Brayton Cycle Power Systems

“…The same figure showed that to provide a decreased compressor inlet temperature, radiator area must grow. Tillette (1987) presented similar results. What, then, is the optimum compressor inlet temperature?…”

High Efficiency Solar Dynamic Space Power Generation System

“…In fact the temperature distribution of CBC waste heat in nuclear dynamic systems is in the range from 300K to 700+800 K [ 7 ] , and for SD systems in the range from 300K to 500K. This means that in SD systems it is not possible to utilize the supercritical ORC cycle described in [l] for nuclear space combined cycles (toluene as working fluid).…”

“…For example ORC systems using toluene as a working fluid have accumulated over 105,000 hours of operation in terrestrial systems and the fluid properties have been extensively evaluated to satisfy the life requirements of the space applications. For the CBC system, both SD and nuclear dynamic (ND) , the cycle efficiency can be increased by the incorporation of a recuperator [7]. However, in SD systems the incorporation of a recuperator is extremely important, because the quantity of heat transferred in the recuperator results in a reduction in the amount of heating required in the receiver (reduction of the concentrator size), in a decrease in the quantity of thermal energy storage material required to supply the heat during the eclipse, and in a reduction in the amount of waste heat to be rejected (efficiency increase), thus reducing the size of both the gas cooler and the radiator.…”