A Look at the Thermodynamic Characteristics of Brayton Cycles for Space Power

Turbomachinery Characteristics of Brayton-Cycle Space-Power-Generation Systems

“…The thermodynamic characteristics of Brayton-cycle space-power systems were presented in reference (1). Since the radiator is a major size and weight contributor to the power plant, minimum radiator area was chosen as the logical criterion for initial selection of the cycle variables.…”

“…Since the radiator is a major size and weight contributor to the power plant, minimum radiator area was chosen as the logical criterion for initial selection of the cycle variables. This criterion, as explained in (1), can be used for solar as well as nuclear systems. The thermodynamic analysis shows that (a) the requirement for minimum radiator area determines the range of turbomachinery pressure ratios to be considered, and (b) the turbomachinery performance significantly affects system performance and size.…”

“…Reynolds number is directly proportional to weight flow and inversely proportional to viscosity for a given flow area. Neglecting, for the moment, the viscosity effect, Reynolds number is directly proportional to molecular weight, since reference (1) shows that weight flow is directly proportional to molecular weight. Reintroducing the viscosity effect, the relative Reynolds numbers for the fluids of interest (assuming helium as unity) are 1 for helium, 6.0 for neon, 15.7 for argon, and 27.0 for krypton.…”