West number


The West number is an empirical parameter used to characterize the performance of Stirling engines and other Stirling systems. A Stirling engine is a heat engine that operates by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there is a net conversion of heat energy to mechanical work. The West number is often used to approximate of the power output of a Stirling engine. The average value is (0.25) for a wide variety of engines, although it may range up to (0.35), particularly for engines operating with a high temperature differential.

Related formulas


WnThe West number (dimensionless)
W0The power output of the engine (watt)
THThe absolute temperature of the expansion space or heater (K)
TKThe absolute temperature of the compression space or cooler (K)
PThe mean average gas pressure (Pa)
VSwept volume of the expansion space (m3)
fThe engine cycle frequency (Hz)