BEALE NUMBER FORMULA
The Beale number can be defined in terms of a Stirling engine’s operating parameters:

 B_{n}= W o P V F
where:
 B_{n} is the Beale number
 Wo is the power output of the engine (watts)
 P is the mean average gas pressure (Pa) or ( MPa, if volume is in cm^{3})
 V is swept volume of the power piston (m^{3}, or cm^{3}, if pressure is in MPa)
 F is the engine cycle frequency (Hz)
Beale number is a parameter that characterizes the the performance of Stirling engines.It is often used to estimate the power output of a String Engine design.For engines operating with a high temperature differential,typical values for the beale number are in the range 0.11 to 0.15