Gamma vs Beta Stirling Engine

[blade]

From a theoretical perspective, beta stirling engines have better efficiencies because they reduce the dead space. According to this link from SunPower

http://www.sunpowerinc.com/library/pdf/ ... ochure.pdf

their free piston beta stirling engines have an efficiency of 36% when the Th/Tc ratio in Kelvin is 3.0. That is approximately, 54% of the Carnot efficiency.

Are the real world efficiencies of gamma stirling engines better? While they may have more dead volume, their layout may allow for more effective regenerators and less conduction loss from the hot end to cold end. Does anyone know? Is the 54% of the Carnot efficiency the best achieved for Stirling engines when the Th/Tc ratio is 3.0?

[Ian S C]

Think they are fairly much equal, the BETA motor can be a bit fiddly to make friction free as far as the displacer rod passing through the piston. Ian S C