On a second test rig in Hannover, the pressure wave machine was investigated in order to study the characteristic
behavior of this type of machinery as well as to get results for the efficiencies. Fig. 7 shows the resulting efficiencies
for the compression side 7Jis,c and for the expansion side 'T};s,e· The results were obtained at the test rig with an
original pressure wave machine that was designed to work as a supercharger. The boundary working conditions
were 21 °C compressor inlet temperature, 30°C expander inlet temperature and 1.4:1 as the pressure ratio.