In our laboratory, we designed, built and tested a 15 Watt model engine in order to get some experience with the technology, the design details and to develop new components such as the control system (we are using electrically activated valves).
Fig. 1 shows the model with some of the components. Unfortunately, the condenser temperature / pressure did not fall below 75°C / 50 kPa (abs). This was caused by the fact that the condenser injection water was drawn from the immediate surroundings (i.e. the injection water had a temperature in the 50-60°C range already). Due to time constraints, the experiments had to be discontinued in May 2016. Efficiencies ranged from 3.0 % (n = 1) to 3.8% (n = 1.5), comparing well with the theoretical maximum efficiencies of 3.6% and 4.5% (for T0 = 100°C and Tcond = 75°C).
And here’s a little video:
It shows a test run of the model engine.