Test results of a medium temperature solar engine

The results of a test programme of a completely fluorinated organic fluid solar engine at fluid temperatures around 250°C are Engine design characteristics. as deduced using the particular fluid properties are briefly described problems encountered in the preliminary test phase and relating to fluid losses, heat exchangers reduced performance and minor mechanical disturbances are illustrated together with the actions undertaken to improve the original engine behaviour. Detailed engine overall and components performance, as derived from a series of tests, carried out with a fuel fired heat source (simulating the actual solar heating loop) are presented. Engine efficiency, with reference to the net power output at the high speed shaft proved to be around 21%, at 250°C turbine inlet temperature which can be compared with 22.6% design value at the same temperature and with 23.6% original goal at 280°C top cycle temperature. The analysis of the heat transfer coefficients within the various heat exchangers support the suspicion that available information on working fluid transport properties is not sufficiently accurate.