Abstract: By quantitatively analyzing the exhaust gas parameters from a bus engine under different driving conditions and calculating the absorption/compression hybrid refrigeration cycle, the structure of the refrigeration generator and its heat transfer area were determined. A model with distributed parameters was built for the heat transfer between the engine exhaust gases and working fluid in the generator. The influences of the generator cooling loads on the characteristic of the hybrid refrigeration cycle were analyzed at different driving speeds. The results showed that at the condition of cooling load 30 kW, so long as the driving speed higher than 100 km/h, the waste heat absorption refrigeration sub-cycle alone can meet completely the cooling request of the bus. When the driving speeds between 35 and 100 km/h, the combination of both absorption and compression refrigeration sub-cycles can supply the sufficient cooling. When driving speeds lower than 35 km/h, the cooling of the bus was provided only by the compression refrigeration sub-cycle.

Key words: thermal energy engineering, exhaust gas waste heat, hybrid refrigeration cycle, coil generator, heat transfer model