An Alternative Thermodynamic Cycle for Reciprocating Piston Engines

Authors

Prof. N. Jackson, Ricardo plc, Shoreham-by-Sea; Prof. A. Atkins, J. Eatwell, Ricardo Innovations Ltd., Shoreham-by-Sea; Dr. R. Morgan, University of Brighton

Year

2015

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 783

Summary

Ricardo has explored an alternative approach to recover exhaust energy from a diesel engine. This combines both Diesel and Ericsson Cycles into an integrated process to recover waste heat within a single thermodynamic cycle. The key changes to the four stroke configuration to implement the integrated cycle are isothermal compression and heat addition from the exhaust gas to the charge air after the end of compression. Transfer of exhaust gas heat at the end of compression requires the use of a “split cycle”, where the four stroke sequence is split into two separate elements; intake and compression are carried out in one cylinder and combustion plus expansion and exhaust in another. Gas is transferred from the compression cylinder to the expansion cylinder via a heat exchanger that transfers heat from the exhaust to this high pressure gas. The use of isothermal compression enhances the recovery of exhaust gas waste heat and significantly improves cycle efficiency. A number of isothermal compression technologies have been explored including use of a water spray during compression and also direct injection of cryogenic nitrogen or air.