A THERMODYNAMIC AND MECHANICAL ENGINEERING INVESTIGATION OF A RECIPROCATING JOULE CYCLE ENGINE

Abstract

Current automotive technology is driving towards developing cleaner and more efficient engines that still conform with the public's demand for power and performance. New technologies are also being developed which expand the public's knowledge and awareness of dual fuel, hybrid and even electric vehicles. Gas Turbines, for use at an automobile level have been left largely unexplored (with the exception of Rover in the 1950' s). The application of continuous combustion to a reciprocating engine results in an operating cycle identical to that of a Gas Turbine, but with a reciprocating compressor and expander. This eliminates the efficiency losses associated with scaling turbines down in size and also the considerable costs while maintaining the advantages of high thermal efficiency, cleaner combustion and hence good emissions characteristics, and allows a degree of operational flexibility. This research undertakes to demonstrate that a reciprocating Gas Turbine engine operating with a Joule (Gas Turbine) Cycle has potential as an alternative form of motive power when applied to an automotive application. A prototype engine has been developed and tested to obtain some basic data. A theoretical model of the cycle has been created on a spreadsheet to enable assessment of the performance of the engine under somewhat idealised conditions. Certain basic assumptions have been made in the model and not all losses have been accounted for, but a clear indication of the engines potential has been gained from this exercise. If an engine could be produced that reflected the relatively high thermal efficiencies (about 40%) predicted by the model then it may prove suitable for automotive applications. The culmination of this research however is the ability to state the potential of the Reciprocating Joule Cycle engine. Unfortunately the prototype engine was unable to sustain itself without external assistance, and even then was unable to operate for extended periods of time due to the combustion chamber. It was therefore felt that the engine would not be suitable for automotive applications due to the extensive development required. It may prove more applicable to static applications.