Modelling and transient simulation of a regenerative open Joule cycle reciprocating Ericsson engine for micro-CHP applications

Abstract

The open Joule cycle reciprocating Ericsson engine shows promising results as regards small-scale cogeneration applications using renewable energies such as biomass or solar energy. Integrating a regenerative heat exchanger into a simple open Joule cycle helps to improve the engine performance thanks to the recovery of the waste heat of hot gases downstream the expander. A dynamic model of a small open Joule cycle Ericsson engine with a shell-andtube counter-flow regenerative heat exchanger is developed and simulated in order to study the operation stability, the system behaviour especially during transient phases, and the control strategies. Compared to the engine configuration without regeneration, simulation results predict a slower hot start-up transient followed by a stable operation of the engine with 21% increase of the engine thermal efficiency, 14.3% increase of the engine power output and a 529.5K exhaust air flow suitable for cogeneration purposes. Subjected to a selected perturbation (10kPa compressor inlet pressure drop) the engine reacts well and the operation is stabilized after a much longer transient phase. Valve settings are also addressed to maintain the system set pressure.