Study and test of a post combustion chamber for a recuperative reheat Stirling machine

Abstract

Stirling machines present a forthcoming potential for substituting the internal combustion engine as an auxiliary power unit in future series hybrid electric powertrains. Different Stirling thermodynamic configurations can be found in the literature. Among them, the recuperative reheat Stirling thermodynamic cycle offers high net specific work and high efficiency, resulting in reduced system's weight, size and integration complexity, as well as reduced vehicle's fuel consumption. This paper presents an experimental investigation of the impact of Stirling combustion reheat process on the system performance and emissions. For that purpose a Stirling combustion chamber was modified and a post combustion chamber was added. The new configuration of the designed combustion chamber was manufactured and tested. The effect of reheating process on pollutant emissions was evaluated by measuring the NOx emissions and compared to the fuel quantity injected in both reheat and no reheat configurations. The test results demonstrate the high importance of reheating process in decreasing the NOx emission. The obtained reduction was more than 50% in comparison to the original construction. Consequently, the recuperative reheat Stirling thermodynamic configuration was selected as the best candidate for replacing the internal combustion engine.