Hybrid stirling engine-adsorption chiller for truck auxiliary power unit applications.

This paper presents preliminary experimental test results for a novel truck auxiliary power unit (APU) design consisting of a 1 kWe free-piston Stirling engine and 2 kWt zeolite-water adsorption chiller that is powered via waste heat from the engine’s cooling jacket. A prototype system was built and tested to study the interaction dynamics between the Stirling engine and adsorption chiller and to determine the performance of the chiller in extreme ambient temperature conditions. The results show that pulsed thermal loading from the chiller on the engine results in engine power spikes to 110-115% of rated power. An average COP of 0.32±0.06 was achieved for the adsorption chiller and its capacity varied in the range of ~1-3 kWt as the recooler temperature was varied from 25-45 °C. The proposed system has many benefits over existing technologies such as low noise, high reliability and clean emissions without any need for additional exhaust treatment.