ISBN: 978-1-56700-537-0
ISBN Online: 978-1-56700-538-7
ISSN Online: 2377-424X
International Heat Transfer Conference 17
INVESTIGATION OF SUPERIMPOSED EFFECTS OF DEAD VOLUMES AND FRICTIONAL PRESSURE LOSS OF RECUPERATORS IN ISOBARIC EXPANSION ENGINES
Abstract
The efficiency of heat engines is significantly influenced by heat recovery in recuperators. In the case of the Bush-type isobaric expansion engine (IEE), a heat engine which can be operated with heat sources starting from 50°C, the thermal efficiency can be significantly increased by using recuperators. On the other hand, internal fluid volumes of the heat exchanger and the pressure loss arising during operation have a negative effect on the thermal efficiency. Until now, mutual interaction of heat recovery, dead volume and pressure loss has not been studied. In this work a new procedure in which a dynamic heat exchanger model and a thermodynamic approach are combined is proposed and used to identify the limitations of heat recovery in IEEs. As a promising application and an illustrative case study, the utilization of waste heat from a data center as a heat source is considered. For this case, six different working fluids and two different heat exchanger designs are investigated. The IEE can achieve 30% of the Carnot efficiency with working fluid CO2. Besides, with CO2, a better engine performance was found for heat exchangers with a smaller cross-section. When operating with working fluid R134a, a high sensitivity to frictional pressure drop was registered.