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Title: Exergy analysis of electrically- and thermally-driven engines to drive heat pumps: An exhaustive comparative study

The choice of driving a heat pump with an electrically$-$or a thermally-driven engine is a vexing question complicated by the carbon footprint and environmental impact of using electricity versus natural gas (or waste heat) as the main driver for the respective engines. The amount of useful work generated by these two distinct engines is the focal point of this paper, which addresses a key question: which engine presents a better choice for a given heat pumping application within the constraints of energy and environmental stewardship? Extensive use of energy, exergy, and availability analysis is necessary to quantify the useful work and to examine the issue holistically for both types of engines. The methodology explains why the output of work from these two distinct engines to satisfy a given load is vastly different, a direct consequence of their inherent Irreversibility. Thermodynamic consistency is guaranteed by satisfaction of the First and Second Laws applied to closed systems and their subsystems. The general conclusion is that thermally-driven engines are not industrious converters of heat to mechanical work.
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  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Energy and Transportation Sciences Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; FWP/IAN CEBT002
Accepted Manuscript
Journal Name:
International Journal of Refrigeration
Additional Journal Information:
Journal Volume: 76; Journal Issue: C; Journal ID: ISSN 0140-7007
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Building Technologies Research and Integration Center (BTRIC)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
42 ENGINEERING; heat pumps; availability; sorption; absorption; thermodynamics; Ground-source; Sustainability
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1414303