Exergetic efficiency of high-temperature-lift chemical heat pump (CHP) based on CaO/CO2 and CaO/H2O working pairs
Journal article, 2013

The use of reversible chemical reactions in recuperation of heat has gained significant interest due to higher magnitude of reaction heat compared to that of the latent or sensible heat. To implement chemical reactions for upgrading heat, a chemical heat pump (CHP) may be used. A CHP uses a reversible chemical reaction where the forward and the reverse reactions take place at two different temperatures, thus allowing heat to be upgraded or degraded depending on the mode of operation. In this work, an exergetic efficiency model for a CHP operating in the temperature-level amplification mode has been developed. The first law and the exergetic efficiencies are compared for two working pairs, namely, CaO/CO2 and CaO/H2O for high-temperature high-lift CHPs. The exergetic efficiency increases for both working pairs with increase in task, TH, decrease in heat source, TM, and increase in condenser, TL, temperatures. It is also observed that the difference in reaction enthalpies and specific heats of the involving reactants affects the extent of increase or decrease in the exergetic efficiency of the CHP operating for temperature-level amplification.

temperature amplification

heat transformer


chemical heat pump (CHP)

second law (exergetic) efficiency


first law efficiency


Mehdi Arjmand

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Longcheng Liu

Royal Institute of Technology (KTH)

Ivars Neretnieks

Royal Institute of Technology (KTH)

International Journal of Energy Research

0363907X (ISSN) 1099114X (eISSN)

Vol. 37 9 1122-1131

Areas of Advance


Subject Categories

Chemical Engineering



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