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Physics   > Home   > Entropy: Thermodynamics – Energy – Environment – Economy   > Special issue ECOS   > Article

Thermodynamic analysis of a high-temperature heat pump using low GWP natural working fluids for upgrading district heating to process heating

Analyse thermodynamique d’une P.A.C. haute temperature a fluide naturel a bas G.W.P. pour renforcer le processus de chauffage d’un réseau de chauffage


Mohsen Sadeghi
Aalborg University
Denmark

Tage Petersen
Danish Technological Institute
Denmark

Zhenyu Yang
Aalborg University
Denmark

Benjamin Zühlsdorf
Danish Technological Institute
Denmark

Kim Stenholdt Madsen
DIN Forsyning A/S
Denmark

Ahmad Arabkoohsar
Aalborg University
Denmark



Published on 17 January 2024   DOI : 10.21494/ISTE.OP.2024.1068

Abstract

Résumé

Keywords

Mots-clés

High-temperature heat pump (HTHP) is a promising technology for decarbonization of process heating through electrification and energy efficiency. Exploiting the potentials requires a simultaneous optimization of the cycle layout and the working fluid. This paper proposes an efficient cascade HTHP and optimizes its thermodynamic performance. Using steam for high-temperature loop and use of alternative hydrocarbons for low-temperature loop are examined. On the application level, district heating is considered as a heat source and evaluated for different supply temperatures, including 80 °C, 70 °C and 40 °C. The results reveal that pentane with highest critical temperature among the suggested hydrocarbons, shows the best energy performance to be paired with steam in the proposed cascade HTHP system. However, concerning the hydrocarbon compressor volumetric heating capacity (VHC) and safety issues, butane is an excellent candidate. In addition, when the heat available in the main transmission lines of district heating unit is considered as the source cooled from 80 °C down 70 °C, the highest value of coefficient of performance (COP) is achieved as 2.74 for the sink condensation temperature of 160 °C.

High-temperature heat pump (HTHP) is a promising technology for decarbonization of process heating through electrification and energy efficiency. Exploiting the potentials requires a simultaneous optimization of the cycle layout and the working fluid. This paper proposes an efficient cascade HTHP and optimizes its thermodynamic performance. Using steam for high-temperature loop and use of alternative hydrocarbons for low-temperature loop are examined. On the application level, district heating is considered as a heat source and evaluated for different supply temperatures, including 80 °C, 70 °C and 40 °C. The results reveal that pentane with highest critical temperature among the suggested hydrocarbons, shows the best energy performance to be paired with steam in the proposed cascade HTHP system. However, concerning the hydrocarbon compressor volumetric heating capacity (VHC) and safety issues, butane is an excellent candidate. In addition, when the heat available in the main transmission lines of district heating unit is considered as the source cooled from 80 °C down 70 °C, the highest value of coefficient of performance (COP) is achieved as 2.74 for the sink condensation temperature of 160 °C.

High-temperature heat pump Low GWP working fluids Steam Hydrocarbons District heating

High-temperature heat pump Low GWP working fluids Steam Hydrocarbons District heating