Ammonia heat pumps for district heating: thermo-economic optimization analysis based on evaporator geometry for either direct expansion or chilled water configurations

• Published in: Journal of physics. Conference series 2023-12, Vol.2648 (1), p.12093
• Main Authors: Passarelli, A F, Viscito, L, Merlo, U, Filippini, S, Mauro, A W
• Format: Article
• Language: English
• Subjects: Ammonia; Cooling; District heating; Economic analysis; Electric heating; Evaporators; Heat exchangers; Heat pumps; Heat transfer coefficients; Heating; Heating systems; Optimization; Physics; Pressure drop; Water temperature; Working fluids
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/2648/1/012093

Electric heat pumps are recognized as a key technology for decarbonization and have received increasing policy support in several countries over the last few years. These devices offer a highly efficient form of electric heating and could make an important contribution to the transition to a low carbon future, especially in case of district heating systems. Within this context, this paper presents a thermo-economic optimization analysis of a 7.35 MW electric heat pump system employed for district heating purposes and using ammonia as working fluid. The implemented code gathers multiple sub-models calibrated ad-hoc from real data or manufacturers’ datasheets. The heat exchangers are simulated by considering phenomenological equations and well-known heat transfer coefficient and pressure drop prediction methods. The optimization analysis is performed at constant condensation temperature that guarantees in/out hot water temperatures of 30/62 °C and is focused on the matching between compressor and evaporator heat exchanger, by considering either a direct expansion system or a chilled water heat pump. Both the coefficient of performance (COP) and the set-up costs are considered as optimization performance indicators for the construction of the Pareto front.