Techno-Economic Analysis of a Heat Pump Cycle Including a Three-Media Refrigerant/Phase Change Material/Water Heat Exchanger in the Hot Superheated Section for Efficient Domestic Hot Water Generation

Johann Emhofer,Gabriel Zsembinszki,Werner Pink,Felix Hochwallner,Tilman Barz,Luisa F. Cabeza,Andreas Strehlow,Birgo Nitsch,Klemens Marx,Michael Wiesflecker

doi:10.3390/app10217873

Johann Emhofer, Gabriel Zsembinszki + Show 8 more

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https://doi.org/10.3390/app10217873

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Abstract

Integration of a three-media refrigerant/phase change material (PCM)/water heat exchanger (RPW-HEX) in the hot superheated section of a heat pump (HP) system is a promising approach to save energy for domestic hot water (DHW) generation in multi-family houses. The RPW-HEX works as a desuperheater and as a latent thermal energy storage in the system. The latent thermal energy storage is charged during heating and cooling operation and discharged for DHW production. For this purpose, the water side of the RPW-HEX is connected to decentralized DHW storage devices. DHW consumption, building standards and climate, energy prices, material costs, and production costs are the constraints for the selection of the optimal storage size and RPW-HEX design. This contribution presents the techno-economic analysis of the RPW-HEX integrated into an R32 air source HP. With the aid of experimentally validated dynamic computer models, the optimal sizing of the RPW-HEX storage is discussed to maximize energy savings and to minimize the investment costs. The results are discussed in the context of a return of investment analysis, practical implementation aspects and energetic potential of the novel technology.

Highlights

Today’s commercially available air source heat pumps (HPs) work highly efficient and make a valuable contribution to achieve climatic goals such as the reduction in the amount of CO2 in our atmosphere
12.4 years for an RPW-HEX storage size of 5 kWh operating in eco-mode with large domestic hot water (DHW) storage devices
20 years of 1083 EUR were found for Case #1, a passive house located in Helsinki with 7.75 standard apartments—operation in eco-mode with 8 large (280 L) DHW storage devices

Summary

Introduction

Today’s commercially available air source heat pumps (HPs) work highly efficient and make a valuable contribution to achieve climatic goals such as the reduction in the amount of CO2 in our atmosphere. In the United States, for example, the share of HP sales for newly constructed buildings exceeds 40% for single-family dwellings, and is nearly 50% for new multi-family buildings. The EU market is expanding quickly, with 12% annual average growth since 2015. Sci. 2020, 10, 7873 are responsible for half of all sales in the European Union, while Sweden, Estonia, Finland and Norway have the highest penetration rates, with more than 25 HPs sold per 1000 households each year [1]

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