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

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.

Life Cycle Assessment of an Innovative Hybrid Energy Storage System for Residential Buildings in Continental Climates

“…Therefore, the use of PV panels and both the thermal and electrical storage systems help increasing the share of renewable energy. A description of system operating modes can be found in [8]. and electrical storage systems help increasing the share of renewable energy.…”

“…With these targets in mind, a new concept was developed, where heating and domestic hot water (DHW) for buildings are produced with a high share of renewable energy (solar photovoltaic (PV)) and integration of both thermal and electrical storage [8]. Moreover, the concept is based on the use of a heat pump with a refrigerant that has low global warming potential (GWP) and is connected to the PV panels with direct current (DC).…”

“…The performance of such a heat exchanger was demonstrated to be highly efficient [16]. Moreover, the economic performance of the full system has also been assessed [8]. The systems showed a payback time of 12.4 year with energy savings of 622 kWh el per year.…”

A New Methodological Approach for the Evaluation of Scaling Up a Latent Storage Module for Integration in Heat Pumps

“…Such an analysis allows design improvement for different applications. Indeed, the latent heat storage system investigated here was studied for different applications, such as the replacement of a standard evaporator in a heat pump for residential buildings [25] and the use for domestic hot water (DHW) production directly from a heat pump cycle in colder climates [12]. Since different applications have different constraints, starting from the analysis here presented, different applications can be targeted and optimized.…”

“…Usually, numerical methods are used, which might include simplified methods based on empirical approaches [8], numerical methods at different scales, such as detailed simulations of a single component [9], and complete studies of the multi-source energy system, usually employing TRNSYS and EnergyPlus [10,11]. The outcome of the sizing is often the techno-economic analysis of the overall system [12,13], but its reliability and meaningfulness are highly dependent on data quality for the underlying models [10], especially for thermal systems whose dynamic behavior is more difficult to describe compared to electric ones, thus requiring experimental validation and calibration [14]. If an experimental approach is used, however, the problem is shifting to the proper methodology Energies 2021, 14, 7470 2 of 17 to be used, since full-scale testing is not feasible in several applications and therefore there is a need to operate the design and component selection based on small-scale components intended for laboratory operation.…”