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This paper presents a case study experimental validation of PISTACHE which is a new presizing tool intended for designers and planners. It facilitates pre-design and allows the evaluation of annual performance and the integration potential of solar heating, cooling and domestic hot water closed systems. This new tool has been performed in order to standardize the sizing methodology and the comparison of the SHC&DHW closed systems. The comparison framework used in PISTACHE has been performed using seasonal performance indicators that were issued and gathered from experimental data provided by several operating plants. Thus, PISTACHE is an easy graphical user interface and free downloadable tool. In order to check the reliability of the new developed tool, two configuration modes are investigated in this experimental study: a simple cooling mode (RAFSOL plant) and a double cooling and heating mode (SONNENKRAFT installation). The whole validation process is performed using the GenOpt optimization program to determine the optimum set of internal parameters for PISTACHE tool.

• An experimental analysis of a liquid-to-water heat pump with R407C is presented. • Experimental results for space heating with domestic hot water production (DHW). • The effect of using or not a liquid–vapor heat exchanger (LVHEx) is evaluated. • DHW and LVHEx affects refrigerant charge distribution inside the heat pump. • DHW production and LVHEx affects the heat pump performance. This paper presents an experimental study of a R407C liquid-to-water heat pump for combined space heating (SH) and domestic hot water (DHW) production. The main components of the heat pump are a scroll compressor, a desuperheater for DHW production, two brazed plate heat exchangers (condenser and evaporator) and a thermostatic expansion valve. A liquid–vapor heat exchanger (LVHEx) has been included in order to study its effect on the heat pump performance. Experimental results for typical operating conditions in the heating mode of operation (low and medium temperature applications) are presented and discussed. These operating conditions are combined with simultaneous DHW production at different flow rates and temperature values. Results show that, in general, the COP is higher with simultaneous SH and DHW production than with SH alone. Also, using the LVHEx yields lower heating and compression powers and, in general, slightly lower COP values. [ABSTRACT FROM AUTHOR]

This paper aims to highlight the potential of solar water heater installations in Morocco. The project involves the comparison of active and passive solutions for energy efficiency in buildings. To this end, a numerical simulation model of solar water heater installations is created under TRNsys. Three hot water demand scenarios (Low, Standard, and High) were taken into account for the six climatic zones defined in the Moroccan thermal regulation of constructions. The same software (TRNsys) is used to model a pilot building consisting of 16 flats. Energy efficiency actions have been applied to the building envelope (insulation and glazing) and simulations are made for the six areas. The simulation results comparing energy and financial savings show the influence of subsidized gas prices on solar water heaters’ relevance despite significant energy savings. This work proves that solar water heaters will be a primary obligation for Morocco, taking into account changes in butane gas prices.

Abstract The present paper is aimed at the energetic analysis of a solar hot water system performed on a dwelling located in different cities in Italy, precisely, from north to south: Bolzano, Turin, Bologna, Rome, Brindisi and Trapani. The study is focused on a group of apartments, where the domestic hot water is provided by a solar system coupled with a storage tank and a recirculation loop; it is worth to mention that the recirculation loop is obligatory on this kind of plants. Therefore, a dynamic energetic study is carried out, assigned the hot water load profiles and the set parameters of the solar collectors with reference to the configurations here tested (flat plane and evacuated tube). Thus, dynamic simulations have been performed by means of TRNSYS simulations tool, setting different parameters: collector configuration and mass flow rate. Several ideas and results emerged from this study, such as the sizing process of the whole system, according to the variation of the solar fraction for all the analyzed scenarios. A digression with simulation results regarding a specific case concludes the paper. More specifically, the study of water temperature oscillations in winter and summer time with reference to the climatic data of Bologna has been carried out under particular operating conditions: i) the pump of the recirculation loop is powered all time (24 hours a day) ii) the pump is switched off during the night, except when the water temperature in the loop falls below a certain threshold temperature. [ABSTRACT FROM AUTHOR]

Solar assisted heat pump systems have been widely applied in domestic hot water productions due to their sustainability and stability in operations. However, their performance efficiency requires further improvement using advanced technologies such as energy storage with phase change materials (PCM) and optimal system controls. Accordingly, a test rig of a new indirect solar assisted heat pump (IDX-SAHP) system has been designed, built and instrumented. The IDX-SAHP system consists of three operational loops: solar thermal, solar assisted heat pump and load profile. A PCM heat exchanger tank was purposely designed and installed in the system solar thermal loop to store solar energy, when applicable, and release heat when required by the heat pump. In addition, an air cooling heat exchanger was also installed in the solar thermal loop to absorb heat from the ambient air for the heat pump. A detailed control strategy has been designed and implemented for the system for efficient operation in different modes and maintain constant load supply water temperature during an operational day. In different weather conditions of sunny and overcast, comprehensive measurements were carried out on the test rig and system structures with and without the PCM tank. Test results showed that the system could efficiently meet the daily domestic hot water demand and the PCM heat exchanger integration exerted a significant effect on system stability and performance efficiency. Quantitatively, the average COP of the IDX-SHAP system with a PCM tank could increase 6.1% and 14.0% on sunny and cloudy days respectively compared to systems without PCM tank integration. [ABSTRACT FROM AUTHOR]

In this paper, the concept design of a small-scale CSP system for residential application is presented and by means of analytical simulations. The concept configuration consists of 48 hexagonal heliostats for a total reflecting surface area of 8.7 m 2 and a nominal power of 5 kW th . The main objective of this work is to describe the design of a small-scale CSP system and to present an analytical simulation tool with the aim to assess the influence of different irradiance data on the performance of the system. Three different Italian locations have been considered: the city of Ghedi for the North of Italy, Roma for the Centre and Bari for the South. The simulations using the solar radiation data (SoDa) in 2005 and the mean year data of the Meteonorm database are analyzed and compared. Results disclose that the performance calculated using single year and mean year irradiance data for Roma and Bari differ less than 10%. Instead, in the case of Ghedi the difference is larger than 20%. In addition, the simulation tool allows to evaluate the thermal energy collected throughout the year: in Roma and Bari it is over 7721 kWh and 7647 kWh respectively, which is a consistent amount of energy that can be used for residential and civil applications; in Ghedi, only 5384 kWh are collected. [ABSTRACT FROM AUTHOR]

• The first review of electrical heat pumps assisted by natural gas is performed. • Many different layouts and control strategies were found. • In most of the analyzed case studies, a rule-based control strategy is assumed. • Researchers presented very heterogeneous key performance indicators. • Exhaustive environmental analyses are very rarely presented. In this paper, a comprehensive review is performed on hybrid systems using electrical Heat Pumps for Heating, Ventilation & Air Conditioning systems and Domestic Hot Water production using case studies from 2016 to 2022. This work particularly focuses on studies that investigated systems with electrical Heat Pumps assisted by a gas boiler. Some studies that considered the exploitation of renewable energy sources, but not as a whole substitute for fossil sources, have also been included. In particular, the analysis investigated the layouts of the systems by considering the type and the size of the components, the control methods applied (by distinguishing rule-based control methods and predictive control methods), and the main performance indices used to calculate energy, exergy, environmental and economic performance. Most of the analysed studies demonstrated that the hybrid systems could be very advantageous if the switch or the integration of the two generators is well managed. Nevertheless, the energy and economic performances are very different for each system studied. They are highly influenced by the control strategies implemented and by the objective functions adopted. Furthermore, climate can influence performance while affecting the Coefficient Of Performance of the heat pump and the availability of energy sources. Regarding economic issues, the systems' performances vary according to specific Country tariff structures. The review reported a promising research activity also pursued by manufacturers of components and equipment. Nevertheless, the paper highlights new possible research and development directions. [ABSTRACT FROM AUTHOR]