Solar Source Heat Pump Research Articles

Effects of ambient conditions on solar assisted heat pump systems: a review.

Solar assisted heat pump (SAHP) systems aim to increase the performance of heat pumps by supporting with solar energy using various heating modes, whose performances depend on ambient conditions. In the literature, SAHP systems are classified by structure types, and the heating mode options are not considered as the main priority of the design but a result of the structure of the system. This paper aimed to investigate the effect of ambient conditions on heating modes, and identify the preferable ambient condition ranges for each SAHP system depends on their heating modes, by using a narrative review of 47 recent studies, that shed light on the problem. For this purpose, direct solar heating (DSH), air source heat pump (ASHP), solar source heat pump (SSHP) and solar-air source heat pump (S/ASHP) modes were stated as the basic heating modes of SAHP systems. In accordance with the literature, SAHP systems were classified as direct expansion solar assisted heat pump (DX-SAHP) and series, parallel and dual source indirect expansion solar assisted heat pumps (IDX-SAHP). Solar irradiation, ambient temperature, relative humidity and wind speed has been taken as major ambient conditions to investigate. Reviewed studies indicated that, parallel and series IDX-SAHP are preferable in high solar irradiations about 800W/m2 with their DSH mode options. Frosting on evaporator is prevented in DX-SAHP with its S/ASHP mode, and even in the presence of frosting, unlike IDX-SAHPs ASHP mode, freezing is a factor that improves performance on flat evaporator in cold and humid conditions. This study indicates that there are obscure areas for future studies to focus on for a better comparison between SAHP types. Moreover, proposed novel designs of this paper, such as solar preheating of air in IDX-SAHP systems to add S/ASHP mode as an option, might enhance the performance and applicability of SAHP systems.

Simulation study of solar-source heat pump system with sensible energy storage

A simulation study of the solar-source heat pump (SSHP) system that consists of solar collector group, heat exchanger (water-to-water), energy storage tank, heat pump with vapor compression and circulating pumps is carried out. The performance of the designed system is investigated both experimentally and theoretically. The performance of coefficient of the heat pump in the refrigerant circuit (COP) and whole system (COPS) is computed in the range of 3.1–4.2 and 2.3–3.3, respectively. The sensible energy stored system used of the water as storage matter is theoretically tested for the first time in the cold climate conditions. A simulation model of the energy stored SSHP is also performed, and the simulation results are compared with the experimental conclusion. In average, the differences between the theoretical and experimental values of the COP and COPS are about 8 and 5%, respectively. It is found that the developed model corresponds well with the experimental data.

Ground or solar source heat pump systems for space heating: Which is better? Energetic assessment based on a case history

Outdoor air is a common heat source for heat pumps, whose limits are well known. However the use of different sources requires additional investment costs. It is then interesting, starting from a given additional investment, on one side to evaluate different compositions for a set of sources and on the other to choose the most favourable source from time to time, according to the building energy demand and the thermal level of each available source. This paper presents a study conducted on the base of a heating system based on multi-source heat pumps. By means of dynamic simulations in TRNSYS, several scenarios were assessed with respect to primary energy consumption in order to define, given an additional budget for the heat pump system, whether it is a good option to invest in ground source or in solar source for the heating systems.The analysis reveals that the most energy efficient solution both for absorption and compression heat pump based systems is to adopt a multi-source system; the ground exchangers should then be sized to allow a minimum ground inlet temperature of −2°C, and the saving in investment cost should be directed to buy solar collectors.

Simulations of Combined Solar Thermal and Heat Pump Systems for Domestic Hot Water and Space Heating

The system combination of solar thermal collectors and heat pumps is a very attractive option for increasing the renewable energy usage at worldwide level for heating and domestic hot water preparation. In this work parallel and series combined solar and heat pump systems are analyzed within the IEA SHC Task44/HPP Annex38 reference conditions for different buildings and a typical Central European climate. Three combined systems have been studied in detail: solar and air source heat pump, solar and ground source heat pump, and exclusively solar source heat pump in combination with an ice storage. Numerical calculations have been performed using two simulation platforms: TRNSYS-17 and Polysun-6®. Comparisons between the two simulation environments have been also provided. Moreover, a reference case without solar has been used to determine the potential efficiency benefits of using solar collectors compared to a system with a heat pump alone in the specified climate and for covering the specified heat load. Simulations presented in this work show that differences in system performance up to 4% can be expected between TRNSYS-17 and Polysun-6® for air source based systems, and higher discrepancies, up to 14% are obtained for ground source based systems. Comparisons between combined solar thermal and heat pump systems with their respective “heat pump only” reference solutions show that the absolute electricity savings of air source are usually higher compared to ground source based systems. Systems using large ice storages are able to reach seasonal performance factors in the range of 5, which is of the order of performance of combined solar and ground source heat pump systems.

Predictive control of radiant floor heating and solar-source heat pump operation in a solar house

Solar radiation can supply a significant portion of the energy requirements of a house through the harmonized use of passive solar design and building-integrated active solar energy systems (e.g., building-integrated photovoltaic, photovoltaic/thermal systems, or solar thermal collectors). Given the variability of solar radiation, energy storage technologies, along with carefully planned control strategies, can offer significant benefits for the performance of these systems in terms of energy consumption, peak load reduction, and thermal comfort for the occupants. This article investigates the application of a predictive control methodology for a solar house. The case study is a room with a simple geometry with high insulation and air-tightness values and large windows (i.e., a typical room found in a passive solar house). Predictive control is applied at two different, but closely linked, levels: (a) local-loop control of a radiant floor heating system and (b) supervisory control of the temperature of a water tank—used for thermal energy storage—heated with a solar-source heat pump. The development of control strategies is facilitated by the use of simplified building models obtained from more detailed models appropriate for building simulation. This methodology provides insight into the relevance of different design and control parameters and makes it easier to apply software tools designed specifically for testing control algorithms.

Experimental thermal performance of a solar source heat-pump system for residential heating in cold climate region

Abstract Solar source heat pump systems present tremendous environmental benefits when compared to the conventional systems for residential applications. In addition to not exhausting natural resources, their main advantage is, in most cases, total absence of almost any air emissions or waste products. In order to investigate the performance of a solar source and energy stored heat-pump system in the province of Erzurum, an experimental set-up was constructed, which consisted of twelve flat-plate solar collector, a sensible heat energy storage tank, a water-to-water plate heat exchanger, a liquid-to-liquid vapor compression heat pump, water circulating pumps and other measurement equipments. The experiments were carried out from January to June of 2004 and, the collector efficiency ( η c ), the heat pump coefficient of performance (COP) and the system performance (COPS) were calculated. In these months performed of the experiments, the outdoor temperature range varies from −10.8 °C to 14.6 °C. This study shows that the system could be used for residential heating in the province of Erzurum having the coldest climate of Turkey.

The Thermal Performance of Refrigerant Cooled Solar Collectors in a Solar Source Heat Pump System

Solar Collectors cooled directly with Refrigerant 12 and acting as the evaporator of a solar source heat pump system has been experimentally investigated. The refrigerant cooled solar collector may be operated at an evaporation temperature lower than its ambient temperature and thus has an efficiency higher than that of the flat plate solar collectors in conventional systems.

A solar source heat pump with refrigerant-cooled solar collectors for cold climates

A heating system best suited to the local requirements and resources of Quebec, Canada, was developed. Solar source heat pump systems with solar collectors cooled directly with R 12 appear to be a promising means of utilizing solar energy in cold climates. The solar collectors may be operated at evaporation temperatures lower than their ambient temperature, and performance improved by cooling it with an evaporative refrigerant, rather than a single phase fluid.