Combined Ground Source Heat Pump Research Articles

Feasibility and investigation of residential HVAC system with combined ground source heat pump and solar thermal collectors in different climates of Iran

Geoexchange is one of the most energy-efficient, environmentally clean, and cost-effective space-conditioning systems available on the market. Seasonal storage of solar energy in geothermal boreholes is sharply interesting as a means of heating and cooling in buildings with different applications. In this study, a closed-loop geo-exchange and solar thermal system with two different heat exchangers are examined in an energy-efficient house. TRNSYS, a simulation software tool, was used to model the yearly performance of the hybrid ground-source heat pump (GSHP) system. Two different types of ground heat exchangers, e.g., tube-in-tube and U-tube were employed. The mass flow rate through the heat exchangers and the solar collector was examined to choose the best scenario for each of them. The economic benefits of a gray water heat recovery system and solar collector were studied; the results show that 517 and 536 US Dollars/Year can be saved from each of them, respectively. System performance analysis was carried out in different cities with various climates in Iran. Moreover, a complete economic assessment was evaluated for all cases. The results show that for the same inlet water temperature to GSHP, the tube-in-tube heat exchanger can pass 45% more flow than the U-tube heat exchanger for the same size as the HP. Furthermore, in the absence of the solar collector, a 2.7 × 108 kJ increase was conducted in the auxiliary heater component yearly. Finally, four different climates were evaluated for the launching of the GSHP system with a solar thermal collector. The hot and dry climate with 27 °C fluid inlet to a heat pump, a total borehole depth of 220 m, and an initial cost of $ 25,047 was selected as the most appropriate weather conditions for launching the system in Iran.

Optimisation for interconnected energy hub system with combined ground source heat pump and borehole thermal storage

Ground source heat pumps (GSHP) give zero-carbon emission heating at a residential level. However, as the heat is discharged, the temperature of the ground drops, leading to a poorer efficiency. Borehole inter-seasonal thermal storage coupled with GSHP maintains the efficiency at a high level. To adequately utilize the high performance of combined GSHP and the borehole system to further increase system efficiency and reduce cost, such a combined heating system is incorporated into the interconnected multi-carrier system to support the heat load of a community. The borehole finite element (FE) model and an equivalent borehole transfer function are proposed and respectively applied to the optimisation to analyze the variation of GSHP performance over the entire optimisation time horizon of 24 h. The results validate the borehole transfer function, and the optimisation computation time is reduced by 17 times compared with the optimisation using the FE model.

Energy and exergy analysis of a combined ground source heat pump system

The main focus of this paper is to analyze the energy and exergy efficiencies of a combined ground source heat pump (GSHP) system whose evaporator component works as a photovoltaic-thermal (PV/T) collector, and to determine the locations of the inefficiencies. This combined GSHP system consists of a heat pump cycle, a radiator thermal cycle, a ground heat exchanger cycle and a cooling tower cycle. The performance effects of the cooling tower have been examined, and optimal operation parameters have been selected to maximize the system efficiency. Exergy destruction rates, exergy efficiencies, exergy loss ratios of the system components and the whole system, as well as the energetic and exergetic coefficient of performance (COP) for the heat pump cycle have been evaluated for investigation of the potential improvement of the system components. From the results, exergy efficiency, COPsys and COPex of the system have been found as 74.72%, 2.895% and 0.39%, respectively. Additionally, parametric studies, including the thermodynamic performance of the system and its components, have been conducted by the change in some operating conditions, as variation of the ambient temperature changes from 0 °C to 30 °C, and the intensity of solar radiation that comes on the PV/T evaporator surface ranges from 400 W/m2 to 900 W/m2.

Analysis of Combined Ground-Source Heat Pump and Water Energy Storage System and its Economic Impact Factors

This paper makes an introduction of the working principle and the technical and economic benefits of the combined ground-source heat pump and water energy storage system. And then according to the characteristic of this system itself and its mode of operation, we can point out that the energy storage rate, the local policy of electricity price and the strategy of operation are the main factors which influent the economic characteristics of the system. Using the initial investment and the operation cost of the system as the economy evaluation index, we respectively analyze the influence of the above factors on the index. And wish the results of the analysis can provide reference on the design of this new type air-conditioning system.

The Ratio of Cumulating Cooling Load in Ground-Source Heat Pump System

In south of China, such as Shanghai and Hangzhou, the single ground-source heat pump is not viable for buildings of all functions. The ratio of cumulating cooling load is vital to the combined ground-source heat pump system, which means ratio of cumulating cooling load removed by secondary cooling source. This paper gives some reasonable ratios of cumulating cooling load through simulating to ground-source heat pump systems of residence, hotel, market and office.

Experimental Study of Heating-Cooling Combined Ground Source Heat Pump System with Horizontal Ground Heat Exchanger

A hot-water and air-conditioning (HWAC) combined ground sourse heat pump(GSHP) system with horizontal ground heat exchanger self-designed and actualized was presented in this paper. The heat transfer performance for the heat exchanger of two different pipe arrangements, three layers and four layers, respectively, was compared. It showed that the heat exchange quantity per pipe length for the pipe arrangement of three layers and four layers are 18.0 W/m and 15.0 W/m. The coefficient of performance (COP) of unit and system could remain 4.8 and 4.2 as GSHP system for heating water, and the COP of heating and cooling combination are up to 8.5 and 7.5, respectively. The power consumption of hot-water in a whole year is 9.0 kwh/t. The economy and feasibility analysis on vertical and horizontal ground heat exchanger were made, which showed that the investment cost per heat exchange quantity of horizontal ground heat exchanger is 51.4% lower than that of the vertical ground heat exchanger, but the occupied area of the former is 7 times larger than the latter's.