Ground Source Heat Pump Unit Research Articles

Life cycle carbon emission calculation model of energy system in public buildings: A case study in Shanghai

Energy consumption and carbon emissions (CE) in the building sector have grown in importance in relation to global climate change for China's sustainable development. Relatively few research have addressed the embodied CE, despite the fact that many have examined the operational CE from energy system operational use. In order to determine the CE of the energy production, transportation, construction, operation, and recycling stages, we therefore put up an integrated model. An inventory analysis of the energy system's life cycle CE, a scenario forecast of various combinations of building energy system equipment, and a case study of the building energy system of a typical office building in Shanghai's service industry. According to the results, the embodied CE emits 38.01 % of its energy, and the operational CE emits 61.99 %. However, we should not underestimate the significance of the impact of the embodied CE. Among all projection scenarios, the suggested CE share is highest (18.40 %) when the system combination of air-source heat pump units, LED lights, and ground-source heat pump units is implemented. In the end, based on the structural analysis of the embodied CE, low-carbon growth strategies and policy recommendations for Shanghai's service sector will be made.

Influence of Geology, Hydrogeology, and Climate on Ground Source Heat Pump Distribution in Slovenia and Selected European Countries

Shallow geothermal energy (SGE) is a renewable energy that could contribute to the decarbonatization of the heating and cooling sector. SGE is predominantly harnessed through ground source heat pump (GSHP) systems. The choice of which type of GSHP system depends on various factors. Understanding these factors is crucial for optimizing the efficiency of GSHP systems and fostering their implementation. In this paper, we have analysed the spatial distribution of GSHPs in Slovenia. We identified 1073 groundwater and 1122 ground-coupled heat pump systems with a total heat pump capacity of almost 30 MW. We quantitatively assessed the influence of geological, hydrogeological, and climate conditions on their spatial distribution. Using the χ2 test and information value method, we identified hydrogeological conditions as the most influential factor for the GSHP systems’ spatial distribution. We also performed the spatial analysis of geological and hydrogeological data in 22 European countries, including Slovenia. We collected the reported numbers of installed GSHP units in 2020 and were able to distinguish the shares of groundwater and ground-coupled heat pump systems for 12 of these countries. The analysis showed that ground-coupled heat pumps predominate in most countries, even if the natural conditions are favourable for groundwater heat pumps.

Analyzing the Performance of Double Spiral Tube Ground Heat Exchangers in a Zero-Energy Building Using Measurement Data

A ground-source heat pump (GSHP) system is a renewable energy technology that effectively reduces greenhouse gas emissions and consequently mitigates the progression of global warming. The thermal efficiency of ground heat exchangers (GHEs) is a critical component in the GSHP system that must be accurately estimated for its long-term operationality. Therefore, in this study, the thermal performance of double-spiral GHEs incorporated within the thermal piles of a zero-energy building in Sapporo, Japan, was investigated using the actual measured data obtained from the site and a novel metric, namely, the coefficient of heat extraction/injection, for a more precise evaluation. Moreover, this study assessed the coefficient of performance (COP) of the GSHP units during various periods of cooling or heating. The temperature of the circulating fluid remained within an ideal operational range over an operational period of 2 years, and the COP calculations indicated a high operational efficiency. The results derived in this study substantially exceeded those of traditional U-tube GHEs, indicating the enhanced efficiency and superior performance of large-diameter thermal piles with augmented thermal capacity. Our findings suggest that GSHP systems with double-spiral-tube GHEs have superior efficiency than conventional GHEs.

Energy, exergy and economic analysis of an integrated ground source heat pump and anaerobic digestion system for Co-generation of heating, cooling and biogas

This study designed and simulated a feasible polygeneration system, which integrated with a ground source heat pump and anaerobic digestion units to co-generate cooling, heating, and biogas for buildings as well as to utilize biomass residues in rural areas. The quantitative investigation of the energy, economics, and exergy of such a system was conducted in a village in Chongqing, China. The results indicated that by incorporating an anaerobic digestion unit, the integrated system could save 21.6% and 32.2% of primary energy, as well as 35.6% and 34.4% of annual costs, when compared to the separated and current systems, respectively. A Sankey diagram of exergy flow showed that exergy efficiency was 32.2%, and the anaerobic digester and heat pump units were the main exergy destruction components. Increasing the operating supplied temperature of the heat pump for the anaerobic digester from 45 °C to 60 °C improved exergy efficiency from 32.2% to 40.7% but decreased the overall energy efficiency ratio from 4.09 to 3.83. In addition, increasing the coefficient of performance (COP) of heat pump units was an effective way to enhance energy and exergy efficiency. The study may aid designers and decision-makers in optimizing the system and its components.

Transient Simulation and Optimization of Regional Integrated Energy System

A modeling method of regional integrated energy system based on bus method and transient simulation is proposed, and the system optimization is based on the dynamic balance of supply and demand in the whole year energy supply cycle. A CCHP system of gas turbine coupled with ground source heat pump and electric refrigeration unit is constructed. The energy relationship of the system is described by bus structure, and the transient calculation model is built on TRNSYS platform. The weighted sum of annual total cost saving rate, primary energy saving rate and environmental pollutant shadow cost saving rate is taken as the optimized objective function, and on the basis of annual dynamic balance, the Hooke-Jeeves algorithm is used for optimization of the system configuration. A complex commercial area in Beijing is taken as an example, and different weighting coefficients are set for optimization of the system configuration. The results show that, from the perspective of economy, environmental benefit and primary energy consumption, performance of the system increases and then decreases with rise of gas turbine power; under the simulated cooling/heating load, the maximum number of optimum configuration is seen in the combination of 35 kW gas turbine + 723 kW GSHP and 1178 kW electric chiller; in comparison with traditional distributed system, the annual cost saving rate, primary energy saving rate and environmental pollutant shadow cost saving rate of the system are 29.4%, 49.6% and 58.2%, respectively.

Measurement and analysis of cooling (heat) performance of renewable energy technology projects based on ground source heat pump systems

The design, configuration and operation of the soil-source heat pump system in four actual projects are monitored, collected and investigated. Combined with various test parameters of the project, the energy efficiency of the ground source heat pump system was compared and measured, and detailed data analysis was conducted from the aspects of heat exchange of ground source heat pump system, heat efficiency coefficient of ground source heat pump system, performance of ground source heat pump unit and performance of soil source heat pump system. It provides a basis for the formulation of operation strategy of soil-source heat pump system in the future, so as to serve the sustainable development of energy saving technology of shallow soil-source heat pump system.

Analysis of refrigeration and heating efficiency of ground source heat pump

This paper studies the efficiency of ground source heat pump(GSHP) used in refrigeration and heating, comparing it with air source heat pump (ASHP) by means of theoretical analysis and experiment. The results were as follows, the cooling efficiency of GSHP in summer is higher than that of heating in winter because of the heat is transferred from high temperature to low temperature during cooling in summer, which can be compared to heat pipe; By calculating the power consumption of pump and fan, it is found that theoretically GSHP unit and system have higher heating efficiency than ASHP; The experiment shows that the daily average COP of the unit and the system is 4.22-4.62 and 3.26-3.55, respectively, both the unit COP and system COP of GSHP is higher than that of ASHP, which is consistent with the theoretical analysis.

Study on Performance of Ground Source Heat Pump System Based on Active Chilled Beam

This paper takes the ground source heat pump unit of a research and development centre in Beijing as the research object. This collected the operation data in the cooling condition and the heating condition respectively. Based on the measured data, this paper calculated the coefficient of performances and the energy efficiency ratio of the unit. The results show that when the active chilled beam is used as the air-conditioning terminal device, the inlet temperature of the heat pump unit is greatly improved. The ground source heat pump unit meets the standard and has a higher energy efficiency ratio; The operation of a single unit is more efficient than that of multiple units at the same time.

An optimal matching strategy for screw compressor for heat pump applications

An optimal matching strategy for screw compressor for heat pump (HP) applications was proposed in this study. The strategy focuses on the optimal matching between the built-in volume ratio (BVR) of screw compressors and the annual cooling and heating load demands. A performance index, the annual integrated coefficient of performance under actual operating conditions (ACOPA), was introduced to represent the actual operational energy efficiency of the HP unit. The optimization mathematical model and generic framework of the optimal matching strategy were developed. The proposed strategy was applied to a ground-source HP unit to assess its performance. The results show that the optimal matching strategy improved the ACOPA by 6% at most, compared to the conventional matching method on BVR.

Modelling and analysis of a ground source heat pump combined with a PV-T and earth energy storage system

This paper presents the development of a mathematical model for the analysis of a ground source heat pump unit combined with photovoltaic-thermal panels and an earth energy storage system. Each sub-system was modelled in MATLAB and then merged to form an overall model of the energy system. The model was used to analyse the performance of the energy system using several test scenarios. The test scenarios saw input data for winter, spring, summer and autumn conditions across the periods of 24 hours. The model was used to simulate the system with differing refrigerants, PV/T module sizes and earth energy bank storage sizes. The heat pump shows a Coeffient of Performance of approximately 5.0 throughout the test scenarios. It was observed that the summer conditions produce an increase in the energy stored within the ground, whilst the winter operation shows a reduction due to increased thermal demand in the building and reduced solar irradiance. The model was shown to be simple and effective to capture the operational characteristics of the combined energy system.

The Contrast Experimental Study of Sewage Source Heat Pump System and Ground Source Heat Pump System in Hot Summer and Cold Winter Area

For two practical engineering case in a University in Guilin, this paper mainly introduces the performance of sewage-source heat pump and ground source heat pump and compare the running status in two kinds of system. The studies have shown that the sewage source heat pump unit COP at about 3.9, the system COP at about 3.3, ground source heat pump unit COP at about 4.5, the system COP at about 3.4.

Issues to improve ground source heat pump units in Korea: Refrigerant application and hot water generation

There is a need for hot water generation in a more efficient and environmentally friendly way for heating, ventilating, and air conditioning systems, and the heat pump is a great candidate for that. In this paper, hot water temperatures generated by ground source heat pump (GSHP) systems in Korea are analysed. It is also important to minimize the use and emission of refrigerants with high global warming potential (GWP) and ozone depletion potential (ODP) to reduce their impact on the environment. In this regard, refrigerants that are used in GSHP units in Korea are investigated. The database is composed of 86 GSHP units certified in Korea according to governmental regulation. The GSHP units are divided into three types: water-to-water, water-to-air, and water-to-air multi heat pump units. The average hot water temperature generated by the certified GSHP units is 43.8 °C with the Korean standard test conditions (NR GT 101). Temperature difference 3.8 °C between inlet and outlet of condenser is less than 5 °C as presented by the European Standard (NF EN standard). In order to replace the boiler and the conventional air conditioning unit with a highly efficient GSHP system, there is the need to increase the hot water generation temperature. With the refrigerants, 53.8% of the 78 water-to-water GSHP units use the hydro chlorofluorocarbon (HCFC) refrigerant, R22, while the others use the hydrofluorocarbon (HFC) refrigerants, R410A, R407C, and R134a. All water-to-air and water-to-air multi heat pump units use R410A refrigerant. Because R22 is a HCFC and has high GWP and ODP, it is being replaced with HFC and natural refrigerants. However, HFC refrigerants also have high GWP. It is therefore recommended to encourage the responsible use or replacement of HFC refrigerants with natural and other alternative refrigerants in Korea.

Simulation and Experimental Research on Screw Ground Source Heat Pump Unit

A grey box model of screw ground source heat pump unit has been established and operating characteristics of the unit using R22 refrigerants were simulated. The effects on refrigerating capacity, heating capacity, power consumption of the compressor and COP on conditions of cooling and heating have been analyzed with different inlet water temperature of evaporator and inlet water temperature of condenser. Results show that main factor which affecting COP of heat pump unit is inlet water temperature of condenser. The change of refrigerating capacity and heating capacity are mainly caused by inlet water temperature of evaporator. Measures can be done to decrease the inlet water temperature of condenser when the unit operates for a long time and to increase inlet water temperature of evaporator on very hot or very cold conditions.

Technical review and economic assessment of ground source heat pump utilization in Taleghan-Iran

GSHP (through ground source heat pump) has been considered as one of the proposed solutions for the convenient energy supply for cooling and heating systems in recent decades. In Iran, the renewable energy organization as the pioneer organization is involved in localization and utilization of renewable energies. It has developed and installed some of these systems in various parts of the country. In this paper, the fundamentals of GSHPs and some related projects in Iran are reviewed. Then, GSHP is compared with commercially available heating/cooling split units economically. Results show that although the return of investment may take a long period, the GSHP units are profitable.

Current status of the performance of GSHP (ground source heat pump) units in the Republic of Korea

Heat pumps, as a process recirculating environmental heat back into useful heat production, fit the environmental requirements of present global policy. They are very useful tools to reduce the need of fossil fuels in space heating and cooling. The government of the Republic of Korea has promoted the distribution of heat pump systems that apply geothermal energy, and has adopted regulation to prevent the use of low efficiency heat pump units. Only heat pump units certified by the government can be used in ground source heat pump (GSHP) systems. Certified heat pump units in the Republic of Korea were analyzed and discussed in this paper. All certified products had cooling capacities less than 280 kW (80 RT). Most of the cooling COPs (Coefficient of Performance)s were found to be superior to heating COPs for GSHP units in the Republic of Korea. To save energy, correspond to environmental regulations and reduce the installation cost of applying GSHP systems, it is suggested that the certification standard concerning underground circulation flow rate should be revised. In addition, there is a need for the revision of the certification standards to include floor heating in order to be able to apply GSHP systems for a variety of purposes.

The Monitoring System of Soil GSHP and the Study in the Geothermal Field

In this paper the monitor system of soil ground source heat pump (GSHP) unit is designed by using LabVIEW. Through automatic acquisition, the monitor system will accept the parameters, such as temperature, pressure of the fluid and so on to achieve the accurate data collection and data transmission .Meanwhile the soil temperature in the geothermal field will be also monitored in winter heating conditions. The results show that the soil temperature relates to the distance between the monitoring wells and the pipe center, the closer, the lower the temperature is; As time going, the soil temperature in geothermal reduces, but not obviously in a short time.

수평형 지열 히트펌프 시스템의 냉난방 성능 분석

ABSTRACT:Ground-coupled heat pump (GCHP) systems utilize the immense renewable storage capacity of the ground as a heat source or sink to provide space heating, cooling, and domestic hot water. The main objective of the present study is to investigate the cooling and heating performance of a small scale GCHP system with horizontal ground heat exchanger (HGHE). In order to evaluate the performance, a water-to-air ground-source heat pump unit connected to a test room with a net floor area of 18.4 m2 and a volume of 64.4 m3 in the Korea Institute of Construction Technology (37°39ʼN, 126°48ʼE) was designed and constructed. This GCHP system mainly consisted of slinky-type HGHE with a total length of 400 m, indoor heat pump, and measuring devices. The peak cooling and heating loads of the test room were 5.07 kW and 4.12 kW, respectively. The experimental results were obtained from March 15, 2011 to August 31, 2011 and the performance coefficients of the system were determined from the measured data. The overall seasonal performance factor (SPF) for cooling was 3.31 while the system delivered heating at a daily average performance coefficients of 2.82.Keywords:Ground-coupled heat pump(지열 히트펌프), Horizontal ground heat exchanger(수평형 지중열교환기), Cooling and heating(냉난방), Seasonal performance factor(SPF, 계간성능계수), COP(성능계수)

Exergy analysis and operational efficiency of a horizontal ground-source heat pump system operated in a low-energy test house under simulated occupancy conditions

This paper presents data, analyses, measures of performance, and conclusions for a ground-source heat pump (GSHP) providing space conditioning to a 345m2 house whose envelope is made of structural insulated panels. The entire house thermal load with RSI-3.7 (RUS-21) walls, triple-pane windows (U-factor of 1.64Wm−2K (0.29Btuh−1ft−2°F−1)) and solar heat gain coefficient of 0.25, a roof assembly with overall thermal resistance of about RSI-8.8 (RUS-50), and low leakage rates of 0.74 ACH at 50Pa, was satisfied with a 2.16 ton (7.56kW) GSHP unit. Coefficient of performance is calculated on the basis of the total power input (including duct, ground loop, and control power losses). Exergy analysis provides a true measure of how closely actual performance approaches the ideal, and it unequivocally identifies, better than energy analysis does, the sources and causes of lost work — the root cause of system inefficiencies and wasted energy.

Thermodynamic analysis and assessment of space heating with ground-source heat pump for sustainable future

In this paper, the thermodynamic modelling of exergy loss, exergy efficiency, exergy destruction rate, environmental destruction coefficient, improvement potential, exergy destruction factor, relative irreversibility, productivity lack and exergetic factor of ground source heat pump (GSHP) system are investigated. The results show that these exergy indexes should be used integratively. Compressor has the maximum exergy destruction rate, followed by the condenser and ground heat exchanger. Exergy efficiencies are obtained as 54.54% and 38.52% for the GSHP unit and whole system, respectively. Related parametric studies concerning about exergy destruction rate and exergy efficiency of the system components are carried out at different ambient temperatures.

Research and Development of Ground Source Heat Pump Unit Remote Real-Time Monitoring System

This paper describes the research and implementation of ground source heat pump unit remote real-time monitoring system, researches in remote real-time monitoring system's overall design, hardware design, software design and implementation of OPC communication. The host computer takes advantage of the human-computer interaction interface of configuration software to achieve the remote real-time monitoring for ground source heat pump unit's running state; the lower computer uses data collector to intensively collect the data which is measured by field measuring instruments, and to achieve remote data transmission based on Ethernet, and then to carry out the communication between the host computer and the lower computer via OPC technology. The results show that the system achieves remote real-time monitoring of ground source heat pump unit, and is stable, easy to operate and provides a reliable basis for the actual energy saving effect's evaluation of ground source heat pump system.