scholarly journals Experimental and Numerical Results on the Performance of a Heat Pump

2019 ◽  
Vol 9 (1) ◽  
pp. 7289-7299
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Pumps ◽  
Cost Comparison ◽  
Coefficient Of Performance ◽  
Ground Heat Exchanger ◽  
Frozen Ground ◽  
Pump System ◽  
Cold Regions ◽  
Heating Oil

A 21 kW ground source heat pump (GSHP) operating since 2013 in Alaska is described in this paper. Six years of successful operation in an extreme climate and measured performance data from 2013 to 2017 prove the viability of heat pumps for extreme cold regions. Summary of performance evaluation data such as monthly electric energy use and cost, savings of the heat pump system compared to the cost of heating oil, energy extracted from the ground, heat delivered to building are tabulated by months. The coefficient of performance (COP) of the heat pump is calculated from the experimental data, which show the COP to vary from a maximum value of 4.15 to a minimum value of 2.34 depending on the heating load of the month and the ground temperature. Cost comparison shows savings by heat pump over regular heating oil boilers of 80% efficiency. In cold regions it is of concern that GSHP can create frozen ground or permafrost around the ground heat exchanger coil by extracting too much heat from the ground. A finite element heat conduction simulation performed over the ground heat exchanger coil spanning over a 30-year period shows that small volumes of frozen ground form around the coil each season, but they melt away during the summer by the recharge of heat from the solar heat gain. The mechanical system of the heat pump, sensors for measurements and cost of the system components are presented, which would be valuable to designers implementing heat pumps in various locations of the world.

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

2011 ◽  
Vol 374-377 ◽  
pp. 398-404 ◽  
Author(s):  
Ying Ning Hu ◽  
Ban Jun Peng ◽  
Shan Shan Hu ◽  
Jun Lin
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Ground Heat Exchanger ◽  
Pipe Length ◽  
Pump System ◽  
Heat Pump System ◽  
Heating And Cooling

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.

scholarly journals Design and Performance Evaluation of a Heat Pump System Utilizing a Permanent Dewatering System

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2273
Author(s):  
Seung-Hoon Park ◽  
Yong-Sung Jang ◽  
Eui-Jong Kim
Keyword(s):  
Energy Source ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Large Scale ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Air Source Heat Pump ◽  
And Performance

The earth provides a vast resource of groundwater from aquifers a few meters beneath the surface. Thus, buildings that use underground space must be equipped with dewatering wells to drain the permeated groundwater to the sewage pipelines to ensure the structural stability of the building. Although the inflowing groundwater temperatures and flow rates are stable enough for groundwater to be used as an energy source, 79% of the permeated groundwater is discarded through the sewers, generating significant sewerage expenses. This study introduced a novel heat exchanger module to utilize the permeated groundwater as an unused energy source using heat pumps, and the performance of the system was evaluated by TRNSYS simulations. First, the sizing of the unit heat exchanger module was proposed according to the mean inflow rate of the permeated groundwater. Second, the heat pump system was configured using multiple modules in the source-side loop. Finally, the performance of the proposed heat pump system was compared with that of a conventional air source heat pump using realistic load and temperature profiles. This preliminary study demonstrated interesting performance results, with a coefficient of performance for heating that was higher than that of a conventional heat pump system by 0.79. The results show the potential utilization of the systems for a construction project requiring large-scale underground spaces, where abundant groundwater is available.

scholarly journals Analysis of Heat Exchange Rate for Low-Depth Modular Ground Heat Exchanger through Real-Scale Experiment

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1893
Author(s):  
Kwonye Kim ◽  
Jaemin Kim ◽  
Yujin Nam ◽  
Euyjoon Lee ◽  
Eunchul Kang ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Heat Extraction ◽  
Ground Heat Exchanger ◽  
Pump System ◽  
Heat Pump System ◽  
Scale Experiment ◽  
Real Scale

A ground source heat pump system is a high-performance technology used for maintaining a stable underground temperature all year-round. However, the high costs for installation, such as for boring and drilling, is a drawback that prevents the system to be rapidly introduced into the market. This study proposes a modular ground heat exchanger (GHX) that can compensate for the disadvantages (such as high-boring/drilling costs) of the conventional vertical GHX. Through a real-scale experiment, a modular GHX was manufactured and buried at a depth of 4 m below ground level; the heat exchange rate and the change in underground temperatures during the GHX operation were tracked and calculated. The average heat exchanges rate was 78.98 W/m and 88.83 W/m during heating and cooling periods, respectively; the underground temperature decreased by 1.2 °C during heat extraction and increased by 4.4 °C during heat emission, with the heat pump (HP) working. The study showed that the modular GHX is a cost-effective alternative to the vertical GHX; further research is needed for application to actual small buildings.

scholarly journals Efficiency and area demand of multi-layer ground heat exchanger using phase change of water

2019 ◽  
Vol 282 ◽  
pp. 02027
Author(s):  
Hauke Hirsch ◽  
Hans Petzold ◽  
John Grunewald
Keyword(s):  
Heat Exchanger ◽  
Numerical Simulations ◽  
Heat Pump ◽  
Simulation Software ◽  
Passive Cooling ◽  
Ground Heat Exchanger ◽  
Pump System ◽  
Heat Pump System ◽  
German Standard ◽  
The Impact

We conducted numerical simulations of a heat pump system connected to a horizontal ground heat exchanger (HGHX), using a coupling of the hygro-thermal simulation software DELPHIN with Modelica. The aim was to study the influence of different HGHX sizes and assemblies as well as the impact of passive cooling on the systems efficiency. We found that the required ground area could be reduced by up to 70 % compared to the recommendation of German standard when the pipes are placed in multiple layers. Passive cooling is possible but has a negligible effect on the systems efficiency.

scholarly journals A Study on the Performance of a Cascade Heat Pump for Generating Hot Water

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4313 ◽  
Author(s):  
Boahen ◽  
Choi
Keyword(s):  
Heat Exchanger ◽  
Energy Saving ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Research Interest ◽  
Coefficient Of Performance ◽  
Energy Saving Potential ◽  
Heating Capacity

The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.

Simulation on Ground Temperature Change of GSHP System in Severe Cold Regions

2014 ◽  
Vol 945-949 ◽  
pp. 2820-2824 ◽  
Author(s):  
Li Bai ◽  
Peng Xuan Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Temperature Change ◽  
Heat Pump ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Cold Regions ◽  
Ground Source ◽  
Ground Coupled Heat Pump ◽  
Operation And Management

For the case of ground-source heat pump in severe cold regions in winter, the heat transfer situation of the ground and ground heat exchanger was dynamically simulated according to the statistics of a project in Changchun to analysis the change of the ground heat, which provided references for the initial design and operation and management of the ground-coupled heat pump in severe cold regions.

scholarly journals Frosting Phenomenon and Frost-Free Technology of Outdoor Air Heat Exchanger for an Air-Source Heat Pump System in China: An Analysis and Review

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2642 ◽  
Author(s):  
Yi Zhang ◽  
Guanmin Zhang ◽  
Aiqun Zhang ◽  
Yinhan Jin ◽  
Ruirui Ru ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Operating Cost ◽  
Heating System ◽  
Coefficient Of Performance ◽  
Outdoor Air ◽  
Pump System ◽  
Heat Pump System ◽  
Reduce Operating Cost ◽  
Air Source Heat Pump

Frost layer on the outdoor air heat exchanger surface in an air-source heat pump (ASHP) can decrease the system coefficient of performance (COP). Although the common defrosting and anti-frosting methods can improve the COP, the periodic defrosting not only reduces the system energy efficiency but also deteriorates the indoor environment. To solve these problems, it is necessary to clearly understand the frosting phenomenon and to achieve the system frost-free operation. This paper focused firstly on the analyses of frosting pathways and frosting maps. Followed by summarizing the characteristics of frost-free technologies. And then the performances of two types of frost-free ASHP (FFASHP) systems were reviewed, and the exergy and economic analysis of a FFASHP heating system were carried out. Finally, the existing problems related to the FFASHP technologies were proposed. Results show that the existing frosting maps need to be further improved. The FFASHP systems can not only achieve continuous frost-free operation but reduce operating cost. And the total COP of the FFASHP heating system is approximately 30–64% higher than that of the conventional ASHP system under the same frosting conditions. However, the investment cost of the FFASHP system increases, and its reliability also needs further field test in a wider frosting environment. In the future, combined with a new frosting map, the control strategy for the FFASHP system should be optimized.

Analysis of an Integrated Thermal Energy System for Applications in Cold Regions

2021 ◽  
pp. 1-32
Author(s):  
Bismark Addo-Binney ◽  
Wahid Besada ◽  
Martin Agelin-Chaab
Keyword(s):  
Heat Pump ◽  
Pump Energy ◽  
Energy System ◽  
Heat Pumps ◽  
Environmental Data ◽  
Coefficient Of Performance ◽  
Space Heating ◽  
Cold Regions ◽  
Heating Capacity ◽  
Better Than

Abstract This paper performed analyses on a proposed direct wind-powered heat pump integrated with a pond which serves as an evaporator for space heating in cold regions. The analysis was conducted using environmental data for selected locations in Canada and the Engineering Equation Solver. Three different pairings of heat pumps and wind turbines were studied (a wind-powered heat pump with a pond as an evaporator, a wind-powered heat pump without a pond, and an electricity-powered heat pump). Energy and exergy analyses were performed on the systems. The novelty in the present study is in the use of a wind turbine to directly power the heat pump and using a pond as the evaporator. The results show that the proposed system has the highest coefficient of performance compared to the others. The average coefficient of performance for the selected locations is 2.7, which is at least 67% better than the others. Similarly, the overall exergy for the proposed system is 16.9%, which is at least 40% better than the others. The average heating capacity of the selected locations for the proposed system is 4.5 kW, which is from 29% to 300% better than the others. Additionally, the sustainability index for the proposed system is the highest for the proposed system. The results have shown that the proposed system has superior overall performance for space heating in cold regions.

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