Thermal Load Test of Ground-Coupled Heat Pump System with Direct Expansion Ground Heat Exchanger

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.

Download Full-text

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

MATEC Web of Conferences ◽

10.1051/matecconf/201928202027 ◽

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.

Download Full-text

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.374-377.398 ◽

2011 ◽

Vol 374-377 ◽

pp. 398-404 ◽

Cited By ~ 1

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.

Download Full-text