OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
temperature below earth. In 17 th century famous French Chemist Lavoisie kept a thermometer 27 m below earth
surface and found that temperature remain constant throughout the year. In 1799 Humboldt found that the
average temperature below the earth surface is 12° C and only variation of temperature is 0.04° C. The Royal
Edinburgh Observatory in Scotland started the exact measurement of ground temperature in 1838.
Figure 1 Underground temperature from a borehole south of Wetzlar [11]
2.1 GSHP Operation Mode
GSHP are used not only for heating but for cooling too. There are typically three modes for operating these
pumps.
Figure.2 Different GSHP Operation Mode
The feasibility of direct cooling is there, when space to be cooled is smaller than heating and the environmental
humidity is less. If the condition opposite then heat pump will act as a chiller and extra additional
dehumidification is required.
The efficiency of Heat Pump will be measured in terms of COP (Coefficient of Performance).
For an electric powered compression heat, COP is expressed as
COP= (Useful Heat / Electric Power Input)
2.2 Various GSHP Systems
GSHP can be classified into open and closed systems, and closed systems may further subdivided into horizontal
and vertical systems, the latter being applicable in a situation when the temperature below a certain depth
remains constant and there is a need to install sufficient heat exchange capacity under a confined surface area. In
GSHP system, many type of bore hole heat exchanger configuration have been installed, [11]
Out of those two basic concepts are
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