Energy saving potentials from the application of heat pipes on geothermal heat pump system

A ground-loop heat exchanger is one of the key components to collect low grade ground heat for a ground source heat pump system. A typical ground source heat pump consists of a refrigerant loop operated by a compressor and a geothermal brine loop operated by a circulation pump. Although ground source heat pumps are known as one of the most efficient HVAC devices, their performance still need to be improved since the energy consumption by the peripherals like the circulation pump are considerable and estimated more than 10% of the total electricity input. In order to reduce the ground circulation energy, a variety of researches such as direct expansion geothermal heat pumps are studied, but no apparent performance improvement was found due to other negative effects like the increase of pressure drop in the ground loop. Geothermal heat pipe can be a good alternative to replace ground-loop heat exchanger for heating purpose. The energy saving potential using heat pipe as ground heat exchanger was investigated by comparing the energy consumption and COP of three types ground source heat pump. As a result, energy consumption for heating in Seoul by 10.3% than direct expansion ground source heat pump and 21.1% than secondary loop ground source heat pump. Therefore, ground source heat pump with geothermal heat pipe can be a suitable choice to save energy in a cold region.