The performance of ground source heat pipes at low constant source temperatures

ABSTRACT

Thermal performance of ground source two-phase closed thermosyphon is investigated theoretically according to different working fluids, different evaporator lengths,, and heat source temperatures. First, a theoretical model of the thermosyphon was created. For the thermosyphon, whose working fluid is ammonia, acetone or methanol, different evaporator lengths, and different heat source temperatures were used for thermal analysis. Analyses are presented in detail with figures. It was observed that the ammonia performed better at the specified working conditions. As the evaporator length increases, the heat transfer capacity of the thermosyphon enhances. However, as the evaporator length increases, the saturation temperature of the fluid also increases due to the effect of hydrostatic pressure, so it was seen that the thermosyphon would not carry heat under these conditions. The maximum heat transfer rate and optimum evaporator lengths for the thermosyphon were determined for the conditions specified and the fluids used in the study.

KEYWORDS:

• Ground source heat pipe
• heat pipe
• optimum evaporator length
• thermosyphon
• two phase closed thermosyphon
• working fluid