3-Dimensional Numerical Modelling to Assess Geothermal Piles Efficiency in Tropical Countries

Abstract

Abstract Nowadays, climate changes caused by intense and continuous greenhouse gases emission is one of the most curtail issues that facing the human beings. Throughout the years, researchers have tried to find other reliable sources available to control the exhaustion of coal, gases, and oil. Geothermal energy is one of these alternatives that have been investigated and considered as one of the most promising renewable and clean energy sources. Tropical climate countries such as Malaysia could benefit from this technology due to its high cooling demand throughout the year. Geothermal piles for instance, are one of the methods that can be used to extract geothermal energy by employing the piles as a heat transfer bodes. Therefore, this paper presents numerical simulations as an early attempt to realise the potential of adopting geothermal piles catered to Malaysia’s soil condition and pile standards for low-rise construction. A pipe with a U-tube shape wase simulated at three different inner diameters (14, 19, and 26) under two inlet dischargers (0.009 m3/s 0.050 m3/s). The U-tube was placed inside concrete square pile with dimensions of 1.5 m width, 1.5 m length and 10 m hight. The simulation was conducted under two soil conditions namely, (i) dry soil, and (ii) soil effected by groundwater. The performance of the geothermal pile was measured by the amount of temperature reduction in the pipe outlet after heat exchange has been done. The results obtained showed that geothermal piles with lower flow discharge (0.009 m3/s) operation produced more temperature reduction in the pipe outlet. Without the presence of groundwater, the 26 cm diameter recorded the highest temperature reduction, with pipe outlet temperature of 29.89 °C equivalent to a 1.0 % reduction. Similarly, with the groundwater effect, the same pipe diameter recorded the highest temperature reduction, with pipe outlet temperature of 28.43 °C equivalent to a 1.57 % reduction. Based on the numerical modelling results it can be said that combination of 26 cm pipe diameter, at 0.009 m3/s flow rate, and the advection effect of groundwater temperature has produced an optimum condition for the geothermal piles in cooling system.