Numerical modeling of heat production using geothermal energy for a snow-melting system

Abstract

The use of geothermal energy for a snow-melting system can be classified into two categories: the direct use of geothermal energy and the extraction of shallow geothermal energy using a geothermal heat pump. The advantages of a snow-melting system that employs geothermal energy include, but are not limited to, that the system: (1) uses energy that is renewable and sustainable, (2) avoids the need for chemical treatments, (3) increases snow removal safety, and (4) lowers CO2 emissions. Moreover, by providing a sustainable temperature higher than 0 °C, such a system can substantially reduce maintenance costs that are due to pavement freeze-thaw cycles. A few applications of snow-melting systems have been demonstrated successfully in different areas of the world, including the United States. However, the pilot studies for these systems usually involved a massive financial investment. Thus, simulations of a snow-melting system via numerical methods may provide insights about the important components that are needed to develop a successful system.This study employed the COMSOL finite element code to conduct numerical analysis of heat collection pipes in a heat collection system in order to simplify the complex heat transfer mechanisms associated with heat extraction. The study focused on heat production modeling and the simulation of heat collection pipes in a stabilized subsurface temperature zone. The measured data show that the temperature stabilizes at 7 °C six meters below the ground surface regardless of the season. Specifically, this paper presents the computations for the heat production that is required in a snow-melting system for eastern North Dakota based on the average climatic data and precipitation using Chapman and Katunich’s equation. A heat extraction process that utilizes heat collection pipes was simulated based on the seasonal heat requirements. The results of the numerical analysis also show the effects of the thermal properties of soils and fluid properties for a heat collection system. This study found that higher soil thermal conductivity values and a reasonable volumetric flow rate are favorable conditions for a successful heat collection system in design, and the system is feasible for eastern North Dakota.