Numerical investigation of the factors affecting the output power from heat exchanger piles

At present, global warming is one of the crucial problems for the world. One of the most important reasons for this problem is fossil fuels. Fossil fuels are the main cause of global warming and pollution. One of the best ways to solve this problem is to use renewable and clean energy resources. So today, the use of renewable and clean energy gains more popularity. One Type of these resources is geothermal; that has many resources and availability. This energy is used for heating and cooling of buildings, tunnels, avoid freezing roads and bridge and so on and by means of Energy Piles this energy is extracted. This scope of knowledge can be studied by two different views; the thermomechanical behavior and amount of extracted energy from Energy Piles. In this paper, the latter case is studied numerically to evaluate effective parameters on its energy efficiency. Because this system consists of three main elements, which are pipe, concrete, and soil, the thermal properties of each element is studied separately. In soil adjacent to the pile, some parameters like groundwater flow and the environmental conditions can influence the efficiency of the system. The geometrical properties of pipes, like installation shape, wall thickness, and diameter, are based on industrial standards. The geometrical properties of all elements can influence the efficiency of the system. Some conditions in pipes, which are imposed from the ground heat source pump (GHSP): like the flow rate in pipe and flow conditions, are also effective on the amount of extracted energy. In this paper, the amount of output energy was reported which is normalized with respect to time and the length of the pile. By increasing the amount of properties such as soil thermal conductivity, pipe diameter, pipe length, the flow rate of fluid in the pipe, length of the pile, the efficiency of the system will be improved. However, increasing the wall thickness of the pipe reduces the amount of extracted energy.