HEAT TRANSFER AND HYDRODYNAMICS OF FILTRATION IN THE SOIL - HEAT EXCHANGER SYSTEM
Abstract
Introduction. To date, heat pump systems are widely used in public utilities for heat supply to buildings. In particular, in the "soil-water" heat pump system, heat is removed from the soil with the help of a soil heat exchanger. The efficiency of its work depends on the intensity of heat transfer through the surface of the heat exchanger. The nature of heat transfer in the soil massif is significantly influenced by the filtration flow of groundwater. This flow can be formed both due to the presence of a temperature gradient in the array, and in the presence of a pressure gradient. In the first case, free convection will occur, and in the second, forced convection, and in many cases both factors may be present in the soil mass. As a result of their action, a groundwater flow is formed in this massif, which in a certain way effects on the mechanism of heat transfer from the soil massif to the heat exchange device.
Results. In this work, numerical simulation of groundwater flow and heat transfer in the soil massif is carried out in the presence of a U-tube vertical soil heat exchanger, which is an element of the heat pump system. For numerical studies, the Darcy–Brinkman-Forchheimer model is used for fluid flow in a porous medium. The influence of the pressure gradient in the soil mass, which causes the movement of groundwater, on the efficiency of the heat exchanger is analyzed. This efficiency is estimated by the amount of heat extracted from the soil. The influence of the dispersion of soil particles on the intensity of heat transfer is also determined.
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