Abstract
As green air conditioning systems, groundwater heat pump systems have been popularized and applied because of their stability and high heat exchange efficiency. However, the low-efficiency recharge caused by clogging restricts the healthy and orderly development of such systems. Physical clogging, accounting for 50% of the total clogging, arises from solid particle accumulation and is the most common type of clogging. In this study, a physical simulation sandbox bench was constructed to simulate groundwater recharge. Tests were conducted under two initial injection pressures of 17.058 kPa and 13.8 kPa and solid matrix particle gradations of 1.026 mm, 1.343 mm, and 1.721 mm to study the migration-deposition of exogenous particles near the injection well induced by groundwater recharging as well as to select suitable downhole filter grades. The results show that when the initial injection pressure and solid matrix particle gradation were low, suspended particles were more susceptible to be sieved and deposited within 24 cm from the injection well. This significantly reduced the permeability and resulted in a rise in the injection pressure. When the high injection pressure of 17.058 kPa was applied, the area in which the permeability coefficient decreases by an order of magnitude compared to the initial value, was less than 10 cm of the wellbore wall, and the quantity of outflow of particles accounted for 34.8% of the inflow. The size range of the suspended particles flowing through the porous medium was 3–30 μm, providing the parameter basis for downhole filter grade selection. This research provides useful insights into the design and optimization of injection projects to prevent particle clogging in groundwater heat pump systems.
Published Version
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