The Potential and Limitations of Using Geothermal-Sourced Chiller Plants to Eliminate Cooling Towers

Abstract

The purpose of this research is to evaluate the feasibility and performance of a vertical ground source refrigeration system for cooling a typical 7300 m2 office building after replacing cooling towers used for condenser cooling with three different designs of ground heat exchangers. To that end, a three-dimensional, transient, and conjugated finite volume model is developed and simulated to compare the thermo-hydraulic performance of the traditional single U-tube with that of double U-shaped, and spiral-shaped ground heat exchangers at different flow rates. Based on the results, spiral shaped ground heat exchangers outperform other designs, as seen by better heat exchange rates between the fluid and the soil, which translates to a greater temperature reduction of the cooling water. This improvement not only allows for using smaller number of boreholes which saves the construction costs compared to other designs, but it also improves the coefficient of performance of the system by significantly lowering the cooling water temperature flowing back to the condenser when compared to the conventional cooling tower. This approach also eliminates cooling tower water consumption (saves about 14,500 L/day), tower noise, annual maintenance expenses, and costs for periodical cooling tower replacement. The presented findings make a significant contribution to society by offering innovative and sustainable solutions for cost reduction, environmental conservation, and energy efficiency.