Energy pile foundation simulation for different configurations of ground source heat exchanger

Geothermal coil heat exchangers of a ground-coupled heat pump (GCHP) system have been simulated in this research for the cooling mode of the heat pump system. Three types of vertical pile-foundation heat exchangers including 1-U-shaped type, 1-W-shaped type and a W-shaped-all round type which 6-U pipes have been connected serially and situated all round inside the pile in order to determine the most efficient type. Heat transfer rates in the three types have been determined via numerical methods which couples convection and conduction through water in pipelines, concrete pile, and soil. Results have been reported to present the heat transfer rate between water, pipe, pile and soil for acquiring the specific outlet temperature of water in comparison of inlet water in three types and three different depths of the pile. This research presents better performance in heat transfer rate between 1-U-shaped, 1-W-shaped, and W-shaped-all round configurations for designing vertical pile-foundation of GCHP. Comparison between serial and parallel connection of pile-foundations in cooling mode has been investigated as well. Results show that a pile-foundation with W-shaped-all round configuration has the best efficiency in heat transfer rate compared to other mentioned types. In addition, serial connection of pile-foundations has better performance and efficiency in comparison to parallel method. (C) 2015 Elsevier Ltd. All rights reserved.