Center for Industrial Mathematics and Statistics » REU 2014 – Performance sensitivity to installation methods in vertical U-Tube geothermal energy harvesting systems-

Keenan Hawekotte

Samuel Naden

Sophia Novitzky

Mahalia Sapp

Overview

Industrial Sponsors: Paul Ormond, P.E., C.G.D. - Haley & Aldrich, Inc and New England Geothermal Professionals Association

Faculty Advisors: Burt S. Tilley, Suzanne L. Weekes

Residential geothermal energy harvesting systems have the potential to provide a cost-effective, low carbon footprint technology for heating and cooling. These systems use piping systems for coolant that either collects energy from the subsurface in the winter, or transports energy from the residence to the subsurface in the summer. We consider here the most common ground source heat pump (GSHP) installations, where a single flexible tubing is inserted in to a vertical bore with a single bend at the bottom of the well. The bore is then filled with grout, and the two ends of the tube at the surface provide the inlet and outlet to the GSHP. The focus of this project is on how the performance of the system depends on the distance between the two vertical portions of the pipe as a function of depth. We consider the temperature evolution in the exchanger and the surrounding soil as a function of time when the coolant volumetric flow rate is fixed, and see how the temperature rise over time depends on the piping geometry and spacing. Time permitting, we shall also consider the case for a time-dependent volumetric flow rate of the fluid and how the net temperature rise is affected by different design choices.