Geothermal and GHX Design in the Mid-Atlantic Region
April 26, 2017
Senior Mechanical Engineer Scott Emery provides insight into geothermal heat pump systems and GHX design.
As part of the April ASHRAE NCC chapter meeting, Scott Emery covered various geothermal topics relating to the design, build, and operation of ground coupled heat exchangers (GHX). Scott focused on the diversity of options within GHX design. He also highlighted the role of geology, formation thermal property testing, and commissioning in building geothermal systems.
The DC region’s geology ranges from coastal plains to the Piedmont. The diversity of geological conditions in the mid-Atlantic region produces a variety of options for geothermal. Geology also impacts the drilling method used for vertical GHX installations.
Buildings operations as well as heating and cooling demands often require careful consideration of GHX design options. Geothermal designers must weigh the pros and cons of using open or closed loops and between vertical or horizontal design. For vertical designs, thermal conductivity testing plays an important role. These tests provide geothermal designers with the information needed to create quality designs of ground loops.
Projects in in the Mid-Atlantic are frequently dominated by cooling concerns and space constraints. With these types of projects, hybrid designs can expand the range of projects employing geothermal while improving energy efficiency and the system’s robustness. Hybrid designs work well because they combine GHXs with traditional heat rejection devices like cooling towers.
Based on field experience, commissioning and retrocommissioning of geoexchange systems can provide tremendous value. Most operational challenges stem from improper operation of building systems. By continuously monitoring these systems, clients can optimize system performance and prevent major problems before they happen. It is therefore important to consider and include geothermal systems during the earliest phases of a project’s concept, design, and development process. By considering them early on and then commissioning the completed system, geothermal systems can run smoothly and effectively.