page_title: Spiral ground heat exchanger
section_title: Optimization of distance between spiral GHEs
hierarchical_section_title: Spiral ground heat exchanger / Integration of spiral GHEs to the building / Optimization of distance between spiral GHEs
caption_attribution_description: English: Thermal interaction
context_page_description: Using of spiral ground heat exchangers in heat pump applications plays a very important role in supplying heating/cooling demands of the buildings cheaply and sustainable. These-days environmental pollution is one of the main concerns among governments and energy consumption of the buildings has a significant portion in it. One of the efficient ways in supplying heating and cooling demands of the buildings is using potential energy stored in ground which is clean and sustainable. These types of systems are called ground source heat pump systems which are used supplying space heating and cooling demands. The initial cost and efficiency of GSHP systems can be influenced by optimal design of ground heat exchangers.
  One of the most important GHEs that is used these days is spiral GHEs. These types of GHEs are cheaper than others and also have some advantages.
  Many parameters influencing thermal performance of spiral GHEs such as external major diameter of borehole, spacing, distance between each turns of spiral GHEs, etc. When we have a large application area, one spiral GHE is not enough for supplying heating or cooling demands of the building.
context_section_description: As it is known, concept of extracting/injecting heat from/to ground is temperature different between two mediums. When there are more than one spiral GHEs embedded in ground it means that we have more thermal interactions in ground. When distance between heat exchangers is low (lower than 5 meter) thermal interactions between them is also too high. By increasing distance between them thermal interactions will be reduced and therefore we have low performance loss in system. Different researches show that at least 6/7 meter distance must be chosen between GHEs. For example, when number of spiral GHEs is nine we have 15%, 18%, 22% performance loss for 7, 6 and 5 meter distance between them respectively.
  In ground source heat pump applications, optimization of distance between GHEs plays an important role in total performance of the system. This value also should be chosen based the availability of application area and also investors needs.
  In Fig. 3 thermal interactions between nine mumbers of spiral GHEs are shown. As it is demonstrated as the time passes thermal interactions between spiral GHEs are increased.
caption: Fig.3: Thermal interaction
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