18 May 2017

P.2.7.12 An investigation on thermal interaction coefficient for multiple borehole heat exchangers


In large scale applications of ground source heat pump systems, multiple Borehole Heat Exchangers (BHE) are used and thermal interactions between BHE becomes an important issue. Thermal Interaction Coefficient (TIC) is a critical parameter to represent the dependency of total heat transfer ratio of multiple BHE on their spacing. For given thermal properties of application field, TIC depends on number of BHE, allocation geometry and operation duration. In this study, a rectangular allocation field having 64 BHE is considered. Dependencies of total heat transfer ratio (HTR) of the field and TIC on aspect ratios of allocation geometry are computationally investigated. Furthermore, the effects of number of BHE and operation duration on TIC are examined. The results can be used during the engineering design of a BHE field to maximize the time averaged total HTR value of a given application field.