The analysis of heating output evaluation methods for borehole heat exchangers

Abstract

Projects involving borehole heat exchangers more often need to undergo a series of tests before implementation. Inserted pipes and cement in the borehole may have diff erent thermal properties. Until recently, such values were determined in approximate, based on values taken from the literature. Special methods are used more often to perform this type of work in order to correctly determine the properties of a borehole heat exchanger. The aim of the study was to present an analysis of thermal properties of borehole heat exchangers with the main emphasis on parameters such as thermal conductivity and thermal resistance.The analyzed data was obtained through the use of three methods:– analysis of the lithological profi le with rock conductivity based on the literature,– analysis of natural temperature profi le in aborehole heat exchanger (logger NIMO-T),– thermal response test.