Thermal conductivity of Irish rocks

Abstract:A database of thermal conductivity values for 50 formations of Irish rock has been established and is presented here. All of the testing was carried out on a single divided bar apparatus at University College Dublin (UCD). The aim of this work is to provide thermal conductivity input parameters for the design of future small to medium-scale geothermal projects in Ireland. Some tests were repeated and additional tests were carried out on two other independent devices in order to prove the reliability and repeatability of the UCD divided bar device. Results were generally found to be within ±5% of one another. The resulting thermal conductivity values are in a narrow range and are consistent with worldwide published values for similar rocks found elsewhere. Rock porosity and the relative abundances of the mineral compositions were found to be the main controlling factors on the thermal conductivity values. No variation with thermal conductivity with depth or rock density was found. Further thermal conductivity tests carried out on rock chippings, 1.8mm to 5mm in size, of some of the lithologies; suggest that this may be a viable measurement technique, though further testing is required to verify this.