Thermal charging of boreholes

This paper presents experimental study of thermal charging the boreholes that are used for inter-seasonal thermal storage of heat and coolth integrated with ground-coupled heat pump and unglazed solar collectors. After 180 days of thermal charging, it was observed that the temperature of the ground at 21m depth and 1m distance from the borehole had increased by 2.5°C. The unglazed collectors are able to collect heat for charging the heat storage borehole at an average of 43.9MJday -1 . The system is able to charge borehole at an average heat transfer rate of 57Wm -1 . A comparison of the experimental results with the simulated results of a TRNSYS model of the system showed a good agreement. The mean efficiency of the unglazed solar collector during 180 days charging operation was found to be 30% and the mean efficiency of the system was found to be 38%. © 2013.