Field Measurements and Modelling Analysis of CO2 Refrigeration Systems with Integrated Geothermal Storage

Abstract: The aim of this study is to investigate the potential of CO2 trans-critical booster refrigeration system integrated with geothermal storage to provide the cooling and the heating demands with high energy efficiency. During summer season, heat is rejected from the CO2 refrigeration system, increasing the amount of sub-cooling and storing this heat into the ground. During winter season, the heat stored in the ground is extracted and used as heat source to provide the heating requirements of the supermarket.  Using field measurements data from medium size supermarkets in Sweden, existing solutions for integrated geothermal storage in a CO2 refrigeration system as well as proposal solution are modelled and compared with stand-alone CO2 trans-critical booster system. The techno-economical comparative analysis shows that hybrid CO2 trans-critical booster system with GSHP as an integrated geothermal solution has 6% lower annual energy use than a stand-alone CO2 system with heat recovery solution for refrigeration and heating in North of Europe. In addition to the computer simulations, field measurements monitoring of ten medium size supermarkets with integrated geothermal storage have been studied. Measurement system proposal guide is done to fulfill a proper energy analysis of the supermarket installation with the integrated solution. Evaluation of the missing measurements is done for the available supermarkets. One important conclusion of this part is that none of the supermarkets analyzed has enough measurement to realize a proper and comprehensive energy analysis.