Heat Pump Data Performance Analysis of Large Scale Ground Source Heat Pump Systems
Abstract: This study aimed at refining and improving current methodology concerning large-scale heat pump performance. This study was performed on two large-scale ground source heat pumps located in Solna (Stockholm). These were connected to an aquifer thermal energy storage system which provided heating and cooling for two office buildings. The heat pumps had been equipped with preliminary sensors from the BMS (Building management system) and been in operation since 2016. In 2019, additional detailed measurement equipment from ClimaCheck was installed to collect comprehensive data from the heat pumps to allow a more comprehensive performance evaluation. This study was primarily performed by data pre-processing of the BMS-data and the ClimaCheck-data. Once this was done, the ClimaCheck parameters were backtracked and recalculated. Subsequently new models for system evaluation was implemented. The most desired parameter to replace in the ClimaCheck model was the mass flow rate, which they obtain though an energy balance over the compressors. The latter part of the study was to see whether the BMS had sufficient data to provide the same information as ClimaCheck. This was done by implementing a regression of the BMS-data, where the heating and cooling capacities from ClimaCheck were used as targets. The results from the study showed that implementing a mass flow rate based upon compressor efficiency instead of an assumed heat loss was difficult and only reliable for higher loads. When evaluating the ClimaCheck parameters, interesting results were found concerning their calculations for the heating capacity, which might not be calculated the way they express in their formulas. The regression from the BMS-data was proven difficult because of the insufficient and lacking data for some instances. Five different models were produced and compared, some models showed accuracy up to 95% depending on the desired metric. It can be concluded that it is possible to estimate the key performance indicators using the BMS-data. It yields good results for the COP’s and very accurate results for the SPF’s over a year. This makes it possible to evaluate the heat pump performance for years prior to the installation of the ClimaCheck system.
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