Performance analysis of high temperature heat pumps and thermal energy storages for a dairy

Abstract

This paper analyses the performance of the integrated energy system of an existing dairy in Bergen, Norway. The investigated dairy has an innovative solution for the thermal process supply by using only heat pumps and thermal energy storage to cover all temperature levels of the existing heating and cooling demand. The aim of the study was to determine the energy consumption and system performance for one winter week and one summer week and compare these results against each other. To evaluate the performance, a comprehensive energy analysis was carried out based on the available process data. The results show for a comparatively energy-intensive week in February that the integrated energy system covers the existing demand and can compensate for demand peaks, with a waste heat recovery rate of over 95% for the process. The chillers and heat pumps achieved high COPs in the range of 4.2 to 5.9, while the overall system achieved a total COP of 4.1. A comparative week in June was then investigated and compared with the results of the operating week in February. Due to higher building cooling demands and lower building heating demands, the demand for dry cooling was significantly increased in the summer, whereas the need for electric heating and district heating was reduced. The achieved COPs in the range of 4.2 to 5.7 were similar in the summer week, meaning that the energy system functions well in different climatic conditions. Based on the results of this study, the performance of the system under different conditions was evaluated and the impact on power consumption and potential use for other climatic regions was discussed.

Performance analysis of high temperature heat pumps and thermal energy storages for a dairy