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The aim of this study was to investigate the current STE systems used in the dairy industry and recommend more efficient STE configurations to improve environmental and economic performances of the dairy processes.

The dairy industry is one of the growing sectors in the food industry with significant thermal energy demand for their processes and temperature requirement of maximum 200 ℃. The use of solar energy for those process will reduce the fossil fuel dependency, greenhouse gas emission, environmental pollution and help to meet emission targets. Therefore, this study investigates the thermal requirements of a dairy company and provides a schematic of two integration concepts between the solar thermal energy system and their processes which are through the common energy supply line and inlets of individual processes. The study involves a case study that uses natural gas-powered boilers, and electrical powered chiller, ice banks and refrigerators to meet heating and cooling energy demand for the processes such as pasteurisation, fermentation and cold milk tanks. The overall energy consumption of the dairy processes is 1315 kWh at the full capacity operation, of which 1195 kWh can be theoretically replaced by the solar thermal energy. The temperature requirements of the processes are between 0 ℃ and 4 ℃ for cooling, and 170 ℃ for the heating. These thermal requirements can be met by using either parabolic trough or linear Fresnel solar thermal collectors along with thermal energy storage. The solar thermal energy integration concepts developed at supply level and process level use steam drum and absorption chiller to transfer the solar energy to the processes. The supply level integration has more advantages due to its easier control over the conventional and solar energy systems.

This study is focused on the integration of an advanced solar thermal system to dairy industry processes. The objectives are to: (i) understand the thermal heating and cooling requirements (ii) simulate different integration scenarios for solar thermal systems applications (iii) assess the solar energy contribution to the system. A case study of a diary company located in Greece was considered.