A combined refrigeration and high-temperature heat pumps systems for a brewery
A case study from a Danish brewery shows potential, but also challenges.
A case study of supplying simultaneous heating and cooling for a year has been evaluated for a Danish brewery and compared to two separate heating and cooling utilities. The study shows that there is potential but also challenges.
The heating demand follows a bi-weekly schedule with very little influence from the season. The demand for cold water follows a seasonal trend with lower loads during colder months. The heat demand fluctuates between 1350 kW and 2330 kW and the cooling demand between 290 kW and 1720 kW. The hot water should be delivered at 145 °C and the cold water at 2 °C.
The results show that the electricity consumption of the heat pump system decreased by 9.8 % at design conditions compared to a separate heat pump and a refrigeration system. However, the separate systems perform better when the ratio between the heating and the cooling demands differs substantially from the design point. This trend is more pronounced for low heating loads and high cooling loads.
The study shows a 2.1 % decrease in power consumption over a year of operation. This margin indicates that the lower OPEX should not be the only reason for choosing a heat pump system as the only heating and cooling utility for all industrial cases. Nevertheless, as the heat pump system had fewer total components than the separate systems, the capital cost could be lower, leading to a better pay-back time on the initial investment. Therefore, the best solution would allow the heat pump system to operate at design conditions most of the time while having flexible, auxiliary utilities to cover the variations in demand maximizing the overall efficiency even at higher initial investments.