Evaluation of a district cooling network using R-744 as the energy carrier: A case study

Due to the increase in global temperatures, there is a need to provide more efficient district cooling systems in the future. In this study, a district cooling system using R-744 as the energy carrier was used to provide comfort cooling at five commercial buildings located in Denmark. The heat of the network was utilised to produce district heating in the local network using a heat pump. Two alternative system designs and operation strategies for the pressure levels throughout the network were analysed and compared on the energy performance. It was found that a system with lower temperature levels and direct cooling at the consumer substations required smaller pipes in the forward line but showed an overall slight increase in power consumption. This was caused by the reduced performance of the central heat pump. The results show, that the operating strategy of pressure levels in the system should be chosen not only to optimise the consumer substation but should also consider the operation of the central heat pump, as this is an important component of both operation and capital expenses.