Supporting district heating and cooling networks with a bifunctional solar assisted absorption chiller

Abstract

Supplying the heating demand of the absorption chillers connected to district heating systems is challenging during summertime when there is not enough demand to take advantage of the high temperature discharge water of the chillers. In this work, a new configuration of a bifunctional solar assisted absorption chiller is proposed by which the heating demand of the chiller is efficiently supplied. This innovative system takes advantage of an evacuated tube solar thermal system and has no cooling tower. The proposed system is designed and simulated for a case study in Denmark, i.e. the Aarhus University Hospital. The effect of applying the proposed system to the performance of the hospital cooling systems and the local district heating network is assessed over an entire year. The results show that the proposed system could make a 30% contribution to the heat preparation process of the absorption chiller during the summer and a 17% contribution seen over the entire year. Aside from this, the system can contribute a large amount of heat production for district heating purposes during the cold months. As such, the effect of replacing the conventional system with the proposed configuration on the CO2 emission of the case study is evaluated. Finally, the two economic criteria of net present value and internal rate of return are used to assess the effectiveness of the project economically, finding it very feasible and economical with a payback period of less than two years.