Transient simulation of polygeneration systems based on PEM fuel cells and solar heating and cooling technologies

This paper presents a dynamic simulation of an innovative polygeneration system based on solar heating and cooling and PEM fuel cells technologies. The polygeneration system is based on the following main components: evacuated solar collectors, single-stage LiBr–H2O absorption chiller and a PEM fuel cell. The fuel cell operates at full load producing electrical energy which is in part consumed by the building lights and equipments. The fuel cell is grid connected in order to perform a convenient net metering. Finally, the system also includes heat exchangers producing domestic hot water in case of scarce space heating/cooling demand. The analysis was carried out by means of a transient simulation model, developed using TRNSYS software and includes the investigation of the dynamic behavior of the building, developed in TRNBUILD. A small university hall, including also a fitness center, was adopted as test case. Energetic and economic models were also developed, in order to assess primary energy savings and the operating and capital costs of the systems under analysis. The results of the case study were analyzed on monthly and yearly basis, paying special attention to the energetic and monetary flows. The results are excellent from the energy saving point of view. On the other hand, the pay back periods can be profitable for the final user only in case of significant public funding.