Investigation of climatic effect on energy performance of trigeneration in building application

Trigeneration is commonly considered as one of the energy-efficient solutions, since the heat recovered from electricity generation can be adopted to produce both heating and cooling for building use. It is generally accepted that the trigeneration system should outperform the conventional separate provisions of cooling, heating and power. However, energy efficiency of the prime mover of trigeneration would be diminished in part-load conditions, which are mainly determined by the changing climatic situations. In this regard, it is not sufficient to consider the energy performance of trigeneration based on the design point. Therefore, this study attempts to conduct year-round evaluation of trigeneration systems subject to climatic effect. Four cities with close longitude but different latitudes were involved, which had different heating-to-cooling ratios in building loads due to climatic conditions. A set of energy performance indicators were applied to thoroughly appraise the trigeneration systems against the conventional provisions. It was found that the extent of energy merit of trigeneration depended on the utilization degree of waste heat, which was associated to the electrical efficiency of prime mover and the building loads caused by climatic effect. While the year-round fuel energy utilization ranged from 61.9 to 83.8%, the respective primary energy reduction only varied from 0.4 to 7.5%. Energy saving potential of trigeneration might not be guaranteed in certain occasions in a year.