Application of the TEWI Methodology to a Desiccant Cooling System Interacting with a Microcogenerator

Desiccant cooling systems, supplied by fossil or renewable fuels, represent a very interesting alternative toconventional electric units based on cooling dehumidification for air conditioning purposes, as they can achievesignificantenergy and emissions savings. The analysis of environmental impact of energy conversion devices, e.g. interms of global warming effect, is usually limited to energy-related emissions (indirect contribution), neglecting directgreenhouse gas emissions related to working fluids, such as refrigerants. The Total Equivalent Warming Impact (TEWI)is a more comprehensive methodology, as it takes into account both direct and an indirect contributions to globalwarming. In this paper, this method is applied to a small scale trigeneration system, in which a microcogenerator, achiller and a boiler interact with a hybrid desiccant-based cooling system, equipped with a silica-gel desiccant wheel.This trigeneration system is compared with other two systems, in order to assess its potentiality in terms of TEWIreduction. The different direct and indirect contributions of the several equipment are evaluated, and the share of thedirect contribution is investigated, considering both the overall TEWI of the complete system, and that of the electricvapour compression device only. Finally, the effect of the greenhouse gas emissions of the electricity production mix andof different values of the Global Warming Potential (GWP) of the refrigerant fluid on the overall TEWI of the threecompared systems is investigated