Effectiveness and constraints of using PV/Thermal collectors for heat-driven chillers

Abstract

In the last year, a continuous deeply increase in energy demands for cooling purposes is observed. Such energy needs are mainly satisfied through conventional vapour compressor chiller (VCC), which foresee the use of electricity usually generated through conventional energy sources. As an alternative, solar cooling plants offer a reliable and environmentally friendly for producing, in a sustainable way, cooling energy. This paper presents the analysis of the performances of an adsorption chiller (ADS) driven by solar energy operating in the Mediterranean area. In particular, this research aims to highlight the effectiveness and constraints of using photovoltaic/thermal (PVT) panels as the energy source of a heat-driven adsorption chiller (PVT ADS). Since the PVT allow producing both thermal and electrical energy it is of fundamental importance to investigate the effects of the operative temperatures on the efficiency of the whole PVT-ADS system. The analysis was conducted developing a dynamic simulation model for a solar cooling plant, for which the adsorption chiller's performances are derived by the 9.75 kW ADS, developed at the Gebze Technical University, Turkey. Cooling and power production has been explored as a function of the regeneration temperature of the ADS chiller. This analysis allowed us to point out the best design for the investigated PVT-ADS system. As a result, a regeneration temperature of 70 ? for a volume of the solar tank of 60 l/m(2) of PVT panel was defined. The investigated PVT-ADS, composed of 49.0 m(2) of glazed PVT panels achieves 51.9 and 40.3 kWh of cooling energy and electrical production respectively, during a typical summer day. Moreover, the comparison between the proposed PVT-ADS with a vapour compressor chiller driven by conventional PV modules (PV-VCC) is proposed. Such comparison shows that the PV-VCC produce about 2.9 kWh of cooling energy, per kW of nominal cooling power installed, more than the PVT-ADS system. Instead, the PVT-ADS guarantees the highest net electrical yield. The results of this study demonstrate the effectiveness of using PVT system as a potential source for solar cooling plants in the Mediterranean area.