SIMULATION OF ENERGY AND ENVIRONMENTAL PERFORMANCE OF A DESICCANT-BASED AHU INTERACTING WITH A CPVT COLLECTOR

Desiccant-based Air Handling Units (AHU) canguarantee significant technical andenergy/environmental advantages with respectto conventional systems, especially when theregeneration of the desiccant material isobtained by means of a renewable energysource, such as solar energy.An emerging technology exploiting solar energyis represented by PVT (PhotoVoltaic/Thermal)collectors, which simultaneously provideelectricity and heat.In PVT collectors electrical efficiency may beimproved, with respect to conventional PV cells,when the outlet temperature of the cooling fluidis sufficiently low. Therefore PVT systems areoften used for low-temperature heat demand.However, PVT collectors may also show highvalues of both thermal and electrical efficiency.This occurs in case of Concentrating PVT(CPVT) collectors equipped with triple junctionPV cell, capable to achieve ultra-high electricalefficiencies (> 20 %) even when the fluid outlettemperature is around 100 °C. An interestingapplication of such CPVT collectors is thedesiccant cooling, as the regenerationtemperature of silica-gel desiccant wheelsranges between 40 °C and 70 °C.A test facility has been located in Benevento(Southern Italy), in which a silica-gel desiccantwheel is inserted in a hybrid AHU, in which thedehumidified process air is cooled by an electricchiller. The AHU has been simulated by meansof TRNSYS software.In this paper, the desiccant-based AHU hasbeen coupled with a novel CPVT, consisting of aparabolic trough concentrator and a lineartriangular receiver. For this component a modelin TRNSYS has been developed too. Electricenergy produced by the CPVT collector is usedto power the auxiliaries of the AHU and thechiller, while thermal energy is used to heat theregeneration air flow. Energy and environmentalperformance of the overall system areevaluated, in terms of primary energy savingand emission reduction with respect to areference case.