Design and simulation of a solar assisted desiccant-based air handling unit

Desiccant-based Air Handling Units (AHU) can guaranteesignificant technical and energy/environmental advantagesrelated to the use of traditional ones (with dehumidification bycooling). For these reasons, a test facility has been located inBenevento (Southern Italy), in which a silica-gel desiccantwheel is inserted in an AHU which treats outside air only. Forthis wheel, the regeneration temperature can be as low as 65 °C,therefore energy savings and emissions reductions are moreconsistent when the regeneration of the desiccant material isobtained by means of available low grade thermal energy, suchas that from solar collectors or cogenerators.In the actual configuration, regeneration is obtained bymeans of thermal energy recovered from a micro-cogenerator(MCHP, Micro Combined Heat and Power) based on a naturalgas-fired reciprocating internal combustion engine, eventuallyintegrated through a natural gas-fired boiler.Future activity aims to reduce the regeneration fossilenergy requirements by introducing a solar collector systemthat substitutes or integrates thermal energy supplied by theMHCP.To this aim, a commercial software has been used to designthe solar collector system (collectors type, absorber area, waterflow rate…) considering the thermal power and temperaturerequirements of the regeneration process.The existing AHU and the designed solar collector systemhave been successively simulated by means of TRNSYSsoftware, in order to evaluate operational data and performanceparameters of the system in a typical week of operation, e.g.thermal-hygrometric conditions of air in the mean sections ofthe AHU, solar collectors efficiency and solar fraction.