“…A mathematical model for DX-SAHP calculations consisting of energy and exergy balance equations is proposed by [48] and applied to a vapour compression DX-SAHP serving a Turkish office. In practice, different SAHP systems -equipped with unglazed evaporator collectors, evaporator collectors and air collectors, exploiting solar and ambient energy -were tested for various applications (air-conditioning, water heating, and drying) under the Singapore meteorological conditions in [50], resulting that, in comparison with a conventional collector, the evaporator-collector efficiencies were higher, ranging from 80% to 90% with an 8.0 coefficient of performance of the heat pump system. A variety of further investigations aimed at modelling, designing and testing solar assisted heat pumps systems is available in literature [13,[51][52][53].…”