In hot climatic conditions, the temperature inside a greenhouse is much higher than the ambient temperature and requires signiﬁcant cooling to maintain the temperature in the optimal range.
A newly published study done by researches of the Hamad bin Khalifa University proposes a novel concept for a self- sustaining greenhouse, which integrates evacuated tube collectors, a multistage ﬂash desalination system, vapor absorption cooling system, and photovoltaic thermal (PV/T) system to produce freshwater, cooling, and electricity.
The PV/T system uses spectrum selective nanoﬂuid that is circulated over the roof of the greenhouse and absorbs solar radiation having wavelengths greater than 1400 nm to reduce cooling load inside the greenhouse and optimize the spectrum use. The performance of the proposed system is evaluated using energy and exergy analysis. The energy efﬁciencies of the evacuated tube collector, desalination unit, and PV/T system are obtained as 45.85%, 46.16%, and 51.25%, respectively.
The absorption cooling system achieves an energetic coefﬁcient of performance of 0.83. The overall energy and exergy efﬁciencies of the proposed system are found to be 30% and 5.88%, respectively. The application of spectrum selective nanoﬂuid on the roof of the greenhouse yields about 26% reduction in the cooling load of the greenhouse.