Performance and economic analysis of a floricultural greenhouse with distributed fan-pad evaporative cooling coupled with solar desiccation

Humidity imparts an adverse effect upon a conventional fan-pad ventilated greenhouse in the tropical and subtropical countries. In the present work, a novel scheme of a desiccant assisted distributed fan-pad ventilated greenhouse system has been proposed for the cultivation of varieties of Gerbera. A thermal model of the proposed system has been developed to predict the greenhouse temperature and compare the same with a reference model study available in literature. To regenerate the desiccant materials, solar thermal energy is used which is harnessed using a number of flat plate collectors. Study reveals that, while the maximum temperature inside the conventional greenhouse without desiccation is about 28.8 °C, the same can be maintained below 27 °C even during the peak sunshine hours of the summer season with the proposed system for the place under consideration (plains of Indian sub-continent). During the monsoon season (June), the maximum greenhouse temperature can be restricted within 26.6 °C with the present system, while during the same period the temperature of the conventional fan-pad ventilated greenhouse reaches about 28.8 °C. A cumulative cash flow model has also been included in the study to examine the payback period and the Net Present value (NPV) of the proposed system. From the economic analysis, it is observed that the payback period of the system is about 6 years, while the NPV is about $9090 (assuming a service life of 15 years) considering the price of Gerbera to be $0.15. The system thus reinforces the viability of the proposed system both from technical and economic point of view.