A solar powered liquid-desiccant cooling system for greenhouses

Lychnos, George and Davies, Philip A. (2008). A solar powered liquid-desiccant cooling system for greenhouses. IN: International Workshop on Greenhouse Environmental Control and Crop Production in Semi-Arid Regions. Kubota, C. and Kacira, M. (eds) ISHS Acta Horticulturae, 797 . Leuven (BE): International Society for Horticultural Science.

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Abstract

Liquid desiccant systems are of potential interest as a means of cooling greenhouses to temperatures below those achieved by conventional means. However, only very little work has been done on this technology with previous workers focussing on the cooling of human dwellings using expensive desiccants such as lithium salts. In this study we are designing a system for greenhouse cooling based on magnesium chloride desiccant which is an abundant and non-toxic substance. Magnesium chloride is found in seawater, for example, and is a by-product from solar salt works. We have carried out a detailed experimental study of the relevant properties of magnesium rich solutions. In addition we have constructed a test rig that includes the main components of the cooling system, namely a dehumidifier and solar regenerator. The dehumidifier is a cross-flow device that consists of a structured packing made of corrugated cellulose paper sheets with different flute angles and embedded cooling tubes. The regenerator is of the open type with insulated backing and fabric covering to spread the flow of desiccant solution. Alongside these experiments we are developing a mathematical model in gPROMS® that combines and simulates the heat and mass transfer processes in these components. The model can be applied to various geographical locations. Here we report predictions for Havana (Cuba) and Manila (Philippines), where we find that average wet-bulb temperatures can be lowered by 2.2 and 3°C, respectively, during the month of May.

Item Type:Book Section
Additional Information:The original publication is available at http://www.actahort.org/members/showpdf?booknrarnr=797_11
Uncontrolled Keywords:greenhouse cooling, liquid desiccant, solar energy
Divisions:Schools_of_Study > Engineering & Applied Science > Engineering Systems & Management (EAS)
Schools_of_Study > Engineering & Applied Science > Mechanical Engineering & Design (EAS)
ID Code:17801
Deposited By:Prof Alfred Admin
Deposited On:04 Dec 2012 14:30
Last Modified:25 Sep 2014 09:41

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