Researchers at the B. R. Ambedkar National Institute of Technology Jalandhar in India have developed a new system relying on a humidification-dehumidification and vapor compression refrigeration (HDH-VCR) cycle and a PV-powered heat pump. The system is intended for the production of desalinated freshwater, cooling, and hot water.
The scientists explained that the proposed system uses the integrated refrigerator and heat pump's cooling and heating energies for its operation. “The plant also has the ability to generate cool air or hot air depending on the season,” they explained. “The cooling from the evaporator of a heat pump is used for the final dehumidification of air.”
This system consists of a PV system, heat pump, fans, air preheaters, humidifiers, dehumidifiers, air reheaters, solar water heaters (SWHs), and water circulation pumps. The working fluid in the VCR is R410A. “The solar PV power plant supplies power to the fan, vapor compressor, and pumps. Water cooling condensers (heat pumps) and SWH provide hot water to humidifiers, air preheaters, and air preheating systems,” the researchers said.
In order to produce cool air, as well as fresh and heated water, the system utilizes the HDH-VCR cycle. HDH is commonly used to control humidity levels in the air stream, first humidifying the air, and then removing surplus moisture. VCR is a process in which a refrigerant changes states between liquid and vapor to absorb heat and cool the air.
“The unique features of the plant are the arrangement of all the two-stage humidification-dehumidification components in a vertical tower, and the easy flow of the fluids in the duct,” the academics explained. “The process design has the potential for application in the residential and industrial sectors.”
They tested the system through a series of theoretical simulations and via a prototype that was tested under real conditions. They found that the system is able to generate up to 5.5 l per hour (LPH) of fresh water, up to 6.8 kW of cooling effect, and up to 4.2 energy performance ratio (EPR) at the air flow rate of 1,000 m3/h. The EPR is the ratio of primary product energy plus its by-product energy.
“The use of refrigerating effects and heat rejection of a heat pump enhances the coefficient of performance (COP) of the system,” the scientists said, without providing specific figures.
They presented the system in the study “Experimental and simulation studies on heat pump integration two stage desalination and cooling system,” which was published in Energy Nexus.
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