Use Of A Closed Heat Pump Low Temperature Multi-effect Desalination System

The seawater desalination technology had developed for dozens of years, and hadbecome to be an effective solution for the problem of lack of water in some areas of theworld. But the distilled water were still far away from to be the substitute of the waterdaily used by people, because of its high price, so the research of how to decrease the costwas on the focus of the engineers.Through the investigation on the MED and VC desalination systems, which canproduce distilled water effectively, we provide a new system. In this new system, theevaporator of heat pump is put in the end effect of MED system and is used to recycle theenergy of vapor outside. The energy absorbed from vapor is enhanced by hot pumpcompressor, then translated into the condenser and used again. So this new systemcombines the advantage of both MED that can produce large amount of water in manyeffects and VC that can use the energy of vapor in the end effect reduplicative. Theseadvantages made this new system produce water effectively and high-yield.Physical and mathematic models are built and used in the calculation of thermalvalues of a device which produce distilled water 10000 ton per day. The cost is estimatedrudely, then a comparison is made between devices with different temperature differenceand different evaporator numbers, the result of comparison shows that the little of thetemperature difference in heat exchange and the more number of evaporators, the little ofthe management cost and total cost the device will have. At the end, the method of systemexergy analyze is used to compare the thermal efficiency of different desalinationtechnologies and the result shows that the design and use of high efficiency hot pumpcompressor and pumps is the key element for the increase of system efficiency.