The Research On Solar Desalination System With Solar Pond

Water is essential for life and it is the basis for social well-being of people. Around97.5%of earth’s water is salt water while only2.5%is fresh water that can be used by humans. Conventional seawater desalination technology could solve the problem of fresh water shortage, but consumed a large amount of fossil fuel and caused the environmental problems. Solar desalination which can solve the resource and environmental problems is one of the promising methods.The system investigated in this paper is an LT-MED system coupled with a salt-gradient solar pond for desalting seawater. Mathematical and economic models of solar desalination system with Salinity-gradient solar pond which supplies the energy and store energy in the system are established based on mass and energy conservation. A C Programming Language and A MATLAB computer models of solar-powered low temperature multi-effect distillation (LT-MED) processes are developed. It researches the change of solar radiation on the surface of solar pond and solar pond supply stream temperature with the running days, and researches the effect of turbidity on solar pond supply stream temperature, the effect of supply stream mass flow rate, the temperature of stream entering into the external heat exchanger, the temperature of stream returning to solar pond, the solar pond area, the heating steam temperature of the first effect, the number of effects of LT-MED system on the thermal and economic performance on solar desalination system.Under the calculation conditions of this paper, the thermal and economic performance on solar desalination system with solar pond and low temperature-multi-effect distillation is presented. With the increasing of the turbidity, solar pond supply stream temperature reduces. The phase position of solar radiation on the surface of solar pond hysteresis than solar pond supply stream temperature; with the increasing of the feed flow rate, the energy supplied by electric heater evaporator heat transfer area, fresh water production and fresh water production per unit collector decrease; and fresh water cost decreases gradually. When the temperature difference of stream through the external heat exchanger is5℃, with the increasing of the temperature of stream entering into the external heat exchanger, the evaporator heat transfer area, fresh water production and fresh water production per unit collector of LT-MED system are constant; the energy supplied by electric heater increases; and fresh water cost increase gradually. With the increasing of the temperature of stream entering into the external heat exchanger, the energy supplied by electric heater, the evaporator heat transfer area, fresh water production and fresh water production per unit collector increase; and fresh water cost decreases firstly and then increases. With the increasing of the temperature of stream returning to solar pond, the energy supplied by electric heater evaporator heat transfer area, fresh water production and fresh water production per unit collector decrease; and fresh water cost changes slightly firstly and then increases gradually. With the increasing of the solar pond area, the energy supplied by electric heater evaporator heat transfer area, fresh water production increase and fresh water production per unit changes slightly, but fresh water cost decreases.This paper also researches the constitute of the system cost and analysis the effect of the price of land, the price of the evaporator’s material, proportion of building and supporting facilities cost on the fresh water cost under the calculation conditions of this paper. The conclusions are helpful to the design and operation of solar desalination plant.