| Tianjin has abundant geothermal water resource but short of fresh water , so this paper put forward a new method to desalinate geothermal water in Tianjin——natural vacuum flash without outer heat resource. The idea of this technique results from references to some related literatures, and from the characteristic of heat pipe——transfer heat by working fluid's macroscopically flow. The aim of this paper is to investigate how to use geothermal resources'low enthalpy heat to make geothermal water, which has amount of heat, convert to"treated waste water"even drinkable water. Under the financial support of Tianjin's nature science social development fund, the feasibility of desalinating geothermal water using own low enthalpy is verified by plenty of dates which were obtained by theoretical analyses and calculations,system design and experimental studies. Because the temperature of geothermal water is low, in order to satisfy the needed quantities of condensing water, large evaporating areas are required. As to solve this contradiction, spray nozzle was added in the flash chamber to enhance heat and mass transfer. This method can increase the flashing rate. Geothermal water was simulated by tap water which was heated to a certain temperature. These systems, which are with two spray nozzles, with a single spray nozzle and with no spray nozzle, were studied. Temperature range of experiment is from 30℃to 80℃.The experiments'results indicate, on the same conditions, the system with single spray nozzle has the highest water yield, but the system with no spray nozzle has the lowest water yield. So the spray nozzle's effect to improve the natural vacuum flash system's flashing rate is confirmed. Another experiment which studied the system with single spray nozzle under certain pressure verified the differential pressure of spray nozzle is not proportioned to the system's performance.
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