Development of a solar thermal water pump with air-water vapour

摘要

The objective of this research was to design and to develop a solar thermal water pump.The pump was powered by hot air-water vapour produced from a flat plate collector coupled with the auxiliary electric heater substituting for an evacuated tube solar collector.The solar water pump system comprised a flat plate solar collector(SC),an overhead tank(OT),a hot water storage tank(ST),an electric heater tank(HT),a liquid piston tank(LT),and a one-way valve for water circulation control.One metre discharge head and 1-3 m suction heads were tested.The LT was filled with the 10％air and 90％water.The pump could operate at the LT temperature of about 98 oC.It was found that,for the suction heads of 1 and 3 m,the total pump efficiency was around 0.0140-0.0301％,and the thermal efficiency was around 32.5-36.3％,respectively.The pump could suck around 7-8 l water from a well in a cycle.The energy inputs were 18 MJ of which 55％was from the auxiliary electric heater and about 45％from solar energy,during 2-h period.The average temperature in storage tank(ST)was around 42.9-46.7 oC sufficiently high for residential use.It was concluded that the suction heads affected the pump efficiency.Increasing air into the system could reduce some energy consumption.Moreover,the pump of 240 l capacity was tested.The energy inputs were only taken from auxiliary electric heater.System operation was controlled by hand.Suction heads of 1,2,3 and 5 m were tested.It was found that the pump could suck water of about 80-90％of pump volume.In addition,temperature,pressure and water pumped per cycle were presented.