Design And Theoretical Analysis On Loop Thermosyphon Solar Steam Generation System

Medium-high temperature steam is widely used in industry, in order to produce about 180°C steam which is needed a lot in industry, a loop thermosyphon solar steam generation system is desighed. This system originally combines the loop thermosyphon with the parabolic trough collector. In this system, loop thermosyphon possessed execellent heat transfer property transfer the solar energy which is collected by the parabolic trough collector to the water in heat exchanger to generate medium-high temperature steam. Some analysis indicate that the technology using loop thermosyphon and the parabolic trough collector to produce medium-high temperature steam is very promising.In this paper, the design of every part of loop thermosyphon solar steam generation system is introduced,.The seal,safety valve and pressure control and other problems are considered.A pressure auto control is used to make pressure fluctuate less than±7%; on the base of loop thermosyphon solar steam generation system, system efficiency and collector efficiency can be computed by measuring the temperatures and pressures of steam in heat exchanger, temperatures on some point of loop thermosyphon, and steam flow rate of exchanger. The measure method of these parameters are introduced.Performance compute model is established by analysing heat transfer process and heat resistance of loop thermosyphon system, and the results indicate that: Heatloss coefficient U_L has no business with solar radiate intensity I, but is quite influenced by emissivityεof absorb coat. Heat loss coefficient U_L increases asemissivityεincreases; Heat loss coefficient U_L increase by 6.43 W/(m~2·K) when using chemical copper black(ε= 0.1 ) compares with using blackbloard lacquer(ε= 0.9); Collector efficiencyη_c and system efficiencyηboth increase with solar radiate intensity I increases, and decreased with emissivityεof absorb coat increases; When using blackboard lacquer(ε= 0.9 ),selectively absorb dope(ε= 0.4 )and chemical copper black(ε= 0.1) as absorb coat, the collectorefficiencyη_c and system efficiencyηboth decrease with the increase of steam temperature in heat exchanger, and collector efficiencyη_c respectively decreases by1.9%, 1.1% and 0.3%, meanwhile system efficiencyηrespectively decreases by 3.6%, 2.8% and 2% as steam temperature increases from 170°C to 200°C.