Experimental Study On Two Phase Flow Instability In Direct Steam Generation Of Solar Thermal Power

Direct steam generation technology (DSG) is a very promising solar thermal power technology,In this system, water as working fluid is heated directly.Compared to oil/ steam heat exchanger system, it has higher thermal efficiency.But DSG technology has to face two-phase flow instability and flow maldistribution of parallel bundle inside collectors.In this paper, an experimental facility is used to research flow rate distribution of two parallel pipes in an evaporator with common inlet and outlet manifolds. The influence of mass flow, inlet subcooling, different heating condition and different tilt angles on Soda two-phase flow stability and flow distribution in the tube is analyzed by comparing the experimental data. In response to these problems, the solution of installing throttling device on the entrance of the parellel pipes is presented. According to the experimental data analysis, the system can work steady in the unstable region.In addition, the theoretical calculation of two-phase stability inside single pipe and two-phase flow distribution inside parallel pipes are introduced, the system stability is also analyzed. Theoretical calculation provides the basis for the analysis of experimental data,they match well each other. The results in this paper can be used for the basic information on the collector design of DSG technology.