The Study Of New Middle/High Temperature Solar Spray-Type Steam Generator

In recent years, with the development of industry in China, steam consumption is rapidly increasing. The steam used in industry is in the range of 100℃～400℃middle/high temperature steam, and mostly from coal boiler or electric boiler. However, the traditional methods of generating steam are no longer fit for the long-term and stable industrial development, because of the environmental pollution and rising costs. Using solar energy to generate middle/high temperature steam is considered as one of the most promising fields in solar middle/high temperature utilization.This paper designs a set of middle/high temperature solar steam generation system, which solves the problems of the solar direct steam generation system. The solar collector and steam generation are divided into two separate parts. The system mainly consists of new-type solar collector, spray-type steam generator, circulating oil pump and oil storage tank, and the heat transfer oil is used as the working fluid.In order to increase the efficiency of solar steam generator, this paper applies the spray technology to the steam generator, and designs a new spray-type steam generator. The heat transfer oil flows in the spiral coils from the top down and the sprayer makes water into droplets and sprays the droplets toward the coils from the bottom up. When the droplets meet the coils, they turn into steam instantaneously.This article simulates the distribution of droplets in the steam generator by using the DPM model, and gets the optimum values of spray cone angle, coil space and coil median surface diameter by counting the number of effective particle flows.Based on the analysis of the heat transfer process, the complete mathematical model is established. This paper analyzes the variations of droplet surface temperature and radius with time through the solution of the integral equations, and discusses the effects of structural parameters and working conditions on vaporizing time. All these make the theoretical foundation for the study of the spray-type solar steam generator, and have guiding significance for the experimental research in the future.