Study On The Void Fraction Of Two-phase Flow In The Evaporative Cooling Generator

The evaporative cooling generator is cooled by the critical heat when the coolant boils, compared with the common cooling methods, cooling by the specific heat of the coolants, evaporative cooling has high efficient, and it is Close-Loop-Self-Cycle so it can save a lot of coolant; and the generator has low temperature and the temperature distribution is much uniform. In 1999, the evaporative cooling generator of LiJiaXia began to generate electricity, and the generator was awarded the National Technology Progress. In 2000, the evaporative cooling generator was considered as one of the four great progresses in generator in CIGRE in Paris in France. It proofed that the evaporative cooling generator had great superiority not only in theory but also in practice. It is competitive in the world market and the future is excellent.The technology of evaporative cooling generator includes several subjects, such as electrical machine, thermal physics, fluid mechanics and mechanics, so it becomes very difficult. The complex transfer of mass and heat in two-phase flow are one of the most important problems in the evaporative cooling technology. The void fraction has much close relationship with flow pattern, pressure drop and average density, so it is a very important parameter.In the foundation of theory and experiment, the experiment equipment was build-up. The testing system included radioactive isotope, which can bring out YRay, and energy spectrum analysis system. The author tested the void fraction of two phase flow in glass pipe, in which F113 liquid and air was injected, and F113 two phase flow in heated copper pipe and compared the conclusion with those that received with GM several years ago. It proofed that it was possible to test the void fraction in the mini pipe of the evaporative cooling generator. The max statistical error formula was derived. It pointed out that increase the statistical number and the differentiability of the system could decrease the system error, and the system error was low at high void fraction and high at low void fraction. At last, the article thought that the variation of void fraction through a heated pipe could be studied by the alteration of the evaporative point in different quality of heat. This is one of the methods to study the void fraction in mini heated pipe.