Research On Insulation And Heat-transfer System Of Stator In Evaporative Cooling Horizontal Electrical Machine

Utilizing the physical phenomena that the heat absorbed by a liquid medium when it is evaporating is much bigger than its specific heat, evaporative cooling is another important cooling method after air cooling, hydrogen cooling and water cooling to medium-sized or large electrical machines. It possesses many superior qualities such as safety and credibility, excellent benefit steady performances , simple and convenient running management. But the stator of a horizontal electrical machine will meet with irrationalities coming from the traditional stator insulation structure, if it adopts the evaporative cooling technique. These irrationalities main show that there are cooperative questions for stator insulation and heat-transfer. As a result these bring forward challenges for evaporative cooling method to be used in the stators of medium-sized or large horizontal electrical machines. Therefore researches on the stator insulation and heat-transfer system of horizontal electrical machines have very important academic significances and applied values. This work studies two different kinds of insulation and heat-transfer system of stator in evaporative cooling horizontal electrical machines.The formative mechanism of gas, liquid, and solid stator-insulation system in evaporative cooling horizontal electrical machine is expounded. And this kind of stator-insulation system should be rationally designed and optimized. So a few of kinds new stator insulation structure in evaporative cooling horizontal electrical machines aimed at meeting different running needs can be developed. Furthermore they can be provided with high performance targets (such as safety , credibility, efficiency, and material utilizing rate).This work puts forward a new kind of stator insulation structure for a specialevaporative cooling commutate asynchronism generator with high power density. For the first time using a simulation tool - EMAS software setting in a workstation, this work calculates the electric and temperature fields in the primary project of the new kind of stator insulation structure. The traditional stator insulation structure is also calculated to be compared with the new one. Therefore the necessary and feasibility of designing new evaporative cooling stator insulation structure are analyzed qualitatively in theory.This work first solves the experimental correlative expression of boiling heat transfer coefficient of the evaporative cooling medium in restricted space in sealed stator body. This offers an important calculation parameter for researching the temperature distribution in evaporative cooling stator.For the first time, this work successfully calculates and simulates temperature field of the gas, liquid, and solid stator-insulation system formed in an evaporative cooling horizontal electrical machine. Basing on the simulation results this work solved mainly the decided stator insulation structure project for the special evaporative cooling commutate asynchronism generator with high power density.In the course of researching stator insulation structure of high voltage and large power rate evaporative cooling turbo-generators, this work first combines the various phenomenon and results in the experimental model testing, with the calculation results of simulation in theory. By this method the electrical insulation qualities and electric field of the gas, liquid, and solid stator-insulation system is researched carefully. Fourthly from the view point of exploration, this work builds a calculation model and an optimizing approach to the new stator insulation structure of evaporative cooling turbo-generators making use of the simulating tool-EMAS. So the optimizing design results of 13.8KV and 24KV rate are obtained. And electric field distributions in slot and ends of 24KV rate stator insulation structure is calculated and analyzed. At last a conclusion that offering by evaporative cooling method, the gas, liquid, and solid stator-insulation system improves greatly the electric distribution in stator slot and ends...