Shunzhou Yu

Experimental research of evaporative cooling technology in the high power rectifier transformer

This paper presents the application of the evaporative cooling technology in the high power rectifier transformer. As the Three Gorges 700MW hydro-generator model needs high-power DC power supply, the evaporative cooling system in three phase bridge non-controlled rectifier is built up. The cooling system of the transformer and the rectifier are connected together. The temperature distribution of the transformer and the rectifier are measured. Experimental results conclude that application of the evaporative cooling technology in the rectifier transformer has the advantages of high cooling efficiency, high insulation, small size, light weight, and so on.

Research on void fraction of gas-liquid two phase flow in evaporative cooling generator in ray test

This paper firstly introduces the basic principle of void fraction of gas-liquid two phase flow in evaporative cooling generator in ray test, calculates the penetrate coefficient of multiple X-ray source in evaporative cooling coolant and its test pipes. The experiment studies the decay laws of x-rays and isotope γ-rays in evaporative cooling coolant, tests the void fraction of gas-liquid two phase flow in evaporative cooling, which is compared with the model theory calculation results. From the analysis and the discussion, it is concluded that using isotopic γ-rays shows moderate energy, good monochromaticity, and the test of void fraction of gas-liquid two phase flow in evaporative cooling is more ideal.

Optimal Design of an Innovative High Temperature Superconducting Generator With the Evaporative Cooling Stator and the Magnetic Flux Oriented Rotor

The optimal design of a 2.4 MVA high temperature superconducting (HTS) generator is presented. The main features of its configuration are the adoption of the evaporative cooling stator and the magnetic flux oriented rotor. The cross section of the field winding in rotor is in circular arch shape, and the magnetic diverter shims are embedded between HTS coils. The technical and economical parameters of the innovated HTS generator are improved effectively. With the help of the commercial software ANSOFT RMxprt and EMpulse modules, the optimal design and detailed calculation of electromagnetic and thermal fields are implemented.

Study on the nonlinear characteristics of the inclined self-circulating evaporative cooling system for wind power generator

The evaporative cooling system for wind power generator inclines at an angle of 3∼5 degrees. Due to the special structure, it forms a liquid-gas two-phase self-circulation. Two-phase flow self-circulating system is a typical nonlinear dynamic system. So it is important to study the nonlinear characteristics. In this paper, the nonlinear characteristics were studied through theoretical analysis and experiment, according to the design parameters of 2MW evaporative inner cooling wind power generator.

Study on the flow distribution characteristics of parallel inclined hollow conductors in the evaporative cooling wind power generator

The evaporative inner cooling technology has a good application prospect in wind power generator. The system for wind power generator has a small inclination angle of 3-5 degrees and the two-phase flow instability has become more obvious. In this paper, the flow distribution characteristics of parallel inclined hollow conductors were studied through experiments and theoretical analysis, according to the design parameters of 2MW evaporative inner cooling wind power generator. Based on the work in this paper, propose a theoretical method to determine the vertical distance between the parallel hollow conductors. This provides a theoretical basis for system design.

γ-ray Test void ratio of gas-liquid two-phase flow and its error analysis in evaporative cooling generator

In the study of gas-liquid two-phase flow and heat transfer of evaporative cooling generator, has important significance to test the accuracy of void ratio. This paper first introduces the principle of ray testing, should pay attention to the selection of γ-ray source. The ray test two-phase flow void ratio of the experimental platform is established. The test data and drift model, one-dimensional model and volumetric gas rate numerical calculation for comparison, analysis of the law of the void ratio of ray test. The error of the test is mainly studied, and the maximum error formula of measuring the void ratio is deduced, and the cause of the error is analyzed. That the ray test evaporative cooling generator gas-liquid void ratio has higher accuracy, is an effective means of testing.

Effect of flow rate on the gas-liquid two-phase pressure drop in the evaporative cooling generator stator bar

In the design of generator evaporative cooling circulation system, usually by using M-N equation, the magnification of the single-phase pressure drop of two-phase frictional pressure drop is determined by the exit steam quality, that the two-phase pressure drop is composed solely of frictional pressure drop, without considering the acceleration pressure and gravity drop, also does not pertain to the effect of flow rate on pressure drop, will bring greater error. This paper aims to improve the accuracy of pressure drop, determination of magnification of two-phase frictional pressure drop of the flow rate and the outlet of the steam quality in common, and combined with the L-M equation and M-N equation, calculated and corrected two-phase frictional pressure drop. Based on the operating conditions of the 400MW evaporative cooling hydro generator, a test platform is established, the two-phase pressure drop impact test by the flow and outlet steam quality. Through the test data and theoretical calculation results show that: the acceleration pressure drop is an important part of two-phase pressure drop, should be independent accounting, and with the increase of flow rate of two-phase pressure drop in the proportion increase; In the range of experimental flow (m=1.33g/s~4.69g/s), the magnification of two-phase frictional pressure drop calculated values and experimental values of the error is within 10%, can better meet the needs of industrial applications.

Research on evaporative cooling medium for large generator

As a frontier cooling technology in the electric machine field, the evaporative cooling technology has significant advantages in cooling performance, insulativity, maintainability, and reliability. These advantages make the evaporative cooling technology fulfill the requirements of cooling system in hydro, turbo, and wind power generators. However, a suitable evaporative cooling medium is hard to obtain. This paper proposes the standards of choosing the cooling medium for the evaporative cooling system.

Shape Optimization of Field Windings in a High Temperature Superconducting Synchronous Generator with Finite Element Method

Publisher Summary This chapter presents the optimal design of high temperature superconducting (HTS) field windings in a demonstrative HTS generator model based on magnetic field analysis by finite element method. The optimal shapes of HTS magnet with iron core and without iron core are studied, and the value of the minimum vertical component of magnetic flux density passing through the surface of HTS tapes in each kind of HTS magnet is achieved. Two types of HTS rotors are analyzed. It is proved that the value of the minimum vertical component can be decreased effectively by adopting flux diverters for the configuration with iron core and by adjusting cross-sectional shape of HTS magnet for the configuration without iron core respectively. It is concluded that the iron core type HTS magnet with diverters and the nonmagnetic core type HTS magnet with step-shaped HTS magnet and iron plates are two effective ways to reduce the value of the minimum vertical component.

Design of Cooling System and Temperature Characteristics Analysis of High Temperature Superconducting Demonstrative Synchronous Generator

Publisher Summary This chapter presents the cooling system of a demonstrative high temperature superconducting (HTS) generator, in which solid nitrogen (SN2) is used as cryogen to keep the operating temperature of HTS synchronous machine. Its tasks are to pursue the minimal volume of HTS magnets and utilize the configuration characteristic of conventional generator. Its hybrid rotor has three novel aspects: the HTS magnets are installed on a warm iron core; four Dewar flasks having racetrack outline are distributed symmetrically, and SN2 is used as cryogen. Furthermore, evaporative cooling technology is applied to solve the cooling problem of the stator, which is more effective than air-cooling technology and more safer than water inner cooling technology. The pressure losses of GHe through rotor are analyzed. It can be inferred that centrifugal force has significant impact on GHe flow, and the effects of pressure and Coriolis force can be ignored. The steady temperature field is also simulated by ANSOFT, and the results indicate that the maximal temperature of HTS coils is lower than 30 K and distributed uniformly, while the GHe (15 K) velocity is 0.2 m/s.