Haihong Dong

Research on two-phase flow instability in two parallel hollow conductors in the evaporating cooling generator

As a new generator cooling technology, the evaporative cooling technology has been researched on various aspects to a certain extent, such as the two-phase flow pressure drop, temperature distribution and etc. But there has no research reported on the two-phase flow instability in the parallel hollow conductors in the evaporative cooling system. The occurrence of two-phase flow instability phenomena can probably make some system parameters change abnormally, such as flux and temperature, and make the cooling system operate abnormally. So its necessary to pay more attention to the instability of two-phase flow to assure the generators cooling effects. In this paper, the two-phase flow instability in two parallel hollow conductors was researched through theoretical simulation and experiments and the boundaries of the instability starting were obtained. The conclusion provides the reference basis for the actual operation of the evaporative cooling system in a certain sense.

Steady-state performance of evaporative cooling system of stator busbar in hydro-generator

The natural circulation evaporative cooling system is a new kind of method for the cooling of stator busbar of hydro-generator, with the advantage of high-security, energy-saving and high efficiency. The feasibility of this method has been validated through the experimental and theoretical analysis in previous researches. In this article, an experimental table of natural circulation evaporative cooling system of stator busbar was established and the steady-state operation characteristics of system were analyzed by experiments. The wall temperature distributions of stator busbar show that the cooling effect of this new cooling technology is satisfactory. The system work pressures were discussed, which is closely related to the system sealability. The flow characteristics of coolant under different work conditions were analyzed. The research results in this paper provide the important basis for the practical application of this new cooling method.

Research on the flow characteristics of different cooling medium in the inner evaporative cooling turbo-generator

In the inner evaporative cooling turbo-generator, the cooling medium flows in the hollow conductor of stator and the cooling system depends on the sensible heat and latent heat of cooling medium to achieve the cooling goal of generator. Due to each cooling medium has unique thermal properties, the flow characteristics of different cooling medium in the hollow conductors is disaffinity. In this paper, two kinds of cooling medium were chosen as the study objects. Through simulating, the flow resistances of different cooling medium in the hollow conductors under different working conditions were compared. The exit dryness and the lengths of two-phase section in the hollow conductors were also discussed and the reason of the discrepancies were analyzed. The simulation results of flow resistances were compared with the experimental data and the accuracy of simulating prediction is satisfactory.

Data monitoring system for evaporative cooling ECR based on LabVIEW

The electron cyclotron resonance ion source magnet is a typical super-high power density magnet, and the evaporative cooling technology is an ideal cooling method for the coils of magnet. In order to ensure the evaporative cooling ECR data monitoring system safe and stable operation, this paper developed a data monitoring system. The system was developed by LabVIEW software based on the OPC technique. This system was designed according to the specific character of evaporative cooling ECR. It has the function such as real-time data acquiring, data display, data analysis, data processing and data storage.

Operating characteristics of different inner evaporative cooling systems of generators

Comparing with the traditional cooling methods of generator, evaporative cooling, a new cooling method, is more suitable for the development demands of huge generators, with the advantages of high-security, high efficiency and energy conservation. The inner cooling system is one of the main application modes of evaporative cooling. In this paper, the experiment tables of natural circulation and forced circulation inner evaporative cooling systems of generators were established. Based on the experimental data, the operating characteristics of those cooling systems were analyzed in detail and compared. The superiority of different inner evaporative cooling systems was obtained and the application occasions were concluded. Mastering the operating characteristics of system is very important to the application of this new cooling method. The conclusions in this paper provide the reference basis for the actual operation of evaporative cooling system.

3D steady-state thermal load analysis of the bus-bar in large-scale generator with evaporative cooling system

In hydro-generator, stator bus bar is a vital electrical part and the overheating problem of it is one of the common accidents in hydro-generator. Based on the characteristics of evaporative cooling technology, reliability of large-scale hydro-generator would be enhanced if applying evaporative cooling technology to the stator bus bar. Because of the complex construction of bus bars, copper loss, as the driving force of self-circulation evaporative cooling system of bus bar, has an uneven and complicated distribution. Firstly, this paper briefly introduces evaporative cooling technology and points out several advantages and research difficulties of evaporative cooling stator bus bar. Secondly, based on theory model of eddy current and the finite element calculation software, 3D steady-state copper losses of a group of bus bars with typical structure are calculated. According to the calculation results, characteristics of thermal load distributions of bus bars with typical structure will be summed up.