Effect of cooling structure on thermal behavior of copper plates of slab continuous casting mold

A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30 ℃and 15 ℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 ram, respectively. The surface temperature without nickel layers is depressed by 10 ℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5 ℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.

Retrofit design of composite cooling structure of a turbine blade by fluid networks and conjugate heat transfer methods

This article discusses the development of the numerical methods of gas flow coupled with heat transfer,and introduces the fluid net-works method for rapid prediction of the performance of the composite cooling structures in turbine blade.The reliability of these methods is verified by comparing experimental data.For a HPT rotor blade,a rapid prediction on the internal cooling structures is first made by using the fluid network analysis,then an assessment of aerodynamic and heat transfer characteristics is conducted.Based on the network analysis results,three ways to improve the design of the cooling structures are tested,i.e.,adjusting the cooling gas flow mass ratios for different inner cooling cavities,reducing the flow resistances of the channel turning structures,and improving the local internal cooling structure geometries with high temperature distribution.Through the verification of full three-dimensional gas/solid/coolant conjugate heat transfer calculation,we conclude that the modified design can make the overall temperature distribution more even by significantly reducing the highest temperature of the blade surface,and reasonably matching the parameters of different coolant inlets.The results show that the proposed calculation methods can remarkably reduce the design cycle of complex turbine blade cooling structure.

Thermal analysis and cooling structure design of the primary collimator in CSNS/RCS

The rapid cycling synchrotron （RCS） of the China Spallation Neutron Source （CSNS） is a high intensity proton ring with beam power of 100 kW. In order to control the residual activation to meet the requirements of hands-on maintenance, a two-stage collimation system has been designed for the RCS. The collimation system consists of one primary collimator made of thin metal to scatter the beam and four secondary collimators as absorbers. Thermal analysis is an important aspect in evaluating the reliability of the collimation system. The calculation of the temperature distribution and thermal stress of the primary collimator with different materials is carried out by using ANSYS code. In order to control the temperature rise and thermal stress of the primary collimator to a reasonable level, an air cooling structure is intended to be used. The mechanical design of the cooling structure is presented, and the cooling efficiency with different chin numbers and wind velocity is also analyzed. Finally, the fatigue lifetime of the collimator under thermal shocks is estimated.

Cooling System Design and Thermal Analysis of Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation synchronous motor has the advantages of uniform and adjustable electromagnetic field, wide speed range and high power density. It has broad application prospects in new energy electric vehicles, wind power generation and other fields. This paper introduces the basic structure of hybrid excitation motor with modular stator, and analyzes the operation principle of hybrid excitation motor. The cooling structure of the water-cooled plate is designed, and the effects of the thickness of the water-cooled plate and the number of water channels in the water-cooled plate on the heat dissipation capacity of the water-cooled plate are analyzed by theoretical and computational fluid dynamics methods. The effects of different water cooling plate structures on water velocity, pressure drop, water pump power consumption and heat dissipation capacity were compared and analyzed. The influence of different inlet flow velocity on the maximum temperature rise of each part of the motor is analyzed, and the temperature of each part of the motor under the optimal water flow is analyzed. The influence of the traditional spiral water jacket cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of the motor components is compared and analyzed. The results show that the water-cooled plate cooling structure is more suitable for the modular stator motor studied in this paper. Based on the water-cooled plate cooling structure, the air-water composite cooling structure is designed, and the effects of the air-water composite cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of each component of the motor are compared and analyzed. The results show that the maximum temperature rise of each component of the motor is reduced under the air-water composite cooling structure.

Thermal analysis and optimization of the EAST ICRH antenna

The ion cyclotron resonance of frequency heating（ICRH） plays an important role in plasma heating.Two ICRH antennas were designed and applied on the EAST tokamak.In order to meet the requirement imposed by high-power and long-pulse operation of EAST in the future,an active cooling system is mandatory to be designed to remove the heat load deposited on the components.Thermal analyses for high heat-load components have been carried out,which presented clear temperature distribution on each component and provided the reference data to do the optimization.Meanwhile,heat pipes were designed to satisfy the high requirement imposed by a Faraday shield and lateral limiter.

Effect of Operational Changes in Reducing Fish Impingement at a Power Plant in Ohio, USA

Both intake volumetric flow and through-screen velocity （the velocity of water as it passes through the screen） are important variables affecting fish impingement at industrial water intake structures including those at power plants. However, there are limited data available on quantitative assessments of impingement following changes in power plant operation such as reduced volumetric flow and intake velocity. Impingement studies were conducted at Bay Shore Power Plant in 2005-2006 （baseline） and again in 2013-2014 following fish protection mitigation which included reduced intake volumetric flows （from 33.5 m^3·s^-1 to 9.1 cm·s^-1）, a reduced through-screen velocity （from approximately 79.2 cm·s^-1 to 11.6 cm·s^-1）, modified traveling screens and installation of a fish-return system to gently and quickly remove any fish that were impinged back into the waterbody. A comparison of baseline and post-mitigation results suggested that with this mitigation in place, impingement reductions can exceed 90% for robust dominant fish species in the area.

Controlled synthesis of hollow magnetic Fe3O4 nanospheres： Effect of the cooling rate

The controlled synthesis of hollow magnetite （Fe3O4） nanospheres of varying sizes and structures was successfully obtained via a facile solvothermal process and varying cooling processes. The Fe3O4 nanospheres were characterized by X-ray diffraction, transmission electron microscopy, scanning elec- tron microscopy, and superconducting quantum interference device magnetometry. The diameters of the as-synthesized nanospheres were controlled at around 500-700 nm by simply changing the cool- ing rate, which had an obvious influence on the morphology and magnetic properties of these Fe3O4 nanospheres. While a low cooling rate triggered the formation and extension of the cracks present in the Fe3O4 nanospheres, a sudden drop of temperature tended to favor multi-site nucleation of the crystals as well as the formation of compact and smooth hollow nanospheres with superior crystallinity and high saturation magnetization. The growth mechanism of hollow magnetite oxide nanospheres was proposed and the correlation between the structure and the magnetic properties of the hollow nanospheres was discussed, which promises the potential of the hollow nanospheres in various applications such as drug delivery and cell separation.

Rotation Effect on Flow and Heat Transfer for High-Temperature Rotor Blade in a Heavy Gas Turbine

In this paper,the composite inner cooling structures of the rotating blade in the first stage heavy gas turbine were modeled and simulated by coupling heat transfer (CHT).The flow characteristics and heat transfer performances were comparatively analyzed under two operations of the stationary and the rotational states.The results show that the turbulence intensity,the flow resistance and the heat transfer level of the rotating coolant are significantly increased compared with the stationary state,which is considered to be obtained by the combined effects of the Coriolis force,the centrifugal force and their derived buoyancy forces.It is pointed out that the rotation leads to the non-uniform flow of film holes at the leading edge of the pressure surface along blade height.In addition,it increases the slope of the limiting streamline,which has a decisive influence on the heat transfer of both the pressure and suction surfaces.The paper provides guidance for the design of a rotating composite cooling structure based on the relations between the stationary and rotational conditions.