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As the electric performances of semiconductor devices are tightly related to their junction temperature, the research on electrical parameters characteristic at different junction temperature is a significant meaning to improve application reliability of IGBT. On the one hand, junction temperature is a key factor to influence electrical parameters of IGBT. On the other hand, electrical parameters...
Lots of experimental researches have been done to a plain tubes segmental baffles lubricating-oil cooler and integral pin-fin tube cooler and the new lubricating-oil cooler made from integral pin-fin tubes and plain tubes mixing in bundles and with double-flow. It is introduced that oil mass flow rate has great influence on coolers performance. Heat transfer coefficient, pressure drop, the heat of...
The Combined cooling, heating and power (CCHP) system should be operated under the optimal scheme to meet the varying demand for cooling, heating and electricity and to reduce cost and save energy for buildings. Based on the analysis of the energy flow, a mixed integer linear program (MILP) optimal model has been developed. The objectives are to minimize the annual total cost, primary energy consumption...
This paper takes the energy savings as assessment criterion for Combined Heat Cooling and Power System, analyzes the conditions CCHP needs to meet in comparison with dispersed generation. Generating efficiency of cogeneration and the effects thermoelectric ratio has on energy-saving performance are analyzed as top priority.
Buckling analysis of structures can be divided into eigenvalue buckling analysis and nonlinear buckling analysis. In this paper, the basic theory of eigenvalue buckling analysis and nonlinear buckling analysis has been described, then using ABAQUS to do eigenvalue buckling analysis and nonlinear buckling analysis on structural elements of an actual project which have prestress, and comparing their...
New methods for high concrete dam cooling by water flowing were introduced in this article. The heat-fluid coupling model, which can better simulate disposition of cooling pipe and water temperature rise along the flow, will bring more accurate simulation results of temperature field. The nonlinear creep model can better reflect the nonlinear relation between concrete creep and stress ratio of concrete...
Three working fluids R125, R143a and R32 were analyzed thermodynamically for the transcritical heat pump with low temperature geothermal source as its heat source. The system parameters investigated include coefficient of performance (COP), volumetric heat capacity (Qv), compressor discharge temperature and the pressure ratio. The results show that Qv, pressure ratio and compressor discharge temperature...
Sewage source heat pump system plays a significant role in energy-saving and environmental protection which can be divided into direct and indirect system. For the shortcoming of research on the direct one, some anti-scaling technology and the heat exchangers to remove the soft dirt are introduced. Based on the exergy method, an analysis is given of energy efficiency in the direct sewage source heat...
Based on elaborating the characteristics of capillary tube air-conditioning system, especially investigated the heat transfer property of this system cooling in summer, and establishes a two-dimensional mathematical model of steady-state heat transfer. In this paper, the Matlab program programmed by a micro-body heat balance method focuses the impact on the ceiling temperature field and the cooling...
NOx emission has been limited in many countries because of its adverse impact on environment. Many new strategies and technologies are developed to restrain the NOx formation in industrial furnaces and power systems. However it is impossible to reduce the NOx infinitely. There should be a critical value that NOx emission can't be reduced anymore. The present paper will estimate the critical value...
To study the influence of LNG fuel supply system on engine cooling system, ensure that the engine cold start performance, an AMESim based LNG fuel supply system simulation model with the key components of vaporizer was proposed. By analyzing the influence of the coolant temperature and flow rate on the phase transition of LNG, and worked out the ranges of temperature and flow rate in vaporizer when...
A lot of experimental research has been done to two kinds of new oil coolers using the pin-fin tube as the heat transfer elements, of which one form is longitudinal flow and the other one is crosswise flow . It was found that the heat transfer coefficient of the former one is 2.2 times as big as that of the latter one when the flow rate is (0.5kg/s) and the number of tubes is the same. The results...
This paper mainly studied the heat dissipation of the heat sink placing on the level of the natural convection cooling conditions by numerical simalation.lt is found that on the conditions of the same width of the heat sink , the power of convection heat dissipation of heat sink can't be increased by reducing spacing of fins(representing an increase of the number offins of heat sink ). By comparing...
The precondition of optimized designing of automotive air-conditioning system is accurate air-conditioning cooling load computation, while the current load computation is mostly estimated according to the experiences, and it is on the stage of exploring for the dynamic load computation. Three kinds of methods on load computation are discussed in this paper based on city model according to typical...
In this paper the performance test results of a liquid desiccant air-conditioning (LDAC) system which uses waste hot water from combined cooling, heat and power system (CCHP) as driven heat resource have been presented. The supply air volume of the air-conditioning system is around 7000m3/h ~ 7500m3/h and its cooling capacity is about 60.43 ~ 95.74KW. It can maintain the supply air temperature under...
For energy-saving or water-saving consideration, performance optimization of air-cooled condenser is important. The optimization calculation results for the cool-end of a 600MW SC air cooling unit show that cool-end optimization has economic benefits for SC and USC air cooling units. Based on the same idea, the idea of cool-end optimization method of USC air cooling units with 1000MW is suggested...
In this study, a centrifugal cooling fan on multiple unit train (MU) was designed based on one-dimensional calculation and three-dimensional numerical simulation. Three-dimensional model was presented based on the one-dimensional calculation. Numerical simulation and thorough analysis were carried out on the blower with software NUMECA. Varieties of projects were considered, and the performance experiment...
The internal cooling effects on a stator blade in a turbine was simulated. The results showed that the thermal barrier coating (TBC) not only lowered the temperature but also made the temperature distribution more uniform, which could decrease the thermal stress and prolong the blade using life to a great extent. The FORTRAN code was used to solve the internal heat transfer coefficient and the temperature...
A three-dimensional Euler-Lagrange model was used to study the distribution of particles in scrubbing-cooling chamber of coal-water-slurry (CWS) entrained-flow gasifier. Comparisons of computational results with experimental data are made. The effects of operating conditions and size grading on the particle number density distribution in chamber is revealed through simulation. The results indicate...
Evaporative cooling technique is successfully applied for large turbo generator following the air-cooled, hydrogen-cooled and water-cooled techniques. Compared with the three techniques, evaporative cooling technique absorbs the heat of thermal parts of generator by vaporization latent heat of coolant, which is sharply more efficient than the specific heat cooling approaches. The temperature rise...
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