Papers by Keyword: Thermodynamics Analysis

Abstract: The objective of this work is to predict for a given concentration, what will be the depth of the boride layer under set conditions using collision theory between atoms and diffusion by means of the Lattice Boltzmann Method.

Abstract: The objective of this paper is to study thermodynamic analysis of R134a-DMAC and R134a-DMAC/CNT vapour absorption system and compare this both system performance. This investigation for R134a-DMAC is carried out based on the correlations available in the literature. The change of thermophysical properties for R134a-DMAC/CNT is predicted and is incorporated in the pure R134a-DMAC correlations. The analysis is carried for 1 kW evaporator capacity and effectiveness of solution heat exchanger is taken as 0.8. Variations in the performance parameters of the system with and without nano fluids are studied against various operating temperatures of generator, absorber and different volume concentration. The result of this theoretical study shows that co-efficient of performance (COP) of system with CNT nano fluid is improved as well as the absorber capacity also increased due to enhanced heat transfer of nano fluids. It also observed that the performance achieved by the pure R134a-DMAC at the elevated generator temperature could be achieved at low generator temperature using R134a-DMAC/CNT.

Abstract: This paper studies the temperature field variation of the chain link as well as the stress and deformation distribution of the pin which works in hot forging and stamping production line with heat recovery function. The approach is to build the model of the chain link with Pro/Engineer and apply it to the simulation with Pro/Mechanica. To be specific, it is to stimulate the thermal conduction of the chain link and the stress state of the pin under high temperature with Pro/Mechanica-Thermal and Pro/Mechanica-Structure module, respectively. The results are the temperature filed nephogram of the chain link as well as the stress and deformation nephogram of the pin. The simulation shows that:1) the temperature reaches 420°C at the contacts of the outer and inner plates at 600s, 2) the maximum stress of the pin is 112Mpa at the ends where the pin meets the outer and inner plates,3) the pins max deformation is 0.0159mm at the middle of the pin. Comparing the simulation to the actual temperature at the contacts of the outer and inner plates,which is measured ten times in advance with average of 439°C ,the simulation is favorable. According to the results above, graphite lubrication should be chosen for the chain and the pin can work properly with deformation rate of 0.795. By this way of simulating with Pro/Mechanica, complicated calculations and repeated tests can be reduced largely, meanwhile, useful parameters and mathematical model can also be provided for manufacturing and process control.

Abstract: Simultaneous desulfurization and denitrification removes SO₂ and NO_x from flue gas in one unit and only uses one absorbent. Using urea as absorbent removing SO₂ and NO_x in semi-dry spouted bed has the enormous developmental potential and wide foreground for it overcomes two shortages of wet process such as the amount of urea is large and the waste water is difficult to handle. The chemical absorption mechanism and thermodynamics of SO₂ and NO_x with urea were studied, the operating condition optimization of spouted bed was determined through several repeating experiment, the effects of some important operational parameters such as molar ratio of urea and gaseous pollutant, inlet temperature of flue gas and approach to adiabatic saturation temperature on SO₂ and NO_x removal efficiency were analyzed. The results provide a foundation for the commercial scale application of simultaneous desulfurization and denitrification technology.

Abstract: Physical simulation model of γ_Fe → α_Fe grain nucleation & growth in isothermal solid-state transformation and the rule of grain nucleation & grain growth’s boundary migration are established. The Genetic Algorithm is introduced in the process of grain nucleation & growth. The grain boundary migration agrees with the theory of grain growth. The system free energy ΔG calculation formula is exported. The thermodynamic criterion of new nucleus growing up is that new grain average radius r_c is bigger than theory critical average radius r_c0 when ΔG is achieved ΔG_max, ΔG is continually decreased at the remaining transformation, the final energy ΔG_f is less than initial energy at the end of transformation; be influenced by the limit of nucleation number N.