scholarly journals Research and Adjustment of Temperature Deviation on Heating Wall of Front and Rear Wall Opposed Coal-fired Boiler of 1000WM Unit

2019 ◽  
Vol 371 ◽  
pp. 042035
Author(s):  
Wang Yongjia ◽  
Chen Ying ◽  
Wang Kai
Keyword(s):  
Rear Wall ◽  
Heating Wall ◽  
Temperature Deviation

Improved Burn-In Stress Methodology for Stress Uniformity

2018 ◽  
Author(s):  
Jungsuk Ko ◽  
Hoonchang yang ◽  
Hyungchae Jeon ◽  
Gyuyoung Nam ◽  
Youngseok Ryu ◽  
...  
Keyword(s):  
Temperature Stress ◽  
Stress Condition ◽  
Temperature Deviation ◽  
Stress Effects ◽  
Hot Temperature ◽  
Production Environments ◽  
Stress Environment ◽  
The Stability ◽  
Stress Uniformity ◽  
Stress Voltage

Abstract The necessity of hot temperature stress is widely recognized as the initial stress methodology to maintain the stability of products from infant defects in device [1, 2]. However, hot temperature stress has a disadvantage in terms of stress uniformity because temperature variation according to stress environment such as chamber, board, and tester accelerates different stress effects per chips. In addition, this stress condition can cause serious reliability problem in the mass production environments. Therefore, the stress temperature should be lowered to minimize the temperature deviation due to the production environments. The reduction of stress temperature cause the lack of stress amount, so optimized stress voltage and time to maintain the stress condition is required. In this study, various stress voltage and time with decreasing temperature were evaluated in consideration of lifetime that unit elements such transistors and capacitors did not degrade by any stress conditions. In addition, it was confirmed that stress uniformity can be improved in the stress condition obtained by the evaluation. Furthermore, the enhanced initial failure screen ability was proven with mass evaluations.

Control of the adiabatic flow reactor by feeding the catalyst solution

1979 ◽  
Vol 44 (8) ◽  
pp. 2352-2365
Author(s):  
Josef Horák ◽  
Zina Sojková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Reaction Temperature ◽  
Control Algorithm ◽  
Flow Reactor ◽  
Operating Temperature ◽  
Temperature Deviation ◽  
Adiabatic Flow ◽  
Dosing Frequency ◽  
Laboratory Reactor

Control algorithm of the operating temperature is described in the reactor, which is operated at constant temperature and composition of the inlet mixture. The temperature is controlled by dosing a constant volume of the catalyst solution. The dosing frequency is determined according to the reaction temperature (deviation of the temperature from the desired value and the sign of the derivative of temperature). The control algorithm has been verified experimentally for the laboratory reactor in unstable steady state.

scholarly journals Uncertainties Analysis on the Prediction of Flow and Heat Transfer of Liquid Sodium with CFD Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhanwei Liu ◽  
Xinyu Li ◽  
Tenglong Cong ◽  
Rui Zhang ◽  
Lingyun Zheng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Coefficient ◽  
Liquid Sodium ◽  
Heat Transfer Characteristics ◽  
Backward Facing Step ◽  
Heating Wall ◽  
Transfer Characteristics ◽  
Cfd Models ◽  
Flow And Heat Transfer

The prediction of flow and heat transfer characteristics of liquid sodium with CFD technology is of significant importance for the design and safety analysis of sodium-cooled fast reactor. The accuracies and uncertainties of the CFD models should be evaluated to improve the confidence of the numerical results. In this work, the uncertainties from the turbulent model, boundary conditions, and physical properties for the flow and heat transfer of liquid sodium were evaluated against the experimental data. The results of uncertainty quantization show that the maximum uncertainties of the Nusselt number and friction coefficient occurred in the transition zone from the inlet to the fully developed region in the circular tube, while they occurred near the reattachment point in the backward-facing step. Furthermore, in backward-facing step flow, the maximum uncertainty of temperature migrated from the heating wall to the geometric center of the channel, while the maximum uncertainty of velocity occurred near the vortex zone. The results of sensitivity analysis illustrate that the Nusselt number was negatively correlated with the thermal conductivity and turbulent Prandtl number, while the friction coefficient was positively correlated with the density and Von Karman constant. This work can be a reference to evaluate the accuracy of the standard k-ε model in predicting the flow and heat transfer characteristics of liquid sodium.

scholarly journals Solid–Liquid Interface Temperature Measurement of Evaporating Droplet Using Thermoresponsive Polymer Aqueous Solution

2021 ◽  
Vol 11 (8) ◽  
pp. 3379
Author(s):  
Hyung Ju Lee ◽  
Chan Ho Jeong ◽  
Dae Yun Kim ◽  
Chang Kyoung Choi ◽  
Seong Hyuk Lee
Keyword(s):  
Refractive Index ◽  
Heated Surface ◽  
Liquid Interface ◽  
Interface Temperature ◽  
Thermoresponsive Polymer ◽  
Temperature Deviation ◽  
Line Region ◽  
Optical And Mechanical Properties ◽  
Solid Liquid Interface ◽  
Solid Liquid

The present study aims to measure the solid–liquid interface temperature of an evaporating droplet on a heated surface using a thermoresponsive polymer. Poly(N-isopropylacrylamide) (pNIPAM) was used owing to its sensitive optical and mechanical properties to the temperature. We also measured the refractive index variation of the pNIPAM solution by using the surface plasmon resonance imaging (SPRi). In particular, the present study proposed a new method to measure the solid–liquid interface temperature using the correlation among reflectance, refractive index, and temperature. It was found that the reflectance of a pNIPAM solution decreased after the droplet deposition. The solid–liquid interface temperature, estimated from the reflectance, showed a lower value at the center of the droplet, and it gradually increased along the radial direction. The lowest temperature at the contact line region is present because of the maximum evaporative cooling. Moreover, the solid–liquid interface temperature deviation increased with the surface temperature, which means solid–liquid interface temperature should be considered at high temperature to predict the evaporation flux of the droplet accurately.

scholarly journals Effects of Temperature on the Flow and Heat Transfer in Gel Fuels: A Numerical Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 821
Author(s):  
Qin-Liu Cao ◽  
Wei-Tao Wu ◽  
Wen-He Liao ◽  
Feng Feng ◽  
Mehrdad Massoudi
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Transport System ◽  
Apparent Viscosity ◽  
Thermal Design ◽  
Straight Pipe ◽  
Heating Wall ◽  
Supply Pressure ◽  
Flow And Heat Transfer ◽  
The Mean

In general, rheological properties of gelled fuels change dramatically when temperature changes. In this work, we investigate flow and heat transfer of water-gel in a straight pipe and a tapered injector for non-isothermal conditions, which mimic the situations when gelled fuels are used in propulsion systems. The gel-fluid is modeled as a non-Newtonian fluid, where the viscosity depends on the shear rate and the temperature; a correlation fitted with experimental data is used. For the fully developed flow in a straight pipe with heating, the mean apparent viscosity at the cross section when the temperature is high is only 44% of the case with low temperature; this indicates that it is feasible to control the viscosity of gel fuel by proper thermal design of pipes. For the flow in the typical tapered injector, larger temperature gradients along the radial direction results in a more obvious plug flow; that is, when the fuel is heated the viscosity near the wall is significantly reduced, but the effect is not obvious in the area far away from the wall. Therefore, for the case of the tapered injector, as the temperature of the heating wall increases, the mean apparent viscosity at the outlet decreases first and increases then due to the high viscosity plug formed near the channel center, which encourages further proper design of the injector in future. Furthermore, the layer of low viscosity near the walls plays a role similar to lubrication, thus the supply pressure of the transport system is significantly reduced; the pressure drop for high temperature is only 62% of that of low temperature. It should be noticed that for a propellent system the heating source is almost free; therefore, by introducing a proper thermal design of the transport system, the viscosity of the gelled fuel can be greatly reduced, thus reducing the power input to the supply pressure at a lower cost.

Thermal Modeling of Unlooped and Looped Pulsating Heat Pipes

2001 ◽  
Vol 123 (6) ◽  
pp. 1159-1172 ◽  
Author(s):  
Mohammad B. Shafii ◽  
Amir Faghri ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Heat Pipes ◽  
Analytical Models ◽  
Charge Ratio ◽  
Sensible Heat ◽  
Governing Equations ◽  
Heating Wall ◽  
Heat Mode ◽  
Explicit Finite Difference

Analytical models for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs are presented in this study. The governing equations are solved using an explicit finite difference scheme to predict the behavior of vapor plugs and liquid slugs. The results show that the effect of gravity on the performance of top heat mode unlooped PHP is insignificant. The effects of diameter, charge ratio, and heating wall temperature on the performance of looped and unlooped PHPs are also investigated. The results also show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat.

Multiobjective Optimization of the Heating Process for Forging Automotive Crankshaft

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Hong-Seok Park ◽  
Xuan-Phuong Dang
Keyword(s):  
Multiobjective Optimization ◽  
Heating System ◽  
Optimization Method ◽  
Heating Process ◽  
Temperature Deviation ◽  
Engineering Data ◽  
Optimization Of Process Parameters ◽  
Mathematical Approximation ◽  
Nondominated Sorting ◽  
Induction Heating System

This paper presents potential approaches that increase the energy efficiency of an in-line induction heating system for forging of an automotive crankshaft. Both heat loss reduction and optimization of process parameters are proposed scientifically in order to minimize the energy consumption and the temperature deviation in the workpiece. We applied the numerical multiobjective optimization method in conjunction with the design of experiment (DOE), mathematical approximation with metamodel, nondominated sorting genetic algorithm (GA), and engineering data mining. The results show that using the insulating covers reduces heat by an amount equivalent to 9% of the energy stored in the heated workpiece, and approximately 5.8% of the energy can be saved by process parameter optimization.

Analog Control of Continuous Copper Wire Annealing Based on Temperature Detecting

2014 ◽  
Vol 487 ◽  
pp. 591-594
Author(s):  
Yong Zhong Lin ◽  
Xue Jun Xu ◽  
Hong Yang Sun ◽  
Zuan Zhen Lu ◽  
Cheng Gang Wang
Keyword(s):  
Annealing Temperature ◽  
Analog Circuit ◽  
Copper Wire ◽  
Temperature Deviation ◽  
Linear Fitting ◽  
Equivalent Relation ◽  
Analog Control

The paper acquires the equivalent relation between the velocity of wires and annealing temperature through deduction, based on the measurement of the annealing temperature. A controller characterizing annealing temperature could be inserted before the traditional PI annealing controller, so that annealing temperature could be controlled while the annealing temperature deviation is simulated by the error of the velocity of wires. In the paper, a kind of analog circuit is chosen to achieve the equivalent relation between the velocity of wires and annealing temperature by linear fitting under the condition of preciseness.

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