Simulation of heat transfer in steel billets during continuous casting

This work is focused on the development of computational algorithms to create a simulator for solving the heat transfer during the continuous casting process of steel. The temperatures and the solid shell thickness profiles were calculated and displayed on the screen for a billet through a defined continuous casting plant （CCP）. The algorithms developed to calculate billet temperatures, involve the solutions of the corresponding equations for the heat removal conditions such as radiation, forced convection, and conduction according to the billet posi- tion through the CCP. This is done by a simultaneous comparison with the kinematics model previously developed. A finite difference method known as Cmnk-Nicholson is applied to solve the two-dimensional computational array （2D model）. Enthalpy （HIJ） and temperature （TIL） in every node are updated at each step time. The routines to display the results have been developed using a graphical user interface （GUI） in the programming language C＋＋. Finally, the results obtained are compared with those of industrial trials for the surface temperature of three steel casters with different plant configurations in different casting conditions.

AXIAL HEAT CONDUCTION MODEL TO PREDICT MAXIMUM HEAT REMOVE OF MINIATURE HEAT PIPE BASED ON GREY MODEL THEORY

Computer chip is always accompanied by the increase of heat dissipation and miniaturization. The miniature heat pipes are widely used in notebook computer to resolve the heat dissipation problems. Maximum heat removed model of miniature heat pipes building by grey model is presented. In order to know the foundation for modeling, the smooth grade of error examination is inquired and the accuracy of grey relational grade is verified. The model can be used to select a suitable heat pipes to solve electric heat problems in the future. Final results show that the grey model only needs four experiment data and its error value is less than 10%, further, it is better than computational fluid dynamics （CFD） model.

Meta-analysis of clinical effect of clearing heat and cooling blood on psoriasis and its effect on inflammatory cytokines

Objective:To evaluate the effect of Qingreliangxue method compared with Acitretin Capsules on clinical efficacy of psoriasis and serum inflammatory cytokines.Methods:The computer searches databases such as CNKI,Wanfang,VIP,PubMed,Embase and Cochrane Library.The search time is from the time the library is built until December 2019.According to the criteria for screening and selection of studies,extract data,use risk assessment tools for quality evaluation,and use Revman 5.3 software to perform meta-analysis on the outcome indicators of the included studis.Results:Finally,20 studies were included,with a total of 1592 patients.The analysis results showed that the total effective rate(OR=3.70,95%CI[2.58,5.30],P<0.00001)and cure rate(OR=2.40,95%CI[1.86,3.10],P<0.00001),PASI score(OR=-2.65,95%CI[-3.60,-1.70],P<0.00001),serum inflammatory cytokines(OR=-8.84,95%CI[-10.52,-7.16],P<0.00001),adverse reactions(OR=0.25,95%CI[0.11,0.57],P=0.001)are superior to Acitretin Capsules.Statistics of the top 10 Chinese medicines in clinical used frequency are,in order,habitat,red peony root,paeonol,honeysuckle,comfrey,soil tuckahoe,salvia miltiorrhiza,buffalo horn,heliotrope,angelica.Conclusion:Based on the current evidence,the treatment of psoriasis with clearing heat and cooling blood as the mainstay of Chinese medicine alone or in combination with Acitretin Capsules can better improve the efficacy,and its mechanism may be related to reducing inflammation.Due to the limitation of the included literature,this conclusion needs to be further verified.

Spectral Feature Analysis of Semiconductor Thin Disk Laser

The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion layer has no enough time to rate to one of the wells, and the non-radiative recombination happens in the barrier. When the thermal effect becomes stronger, the chip will be not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer which is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs. This three QWs structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etching equipment is also improved to control the surface unevenness to be within 50 nm.

Study of Accident Progression in Unsealed WWER-1000/V320 Reactor during Maintenance

This paper discusses the results obtained during an investigation of WWER-1000 Nuclear Power Plant (NPP) behavior at shutdown reactor during maintenance. For the purpose of the analysis is selected a plant operating state with unsealed primary circuit by removing the MCP head. The reference nuclear power plant is Unit 6 at Kozloduy NPP (KNPP) site. RELAP5/ MOD3.2 computer code has been used to simulate the transient for WWER-1000/V320 NPP model. A model of WWER-1000 based on Unit 6 of KNPP has been developed for the RELAP5/MOD3.2 code at the Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS), Sofia. The plant modifications performed in frame of modernization program have been taken into account for the investigated conditions for the unsealed primary circuit. The most specific in this analysis compared to the analyses of NPP accidents at full power is the unavailability of some important safety systems. For the purpose of the present investigation two scenarios have been studied, involving a different number of safety systems with and without operator actions. The selected initiating event and scenarios are used in support of analytical validation of Emergency Operating Procedures (EOP) at low power and they are based on the suggestions of leading KNPP experts and are important in support of analytical validation of EOP at low power.

Discussion on the application of Ginseng efficacy from"Treatise on Spleen and Stomach"

According to the original works of an ancient Chinese medicine book"Treatise on Spleen and Stomach"(Detailed Analysis of Spleen and Stomach Diseases;1249 C.E.)written by Li Dongyuan(1180-1251 C.E),and related explanations of later physicians,the efficacy and application of Ginseng(Ginseng Radix et Rhizoma)in related prescriptions were investigated from the aspects of dosage,usage and treatment methods.Ginseng appeared in 27 named prescriptions,including 20 decoctions,4 pill and 3 powder.In terms of dosage and usage,the common dosage of Ginseng is five points,mainly decoction.Most of the processing methods are"Fuju"(Bite up the medicine with your mouth so it can be taken.)and decoction with water.In terms of treatment methods,Ginseng is used in the sweet temperature and heat removing method and Nourishes Qi and Eliminates Evils Method(build your body to cure disease)in Li Dongyuan's"Treatise on Spleen and Stomach".Explaining Sweet Temperature Heat Removal Method(Use sweet and warm medicines to treat Qi-deficiency fever or Blood-deficiency fever;there are many reasons for fever,and cold and cooling medicines with heat-clearing effect are generally used for treatment.Use bitter cold medicine,so as not to consume the body's Yang.)takes Buzhong Yiqi Decoction(BYD)as an example,and explaining the Nourishes Qi and Eliminates Evils Method takes Mahuang-renshen-shaoyao decoction as an example.At the same time,"Treatise on Spleen and Stomach"matured in the Jin and Yuan Dynasties(1115-1368 C.E.).Its system of weights and measures,terminology and medical theory are quite different from those of modern Chinese medicine.Therefore,when researching the dosage,usage and treatment methods of Ginseng,we will explore the controversial points,and explain them by using modern Chinese medicine theory,so as to guide the clinical medication more accurately.

Experimental study of primary and secondary side coupling natural convection heat transfer characteristics of the passive residual heat removal system in AP1000

Passive residual heat removal heat exchanger(PRHR HX),which is a newly designed equipment in the advanced reactors of AP1000 and CAP1400,plays an important role in critical accidental conditions.The primary and secondary side coupling heat transfer characteristics of the passive residual heat removal system(PRHRS)determine the capacity to remove core decay heat during the accidents.Therefore,it is necessary to investigate the heat transfer characteristics and develop applicable heat transfer formulas for optimized design.In the present paper,an overall scaled-down natural circulation loop of PRHRS in AP1000,which comprises a scaleddown in-containment refueling water storage tank(IRWST)and PRHR HX models and a simulator of the reactor core,is built to simulate the natural circulation process in residual heat removal accidents.A series of experiments are conducted to study thermal-hydraulic behaviors in both sides of the miniaturized PRHR HX which is simulated by 12 symmetric arranged C-shape tubes.For the local PRHR HX heat transfer performance,traditional natural convection correlations for both the horizontal and vertical bundles are compared with the experimental data to validate their applicability for the specific heat transfer condition.Moreover,the revised natural convection heat transfer correlations based on the present experimental data are developed for PRHR HX vertical and lower horizontal bundles.This paper provides essential references for the PRHRS operation and further optimized design.

Application of Finite Difference Method to the Analysis of HTTR Reactor Cavity Natural Convection

An attempt is made to investigate the ability of the revised K FIX code to the solution to natural convection. The new experimental data of the benchmark problem of the IAEA coordinated research program (CRP 3) on heat transport and afterheat removal for GCRs under accident conditions provided by JAERI are used to calculate nitrogen natural convection in the pressurized vessel and air natural convection in the reactor cavity by using this revised code. Based on analysis, a refined mesh is used to solve the differential equations so as to get more detailed and more accurate result. The obtained velocity profiles are consistent with the result of TRIO EF code and the result of Bechtel laboratory. It can be drawn that the revised K FIX code can be used to solve this kind of problems.

A novel application of fluidization-Integrating three processes in reclaiming foundry sand

Immersion of automotive parts in a fluidized bed of foundry sand is used to both strip the castings free from moulding sand and to heat-treat the castings at 500℃. The fluid bed is heated by hot gases from a burner directed first into a serpentine heat exchanger located near one side-wall of the rectangular tank, and then into a distributor consisting of horizontal sparger pipes having maintenance standpipes fixed into their upper surfaces.