Temperature Drop of Molten Metals in Open Channels

The temperature drop of molten metal flowing in open channels is numerically determined. Rectangular, trapezoidal and triangular geometries are considered. The overall heat transfer coefficients for the bottom, side walls and free surface of the channel have been taken from the literature. For each geometry, the volumetric flow rate, mean residence time and temperature drop as a function of the channel inclination angle were determined. The rectangular and trapezoidal geometries present the smallest temperature drops, while the triangular geometry presents the greatest temperature drop. The factors that most affect this drop are the value of the free surface area of the channel, and the average residence time of the molten metal in the channel.

Improvement of Temperature Drop Model Parameters for 4200mm/3500mm Rolling of Baosteel Medium and Thick Plate

Based on the temperature situation during the rolling process of 4200 mm/3500 mm medium and thick plates at Baosteel,this article analyzes the influencing factors of temperature changes during the rolling process from the perspective of heat transfer theory and the temperature change law during the rolling process.The temperature loss during the four rolling processes is tracked on site,and the temperature drop model parameters during the rolling process of 4200mm/3500mm medium and thick plates at Baosteel are quantitatively provided.It is applied to actual rolling production and has achieved good results.

Study of main factors influencing unsteady-state temperature drop in oil tank storage under dynamic thermal environment coupling

With the increasing oil demand, the construction of oil energy reserves in China needs to be further strengthened. However, given that there has been no research on the main influencing factors of crude oil temperature drop in storage tanks under actual dynamically changing environments, this paper considers the influence of dynamic thermal environment and internal crude oil physical properties on the fluctuating changes in crude oil temperature. A theoretical model of the unsteady-state temperature drop heat transfer process is developed from a three-dimensional perspective. According to the temperature drop variation law of crude oil storage tank under the coupling effect of various heat transfer modes such as external forced convection, thermal radiation, and internal natural convection, the external dynamic thermal environment influence zone, the internal crude oil physical property influence zone, and the intermediate transition zone of the tank are proposed. And the multiple non-linear regression method is used to quantitatively characterize the influence of external ambient temperature, solar radiation, wind speed, internal crude oil density, viscosity, and specific heat capacity on the temperature drop of crude oil in each influencing zone. The results of this paper not only quantitatively explain the main influencing factors of the oil temperature drop in the top, wall, and bottom regions of the tank, but also provide a theoretical reference for oil security reserves under a dynamic thermal environment.

Dynamic changes of phenolic compound contents in leaf and bark of poplar during autumn temperature drop

We investigated seasonal dynamics of phenolics substance in leaf and bark of two cultivars of poplar, Populus alba×berolinensis and P. בZhonglin Sanbei 1’, during autumn temperature drop for analyzing the roles of phenolic secondary metabolites in cold resistance. Results show that the contents of condensed tannin and flavonoid in poplar leaf and the flavonoid contents in bark of P. בZhonglin Sanbei 1’ were increased with the decrease of autumn minimum temperature, showing a significantly negative correlation between the contents of soluble phenolic substance in the leaves and changeable temperature. In contrast, lignin content in the poplar leaves is decreased in the process of temperature drop, showing a significantly positive correlation. These results indicate that the variation in phenolic substance has a close correlation with its cold-resistance during the autumn temperature drop.

Fiber Concrete under Temperature Drop Load with Stochastic FEM

Plain concrete plate and fiber concrete plate subjected to temperature drop load were analyzed on stochastic finite element method (FEM).It is found that fibers can enhance concrete ability to resist tem- perature drop load for improving concrete's fracture energy and deferring the crack process.It is found for concrete not to improve apparently its tensile strength and fracture energy is recommended to be its appraisal parameter.

A brief investigation on transversal temperature distribution during hot rolling

Temperature evolution of a working piece during hot rolling has a significant influence on the microstmcture and final mechanical properties of the material. As the measurement technologies improve, on-line measurement of the temperature across the strip width has become accessible, and thus monitoring and control of the transversal temperature distribution during hot rolling can be realized. The scanning of the temperature across the strip width can help us to understand the state of the temperature variation at the strip edges and as a result help us improve the temperature homogeneity of the strip. In this paper, reaearch on temperature distribution along the strip width is reviewed first, and then the mechanism of the scanning measuring devices is introduced. With the temperature scanning measurement data taken from the finishing mill entry point and the down coiler entry point, the temperature distribution at the strip edges is analyzed. It is pointed out that the roughing process is the main contributor to the temperature inhomogeneity. Furthermore,the contribution of the edger heater to the temperature homogeneity is investigated.

Co-seismic Water Level and Temperature Responses of Some Wells to Far-Field Strong Earthquakes and Their Mechanisms

The observation of water temperature in deep wells has been carried out for more than 20 years in China.However,study on the mechanism of water temperature response to earthquakes is inadequate.During the study of the co-seismic response characteristics of water level and temperature in 121 wells within the China subsurface fluid monitoring network at the time of the December 26,2004,M-S8.7 Indonesia earthquake,we found regular response characteristics,that is,when the water level in a deep well oscillates,the water temperature in the same well will mostly experience a cycle from dropping to restoration at the same time.The process will continue for dozens of minutes to several hours.In order to confirm the observed phenomenon,we collected the digital water level and temperature observation data for 39 far-field strong earthquakes from the Tangshan well in Hebei Province(with the data set beginning in 2001).The same response characteristics were observed.Based on the analysis of the influencing factors that may cause the water temperature drop,the authors suggest the gas escape mechanism for co-seismic water temperature drop and posit two main factors that influence the water temperature drop during the process of gas escape.Finally,the authors provide a rational explanation of some observed phenomena based on the mechanism.

An experimental study on the choked flow characteristics of CO_(2) pipelines in various phases

High pressure pipeline transportation has been an established technology for economically transporting large amounts of CO_(2).However,there are still issues and associated risks that have to be effectively addressed and adequately understood.It is well known that a strong JouleThomson Cooling effect can occur when pressurized CO_(2) flows through a choke valve.Thus,to investigate the choking characteristics especially the temperature drop of high pressure CO_(2),a new laboratory scale experimental setup(total length of 14.85 m and the inner diameter of 15 mm)was constructed.Steady choked flow and transient choked flow tests were carried out respectively for pressurized CO_(2) in various initial phases.The phase transitions and temperature drop characteristics were then studied following the choked flow and the results show that the phase transitions in steady choked flow differs significantly from that in transient choked flow.For transient choked flow of various initial phases,all the flows downstream would transfer from single phase to gas-liquid twophase flow.Furthermore,the effect of water on transient choked flow of supercritical CO_(2) pipeline was investigated,and the phenomena of solid particles deposition was captured which was paramount importance of ensuring the safety operation of CO_(2)pipelines when throttling by the choke valves.

An Idea of Extracting Fresh Water from the Atmosphere

Based on principles of vapor coagulation, a method of extracting fresh water from the atmosphere was put forward. Its principles are simple, and it is easy to make and install the equipment made cheaply. Moreover, there is no or much less energy consumed during the extraction process, so there is no environmental pollution. In a word, this method of extracting fresh water from the atmosphere is of great practical value.

Study of Multilayer Flow Insulation Utilizing Open-Cellular Porous Plates

To improve the performance of the single layer flow insulation system utilizing open-cellular porous plate, the multilayer porous gas enthalpy-radiation converter is proposed and investigated experimentally and theoretically. Two open-cellular porous materials with different porosity pore per inch and surface reflectivity have been examined. Each porous plate has the same thickness of a half of the single layer one. Both porous materials are not combined continuously but divided by free space. For the prediction model, two energy equations of the fluid and solid phases are employed, in which the convective heat transfer between both phases is described based on the empirical volumetric heat transfer coefficient. In addition, the radiative transfer equations are resolved by Pj approximation. When an equivalent blackbody radiation temperature of the radiation coming from the upstream region exceeds inlet gas temperature, use of a high reflective porous plate on the upstream side and a low reflective porous plate on the downstream side is quite effective to increase gas temperature drop across the converter. the multilayer porous converter should be made of pure scattering and porous layer, respectively. In order to obtain maximum gas temperature drop in that case, pure absorbing porous plate as the upstream and downstream

Simulation of Thermal Insulation of Top-Surface Slag Layers in Continuous Casting Mold

A computational model of thermal behavior of the top-surface slag layers in continuous casting mold was applied to interpret the thermal insulation of mold powder. The temperature drop of liquid steel caused by heat re moral at the interface of molten steel and slag in mold was proposed to evaluate the thermal insulation of mold slag. The calculation results show that slag consumption is one of important factor influencing the temperature drop, while the casting speed has no obvious effect on it. With the increase of slag consumption, the temperature drop is increased.