Research on Ultra-Fast Cooling Heat Transfer Coefficient Affecting Law for Hot Strip Mill

2014 ◽  
Vol 788 ◽  
pp. 346-350
Author(s):  
Lian Yun Jiang ◽  
Guo Yuan ◽  
Zhen Lei Li ◽  
Di Wu ◽  
Guo Dong Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Temperature ◽  
Water Spray ◽  
Cooling Process ◽  
Running Speed ◽  
Ultra Fast Cooling ◽  
Fast Cooling ◽  
Temperature Water

The ultra-fast cooling technology has been developed rapidly in order to develop iron and steel material with high performance. A variety of factors including the strip running speed, water temperature, water spray speed and strip temperature will affect strip cooling aspect during ultra-fast cooling process. These factors, which affect heat transfer coefficient, should be analyzed in order to achieve accurate control of strip cooling path during ultra-fast cooling process. The heat transfer coefficients of the hot rolled strip with various cooling parameters were obtained by numerical calculation method. By comparison, the influencing law that the cooling process parameters had made to heat transfer coefficient were obtained. It was found that strip running speed can affect heat transfer coefficient by influencing residual water distribution on top of the strip surface. Water temperature, water spray speed and strip temperature can also affect heat transfer coefficient with different changing law.

Analysis on the Influencing Factors of Heat Transfer for the Slot Nozzle Convection Impact in Rolled Strip Preposition Ultra-Fast Cooling

2015 ◽  
Vol 817 ◽  
pp. 198-203
Author(s):  
Jian Hui Shi ◽  
Guo Yuan ◽  
Lian Yun Jiang ◽  
Kun Zhao ◽  
Guo Dong Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Rolling ◽  
Average Heat Transfer Coefficient ◽  
Cooling Process ◽  
Average Heat ◽  
Slot Nozzle ◽  
Ultra Fast Cooling ◽  
Fast Cooling

The aim of this work is to optimize process design parameters of the hot rolling steel strip preposition ultra-fast cooling (UFC) system, and improve the stability and uniformity of micro heat transfer during the high strength cooling process of hot rolling strip. According to the technology and equipment feature of the pre-UFC system for a factory, the convective heat transfer process of single nozzle and strip in UFC system was studied numerically by the fluid-structure interaction finite element method (FEM). The influence of different parameters on the slot impinging jet heat transfer coefficient was obtained, such as jet angle, the jet velocity, the slot nozzle width and water temperature. The results show that on the ultra-fast cooling process of the strip in the initial temperature of 850 °C and thickness of 8 mm, the global average heat transfer coefficient can be increased with the increase of jet velocity, and decrease of the cooling water temperature. The jet angle and the slot nozzle width have minimal effect on it for the whole heat transfer zone. The local average heat transfer coefficient first increased and then decreased with the increase of jet angle and slot nozzle width at the jet impingement location.

scholarly journals METHOD ACHIEVING COOLING UNIFORMITY AND OPTIMAL PLATE-CURVATURE DURING ULTRA-FAST COOLING IN A HSM

2021 ◽  
Vol 55 (3) ◽  
Author(s):  
Lianyun Jiang ◽  
Yaoyu Wei ◽  
Zhenlei Li ◽  
Lifeng Ma
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Flux ◽  
Flux Ratio ◽  
Bottom Surface ◽  
Ultra Fast Cooling ◽  
Plate Curvature ◽  
Fast Cooling ◽  
The Heat Transfer Coefficient

The flow field in the top and bottom surface of the hot rolled strip is different during cooling process with effect of gravity. Then it can affect the strip cooling uniformity of the top and bottom surface, and the plate curvature problems may be appeared. The finite element method was taken to study the plate curvature affecting law and a conclusion was obtained: the uniformity of the heat transfer coefficient in the top and bottom surface was the key to keep plate curvature well after rolling. The finite volume method was taken to calculate the heat transfer coefficient during run-out table laminar cooling (LC) and ultra-fast cooling (UFC) with different top nozzle fluxes and water flux ratios. The heat transfer coefficient and its distribution with different cooling methods and process parameters were obtained, and some conclusions were obtained by analysis: the bottom and top surface heat transfer coefficient can be kept nearly the same by adjusting water flux ratio between the bottom nozzle and top nozzle. The optimal water flux ratios of laminar cooling were 1.20 and 1.15 when top nozzle fluxes were 100m3/h and 120m3/h respectively. The optimal water flux ratios of ultra fast cooling were 1.08, 1.10, 1.15, 1.20 and 1.20 when top nozzle fluxes were 80m3/h, 100m3/h, 120m3/h, 140m3/h and 160m3/h respectively. The obtained results and water flux ratio calculating model were used in several strip cooling lines of the hot strip mill lines and obtained favorable effect.

The Deformation Rule of the Cooled U75V Heavy Rail Caused by the Different Heat Transfer Coefficient

2011 ◽  
Vol 299-300 ◽  
pp. 1005-1011 ◽  
Author(s):  
Ming Xin Gao ◽  
Pei Long Wang ◽  
Hao Jia ◽  
Shan Hu Tong ◽  
Hua Song ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Reference Value ◽  
Ansys Software ◽  
Cooling Process ◽  
Technological Parameters ◽  
The Heat Transfer Coefficient ◽  
Heavy Rail

When rolled heavy rail is on the cooling bed for natural cooling, the heat transfer coefficient has important effect on the bending and section sizes of cooled heavy rail. In the paper, the heat-stress couple module ofANSYS software is adopted to carry on numerical simulation on the cooling process of 60kg/m U75V heavy rail, and we obtain the change rule that heat transfer coefficient has effect on bending curvature and section sizes of cooled heavy rail. This study is of great reference value on cooling bed design and the formulation of cooling technological parameters for high speed heavy rail.

scholarly journals Heat-transfer characteristics of ammonia-water falling film generation outside a vertical tube

2017 ◽  
Vol 21 (3) ◽  
pp. 1251-1259 ◽  
Author(s):  
Chao Luo ◽  
Jun Zhao ◽  
Weibin Ma
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Temperature ◽  
Water Solution ◽  
Hot Water ◽  
Falling Film ◽  
Ammonia Water ◽  
Overall Heat Transfer Coefficient ◽  
Spray Density

A heat transfer experimental of vertical out-tube falling film was conducted with different inlet spray density of ammonia-water solution and inlet hot water temperature. The inlet liquid mass concentration was selected as 60% of ammonia. The experiments showed that the overall heat transfer coefficient increases with the increase of inlet spray density and a maximum overall heat transfer coefficient could be obtained in an optimum spray density of ammonia-water solution, ?, between 0.26 and 0.29 kg/ms. The generation of ammonia vapor outside the vertical falling film had a similar trend with the overall heat transfer coefficient basing on different spray density. The effect of hot water temperature difference, ?T, on overall heat transfer coefficient showed that ?T between 10 and 13 K is the optimum temperature difference of the vertical falling film generation

Physical Modeling and Simulation of the Cooling-Down of Fused-Cast Refractories

2020 ◽  
Vol 996 ◽  
pp. 142-150
Author(s):  
Run Feng Wang ◽  
Ao Huang ◽  
Yan Zhu Huo ◽  
Li Jun Mei ◽  
Hong Jin Rao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Physical Simulation ◽  
Temperature Record ◽  
Measured Temperature ◽  
Interfacial Heat Transfer Coefficient ◽  
Interfacial Heat Transfer ◽  
Cooling Process

The accurate description of the interfacial heat transfer coefficient is of great significance for the accurate measurement of the temperature field in the process of casting cooling. In this paper, the solidification process of metallic tin in refractory mould was studied by physical simulation experiment, and the on-site temperature measurement of the mold structure was carried out. According to the temperature record, the numerical simulation method is used to realize the fitting of the calculated temperature and the measured temperature. The reversible method was used to calculate the interfacial heat transfer coefficient between the casting and the mould, and then the evolution of the internal temperature field of the casting during the cooling process was determined. The results show that the melt has a large shrinkage during the cooling process, and the interface heat transfer coefficient can reach 300 W·m-2·K-1, which provides a mathematical model for the annealing process of fused-cast refractories.

Implementation of the Axially Symmetrical and Three Dimensional Finite Element Models to the Determination of the Heat Transfer Coefficient Distribution on the Hot Plate Surface Cooled by the Water Spray Nozzle

2012 ◽  
Vol 504-506 ◽  
pp. 1055-1060 ◽  
Author(s):  
Zbigniew Malinowski ◽  
Tadeusz Telejko ◽  
Beata Hadala ◽  
Agnieszka Cebo-Rudnicka
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Spray Nozzle ◽  
Water Spray ◽  
Coefficient Distribution ◽  
The Heat Transfer Coefficient ◽  
Material Temperature

Plate and strip hot rolling lines are equipped with water cooling systems used to control the deformed material temperature. This system has a great importance in the case of thermal - mechanical deformation of steel which is focused on formation a proper microstructure and mechanical properties. The desired rate of cooling is achieved by water spray or laminar cooling applied to the hot surface of a strip. The water flow rate and pressure can be changed in a wide range and it will result in a very different heat transfer from the cooled material to the cooling water. The suitable cooling rate and the deformed material temperature can be determined based on numerical simulations. In this case thermal boundary conditions have to be specified on the cooled surface. The determination of the heat transfer coefficient distribution in the area of the water spray nozzle would improve numerical simulations significantly. In the paper an attempt is made to determine the heat transfer coefficient distribution on the hot plate surface cooled by the water spray nozzle. In the inverse method direct axially symmetrical and three dimensional solutions to the plate temperature field have been implemented. The computation time and the achieved accuracy have been compared for five cases. The studied cases differed in the maximum value of the heat transfer coefficient in nozzle spray axis and its distribution in the cooling time.

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