A Study Regarding the Unsteady Heat Transfer and Phase Change

2014 ◽  
Vol 659 ◽  
pp. 353-358
Author(s):  
Gelu Coman ◽  
Cristian Iosifescu ◽  
Valeriu Damian
Keyword(s):  
Heat Transfer ◽  
Numerical Modeling ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Finite Elements ◽  
Experimental Research ◽  
Theoretical Study ◽  
Ice Formation ◽  
Unsteady Heat Transfer ◽  
Cooling Pipes

The paper presents the experimental and theoretical study for temperature distribution around the cooling pipes of an ice rink pad. The heat transfer in the skating rink track is nonstationary and phase changing. In case of skating rinks equipped with pipe registers, the temperature field during the ice formation process can’t be modeled by analytical methods. The experimental research was targeted on finding the temperatures in several points of the pad and also details on ice shape and quality around the pipes. The temperatures measured on the skating ring surface using thermocouples is impossible due to the larger diameter of the thermocouple bulb compared with the air-water surfaces thickness. For this reason we used to measure the temperature by thermography method, thus reducing the errors The experimental results were compared against the numerical modeling using finite elements.

Numerical Simulation of Solidification Process for a Machine Tool Bed

2011 ◽  
Vol 675-677 ◽  
pp. 987-990
Author(s):  
Ling Tang ◽  
Xu Dong Wang ◽  
Hai Jing Zhao ◽  
Man Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Machine Tool ◽  
Computation Time ◽  
Solidification Process ◽  
Field Calculation ◽  
Original Design ◽  
Calculation Results ◽  
Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

Analytical Modeling of Temperature Distribution in Interposer-Based Microelectronic Systems

2013 ◽  
Author(s):  
Leila Choobineh ◽  
Dereje Agonafer ◽  
Ankur Jain
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Analytical Modeling ◽  
Three Dimensional ◽  
Heat Transfer Process ◽  
Thermal Design ◽  
Research Attention ◽  
On Chip

Heterogeneous integration in microelectronic systems using interposer technology has attracted significant research attention in the past few years. Interposer technology is based on stacking of several heterogeneous chips on a common carrier substrate, also referred to as the interposer. Compared to other technologies such as System-on-Chip (SoC) or System-in-Package (SiP), interposer-based integration offers several technological advantages. However, the thermal management of an interposer-based system is not well understood. The presence of multiple heat sources in various die and the interposer itself needs to be accounted for in any effective thermal model. While a finite-element based simulation may provide a reasonable temperature prediction tool, an analytical solution is highly desirable for understanding the fundamentals of the heat transfer process in interposers. In this paper, we describe our recent work on analytical modeling of heat transfer in interposer-based microelectronic systems. The basic governing energy conservation equations are solved to derive analytical expressions for the temperature distribution in an interposer-based microelectronic system. These solutions are combined with an iterative approach to provide the three-dimensional temperature field in an interposer. Results are in excellent agreement with finite-element solutions. The analytical model is utilized to study the effect of various parameters on the temperature field in an interposer system. Results from this work may be helpful in the thermal design of microelectronic systems containing interposers.

THE THERMAL MODE OF LARGE-SPAN EXCA VATIONS DURING THE CONSTRUCTION OF NUCLEAR POWER FACILITIES

2020 ◽  
Vol 2 (1) ◽  
pp. 289-301
Author(s):  
I.P. KARNACHEV ◽  
◽  
V.G. NIKOLAEV ◽  
V.V. BIRYUKOV ◽  
S.A. GUSAK ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Mathematical Models ◽  
Experimental Research ◽  
Nuclear Power ◽  
Power Plants ◽  
Phase Transfer ◽  
Thermal Mode ◽  
Large Span ◽  
Transfer Processes

The paper observes particular experimental research results on increase of stability of mining excavations in a permafrost area under low positive temperatures. The authors discuss the tasks on determining the temperature field parameters around the different-section excavations of underground small nuclear power plants at the construction stage. The mathematical models were designed for heat transfer processes in frozen rocks. The rocks were simulated as pore media filled with water with phase transfer under heating. This allowed creating virtual computing stands on which it became possible to work out the thermal modes of excavation driving.

Numerical Assessment on Time-Varying Temperature Field of Bridge Tower under Solar Radiation

2012 ◽  
Vol 204-208 ◽  
pp. 2236-2239 ◽  
Author(s):  
Bo Chen ◽  
Wei Hua Guo ◽  
Chun Fang Song ◽  
Kai Kai Lu
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Ambient Air ◽  
Heat Transfer Analysis ◽  
Time Varying ◽  
Long Span ◽  
Bridge Tower

Bridge tower, time-varying temperature field, heat transfer analysis, finite element model. Abstract. Long span suspension bridges are subjected to daily, seasonal and yearly environmental thermal effects induced by solar radiation and ambient air temperature. This paper aims to investigate the temperature distribution of a tower of a long span suspension bridge. Two-dimensional heat transfer models are utilized to determine the time-dependent temperature distribution of the bridge tower of the bridge. The solar radiation model is utilized to examine the time-varying temperature distribution. Finite element models are constructed for the bridge tower to compute the temperature distribution. The numerical models can successfully predict the structural temperature field at different time. The methodology employed in the paper can be applied to other long-span bridges as well.

Unsteady Stagnation Point Heat Transfer with Blowing or Suction

1981 ◽  
Vol 103 (3) ◽  
pp. 448-452 ◽  
Author(s):  
Takao Sano
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Prandtl Number ◽  
Asymptotic Solution ◽  
Stagnation Point ◽  
Wall Temperature ◽  
Step Change ◽  
Surface Heat ◽  
Unsteady Heat Transfer ◽  
Prandtl Numbers

The effects of blowing and suction on unsteady heat transfer at a stagnation point due to a step change in wall temperature are examined. Two asymptotic solutions for the temperature field at large and small Prandtl numbers are presented. It is shown that the asymptotic solution for large Prandtl number gives sufficiently accurate results for the surface heat transfer even for the moderate values of Prandtl number if Euler transformation is applied to the series.

scholarly journals Mathematical model of heat transfer in roll caliber

2019 ◽  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Boundary Value Problem ◽  
Boundary Conditions ◽  
Heat Equation ◽  
Rolling Mill ◽  
Thermal Process ◽  
Stationary Heat

A physical model of the thermal process in the roll caliber during the rolling of the tape on a two-roll rolling mill was constructed. A mathematical model of the temperature field of a rolling hollow roll of a rolling state of a cylindrical shape rotating about its axis with constant angular velocity is proposed. The mathematical model takes into account different conditions of heat exchange of the inner and outer surfaces of the roll with the belt and its surrounding environment. The temperature field of a hollow roll of a rolling mill is considered as an initial boundary-value problem for a homogeneous non-stationary heat equation with inhomogeneous, nonlinear boundary conditions, which also depend on the angle of rotation of the roll around its axis. The equation describes the temperature field of the rolls during uncontrolled heat transfer during rolling. It significantly depends on the time and number of revolutions around its axis. With a large number of revolutions of the roll around its axis, a quasi-stationary temperature distribution occurs. Therefore, the simplified problem of determining a quasistationary temperature field, which is associated with a thermal process that is time-independent, is considered further in the work. In this case, the temperature field is described using the boundary value problem in a ring for a homogeneous stationary heat equation with inhomogeneous boundary conditions and heat transfer conditions outside the ring, which lie from the angular coordinate. After the averaging operation, the solution of this problem is reduced to solving the equivalent integral equation of Hammerstein type with a kernel in the form of the Green's function. The Mathcad computer mathematical system builds the temperature distribution of the roll surface. An algorithm for solving a inhomogeneous problem was developed and the temperature distribution of the roll was constructed.

Thermal Hydraulic Analysis of a Water Tank With Large Aspect Ratio

2014 ◽  
Author(s):  
Qi Min ◽  
Li Zhang ◽  
Hongtao Wang ◽  
Junpeng Zhai
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Aspect Ratio ◽  
Hot Water ◽  
Water Tank ◽  
Large Aspect Ratio ◽  
Strong Function ◽  
Uniform Temperature Field ◽  
Cooling Pipes ◽  
Thermal Hydraulic Analysis

A special-shaped water tank with large aspect ratio and limited volume for cooling was investigated using computational fluid dynamics. The influence of a separator on the heat transfer ability in the water tank is analyzed. When there is no separator, the arrangement of cooling pipes is very important to the heat transfer and temperature field in the water tank. The total heat flux of the pipe bundle and the temperature field will become bad if the pipe bundle is arranged not uniform in the water tank. Adding a separator can greatly enhance the integral natural convection of cold and hot water in the water tank and a uniform temperature field and regular velocity field could be got. The heat transfer ability for the structure with a separator is better than the structure without a separator, and is not sensible to the arrangement of the pipe bundle. The heat transfer ability also did not change when the position of separator and pipe bundle exchanged, and is not a strong function of the distance between separator and the pipe bundle or the wall of the water tank. Finally, the inclination of the water tank is discussed.

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