Numerical simulation and theoretical analysis of heat transfer in a moving packed bed with the local internal heat source

2015 ◽  
Vol 85 ◽  
pp. 418-425 ◽  
Author(s):  
Yongwei Wang ◽  
Wenxuan Xi ◽  
Xiulan Huai ◽  
Xunfeng Li ◽  
Jun Cai
2019 ◽  
Vol 297 ◽  
pp. 95-104
Author(s):  
Sihem Bouzid ◽  
Nacer Hebbir ◽  
Yamina Harnane

This work concerns the numerical modeling of stationary conduction heat transfer in a 3D three-dimensional anisotropic material subjected to an internal heat source, based on the finite element method MEF and using the Galerkin method. The field of study is a cube representing the seven crystalline systems subjected to an internal heat source and convective boundaries. The obtained equation system is solved by the LU method. The automatic mesh is managed for all the domain nodes via the program which we have written in FORTRAN language. This program allowed temperature field calculation and was applied for different crystalline systems: monoclinic, triclinic, orthorhombic, trigonal, cubic that are identified by their thermal conductivity tensors [kij]. The obtained temperature profiles obtained are in accordance with heat transfer theory and clearly illustrate the crystalline structure symmetry; this calculation permits to predict the possible thermal deformations in an anisotropic solid.


Author(s):  
Gheorghe Juncu

The effect of thermal radiation on the two – dimensional, steady-state, conjugate heat transfer from a circular cylinder with an internal heat source in steady laminar crossflow is investigated in this work. P0 (Rosseland) and P1 approximations were used to model the radiative transfer. The mathematical model equations were solved numerically. Qualitatively, P0 and P1 approximations show the same effect of thermal radiation on conjugate heat transfer; the increase in the radiation – conduction parameter decreases the cylinder surface temperature and increases the heat transfer rate. Quantitatively, there are significant differences between the results provided by the two approximations.


Author(s):  
Francesco Di Lecce ◽  
Sandra Dulla ◽  
Piero Ravetto ◽  
Antonio Cammi ◽  
Stefano Lorenzi ◽  
...  

Heat transfer phenomena involving internally heated fluid flows are of particular interest in several industrial applications, in chemical plants as in the nuclear field. This topic is relevant for the development of the Molten Salt Reactors (MSRs) since it involves the safety characteristics of the liquid molten salt fuel. In the literature, there is a lack of systematic studies on the heat transfer mechanism and correlations for flows in ducts featuring an internal heat source, apart from some analytical studies performed in Fiorina et al., “Thermal-hydraulics of internally heated molten salts and application to the MSFR”, Journal of physics, Conference series 501 (2014). In this work, the Nusselt number is computed multiplying the traditional Nu for internal flows times a corrective factor to account for the internal heat source. As a main outcome of this work, it is possible to obtain a CFD-based improved estimate of the corrective factor correlation for turbulent flow regime with respect to the work by Fiorina. The numerical CFD analysis is performed with the open source code Open FOAM. Despite its simplicity, the method is general and applicable for any geometrical and thermal situations.


Author(s):  
A.A. Bagaev ◽  
◽  
S.O. Bobrovskiy ◽  

Indirect electrical resistance heating systems are heat-ers with internal heat sources and are widely used in agri-culture for heating gaseous and liquid media. Such sys-tems are characterized by insufficient intensity of heat ex-change processes. This implies a large heat transfer sur-face area and significant geometric size. Earlier, an attempt was made to solve the problem of increasing the efficiency of heat transfer processes and minimizing the geometric size of the heat exchanger. For this purpose, the heat ex-change characteristics were simulated and the geometric dimensions of three heat exchange systems were deter-mined: “pipe with internal heat sources in a dielectric pipe”, “pipe with an internal heat source -a membraneof heated liquid” and “cylindrical coil -heated liquid”. The analysis of these heat exchange systems has shown that the most promising is a coil-type heat exchanger. This system has the best heat transfer characteristics and the most compact size. To confirm the correctness of the applied method of calculating the heat exchange and geometric parameters of the heat exchanger, the simulation of the temperature dis-tribution of the heated liquid in the channel of the coil heat exchanger is implemented in this work. The verification calculations carried out under the formulated assumptions, using the example of a coil heat exchanger, show that the method for determining the heat exchange and geometric parameters of heat exchangers is correct. As a result of the simulation, it has been found that the error in determining the required channel length of the coil heat exchanger, the number of turns and the height of the coil to reach the liq-uid temperature at the outlet of 75°C does not exceed 4%. A similar conclusion can be made regarding the heat ex-changers of the types “pipe with internal heat sources -heated liquid” and “pipe with an internal heat source -a membraneof heated liquid”.


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