Higher-order time-differential heat transfer model with three-phase lag including memory-dependent derivatives

2021 ◽  
Vol 128 ◽  
pp. 105649
Author(s):  
Ahmed E. Abouelregal ◽  
Ömer Civalek ◽  
Hakan F. Oztop
Keyword(s):  
Heat Transfer ◽  
Higher Order ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Phase Lag ◽  
Differential Heat ◽  
Three Phase ◽  
Time Differential

scholarly journals Investigation of Heat Diffusion at Nanoscale Based on Thermal Analysis of Real Test Structure

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2379 ◽  
Author(s):  
Tomasz Raszkowski ◽  
Mariusz Zubert
Keyword(s):  
Heat Transfer ◽  
Numerical Algorithms ◽  
Silicon Layer ◽  
Heat Transfer Model ◽  
Test Structure ◽  
Heat Diffusion ◽  
Transfer Model ◽  
Phase Lag ◽  
Bottom Part ◽  
Proposed Model

This paper presents an analysis related to thermal simulation of the test structure dedicated to heat-diffusion investigation at the nanoscale. The test structure consists of thin platinum resistors mounted on wafer made of silicon dioxide. A bottom part of the structure contains the silicon layer. Simulations were carried out based on the thermal simulator prepared by the authors. Simulation results were compared with real measurement outputs yielded for the mentioned test structure. The authors also propose the Grünwald–Letnikov fractional space-derivative Dual-Phase-Lag heat transfer model as a more accurate model than the classical Fourier–Kirchhoff (F–K) heat transfer model. The approximation schema of proposed model is also proposed. The accuracy and computational properties of both numerical algorithms are presented in detail.

scholarly journals A Numerical Method for Analysing Heat Conduction in Composites Containing Encapsulated Phase Change Materials

2018 ◽  
Vol 237 ◽  
pp. 02012
Author(s):  
Hui Wang ◽  
Qing-Hua Qin
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Composite System ◽  
Matrix Material ◽  
Heat Transfer Model ◽  
Transient Heat Transfer ◽  
Cement Matrix ◽  
Transfer Model ◽  
Two Phase ◽  
Three Phase

In this study, a three-dimensional transient heat transfer model in a three-phase composite system is established to investigate effects of temperature reduction in a composite system due to the use of encapsulated phase change material (PCM). The entire composite system is composed of cement matrix material, PCM, and hollow metal microspheres (HMSs) which are introduced to accelerate the phase change efficiency of the PCM and to simultaneously hold the liquid phase of the PCM. The present transient heat transfer model is numerically solved via finite element technique for investigating the transient thermal performance of the three-phase composite system. The temperature distribution on the specific area is compared to that in the pure cement material and the two-phase composite system without metal shell for demonstrating the ability of temperature adjustment of the PCM. Finally, effects of the spatial distribution of HMS on the temperature variation in the three-phase composite system is further investigated to provide comprehensive understanding on energy adjustment of this composite system.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

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