Laser-Induced Thermal Processes: Heat Transfer, Generation of Stresses, Melting and Solidification, Vaporization, and Phase Explosion

2021 ◽  
pp. 83-163
Author(s):  
Maxim V. Shugaev ◽  
Miao He ◽  
Yoann Levy ◽  
Alberto Mazzi ◽  
Antonio Miotello ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Processes ◽  
Phase Explosion ◽  
Melting And Solidification

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

scholarly journals Heat transfer study of poly-c PV system integrated with phase change material under semi-arid area (Errachidia-Drâa Tafilalet)

2021 ◽  
Vol 297 ◽  
pp. 01008
Author(s):  
Ibtissam Lamaamar ◽  
Amine Tilioua ◽  
Zaineb Benzaid ◽  
Abdelouahed Ait Msaad ◽  
Moulay Ahmed Hamdi Alaoui
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Operating Temperature ◽  
Pv System ◽  
Pv Module ◽  
Solidification Processes ◽  
Change Material ◽  
Transfer Study ◽  
Melting And Solidification

The high operating temperature of the photovoltaic (PV) modules decreases significantly its efficiency. The integration of phase change material (PCM) is one of the feasible techniques for reducing the operating temperature of the PV module. A numerical simulation of the PV module with PCM and without PCM has been realized. The thermal behavior of the PV module was evaluated at the melting and solidification processes of PCM. The results show that the integration of RT35HC PCM with a thickness of 4 cm reduces the temperature of the PV module by 8 °C compared to the reference module. Compared the RT35 and RT35HC, we found that the latent heat has a significant effect on the PCM thermal comportment. Furthermore, it has been found that the thermal resistance of the layers plays an important role to dissipate the heat from the PV cells to the PCM layer, consequently improving the heat transfer inside the PV/PCM system.

scholarly journals TWO APPROACHES TO THE COMPUTATION OF ELECTROTHERMAL PROCESSES AT INDUCTION HEATING OF MOVING INGOTS – BY FIELD THEORY AND THERMAL CIRCUIT THEORY

2021 ◽  
Vol 2021 (59) ◽  
pp. 5-10
Author(s):  
A.A. Shcherba ◽  
◽  
A.D. Podoltsev ◽  
I.M. Kucheriava ◽  
V.M. Zolotarev ◽  
...  
Keyword(s):  
Field Theory ◽  
Heat Transfer ◽  
Temperature Distribution ◽  
Induction Heating ◽  
Thermal Field ◽  
Circuit Theory ◽  
Thermal Processes ◽  
Computational Results ◽  
Thermal Circuit ◽  
Good Agreement

The model for the computation of thermal processes in induction heating installations with moving ingots is developed using equivalent thermal circuits. The controlled current sources as additional elements in the model are used to take into account the convective heat transfer along the moving ingot. The model is implemented in the program Matlab/Simulink and makes it possible to determine the temperature distribution along the ingot under steady-state heating conditions. The results are compared with data obtained by the alternative method which is based on the electromagnetic and thermal field theory and realized in the Comsol program. As shown the computational results by two methods concerning the temperature distribution along the ingot are in good agreement. The existing advantages and shortcomings of the used approaches are discussed. Ref. 8, fig. 3, table.

Second Law Analysis of Tree-Shaped Fins for the Heat Transfer Enhancement in a PCM Thermal Storage System

2013 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Elisa Guelpa ◽  
Vittorio Verda
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Heat Transfer Enhancement ◽  
Solidification Rate ◽  
High Energy ◽  
Second Law ◽  
Transfer Enhancement ◽  
Energy Storage Devices ◽  
Second Law Analysis ◽  
Melting And Solidification

Latent heat thermal energy storage (LHTES) systems based on phase change materials (PCMs) are a promising option to be employed as effective energy storage devices. PCM allows one to achieve high energy storage density and almost constant temperature energy retrieval, however LHTES systems performance is limited by poor thermal conductivity of the PCMs which leads to unacceptably low melting and solidification rates. Thus, heat transfer enhancement techniques are required in order to obtain acceptable melting and solidification rates. The preliminary design of a shell-and-tube LHTES unit is investigated by means of computational fluid-dynamics (CFD). Three different fin designs are considered: a conventional radial fin, a constructal Y-shaped fin design and a non-constructal Y-shaped configuration previously investigated by the authors. The performances of each fin configuration are evaluated by means of a Second-law analysis. Moreover, local and global entropy generation rates are analyzed in order to show the main source of thermodynamic irreversibilities occurring in the system. The analysis indicates that solidification rate is significantly enhanced when Y-shaped fins are adopted in the LHTES unit, however the constructal Y-shaped geometry is not optimal since further improvements can be achieved by means of a Y-shaped fins with elongated secondary branches.

Heat Transfer to Oil Shale in a Closely Spaced Bundle as an Approximation to a Packed Bed

1981 ◽  
Vol 103 (4) ◽  
pp. 307-317
Author(s):  
K. S. Udell ◽  
H. R. Jacobs
Keyword(s):  
Heat Transfer ◽  
Oil Shale ◽  
Tube Bundle ◽  
Packed Bed ◽  
Cylindrical Sample ◽  
Chemical Processes ◽  
Published Data ◽  
Thermal Processes ◽  
Gas Temperature

The heat transfer to a single cylindrical sample of oil shale in a staggered tube bundle was studied both numerically and experimentally in order to evaluate the thermal and chemical processes associated with the retorting of oil shale in packed beds particular to in-situ processing. The cylinders were subjected to constant gas temperatures and to gas temperature histories experienced in an actual combustion retort. The results of the numerical modeling were compared with the experimental data in order to evaluate the model’s performance. It was found that the model satisfactorily described the thermal processes experienced during the combustion retorting of oil shale within the limits of the accuracy of published data on oil shale thermal properties and chemical kinetics. Net heat transfer to cylindrical oil shale samples in a staggered bundle configuration was also calculated and was shown to nearly duplicate published data related to gas-solid heat transfer in a packed bed combustion retort.

Methods for calculating thermal processes under conditions of natural convection of gaseous methane under the influence of electrostatic fields

2021 ◽  
Author(s):  
V.A. Altunin ◽  
K.V. Altunin ◽  
M.R. Abdullin ◽  
M.R. Chigarev ◽  
I.N. Aliev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Power Plants ◽  
Experimental Studies ◽  
Thermal Processes ◽  
Technical Literature ◽  
New Methods ◽  
Electric Wind ◽  
Electrostatic Fields ◽  
General Method

Relying on the review and analysis of scientific and technical literature, as well as the results of experimental studies, we developed new methods for calculating thermal processes occurring in gaseous methane during its natural convection, under the influence of electrostatic fields. In this study we show methods for calculating and determining the coefficients of heat transfer to gaseous methane under the influence of electric wind, as well as methods for calculating and determining the effect of electrostatic fields on the negative process of sedimentation on a heated experimental working plate in the volume of gaseous methane. A general method has been developed for the effective and safe application of electrostatic fields in gaseous methane, which must be carried out in the calculations, design, creation, and operation of new engines, power plants, and techno systems for single and reusable ground, air, aerospace and space-based aircraft.

Sign in / Sign up

Export Citation Format

Share Document