scholarly journals Thermal properties of limestone rock by pulse transient technique using slab model accounting the heat transfer coefficient and heat capacity of heat source

2020 ◽  
Author(s):  
Rupali Tiwari ◽  
Vlastimil Boháč ◽  
Peter Dieška ◽  
Gregor Götzl
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Transfer Coefficient ◽  
Thermal Properties ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Slab Model ◽  
Limestone Rock ◽  
The Heat Transfer Coefficient ◽  
Pulse Transient Technique

scholarly journals Thermophysical Parameters of Carbonate Rock estimated by Slab Model Developed for Pulse Transient Technique

2020 ◽  
Vol 20 (5) ◽  
pp. 218-223
Author(s):  
Rupali Tiwari ◽  
Vlastimil Boháč ◽  
Peter Dieška ◽  
Gregor Götzl
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Parameter Estimation ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Carbonate Rock ◽  
Slab Model ◽  
Thermophysical Parameters ◽  
The Heat Transfer Coefficient ◽  
Pulse Transient Technique

AbstractThe slab model has been used for parameter estimation from the measurement performed by the Pulse Transient Technique. The estimation of thermophysical parameters was done on carbonate rock sample. In addition to basic thermal parameter for example thermal diffusivity, thermal conductivity and specific heat capacity, the slab model takes into account the heat capacity of the heat source, as well as the heat transfer coefficient between the heat source and the sample. The thermophysical parameters were estimated for the case when thermal conductive paste as a heat contact agent was not used for the measurements. The paste contains silicone oil that penetrates into the porous stone material and thus causes irreversible changes of properties during the measurement so we decided not to use it. The experiment was done with dry contacts at the interfaces that causes the disturbances in the measurement that have been introduced and resolved using the slab model. Uncertainty analysis of the estimation of the parameters by the slab model was done for real measurements conducted on the carbonate rock. In this paper we analyzed the quality of the temperature response fit in dependency on the originally free fitted parameters of the heat transfer coefficient and the heat capacity of the heat source that was replaced by constant values in two steps. The heat capacity of the heat source was calculated from the material properties, e.g., the nickel and Kapton. The fit results obtained by the slab model were compared with the data obtained by the ideal and cuboid model. The analysis of the sensitivity coefficients and calculated uncertainties of estimated parameters with the slab model help to improve the accuracy of parameter estimation.

Nanoparticle aggregation kinematics on the quadratic convective magnetohydrodynamic flow of nanomaterial past an inclined flat plate with sensitivity analysis

2021 ◽  
pp. 095440892110562
Author(s):  
AS Sabu ◽  
Joby Mackolil ◽  
B Mahanthesh ◽  
Alphonsa Mathew
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Sensitivity Analysis ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Inclined Plate ◽  
The Impact ◽  
The Heat Transfer Coefficient

The study focuses on the aggregation kinematics in the quadratic convective magneto-hydrodynamics of ethylene glycol-titania ([Formula: see text]) nanofluid flowing through an inclined flat plate. The modified Krieger-Dougherty and Maxwell-Bruggeman models are used for the effective viscosity and thermal conductivity to account for the aggregation aspect. The effects of an exponential space-dependent heat source and thermal radiation are incorporated. The impact of pertinent parameters on the heat transfer coefficient is explored by using the Response Surface Methodology and Sensitivity Analysis. The effects of several parameters on the skin friction and heat transfer coefficient at the plate are displayed via surface graphs. The velocity and thermal profiles are compared for two physical scenarios: flow over a vertical plate and flow over an inclined plate. The nonlinear problem is solved using the Runge–Kutta-based shooting technique. It was found that the velocity profile significantly decreased as the inclination of the plate increased on the other hand the temperature profile improved. The heat transfer coefficient decreased due to the increase in the Hartmann number. The exponential heat source has a decreasing effect on the heat flux and the angle of inclination is more sensitive to the heat transfer coefficient than other variables. Further, when radiation is incremented, the sensitivity of the heat flux toward the inclination angle augments at the rate 0.5094% and the sensitivity toward the exponential heat source augments at the rate 0.0925%. In addition, 41.1388% decrement in wall shear stress is observed when the plate inclination is incremented from [Formula: see text] to [Formula: see text].

Evaluation of Heating Process of Apple, Eggplant, Zucchini and Potato by Means of Their Thermal Properties

2016 ◽  
Author(s):  
Hilario Terres ◽  
Sandra Chavez ◽  
Raymundo Lopez ◽  
Arturo Lizardi ◽  
Araceli Lara
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Properties ◽  
Transfer Coefficient ◽  
Biot Number ◽  
Heating Process ◽  
Energy Devices ◽  
Heating Device ◽  
The Heat Transfer Coefficient ◽  
Transitory State

In this work, the heating process for apple, eggplant, zucchini and potato by means of evaluation of their thermal properties and the Biot number determined in experimental form is presented. The heating process is carried out using a solar cooker box-type as heating device. The thermal experimental properties determined are conductivity (k), density (D), specific heat (C), diffusivity (Dif) and the Biot number (Bi) for each product evaluated. In the experimentation, temperatures for center and surface in each product and water were measured in controlled conditions. For those measures, a device Compact Fieldpoint and thermocouples placed in the points studied were used. By using correlations with temperature as function, k, D and C were calculated, while by using equations in transitory state for the products modeled as sphere and cylinder was possible to estimate the Biot number after calculation of the heat transfer coefficient for each case. Results indicate the higher value for k, C and Dif correspond to zucchini (0.65 W/m °C, 4084.5 J/kg °C, 1.5 × 10−7 m2), while higher value for D correspond to potato (1197.5 kg/m3). The lowest values for k and C were obtained for potato (0.59 W/m °C, 3658.3 J/kg °C) while lowest values for D and Dif, correspond to zucchini (998.2 kg/m3) and potato (1.45 × 10−7 m2/s) respectively. The maximum and minimum values for Bi corresponded to potato (21.4) and zucchini (0.41) in respective way. The results obtained are very useful in applications for solar energy devices, where estimates for properties are very important to generate new results, for example, numerical simulations. Also, results could be used to evaluate the cooking power in solar cookers when the study object is oriented in that direction.

Effect of a Shield on Mixed Convection in a Rectangular Enclosure with Moving Cold Sidewalls and a Heat Source on the Bottom Wall

2010 ◽  
Vol 297-301 ◽  
pp. 584-589
Author(s):  
Ghanbar Ali Sheikhzadeh ◽  
S.H. Musavi ◽  
N. Sadoughi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Heat Dissipation ◽  
Bottom Wall ◽  
Governing Equations ◽  
Thermal Shield ◽  
The Heat Transfer Coefficient ◽  
Specific Distance

In this work, the mixed convention of air inside a rectangular cavity with moving cold sidewalls is studied numerically. A constant flux heat source is attached to the bottom wall of the cavity. A thin thermal shield is located at a specific distance above the heat source. The governing equations are solved using appropriate numerical methods. A parametric study has been conducted and the effects of heat source length, its location and the shield distance from the source on the heat transfer have been investigated. The results show that the heat dissipation increases as the heat source and the shield are moved up to a certain distance towards either sidewall. However, moving them beyond this limiting distance results in the reduction of heat dissipation. It is shown that the presence of shield results in the reduction of the heat transfer coefficient. However, for the normalized distance of the shield from the heat source greater than , the shield’s effect on the reduction of the heat transfer coefficient is less than.

scholarly journals Study on the Thermal Properties of Hollow Shale Blocks as Self-Insulating Wall Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Guo-liang Bai ◽  
Ning-jun Du ◽  
Ya-zhou Xu ◽  
Chao-gang Qin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Properties ◽  
Transfer Coefficient ◽  
Wall Material ◽  
Element Analysis ◽  
Experimental Heat ◽  
Wall Materials ◽  
Save Energy ◽  
The Heat Transfer Coefficient

To reduce energy consumption and protect the environment, a type of hollow shale block with 29 rows of holes was designed and produced. This paper investigated the thermal properties of hollow shale blocks and walls. First, the guarding heat-box method was used to obtain the heat transfer coefficient of the hollow shale block walls. The experimental heat transfer coefficient is 0.726 W/m2·K, which would save energy compared to traditional wall materials. Then, the theoretical value of the heat transfer coefficient was calculated to be 0.546 W/m2·K. Furthermore, the one-dimensional steady heat conduction process for the block and walls was simulated using the finite element analysis software ANSYS. The predicted heat transfer coefficient for the walls was 0.671 W/m2·K, which was in good agreement with the test results. With the outstanding self-insulation properties, this type of hollow shale block could be used as a wall material without any additional insulation measures in masonry structures.

Relation Between the Thermal Effectiveness of Overall Parallel and Counterflow Heat Exchanger Geometries

1989 ◽  
Vol 111 (2) ◽  
pp. 294-299 ◽  
Author(s):  
A. Pignotti
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Rate Ratio ◽  
Simple Relation ◽  
Two Fluids ◽  
The Heat Transfer Coefficient

A simple relation is established between the thermal effectiveness of two heat exchanger configurations that differ from each other in the inversion of either one of the two fluids. Using this relation, if the expression for the effectiveness of a configuration, as a function of the heat capacity rate ratio, and the number of heat transfer units, is known, the corresponding expression for the “inverse” configuration is immediately obtained. The relation is valid under the assumptions of temperature independence of the heat transfer coefficient and heat capacity rates, when one of the fluids proceeds through the exchanger in a single, mixed stream. The property is illustrated with several examples from the available literature.

Influence of an internal heat source on the heat-transfer coefficient

Atomic Energy ◽  
1961 ◽  
Vol 7 (3) ◽  
pp. 743-744
Author(s):  
S. S. Kutateladze ◽  
N. I. Ivashchenko ◽  
T. V. Zablotskaya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Internal Heat ◽  
Internal Heat Source ◽  
The Heat Transfer Coefficient
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