Extended reversible problem involving mass diffusion, heat flow and thermal inertia

1994 ◽  
pp. 150-193
Author(s):  
Stanislaw Sieniutycz
Keyword(s):  
Heat Flow ◽  
Thermal Inertia ◽  
Mass Diffusion

Three Dimensional Transient Finite Element Analysis for Microstructure Formation and Residual Stresses in Double-Pass Laser Aided DMD Process

2004 ◽  
Author(s):  
S. Ghosh ◽  
J. Choi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Flow ◽  
Thermal Stresses ◽  
High Energy ◽  
Mass Diffusion ◽  
Mushy Region ◽  
Element Analysis ◽  
Energy Beam ◽  
Solid Liquid

Despite immense advances in Laser Aided Direct Metal/Material Deposition (LADMD) process many issues concerning the effects of process parameters on the stability of variety of properties and the integrity of microstructure have been reported. Modeling of heat flow seems to be a standard practice to couple heat flow calculations to related macroscopic phenomena such as fluid flow in the melt and solid-liquid mushy region, macrosegregation and thermal stresses. A key component in these models is the coupling between thermal and solute fields. Like macrostructural phenomena even microstructural features such as phase appearance, morphology, grain size or spacing are certainly no less important. The focus of this paper is the solute transport, in particular the manner in which process scale transport is coupled to transport at the local scale of the solid-liquid interface which requires a modeling of the redistribution of solutes at the scale of the secondary arm spaces in the dendritic mushy region. Basic microsegregation models which assume either no mass diffusion in the solid (Gulliver-Scheil) or complete diffusion in the solid (equilibrium lever rule) in a fixed arm space are inappropriate in high energy beam processes involving significantly high cooling rates. This paper aims at incorporating a model that accounts for finite mass diffusion and coarsening of the arm space. Due to the complexity and nonlinearity of LADMD process, analytical solutions can rarely address the practical manufacturing process. Consequently, this is an attempt towards a methodology of finite element analysis to predict solidification microstructure and thermal stresses. The simulation has been carried out for H13 tool steel deposited on a mild steel substrate. However, the program can easily be extended to a wide variety of steels.

Heat flow and mass diffusion in binary Lennard-Jones mixtures. II

1992 ◽  
Vol 46 (4) ◽  
pp. 1960-1966 ◽  
Author(s):  
Sten Sarman ◽  
Denis J. Evans
Keyword(s):  
Heat Flow ◽  
Mass Diffusion ◽  
Lennard Jones

scholarly journals Reverse heat flow with Peltier-induced thermoinductive effect

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kenjiro Okawa ◽  
Yasutaka Amagai ◽  
Hiroyuki Fujiki ◽  
Nobu-Hisa Kaneko
Keyword(s):  
Exact Solution ◽  
Heat Flow ◽  
Thermal Inertia ◽  
Peltier Effect ◽  
Local Cooling ◽  
High Temperature Side ◽  
Inductive Component ◽  
Ac Current ◽  
Single Material ◽  
Temperature Side

AbstractThe concept of “thermal inductance” expands the options of thermal circuits design. However, the inductive component is the only missing components in thermal circuits unlike their electromagnetic counterparts. Herein, we report an electrically controllable reverse heat flow, in which heat flows from a low-temperature side to a high-temperature side locally and temporarily in a single material by imposing thermal inertia and ac current. This effect can be regarded as an equivalent of the “thermoinductive” effect induced by the Peltier effect. We derive the exact solution indicating that this reverse heat flow occurs universally in solid-state systems, and that it is considerably enhanced by thermoelectric properties. A local cooling of 25 mK is demonstrated in (Bi,Sb)2Te3, which is explained by our exact solution. This effect can be directly applicable to the potential fabrication of “thermoinductor” in thermal circuits.

GEOLOGICAL AND GEOPHYSICAL STUDY FOR ELABORATION OF GEOTHERMAL MODEL IN ORADEA-BAILE FELIX AREA

2020 ◽  
Author(s):  
Laurențiu Asimopolos ◽  
Natalia-Silvia Asimopoli
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Gradient ◽  
Thermal Inertia ◽  
Geothermal Gradient ◽  
Point Of View ◽  
Hot Water ◽  
Thermal Methods ◽  
Thermal Anomalies ◽  
Average Value

Thermal methods consist of measuring thermal gradient and satellite data, which can be used to determine the Earth's surface temperature and thermal inertia of surficial materials, of thermal infrared radiation emitted at the Earth's surface. Thermal gradient measuring, with a knowledge of the thermal conductivity provides a measure of heat flow. Conditions that may increase or decrease and heat flow are influenced by hydrologic, topographic factors and anomalous thermal conductivity. Also, oxidation of sulphide bodies in-place or on waste deposits, if sufficiently rapid, can generate thermal anomalies, which can provide a measure of the amount of metal being released to the environment. The geothermal gradient on the territory of Romania, the increase of the temperature with the depth, has an average value of 2.5°-3°C/100m, which corresponds to a temperature of 100° C at 3000 m deep. There are many areas where the value of the geothermal gradient differs considerably from this average. For example, in areas where the rock plate suffered rapid dips and the basin was filled with sediment "very young "from a geological point of view, the geothermal gradient may be less than 1° C/100m. On the other hand, in other geothermal areas the gradient exceeds much this average. These areas are true underground thermal reservoirs of potentially high geothermal energy which under certain favourable conditions can be exploited to serve heating installations and domestic hot water systems. The geothermal prospecting for the entire territory of Romania, carried out by temperature measurements allowed the development of geothermal maps, highlighting the temperature distribution at different depths. Geophysical data obtained through various methods and geophysical modelling provide generalized and non-unique solutions to the geometry of underground geological relations as well as to the physical characteristics of different formations. The non-uniqueness of these models (solutions to the direct problem) arises from the impossibility of knowing the boundary conditions between different strata, which together with the propagation equations of the different fields (depending on the geophysical method used for the investigation of the basement) form the systems that offer the solutions of the model

Heat flow and mass diffusion in binary Lennard-Jones mixtures

1992 ◽  
Vol 45 (4) ◽  
pp. 2370-2379 ◽  
Author(s):  
Sten Sarman ◽  
Denis J. Evans
Keyword(s):  
Heat Flow ◽  
Mass Diffusion ◽  
Lennard Jones

scholarly journals Mars Regolith Properties as Constrained from HP3 Mole Operations and Thermal Measurements

2020 ◽  
Author(s):  
Tilman Spohn ◽  
Matthias Grott ◽  
Nils Müller ◽  
Jörg Knollenberg ◽  
Christian Krause ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Lower Bound ◽  
Heat Flow ◽  
Thermal Inertia ◽  
Geothermal Gradient ◽  
Thermal Measurements ◽  
Initial Penetration ◽  
Flow Through ◽  
Homogeneous Soil ◽  
Insight Mission

<p>The Heat Flow and Physical Properties Package HP<sup>3</sup> onboard the Nasa InSight mission has been on the surface of Mars for more than one Earth year. The instrument's primary goal is to measure Mars' surface heat flow through measuring the geothermal gradient and the thermal condunctivity at depths between 3 and 5m. To get to depth, the package includes a penetrator nicknamed the "Mole"  equipped with sensors to precisely measure the thermal conductivity. The Mole tows a tether with printed temperature sensors;  a device to measure the length of the tether towed and a tiltmeter will help to track the path of the Mole and the tether. Progress of the Mole has been stymied by difficulties of digging into the regolith. The Mole functions as a mechanical diode with an internal hammer mechanism that drives it forward. Recoil is balanced mostly by internal masses but a remaining 3 to 5N has to be absorbed by hull friction. The Mole was designed to work in cohesionless sand but at the InSight landing a cohesive duricrust of at least 7cm thickness but possibly 20cm thick was found. Upon initial penetration to 35cm depth, the Mole punched a hole about 6cm wide and 7cm deep into the duricrust, leaving more than a fourth of its length without hull friction.  It is widely agreed that the lack of friction is the reason for the failure to penetrate further. The HP<sup>3</sup> team has since used the robotic arm with its scoop to pin the Mole to the wall of the hole and helped it penetrate further to almost 40cm. The initial penetration rate of the Mole has been used to estimate a penetration resistance of 300kPa. Attempts to crush the duricrust a few cm away from the pit have been unsuccessful from which a lower bound to the compressive strength of 350kPa is estimated.  Analysis of the slope of the steep walls of the hole gave a lower bound to cohesion of 10kPa. As for thermal properties, a measurement of the thermal conductivity of the regolith with the Mole thermal sensors resulted in 0.045 Wm<sup>-1</sup>K<sup>-1</sup>.  The value is considerably uncertain because part of the Mole having contact to air.  The HP³ radiometer has been monitoring the surface temperature next to the lander and a thermal model fitted to the data give a regolith thermal inertia of  189 ± 10 J m<sup>-2</sup> K<sup>-1</sup> s<sup>-1/2</sup>. With best estimates of heat capacity and density, this corresponds to a thermal conductivity of 0.045 Wm<sup>-1</sup>K<sup>-1</sup>, consistent with the above measurement using the Mole. The data can be fitted well with a homogeneous soil model, but observations of Phobos eclipses in March 2019 indicate that there possibly is a thin top layer of lower thermal conductivity. A model with a top 5 mm layer of 0.02 Wm-1K-1 above a half-space of 0.05 Wm-1K-1 matches the amplitudes of both the diurnal and eclipse temperature curves. Another set of eclipses will occur in April 2020.</p><p> </p>

Burgers fluid flow in perspective of Buongiorno’s model with improved heat and mass flux theory for stretching cylinder

2020 ◽  
Vol 92 (3) ◽  
pp. 31101
Author(s):  
Zahoor Iqbal ◽  
Masood Khan ◽  
Awais Ahmed
Keyword(s):  
Diffusion Process ◽  
Mathematical Formulation ◽  
Thermal Relaxation ◽  
Mass Diffusion ◽  
Stretching Cylinder ◽  
Discussion Section ◽  
Buongiorno’S Model ◽  
Homotopy Analysis ◽  
Burgers Fluid ◽  
Diffusion Phenomena

In this study, an effort is made to model the thermal conduction and mass diffusion phenomena in perspective of Buongiorno’s model and Cattaneo-Christov theory for 2D flow of magnetized Burgers nanofluid due to stretching cylinder. Moreover, the impacts of Joule heating and heat source are also included to investigate the heat flow mechanism. Additionally, mass diffusion process in flow of nanofluid is examined by employing the influence of chemical reaction. Mathematical modelling of momentum, heat and mass diffusion equations is carried out in mathematical formulation section of the manuscript. Homotopy analysis method (HAM) in Wolfram Mathematica is utilized to analyze the effects of physical dimensionless constants on flow, temperature and solutal distributions of Burgers nanofluid. Graphical results are depicted and physically justified in results and discussion section. At the end of the manuscript the section of closing remarks is also included to highlight the main findings of this study. It is revealed that an escalation in thermal relaxation time constant leads to ascend the temperature curves of nanofluid. Additionally, depreciation is assessed in mass diffusion process due to escalating amount of thermophoretic force constant.

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