Internal temperature distribution

Analysis of these experiments is simplified by the fact that the thermal conductivity of fused silica is much greater than that of air. Therefore, the microsphere can be treated as being in thermal equilibrium (uniform internal temperature distribution) at all times because of its very fast internal relaxation33. We assume that heat loss through the stems is negligible because of their small masses and long conduction... 

ABSTRACT Internal temperature distribution and mass were measured during drying and pyrolysis of cylindrical samples of wood of 0, 14 and 44% moisture. A onedimensional model of drying and pyrolysis is modified to reflect the anisotropy of the wood. Inclusion of an instant axial convective mass flow is shown to reduce the time of conversion compared to simulations with no axial flow. This mass flow, contrary to a convective mass flow through a porous structure, is not in thermal equilibrium with the solid phase. The gas leaves at a lower temperature compared to the temperature of the solid phase and is thus neglected in the energy equation. 

In the absence of phase change, the temperature distribution within the material is established by the size, power, and shape of the beam, along with the thermophysical properties of the material. Prediction of the internal temperature distribution in moving materials heated... 

Pulsed sources can be used to tailor the material s internal temperature distribution. Pulsing is typically used to sharpen spatial temperature gradients. Solutions to Eq. 18.9 involving a single pulse for Pe = 0, p = 1 have been obtained by a number of researchers, and consideration of the general case of pulsed irradiation of a moving material with elliptical Gaussian beams is presented by Sanders [27],... 

The effect of thermal conductivity on heat flow and internal temperature distribution is shown in figure 2.6 for three same-size bars or slabs of ferrous alloys 1, 6, and 13 (from fig. 2.5) heated from two sides. The surface temperatures of all three will rise very quickly, but the interior temperatures of 6 and 13 will rise more slowly because of their poorer diffusivities. The 13 bar will take the longest time to come to thorough equilibrium with furnace temperature. 

The thermal loading can be determined by the temperarnre distribution of the contact faces. There are several measuring methods (see Cutting Temperature). The internal temperature distributions in the cutting wedge can be also calculated by the FEM. From that point on, these methods are able to derive thermally induced stress distributions (Fig. 2). 

In 1939 Frank-Kamenetskii considered circumstances where Newtonian cooling was only an empirical approximation, and where the escape of heat was impeded internally by the thermal properties of the medium. (This will always be the case for a large enough system.) An internal temperature-distribution with a maximum at the middle results. For stability, this central temperature may not exceed a critical value. For a sphere with its surface at T the relationship is ... 

Chang M H and Cheng C H (2005), Non destructive inverse methods for determination of irregular internal temperatures distribution in PEMFCs , J. Power Sources, 142, 200-210. 

Example of an HACCP System. The HACCP system can be used to ensure production of a safe cooked, sHced turkey breast with gravy, which has been vacuum packaged in a flexible plastic pouch and subjected to a final heat treatment prior to distribution (37). Raw turkey breasts are trimmed, then injected with a solution containing sodium chloride and sodium phosphate. Next, the meat is placed into a tumbler. After tumbling, the meat is stuffed into a casing, placed onto racks, and moved into a cook tank, where it is cooked to an internal temperature of at least 71.1°C (160°F). After... 

With respect to selecting measurements, emphasis should include measurements within the equipment such as tower internal temperatures and compositions, internal reac tor conditions, and intermediate exchanger temperatures in multipass exchangers. Trace component compositions provide particular insight into distillation-column performance. Those components that fall between the heavy and light keys and distribute in the products can usually be described by a variety of models and parameter estimates They provide little insight into the column performance. 

If an electric current flows through a wire, ihe heat generated internally will result in a temperature distribution between the central axis and the surface of the wire. This type of problem will also arise in chemical or nuclear reactors where heat is generated internally. It is necessary to determine the temperature distribution in such a system and the maximum temperature which will occur. 

Figure 20. Calculated temperature distribution in a large cylindrical carbon anode design with an internal metal conductor.

With the surface ionization source it is generally assumed that the reactant ion internal state distribution is characterized by the source temperature and that the majority of the reactant ions are in their ground electronic state. This contrasts with the uncertainty in reactant state distributions when transition metal ions are generated by electron impact fragmentation of volatile organometallic precursors (10) or by laser evaporation and ionization of solid metal targets (11). Many examples... 

In the Lagrangian approach, individual parcels or blobs of (miscible) fluid added via some feed pipe or otherwise are tracked, while they may exhibit properties (density, viscosity, concentrations, color, temperature, but also vorti-city) that distinguish them from the ambient fluid. Their path through the turbulent-flow field in response to the local advection and further local forces if applicable) is calculated by means of Newton s law, usually under the assumption of one-way coupling that these parcels do not affect the flow field. On their way through the tank, these parcels or blobs may mix or exchange mass and/or temperature with the ambient fluid or may adapt shape or internal velocity distributions in response to events in the surrounding fluid. 

To study the effects due to droplet heating, one must determine the temperature distribution T(r, t) within the droplet. In the absence of any internal motion, the unsteady heat transfer process within the droplet is simply described by the heat conduction equation and its boundary conditions... 

For the differential control volume shown (assume a 2n circumferential extent), derive expressions for the heat-transfer rate, including internal heat generation and thermal conduction. State the net conduction heat-transfer rate in terms of the temperature distribution that is, evaluate f q ndA. Take care when evaluating the differential areas. Identify and neglect higher-order terms. 

Figure 10.15 shows the simulated temperature distribution in the electrolyte for the single-cell stack model. In this calculation, the cell operating voltage is set at 0.16 V at which the electrolyte sheet cracked in the internal heat evolution test. In Figure 10.15, it can be observed that the temperature is almost 1273 K outside the anode/electrolyte/cathode area where heat is generated. Near the fuel inlet at the channel, the temperature increases steeply and the maximum temperature spreads over a wide area to the downstream of the fuel flow the maximum temperature difference in the electrolyte is around 60 K. 

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