Temperature Distribution Inside Research Articles

On the effect of volatility on thermophoresis of aerosols

Publisher Summary This chapter focuses on the problem of thermophoresis in gases taking into account a volatility of particle substance. The effect of volatility on thermophoresis is twofold—that is, the temperature distribution inside and outside the particle changes and the surrounding space fills with the vapor of the volatile substance leading to thermal diffusion in the mixture and an uncompensated transfer of momentum from gas molecules to the particle. At room temperature, the change in the temperature field is more essential for particles with low thermal conductivity. The fact that the experimentally obtained values of thermophoretic velocity significantly exceed the computed ones—by Epstein's formula—cannot be accounted for solely be the effect of volatility.

Heat transfer at thin molten layer crystallization I. Molten layer cooling stage

The paper presents a theoretical study of heat transfer at the cooling stage of the crystallization process of a horizontal molten layer. The obtained mathematical model, based on a physical model and on the differential equation for temperature, enabled to study the influence of some parameters (the global heat transfer coefficient between the molten layer and the cooling agent and the thickness of the layer) on the temperature distribution inside on urea1 molten layer.

Non-Invasive Thermometry in Hyperthermia by NMR Chemical Shift

Summary The temperature dependence of the chemical shift for protons of CH2 groups franked to D2O was supported experimentally. The linear correlation between these parameters was established for all animal tissues examined in vivo. The temperature coefficient of regression common for all the tissues: as found as a value of (0.01010±0.0042) ppm/°C. On the basis of these data it seems most interesting to use the changes of the chemical shift for protons of GH2 groups relative to D2O as a standard for detection and mapping of the spatial temperature distribution inside of biological systems. This method may be found useful for hyperthermia and thermodiagnosis.

Temperature distribution in side- and end-pumped laser crystal rods: temporal and spatial variations

Knowledge of the temperature distribution of laser rods end pumped by laser diodes or other laser systems is relevant when thermal stress and crystal damage are expected. The temperature of a multipulsed or continuously pumped laser rod is given as a double-series expression and as a function of time. The mathematical model considers all surface cooling rates, the spatial and temporal variations of the pump beam, and the specific heat and thermal conductivity of the rod material. This eigenfunction expansion representation was employed to predict the spatial and time-dependent quasi-steady-state temperature in Ti:sapphire, Nd:YAG, and Cr:LiSAF laser rods of specific dimensions.

Optimum excitation of phases and amplitudes in a phased array hyperthermia system.

In order to achieve a desired temperature distribution inside and outside of malignant tissues, optimization techniques could be used in phased array hyperthermia systems to control effectively the amplitude and phase of the radiating elements. The optimization of a four-element phased array hyperthermia system operating at 432 MHz is examined theoretically. The proposed technique is based on a detailed physical model of the tissue medium to be heated in terms of both electromagnetic and thermal properties. A penalty function technique using a Newton method is applied to determine the optimum phases and amplitudes of the array. Several array geometries have been studied and numerical results are presented.

On the Observability and Stability of the Temperature Distribution in a Composite Heat Conductor

An infinite slab of finite thickness is composed of two given homogeneous isotropic slab heat conductors whose thermal properties are constants. Assuming that temperature conditions uniform in the space variables are applied and maintained at the boundaries, the problem of the observability of the temperature distribution inside from the boundary temperatures and the temperature at the interface of the two different materials is considered. Continuous dependence of the temperature distribution upon the data is studied.

A Certain Problem in Heat Conduction

A homogeneous sphere is surrounded by an infinite homogeneous medium. Heat is generated inside the sphere at a prescribed rate. The temperature distribution inside and outside the sphere is computed.