Search Results

You are looking at 1 - 10 of 296 items for :

  • "heat transfer" x
  • All content x
Clear All

Abstract  

A simple one-dimensional, axisymmetric model of a gas-pressure deformation calorimeter containing a lumped heat source accounts for observed pressure changes in terms of conductive and radiant components of heat transfer. Agreement is generally good between experimental data and the predicted calorimeter response for the range of source dimensions, heating rates, and test temperatures investigated in the study.

Restricted access

.B. Tabrizi G. Ahmadi 2002 Modeling of heat transfer in turbulent gas-solid flow Int. J. Heat Mass Transfer 45

Restricted access

Abstract  

A theoretical approach has been used to show that, except for certain types of reaction mechanism, the ease with which it is possible to distinguish the form of the reaction mechanism by the reduced-time plot method depends particularly on the rate of transfer of heat into the sample. The original reduced-time plots [1] were calculated from model equatioons which assume that the sample is, from the outset, at a fixed temperature and remains under isothermal conditions throughout the reaction. The variations produced in the appearance of reduced-time plots when the sample is programmed to rise to a given fixed temperature through various temperature schedules have been investigated. It is shown that even relatively rapid temperature rises can produce distortion of the reduced-time plots for various reaction equations. If the reaction mechanism is known, however, fairly accurate values of the activation energy for the reaction can be determined, even when the furnace used has relatively poor heat-transfer characteristics.

Restricted access

Introduction Unaware of physical laws about heat and humidity transfer through textile layers, man started wearing clothing based on his natural needs. In spite of this fact, theories about heat transfer were primarily used in

Restricted access

the basis of numerical solution into heat transfer equation in Eulerian coordinates using finite difference method in forward Euler's time integration scheme. A heat source model is developed for the laser beam deep penetration welding, allowing better

Open access

Abstract  

An analysis developed in previous work has been further refined in order to study the effect of heat transfer on the heat capacity and phase angle measurements by TMDSC. In the present model, a temperature gradient within the sample has been taken into account by allowing for heat transfer by thermal conduction within the sample. The influence of the properties of the sensors, the heat transfer conditions between the sensor and sample,and the properties of the sample have been investigated by varying each parameter in turn. The results show that heat capacity measurements are reliable only within a restricted frequency range, for which the experimental conditions are such that the heat transfer phase angle depends linearly on the modulation frequency.

Restricted access

1 Introduction Boiling heat transfer and two-phase flow plays a significant role in many heat exchange systems. Boiling heat transfer mode is an efficient mode among other heat transfer modes, and this is due to the latent heat of vaporization that

Open access

assemblies is affected by several factors, which are fiber volume percentage, fiber radius, temperature, and fiber emissivity. Wu et al. [ 14 ] investigated the influence of the above parameters on radiative heat transfer systematically based on the model of

Restricted access

. [3] Awbi H. B. Calculation of convective heat transfer coefficients of room surfaces for natural convection , Energy Build , Vol. 28 , No. 2

Open access

The results of an investigation of heat transfer in a new type of insulation (microsphere insulation) are presented. The effects of the microsphere diameter, the concentration of metallized microspheres and the residual gas pressure on the thermal conductivity of the insulation were investigated. Measurements were made of the thermal conductivity at 77 to 300 K of microspheres with differing diameters (e.g. 95, 130 and 270 μm) and of samples with silver metallized microsphere concentrations of 7 and 32%. Measurements of average thermal conductivity (77–296 K) were made at residual gas pressuresk(p) in the range from 10−3 Pa to 105 Pa for pure nitrogen. The component of heat transfer by gas,k gc (p), was estimated.

Restricted access