Solution Of Heat Transfer Equation Research Articles

The prediction of the temperature distribution and weld pool geometry in the gas metal arc welding process

The main objective of this study is to generate new understanding and improve computer methods for calculating the thermal cycles in the near weld region during gas metal arc (GMA) welding. Predicting the thermal cycle also provides an estimate of the depth of weld penetration, the geometry of the weld pool and the cooling rates. Both 2D and 3D finite-element models have been developed using the solution of heat-transfer equations. The accuracy of the predicted cooling times, weld penetrations and the lengths of the weld pools are compared with experimentally obtained values for bead-on-plate welds. A mechanical weld pool ejection rig developed in this study provided a quick and ready means of defining a full 3D weld-pool shape. A new numerical approach, `split heat source model' has been developed to model the arc heat. This gives good agreement with experimental data for a range of welding conditions.

Evaporation Kinetics of Single Droplets Containing Dissolved Bioaiass

ABSTRACT Luikov approach was applied to predict drying time and temperature of a droplet containing liquid substrate of entobacterin in the falling drying rate period. Analytical expressions describing both average and local temperatures of the particle in the drying process were derived and solved. Constants necessary to solve the equations, describing certain material properties and material moisture bonding were found in simple experiments. An experimental relationship of Rebinder number and moisture content of the material enabled to calculate changes of average droplet temperature in the falling drying rate period. Analytical solutions of heat transfer equations for shrinkage core model both for a linear and exponential change of moisture content of the droplet in the drying process were delivered. Employing experimental heat transfer coefficient, drying time and droplct temperature field were determined. Comparison of experimental and predicted drying times as well as droplet temperatures shows smal...

A Two-Layer Slab Method for Measuring Thermal Diffusivity of Polymer by Irradiated Light Heat-Wave. I.

A two-layer slab method is developed for determining the thermal diffusivity of polymer with the modulated light heat source. A solution of heat transfer equation is obtained for an infinitely wide two-layer slab, and the expression for the temperature-wave phase shift is given. The use of phase shift measurement avoids some of the problems associated with temperature measuring instrumentation of polymer. Measurement is possible even at a softening temperature because one of two layers in a slab plays the role of a mechanical holder. An analysis of energy loss at the back surface indicates that experiment should be feasible even when losses are so large. An abrupt change of thermal diffusivity at about 50°C higher than the glass temperature as well as the well known abrupt change at the glass temperature, is obtained in as well as the polystyrene, polymethacrylate, and nylon 6.