> > Transient Thermal Analysis Problems

Transient Thermal Analysis Problems
This chapter contains transient thermal analysis problems and Thermal's results. In a transient thermal analysis, Thermal calculates the thermal response of your model to heat loads that change with time and that are subject to specified constraints. Thermal also automatically calculates all predefined measures that apply to a model.
This section contains the following models:
mvtt001: 3D Solid Transient Heat Flow
mvtt002: 3D Solid Plate with Convection
mvtt001: 3D Solid Transient Heat Flow
 Analysis Type: Transient Thermal Model Type: 3D Comparison: Theory Reference: Holman, J.P. Heat Transfer. 5th ed. McGraw-Hill Book Co., Inc., 1981. Example 4.2. Description: A large solid cylinder of steel is at an initial uniform temperature of 35 C. One end is then exposed to a constant surface heat flux of 3.2e5 W/m2. Find the temperature after 30 s at a depth of 2.5 cm from the heated end. Specifications
 Element Type: tet (362) Units: s m W C Dimensions: radius 0.25 length 6.5 Properties: Mass Density 8000 kg/m3 Thermal Expansion 1.4e-5 m2/s Conductivity 45 W/m C Specific Heat 401.79 J/kg C
 Prescribed Temps: Location/Magnitude: therm_constr1 everywhere: 35 C therm_load1 placed on surface ABDC: 320000 W/m2
Comparison of Results Data
 Theory Thermal % Difference Point E (m=temp_2_5) 79.3 79.25 0.06% Single-Pass Adaptive Convergence Max P: 6 No. Equations: 3909
mvtt002: 3D Solid Plate with Convection
 Analysis Type: Transient Thermal Model Type: 3D Comparison: Theory Reference: Holman, J.P. Heat Transfer. 5th ed. McGraw-Hill Book Co., Inc., 1981. Example 4.5. Description: A plate of steel is at an initial uniform temperature of 200 C. All exposed surfaces of the plate are then suddenly subjected to a convection condition of 70 C with a heat transfer coefficient of 525 W/m2 C. Find the temperature after 60 s at a depth of 1.25 cm from one of the exposed faces. Specifications
 Element Type: bricks (48) Units: s m W C Dimensions: width: 0.3 height: 0.3 thickness: 0.05 Properties: Mass Density 2700 kg/m3 Specific Heat 900 J/kg C Conductivity 215 W/m C
 Prescribed Temps: Location/Magnitude: therm_constr1 placed on all exposed surfaces• thermal transfer coefficient: 525 W/m2 C• bulk temperature: 70 C Initial temperature entire body at 200 C
Comparison of Results Data
 Theory Thermal % Difference Point A (m=pnt_1_25cm) 147.7 145.2 1.7 % Single-Pass Adaptive Convergence Max P: 4 No. Equations: 898