/[ascend]/trunk/models/johnpye/radialheatloss.a4c
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revision 616 by johnpye, Wed May 17 06:34:46 2006 UTC revision 617 by johnpye, Wed May 17 06:58:19 2006 UTC
# Line 46  END radial_loss; Line 46  END radial_loss;
46  MODEL wall_conduction REFINES radial_loss;  MODEL wall_conduction REFINES radial_loss;
47      k IS_A thermal_conductivity;      k IS_A thermal_conductivity;
48            
49      q = 2 * 1{PI} * L * k *(T_1 - T_2) / ln(D_2/D_1);      q = 2 * 1{PI} * L * k * (T_1 - T_2) / ln(D_2/D_1);
50    
51  END wall_conduction;  END wall_conduction;
52    
# Line 56  END wall_conduction; Line 56  END wall_conduction;
56  MODEL convection_boundary REFINES radial_loss;  MODEL convection_boundary REFINES radial_loss;
57      h IS_A heat_transfer_coefficient;      h IS_A heat_transfer_coefficient;
58      D_1, D_2 ARE_THE_SAME;      D_1, D_2 ARE_THE_SAME;
59            
60        (* heat loss is positive if T_1 > T_2 *)
61      q = h * 1{PI} * D_1 * (T_1 - T_2);      q = h * 1{PI} * D_1 * (T_1 - T_2);
62    
63  END convection_boundary;  END convection_boundary;
64    
65    (**
66        This modes a thick pipe with internal flow, surrounded by 100mm of
67        insulation and a thin external metal shell. In other words, a fairly
68        typical lagged high-temperature pipe as used in power and chemical plant
69        applications.
70    
71        Solve the model, then examine the values of T_1 and T_2 for each layer.
72    
73        @TODO add ability to plot the temperature versus radial distance...
74    *)
75  MODEL pipe_test REFINES radial_loss;  MODEL pipe_test REFINES radial_loss;
76    
77      n IS_A integer_constant;      n IS_A integer_constant;
78      n:==5;      n:==5;
79    
80        U IS_A heat_transfer_coefficient;
81        q = U * (1{PI} * D_1) * (loss[1].T_2 - T_2);
82        
83      loss[1..5] IS_A radial_loss;      loss[1..5] IS_A radial_loss;
84    
85      loss[1] IS_REFINED_TO convection_boundary;      loss[1] IS_REFINED_TO convection_boundary;
# Line 122  METHOD values; Line 136  METHOD values;
136      loss[4].k := 240 {W/m/K}; (* aluminium, Ashby & Jones, Eng Matls 2, p.11 *)      loss[4].k := 240 {W/m/K}; (* aluminium, Ashby & Jones, Eng Matls 2, p.11 *)
137      loss[5].h := 50 {W/m^2/K};      loss[5].h := 50 {W/m^2/K};
138            
139      loss[1].D_1 := 0.05 {m}; (* pipe interior *)      loss[2].D_1 := 0.05 {m}; (* pipe interior *)
140      loss[1].D_2 := 0.07 {m}; (* pipe exterior *)      loss[2].D_2 := 0.07 {m}; (* pipe exterior *)
141      loss[4].D_1 := 0.17 {m}; (* cover interior *)      loss[4].D_1 := 0.17 {m}; (* cover interior *)
142      loss[4].D_2 := 0.19 {m}; (* cover exterior *)      loss[4].D_2 := 0.19 {m}; (* cover exterior *)
143  END values;  END values;
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john.pye@anu.edu.au
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