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 |
|
|
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; |
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; |