/[ascend]/trunk/models/solar/trough_receiver.a4c
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revision 2624 by jpye, Tue May 15 23:02:57 2012 UTC revision 2625 by jpye, Tue May 15 23:49:15 2012 UTC
# Line 4  REQUIRE "atoms.a4l"; Line 4  REQUIRE "atoms.a4l";
4  MODEL receiver_loss_base;  MODEL receiver_loss_base;
5  END receiver_loss_base;  END receiver_loss_base;
6    
7    
8  (*  (*
9      Loss parameters for the Luz evacuated tube receiver as provided in      Loss parameters for the Luz evacuated tube receiver as provided in
10      Patnode thesis.      Patnode thesis.
# Line 19  MODEL luz_loss_parameters( Line 20  MODEL luz_loss_parameters(
20          (* an intact HCE, evacuated air at 0.0001 Torr *)          (* an intact HCE, evacuated air at 0.0001 Torr *)
21          a[0] :== -9.463033e+00 {W/m^2};          a[0] :== -9.463033e+00 {W/m^2};
22          a[1] :==  3.029616e-01 {W/m^2/K};          a[1] :==  3.029616e-01 {W/m^2/K};
23          a[2] :==  -1.38633e-03 {W/m^2/K^2};          a[2] :== -1.386833e-03 {W/m^2/K^2};
24          a[3] :==  6.929243e-06 {W/m^2/K^3};          a[3] :==  6.929243e-06 {W/m^2/K^3};
25          b[0] :==  7.649610e-02 {m};          b[0] :==  7.649610e-02 {m};
26          b[1] :==  1.128818e-07 {m/K^2};          b[1] :==  1.128818e-07 {m/K^2};
# Line 65  MODEL receiver_loss_local( Line 66  MODEL receiver_loss_local(
66      Qd_loss = a[0] + a[1]*T + a[2]*T^2 + a[3]*T^3+ DNI*(b[0] + b[1]*T^2);      Qd_loss = a[0] + a[1]*T + a[2]*T^2 + a[3]*T^3+ DNI*(b[0] + b[1]*T^2);
67  END receiver_loss_local;  END receiver_loss_local;
68    
69        
70  (*  (*
71      Receiver (HCE) heat loss calculated by integration along a length of tube,      Receiver (HCE) heat loss calculated by integration along a length of tube,
72      as function of inlet and outlet temperature, plus DNI.      as function of inlet and outlet temperature, plus DNI.
# Line 86  MODEL receiver_loss_integ( Line 87  MODEL receiver_loss_integ(
87      T_o = T_o_K - 273.15 {K};      T_o = T_o_K - 273.15 {K};
88    
89      (* heat loss calculated as integral wrt temperature, Patnode eq 2.18. *)      (* heat loss calculated as integral wrt temperature, Patnode eq 2.18. *)
90      Qd_loss IS_A power_per_length;        Qd_loss IS_A power_per_length;
91      Qd_loss * (T_o - T_i) = SUM[a[i]/(i+1)*(T_o^(i+1) - T_i^(i+1)) | i IN [0..3]] + DNI * (b[0]*(T_o - T_i) + b[1]/3.*(T_o^3 - T_i^3));      Qd_loss = SUM[a[i]/(i+1)*(T_o^(i+1) - T_i^(i+1))/(T_o - T_i) | i IN [0..3]] + DNI * (b[0]) + b[1]/3.*(T_o^3 - T_i^3)/(T_o - T_i);
92    
93        (* NOTE the above form seems to avoid Qd_loss converging to zero and T_o --> T_i *)
94      (* NOTE above eq assumes linear temperature rise with position? is that suff valid? *)      (* NOTE above eq assumes linear temperature rise with position? is that suff valid? *)
95      (* NOTE above eq assumes ambient temperature of 25 C (Patnode sect 2.3.2) -- should adjust for changes in T_amb?? *)      (* NOTE above eq assumes ambient temperature of 25 C (Patnode sect 2.3.2) -- should adjust for changes in T_amb?? *)
96      (* NOTE also the equation in Lippke 1995 for bare tubes, which has a different form and requires wind speed *)      (* NOTE also the equation in Lippke 1995 for bare tubes, which has a different form and requires wind speed *)

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john.pye@anu.edu.au
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