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Wed Jan 25 03:10:42 2006 UTC (14 years, 9 months ago) by johnpye
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Sort-of-working very simple circuit model
1 johnpye 217 REQUIRE "johnpye/ideal_steam.a4c";
2     REQUIRE "johnpye/iapws_sat_curves.a4c";
3    
4     MODEL absorber;
5     (* assumptions:
6     outlet is saturated steam
7     inlet is saturated water at the specified pressure
8     no pressure drop
9     no temperature change
10     all Q is absorbed by water
11     steam generation is constant along length as mass rate, so x rises linearly.
12     *)
13     S_out IS_A ideal_steam; (* outlet steam state *)
14     sat IS_A iapws_sat_density;
15     T ALIASES S_out.T;
16     T,sat.T ARE_THE_SAME;
17     rho_gas ALIASES S_out.rho;
18     rho_gas, sat.rhog ARE_THE_SAME;
19    
20     p ALIASES S_out.p;
21    
22     mdot_water_in IS_A mass_rate;
23     mdot_water_out IS_A mass_rate;
24     mdot_gas_out IS_A mass_rate;
25     Vdot_gas_out IS_A volume_rate;
26    
27     m_water IS_A mass;
28     m_gas IS_A mass;
29    
30     Q IS_A energy_rate; (* heat absorbed *)
31    
32     (* assume saturated water at inlet, so any heat added immediately creates some steam *)
33     Hdot_in IS_A energy_rate;
34     Hdot_out IS_A energy_rate;
35     h_water IS_A specific_enthalpy;
36     z01: h_water = 400 {kJ/kg} + p / (1000 {kg/m^3});
37    
38     z02: Hdot_in = mdot_water_in * h_water;
39     z03: Hdot_out = mdot_water_out * h_water + mdot_gas_out * S_out.h;
40    
41     (* 1st law thermo *)
42     z04: Q = Hdot_out - Hdot_in;
43    
44     (* mass conservation *)
45     z05: mdot_water_in = mdot_water_out + mdot_gas_out;
46    
47     x_exit IS_A fraction;
48     z06: x_exit * mdot_water_in = mdot_gas_out;
49    
50     (* assume that steam evolves linearly along length, so average x allow mass of water to be calculated *)
51     x IS_A fraction;
52     z07: x = (0 + x_exit)/2;
53    
54     (* assuming a slip-ratio of 1, we can get the average void ratio, eq 2.13 from Behnia *)
55     alpha IS_A fraction;
56     z08: alpha * S_out.rho * (1-x) = 1000{kg/m^3} * x * (1-alpha);
57    
58     z09: m_water = 1000{kg/m^3} * (1-alpha)*V_total;
59     z10: m_gas = S_out.rho * alpha*V_total;
60    
61     z11: Vdot_gas_out = mdot_gas_out / rho_gas;
62     V_total IS_A volume;
63    
64     METHODS
65     METHOD default_self;
66     RUN reset;
67     RUN values;
68     END default_self;
69     METHOD specify;
70     V_total.fixed := TRUE;
71     mdot_water_in.fixed := TRUE;
72     Q.fixed := TRUE;
73     p.fixed := TRUE;
74     END specify;
75     METHOD values;
76     V_total := 300{m} * 16 * 1{PI}*( 40{mm} )^2;
77     mdot_water_in := 0.4 {kg/s};
78     Q := 1000 {W/m^2} * 27(*concentration*) * 500{mm} * 60{m};
79     p := 5 {bar};
80     END values;
81    
82     END absorber;

john.pye@anu.edu.au
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