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Revision 292 - (show annotations) (download) (as text)
Fri Feb 10 04:19:11 2006 UTC (14 years, 8 months ago) by johnpye
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Simple absorber loop that kinda converges
1 REQUIRE "johnpye/iapws95.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 iapws95_2phase; (* 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 FIX V_total, mdot_water_in, Q, T;
71 END specify;
72 METHOD values;
73 V_total := 300{m} * 16 * 1{PI}*( 40{mm} )^2;
74 mdot_water_in := 0.4 {kg/s};
75 Q := 800 {W/m^2} * 27(*concentration*) * 500{mm} * 60{m};
76 T := 500 {K};
77 (* free vars *)
78 END values;
79
80 END absorber;

john.pye@anu.edu.au
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