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Annotation of /trunk/models/johnpye/absorber.a4c

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Revision 327 - (hide annotations) (download) (as text)
Fri Feb 24 02:04:49 2006 UTC (14 years, 8 months ago) by johnpye
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Adding some labels to equations in iapws95.a4c file
Adding some scaling commands, but still to no avail.
1 johnpye 265 REQUIRE "johnpye/iapws95.a4c";
2 johnpye 217 REQUIRE "johnpye/iapws_sat_curves.a4c";
3    
4 johnpye 320
5 johnpye 217 MODEL absorber;
6     (* assumptions:
7     outlet is saturated steam
8     inlet is saturated water at the specified pressure
9     no pressure drop
10     no temperature change
11     all Q is absorbed by water
12     steam generation is constant along length as mass rate, so x rises linearly.
13     *)
14 johnpye 265 S_out IS_A iapws95_2phase; (* outlet steam state *)
15 johnpye 217 sat IS_A iapws_sat_density;
16     T ALIASES S_out.T;
17     T,sat.T ARE_THE_SAME;
18     rho_gas ALIASES S_out.rho;
19     rho_gas, sat.rhog ARE_THE_SAME;
20    
21     p ALIASES S_out.p;
22    
23     mdot_water_in IS_A mass_rate;
24     mdot_water_out IS_A mass_rate;
25     mdot_gas_out IS_A mass_rate;
26     Vdot_gas_out IS_A volume_rate;
27 johnpye 327 mdot_out ALIASES mdot_water_in;
28 johnpye 217
29     m_water IS_A mass;
30     m_gas IS_A mass;
31    
32     Q IS_A energy_rate; (* heat absorbed *)
33    
34     (* assume saturated water at inlet, so any heat added immediately creates some steam *)
35     Hdot_in IS_A energy_rate;
36     Hdot_out IS_A energy_rate;
37     h_water IS_A specific_enthalpy;
38     z01: h_water = 400 {kJ/kg} + p / (1000 {kg/m^3});
39    
40     z02: Hdot_in = mdot_water_in * h_water;
41     z03: Hdot_out = mdot_water_out * h_water + mdot_gas_out * S_out.h;
42    
43     (* 1st law thermo *)
44     z04: Q = Hdot_out - Hdot_in;
45    
46     (* mass conservation *)
47     z05: mdot_water_in = mdot_water_out + mdot_gas_out;
48    
49     x_exit IS_A fraction;
50     z06: x_exit * mdot_water_in = mdot_gas_out;
51    
52     (* assume that steam evolves linearly along length, so average x allow mass of water to be calculated *)
53     x IS_A fraction;
54     z07: x = (0 + x_exit)/2;
55    
56     (* assuming a slip-ratio of 1, we can get the average void ratio, eq 2.13 from Behnia *)
57     alpha IS_A fraction;
58     z08: alpha * S_out.rho * (1-x) = 1000{kg/m^3} * x * (1-alpha);
59    
60     z09: m_water = 1000{kg/m^3} * (1-alpha)*V_total;
61     z10: m_gas = S_out.rho * alpha*V_total;
62    
63     z11: Vdot_gas_out = mdot_gas_out / rho_gas;
64     V_total IS_A volume;
65    
66     METHODS
67     METHOD default_self;
68     RUN reset;
69     RUN values;
70     END default_self;
71     METHOD specify;
72 johnpye 292 FIX V_total, mdot_water_in, Q, T;
73 johnpye 217 END specify;
74     METHOD values;
75     V_total := 300{m} * 16 * 1{PI}*( 40{mm} )^2;
76     mdot_water_in := 0.4 {kg/s};
77 johnpye 292 Q := 800 {W/m^2} * 27(*concentration*) * 500{mm} * 60{m};
78     T := 500 {K};
79     (* free vars *)
80 johnpye 217 END values;
81    
82     END absorber;
83 johnpye 320
84    
85     (*
86     This model seems completely correct but it won't converge.
87     It's a problem with the S_out converging from defined (p,h).
88    
89     Need to investivate
90     *)
91     MODEL absorber2;
92     S_in IS_A iapws95_2phase;
93     S_out IS_A iapws95_2phase;
94     mdot_in IS_A mass_rate;
95     mdot_out IS_A mass_rate;
96     Q IS_A energy_rate;
97     m_water IS_A mass;
98     V_total IS_A volume;
99    
100     H_in IS_A energy_rate;
101     H_in = mdot_in*S_in.h;
102     H_out IS_A energy_rate;
103     H_out = mdot_out*S_out.h;
104    
105     Q = H_out - H_in;
106    
107     mdot_out = mdot_in;
108     S_out.p = S_in.p;
109    
110     x_avg IS_A fraction;
111     alpha IS_A fraction;
112     x_avg = (S_in.x + S_out.x) / 2;
113     alpha * S_out.rho * (1-x_avg) = 1000{kg/m^3} * x_avg * (1-alpha);
114    
115     m_water = S_in.rhol * (1-alpha) * V_total;
116    
117     METHODS
118     METHOD default_self;
119     RUN reset; RUN values;
120     RUN scale_self;
121     END default_self;
122    
123     METHOD scale_self;
124     S_out.Sl.rho.nominal := 800 {kg/m^3};
125     END scale_self;
126    
127     METHOD specify;
128     FIX V_total, Q;
129     FIX mdot_in, S_in.T, S_in.rho;
130     END specify;
131    
132     METHOD values;
133     V_total := 300{m} * 16 * 1{PI}*( 40{mm} )^2;
134     mdot_in := 0.4 {kg/s};
135     Q := 800 {W/m^2} * 27(*concentration*) * 500{mm} * 60{m};
136     S_in.T := 175 {K} + 273.15 {K};
137     S_in.rho := 892 {kg/m^3};
138    
139     (* free *)
140     S_out.T := S_in.T;
141     S_out.rho := S_in.rho;
142     END values;
143    
144     END absorber2;

john.pye@anu.edu.au
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