models/johnpye/surgetank.a4c

REQUIRE "johnpye/ideal_steam.a4c";

(*
	Here is a fixed volume of gas confined in a volume.
	We can see that fixing the mass in the vessel then
	heating it up will increase the pressure.
*)
MODEL gas_vessel;
	S IS_A ideal_steam;
	T ALIASES S.T;
	p ALIASES S.p;
	rho ALIASES S.rho;
	h ALIASES S.h;
	m_gas IS_A mass;
	V_gas IS_A volume;

	m_gas = S.rho * V_gas;

METHODS
METHOD default_self;
	RUN reset; RUN values;
END default_self;
METHOD specify;
	FIX T;
	FIX p;
	FREE S.rho;
	FIX V_gas;
END specify;
METHOD values;
	T := 298 {K};
	p := 1 {bar};
	V_gas := 1 {m^3};
END values;
METHOD self_test;
	ASSERT abs(m_gas - 0.727101 {kg}) < 0.0001 {kg};
END self_test;
END gas_vessel;

(*
	This model adds a variable volume of water at the base
	of the tank, but makes the tank volume fixed. As a result
	Pumping water into the tank results in higher pressure
	for a given fixed mass of gas.
*)
MODEL vessel_with_water REFINES gas_vessel;
	m_water IS_A mass;
	V_water IS_A volume;
	V_vessel IS_A volume;
	V_water + V_gas = V_vessel;
	rho_water IS_A mass_density;
	m_water = rho_water * V_water; (* incompressible water *)
METHODS
METHOD default_self;
	RUN reset; RUN values;
END default_self;
METHOD specify;
	FIX rho_water;
	FIX T;
	FIX V_vessel;
	FIX m_gas;
	FIX m_water;
END specify;
METHOD values;
	T := 298 {K};
	rho_water := 1000 {kg/m^3};
	V_vessel := 12000 {L};
	m_gas := 7.27101 {kg};
	m_water := 2000 {kg};
END values;
METHOD self_test;
	ASSERT abs(p - 1 {bar}) < 10 {Pa};
END self_test;
	
END vessel_with_water;

(*
	Surge tank: add mass in and out streams. It will be assumed that the mass
	flow in balances the mass flow out, but there's got to be some effect
	of pressure...
*)

MODEL surgetank REFINES vessel_with_water;
	mdot_water_in IS_A mass_rate;
	mdot_water_out IS_A mass_rate;
	
	mdot_water_in = mdot_water_out;

METHODS
METHOD specify;
	RUN vessel_with_water::specify;
	FIX mdot_water_in;
END specify;

METHOD values;
	RUN vessel_with_water::values;
	mdot_water_in := 1.0 {kg/s};
END values;

METHOD default_self;
	RUN reset; RUN values;
END default_self;

END surgetank;
1	REQUIRE "johnpye/ideal_steam.a4c";
2
3	(*
4	Here is a fixed volume of gas confined in a volume.
5	We can see that fixing the mass in the vessel then
6	heating it up will increase the pressure.
7	*)
8	MODEL gas_vessel;
9	S IS_A ideal_steam;
10	T ALIASES S.T;
11	p ALIASES S.p;
12	rho ALIASES S.rho;
13	h ALIASES S.h;
14	m_gas IS_A mass;
15	V_gas IS_A volume;
16
17	m_gas = S.rho * V_gas;
18
19	METHODS
20	METHOD default_self;
21	RUN reset; RUN values;
22	END default_self;
23	METHOD specify;
24	FIX T;
25	FIX p;
26	FREE S.rho;
27	FIX V_gas;
28	END specify;
29	METHOD values;
30	T := 298 {K};
31	p := 1 {bar};
32	V_gas := 1 {m^3};
33	END values;
34	METHOD self_test;
35	ASSERT abs(m_gas - 0.727101 {kg}) < 0.0001 {kg};
36	END self_test;
37	END gas_vessel;
38
39	(*
40	This model adds a variable volume of water at the base
41	of the tank, but makes the tank volume fixed. As a result
42	Pumping water into the tank results in higher pressure
43	for a given fixed mass of gas.
44	*)
45	MODEL vessel_with_water REFINES gas_vessel;
46	m_water IS_A mass;
47	V_water IS_A volume;
48	V_vessel IS_A volume;
49	V_water + V_gas = V_vessel;
50	rho_water IS_A mass_density;
51	m_water = rho_water * V_water; (* incompressible water *)
52	METHODS
53	METHOD default_self;
54	RUN reset; RUN values;
55	END default_self;
56	METHOD specify;
57	FIX rho_water;
58	FIX T;
59	FIX V_vessel;
60	FIX m_gas;
61	FIX m_water;
62	END specify;
63	METHOD values;
64	T := 298 {K};
65	rho_water := 1000 {kg/m^3};
66	V_vessel := 12000 {L};
67	m_gas := 7.27101 {kg};
68	m_water := 2000 {kg};
69	END values;
70	METHOD self_test;
71	ASSERT abs(p - 1 {bar}) < 10 {Pa};
72	END self_test;
73
74	END vessel_with_water;
75
76	(*
77	Surge tank: add mass in and out streams. It will be assumed that the mass
78	flow in balances the mass flow out, but there's got to be some effect
79	of pressure...
80	*)
81
82	MODEL surgetank REFINES vessel_with_water;
83	mdot_water_in IS_A mass_rate;
84	mdot_water_out IS_A mass_rate;
85
86	mdot_water_in = mdot_water_out;
87
88	METHODS
89	METHOD specify;
90	RUN vessel_with_water::specify;
91	FIX mdot_water_in;
92	END specify;
93
94	METHOD values;
95	RUN vessel_with_water::values;
96	mdot_water_in := 1.0 {kg/s};
97	END values;
98
99	METHOD default_self;
100	RUN reset; RUN values;
101	END default_self;
102
103	END surgetank;