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Moist Air Properties (MA)

R2026b

Global moist air properties for attached circuit

  • Moist Air Properties (MA) block

Libraries:
Simscape / Foundation Library / Moist Air / Utilities

Description

The Moist Air Properties (MA) block defines the moist air properties that act as global parameters for all the blocks connected to a circuit. The moist air mixture is composed of dry air, water vapor, and optional trace gas or water droplets. The default trace gas is carbon dioxide.

Dry air, water vapor, and trace gas are assumed to be semiperfect gas. Pressure, temperature, and density obey the ideal gas law. Other properties are functions of temperature. You specify them as one-dimensional arrays corresponding to the Temperature vector.

Each topologically distinct moist air circuit in a diagram can have a Moist Air Properties (MA) block connected to it. If no Moist Air Properties (MA) block is attached to a circuit, the blocks in this circuit use the properties corresponding to the default Moist Air Properties (MA) block parameter values.

The default values for the block parameters and lookup tables are based on the REFPROP database, developed by NIST (https://www.nist.gov/srd/refprop).

Examples

Ports

Conserving

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Conserving port that connects the block to the moist air network. You can connect it to any point on a moist air connection line in a block diagram. When you connect the Moist Air Properties (MA) block to a connection line, the software automatically identifies the moist air blocks connected to the particular circuit and propagates the properties to all these blocks.

Programmatic Use

Port: A

Parameters

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Dry Air

Universal gas constant divided by molar mass of dry air.

Programmatic Use

Parameter: R_a

Vector of temperature values, to be used for table lookup of other properties as a function of temperature. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [-56.55, -50 : 10 : -10, -5 : 1 : 5, 10 : 10 : 350]' degC.

Programmatic Use

Parameter: T_TLU

The vector of specific enthalpy values of dry air, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size.

The default value is [342.416126230579; 349.005511058471; 359.063577249119; 369.119948684177; 379.175469465129; 389.230944678417; 394.258910928084; 395.264534937366; 396.27017101329; 397.275819932805; 398.281482472874; 399.287159410541; 400.292851523015; 401.298559587728; 402.304284382408; 403.310026685143; 404.315787274435; 409.34489180313; 419.404921755863; 429.468036401264; 439.535033154839; 449.606720928652; 459.683919949603; 469.767460521911; 479.858181001348; 489.956925196484; 500.064539372946; 510.181869006204; 520.309755403634; 530.449032296018; 540.60052248087; 550.765034584465; 560.943359995745; 571.136270013102; 581.344513234296; 591.568813210327; 601.809866375885; 612.068340261954; 622.344871990218; 632.640067043998; 642.95449830646; 653.288705353699; 663.643193987949; 674.018435994423; 684.414869104228; 694.832897145098; 705.272890361557; 715.735185886199; 726.220088344236; 736.727870574087; 747.258774447567; 757.813011774199] kJ/kg.

Programmatic Use

Parameter: h_a_TLU

The vector of dynamic viscosity values of dry air, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size.

The default value is [14.2568883320012; 14.6140127728333; 15.1517277055779; 15.6806860159119; 16.2012351072083; 16.7137043125028; 16.9670071730589; 17.017438062815; 17.0677930842452; 17.1180725309876; 17.1682766951315; 17.2184058672268; 17.2684603362935; 17.3184403898301; 17.3683463138234; 17.4181783927569; 17.4679369096204; 17.7156358640698; 18.2056751785154; 18.68879035749; 19.1652344664982; 19.6352478927873; 20.099059103658; 20.5568853601578; 21.0089333871663; 21.4554000014051; 21.8964726992323; 22.3323302062775; 22.7631429910631; 23.1890737447833; 23.6102778293792; 24.0269036959922; 24.4390932757886; 24.8469823450548; 25.2507008663546; 25.6503733074314; 26.0461189394339; 26.4380521159325; 26.8262825340948; 27.2109154792923; 27.5920520543128; 27.969789394274; 28.3442208682439; 28.7154362685068; 29.0835219883356; 29.4485611890712; 29.8106339572472; 30.1698174524429; 30.5261860464955; 30.8798114546565; 31.2307628592324; 31.5791070262086] s*μPa.

Programmatic Use

Parameter: mu_a_TLU

The vector of thermal conductivity values of dry air, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size.

The default value is [19.8808489374933; 20.4162454629695; 21.2248743590758; 22.0232452890903; 22.8117314495857; 23.5906913619588; 23.9767075412237; 24.053639990175; 24.1304826682191; 24.2072359051629; 24.2839000294007; 24.3604753679152; 24.4369622462801; 24.5133609886625; 24.5896719178249; 24.6658953551279; 24.7420316205333; 25.1214164701832; 25.8738283029331; 26.6180150229276; 27.3542674377332; 28.0828634735341; 28.8040686837224; 29.5181367785657; 30.2253101618423; 30.9258204644224; 31.6198890677835; 32.3077276126633; 32.9895384896798; 33.6655153099498; 34.33584335461; 35.0007000027879; 35.6602551380254; 36.3146715334901; 36.9641052165342; 37.6087058133173; 38.248616874307; 38.8839761815308; 39.5149160384798; 40.1415635435708; 40.7640408480637; 41.3824653993118; 41.9969501701893; 42.6076038755117; 43.2145311762238; 43.8178328720941; 44.4176060836121; 45.013944423749; 45.6069381602018; 46.1966743687041; 46.783237077953; 47.3667074066625] mW/m/K.

Programmatic Use

Parameter: k_a_TLU

Lowest pressure allowed in the moist air network. The simulation issues an error when pressure is out of range.

Programmatic Use

Parameter: p_min

Highest pressure allowed in the moist air network. The simulation issues an error when pressure is out of range.

Programmatic Use

Parameter: p_max

Lowest temperature allowed in the moist air network. The simulation issues an error when temperature is out of range.

Programmatic Use

Parameter: T_min

Highest temperature allowed in the moist air network. The simulation issues an error when temperature is out of range.

Programmatic Use

Parameter: T_max

Select what happens if the moist air pressure or temperature go beyond the valid range during simulation:

  • None ― The block does not return an error if the properties go out of range.

  • Warning ― The block issues a warning, but continues the simulation.

  • Error ― The block returns an error and stops the simulation.

Programmatic Use

Parameter: properties_range_check
Values: "simscape.enum.assert.action.error" | "simscape.enum.assert.action.warn" | "simscape.enum.assert.action.none"

Absolute pressure of the environment.

Programmatic Use

Parameter: p_atm

Absolute temperature of the environment.

Programmatic Use

Parameter: T_atm

Water Vapor

Select whether the block models entrained water droplets in the moist air mixture. If you clear this checkbox, the model ignores any nonzero values for water droplets in the parameters and inputs of blocks connected to the network. The block equations listed on the block reference pages replace the water droplet terms in calculations with 0.

For more information on modeling water droplets, see Modeling Moisture and Trace Gas Levels.

Programmatic Use

Parameter: enable_droplets
Values: "true" | "false"

Universal gas constant divided by molar mass of water vapor.

Programmatic Use

Parameter: R_w

Vector of vapor saturation values for water as a function of temperature, to be used for one-dimensional table lookup. Moist air becomes saturated when the partial pressure of water vapor is equal to the water vapor saturation pressure. Therefore, condensation may occur. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [1.71168953425982e-06; 3.93770601979424e-06; 1.28411717710344e-05; 3.80051394873809e-05; .00010323902900209; .000259873810798063; .000401741022116384; .000437454836117844; .000476040820618202; .000517704666185737; .000562664883741207; .000611212677444345; .000657088049117899; .000705987905898279; .000758082381149132; .000813549384183233; .000872574861129522; .00122818386934022; .0023392147667769; .00424668834054807; .00738442748706953; .0123512704340234; .0199458019246787; .0312006356960619; .0474147199263783; .0701823607447713; .10141797792131; .143375967241115; .198665399739302; .270259606559999; .361500961984849; .476101381081492; .618139196722055; .792053183687694; 1.0026345688121; 1.25501792086105; 1.55467186826983; 1.90739066433297; 2.31928772772542; 2.79679245576864; 3.34665187151016; 3.97593907083533; 4.69207105435535; 5.5028394740883; 6.41645928168037; 7.4416425436169; 8.58770832955728; 9.86474556030261; 11.2838558865497; 12.8575218898034; 14.6001810568052; 16.5291642526045] MPa.

Programmatic Use

Parameter: p_ws_TLU

Vector of the difference between the specific enthalpy of saturated water vapor and the specific enthalpy of saturated liquid water as a function of temperature, to be used for one-dimensional table lookup. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [2836.88241275372; 2837.81392500514; 2838.63937175807; 2838.7309929628; 2838.06905313927; 2836.62597341095; 2835.60023952573; 2835.37006381376; 2835.13143158077; 2834.88429145066; 2834.62859062897; 2500.93420564316; 2498.55329907119; 2496.17495082036; 2493.79885912205; 2491.42474723191; 2489.05236104642; 2477.20875029194; 2453.54955988604; 2429.83856603313; 2406.00136954922; 2381.97406342174; 2357.69101156389; 2333.08088387814; 2308.06565480412; 2282.56034405021; 2256.47287422313; 2229.70428017508; 2202.14968030993; 2173.69998896199; 2144.24368406447; 2113.66758247452; 2081.85585110571; 2048.68725710494; 2014.03141249899; 1977.7449923284; 1939.66849592886; 1899.62342931686; 1857.40930169838; 1812.79975416601; 1765.53721731251; 1715.32525772152; 1661.81700477787; 1604.59703745016; 1543.1534616334; 1476.83692476464; 1404.80240352424; 1325.92091736114; 1238.61667822208; 1140.5102987018; 1027.62017777647; 892.733785613825] kJ/kg.

Programmatic Use

Parameter: h_w_vap_TLU

The vector of specific enthalpy values of water vapor, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [2396.55944251649; 2408.68643343608; 2427.1988031141; 2445.702165897; 2464.18429108356; 2482.62529466839; 2491.82135326629; 2493.6580151792; 2495.49372578218; 2497.32843835745; 2499.16210446923; 2500.99462758899; 2502.83092214066; 2504.6665223621; 2506.50140563013; 2508.335548891; 2510.16892865793; 2519.32352241995; 2537.56068088674; 2555.67742615292; 2573.6403223998; 2591.4109179101; 2608.9455037701; 2626.19492016262; 2643.10444358428; 2659.61377634497; 2675.58278696023; 2696.1846256545; 2716.49989553741; 2736.6235210957; 2756.61216047011; 2776.50561773853; 2796.33378922508; 2816.11979583049; 2835.88181423877; 2855.63430574511; 2875.38889327595; 2895.15500577172; 2914.94035964689; 2934.75132290228; 2954.59319330244; 2974.47041285505; 2994.38673458964; 3014.34535328009; 3034.34900867103; 3054.40006755764; 3074.50058946898; 3094.65237953784; 3114.85703128106; 3135.11596137801; 3155.43043805905; 3175.80160435813] kJ/kg.

Programmatic Use

Parameter: h_w_TLU

The vector of dynamic viscosity values of water vapor, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [6.81365662228272; 7.04953750742707; 7.40970098298307; 7.76991278093907; 8.13017290129507; 8.49048134405107; 8.67065368632907; 8.70668960445667; 8.74272600580827; 8.77876289038387; 8.81480025818347; 8.85083810920707; 8.88687644345467; 8.92291526092627; 8.95895456162187; 8.99499434554147; 9.03103461268507; 9.21124319676307; 9.57169660671907; 9.93219833907507; 10.2927483938311; 10.6533467709871; 11.0139934705431; 11.3746884924991; 11.7354318368551; 12.0962235036111; 12.4570634927671; 12.8179518043231; 13.1788884382791; 13.5398733946351; 13.9009066733911; 14.2619882745471; 14.6231181981031; 14.9842964440591; 15.3455230124151; 15.7067979031711; 16.0681211163271; 16.4294926518831; 16.7909125098391; 17.1523806901951; 17.5138971929511; 17.8754620181071; 18.2370751656631; 18.5987366356191; 18.9604464279751; 19.3222045427311; 19.6840109798871; 20.0458657394431; 20.4077688213991; 20.7697202257551; 21.1317199525111; 21.4937680016671] s*μPa.

Programmatic Use

Parameter: mu_w_TLU

The vector of thermal conductivity values of water vapor, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [11.46288215976; 11.941997488935; 12.676358586935; 13.414208884935; 14.155548382935; 14.900377080935; 15.274099879935; 15.348949115735; 15.423833243535; 15.498752263335; 15.573706175135; 15.648694978935; 15.723718674735; 15.798777262535; 15.873870742335; 15.948999114135; 16.024162377935; 16.400502076935; 17.155798374935; 17.914583872935; 18.676858570935; 19.442622468935; 20.211875566935; 20.984617864935; 21.760849362935; 22.540570060935; 23.323779958935; 24.110479056935; 24.900667354935; 25.694344852935; 26.491511550935; 27.292167448935; 28.096312546935; 28.903946844935; 29.715070342935; 30.529683040935; 31.347784938935; 32.169376036935; 32.994456334935; 33.823025832935; 34.655084530935; 35.490632428935; 36.329669526935; 37.172195824935; 38.018211322935; 38.867716020935; 39.720709918935; 40.577193016935; 41.437165314935; 42.300626812935; 43.167577510935; 44.038017408935] mW/m/K.

Programmatic Use

Parameter: k_w_TLU

Coefficient for the diffusive flux of water vapor in the moist air mixture due to the difference in concentration of water vapor. During mixture flow reversal, the water vapor mass flow rate at the ports smoothly transitions between the upstream and downstream value based on the diffusivity.

Programmatic Use

Parameter: D_w

Trace Gas

Select how the block models the amount of trace gas in the air mixture:

  • None — No trace gas is present. The moist air mixture consists of only dry air and water vapor. Any nonzero values of trace gas level in parameters and variable targets of the blocks connected to the circuit are ignored. All connections to the trace gas source blocks in the model are also ignored. Therefore, you do not need to modify your model based on the trace gas modeling selection.

  • Track mass fraction only — The trace gas level can be nonzero and vary during simulation. However, the amount of trace gas is assumed to be small enough to have a negligible impact on the fluid properties of the moist air mixture.

  • Track mass fraction and gas properties — The trace gas level can be nonzero and vary during simulation. The fluid properties of the moist air mixture depend on the amount of trace gas in the mixture.

For more information on the impact of these options on block and system equations, see Trace Gas Modeling Options.

Programmatic Use

Parameter: trace_gas_model
Values: "foundation.enum.trace_gas_model.none" | "foundation.enum.trace_gas_model.track_fraction" | "foundation.enum.trace_gas_model.track_properties"

Universal gas constant divided by molar mass of trace gas.

Dependencies

Enabled when the Trace gas model parameter is set to Track mass fraction only or Track mass fraction and gas properties.

Programmatic Use

Parameter: R_g

The vector of specific enthalpy values of trace gas, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [439.555216260064; 444.670268200251; 452.538618847003; 460.487124258496; 468.522588768941; 476.649415958793; 480.74798538725; 481.57054318762; 482.394052398751; 483.218514288831; 484.043930029015; 484.870300696555; 485.697627277859; 486.525910671489; 487.355151691079; 488.185351068185; 489.016509455051; 493.186704139431; 501.599194953048; 510.107689961685; 518.711611080182; 527.410026793075; 536.201764778798; 545.085474203452; 554.059675505208; 563.122805485367; 572.27325096919; 581.509373027928; 590.829525105886; 600.232066705818; 609.715373581392; 619.277845178105; 628.917909922924; 638.634028838794; 648.424697859328; 658.288449140109; 668.223851601449; 678.229510889093; 688.304068901113; 698.44620299875; 708.654624994591; 718.928079991818; 729.265345132425; 739.665228299475; 750.126566808087; 760.648226111439; 771.229098541268; 781.868102096908; 792.564179292476; 803.316296068366; 814.123440770426; 824.984623198037] kJ/kg.

Dependencies

Enabled when the Trace gas model parameter is set to Track mass fraction and gas properties.

Programmatic Use

Parameter: h_g_TLU

The vector of dynamic viscosity values of trace gas, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [10.8921054191698; 11.2215357085649; 11.7233300740382; 12.2234238147811; 12.7215124453467; 13.2173328890673; 13.4643203184773; 13.5136406274989; 13.562934752385; 13.6122025024997; 13.6614436900741; 13.7106581301692; 13.7598456406398; 13.8090060420983; 13.8581391578796; 13.9072448140062; 13.9563228391538; 14.2012926853717; 14.6890687376044; 15.1738428124161; 15.6554929043332; 16.1339159800463; 16.6090257998657; 17.0807510097148; 17.5490334645512; 18.0138267508952; 18.4750948814453; 18.9328111390399; 19.3869570507278; 19.8375214755778; 20.2844997922255; 20.7278931741254; 21.1677079421287; 21.6039549853963; 22.036649242835; 22.4658092382469; 22.8914566632375; 23.3136160026627; 23.7323141980278; 24.1475803447965; 24.5594454200432; 24.9679420372927; 25.3731042257492; 25.774967231431; 26.1735673380029; 26.5689417053362; 26.9611282240413; 27.350165384404; 27.73609215832; 28.118947892972; 28.4987722151178; 28.8756049449796] s*μPa.

Dependencies

Enabled when the Trace gas model parameter is set to Track mass fraction and gas properties.

Programmatic Use

Parameter: mu_g_TLU

The vector of thermal conductivity values of trace gas, to be used for one-dimensional table lookup based on the corresponding temperature value. The vector size must be the same as the temperature vector size. Dry air, water vapor, and trace gas properties share the same temperature vector.

The default value is [10.489430678843; 10.9507672150864; 11.666197960308; 12.392559739764; 13.1299519771612; 13.8778409888416; 14.2554325416312; 14.3312274189707; 14.4071122346908; 14.4830860227061; 14.5591478179508; 14.6352966574703; 14.7115315815553; 14.787851634907; 14.8642558678259; 14.9407433374142; 15.0173131087819; 15.401364480906; 16.1751373988038; 16.9558134611595; 17.7432208682398; 18.5366976599676; 19.3360988502003; 20.1412225692689; 20.9517507672929; 21.7672310558863; 22.5871115634685; 23.4107980865695; 24.2377021890869; 25.0672663781241; 25.8989689893876; 26.732318357514; 27.5668446164644; 28.4020933015927; 29.2376215872816; 30.0729965057542; 30.9077942826816; 31.7416001931033; 32.5740086297993; 33.4046232539953; 34.2330571812868; 35.0589331874899; 35.8818839295189; 36.701552179391; 37.5175910702657; 38.3296643536716; 39.1374466671854; 39.9406238119064; 40.7388930391313; 41.5319633456945; 42.3195557774861; 43.1014037407076] mW/m/K.

Dependencies

Enabled when the Trace gas model parameter is set to Track mass fraction and gas properties.

Programmatic Use

Parameter: k_g_TLU

Coefficient for the diffusive flux of trace gas in the moist air mixture due to the difference in concentration of trace gas. During mixture flow reversal, the trace gas mass flow rate at the ports smoothly transitions between the upstream and downstream value based on the diffusivity.

Dependencies

Enabled when the Trace gas model parameter is set to Track mass fraction only or Track mass fraction and gas properties.

Programmatic Use

Parameter: D_g

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2018a

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