- Chemkin-II input
MIYOSHI Group, Univ. Tokyo
MIYOSHI Group, Univ. Tokyo
This document describes the format of the chemkin-II input files.
!----------------------------------------------------------------------- ! 'exmHCO01.inp' ! C-H-O system machanism based on ... !----------------------------------------------------------------------- ELEMENTS H C N O END !----------------------------------------------------------------------- SPECIES H2 H O2 O OH HO2 H2O2 H2O N2 CH3 CH4 ...(snip)... END !----------------------------------------------------------------------- THERMO CH3 121286C 1H 3 G 0300.00 5000.00 1000.00 1 0.02844051E+02 0.06137974E-01-0.02230345E-04 0.03785161E-08-0.02452159E-12 2 0.16437809E+05 0.05452697E+02 0.02430442E+02 0.11124099E-01-0.01680220E-03 3 0.16218288E-07-0.05864952E-10 0.16423781E+05 0.06789794E+02 4 END !----------------------------------------------------------------------- REACTIONS KJOULES/MOLE MOLECULES H + CH3 (+M) = CH4 (+M) 3.50E-10 0. 0. !94CEC (300-1000K) LOW /1.726E-24 -1.8 0./ ! for M=Ar TROE /0.63 61. 3315./ ...(snip)... END !-----------------------------------------------------------------------
ELEMENTS H O AR CL ENDexample-2
ELEMENTS H O C N HE END
reac1 + reac2 + reac3 = prod1 + prod1 + prod3The number of the reactants or the products must be no less than one and no more than three. The name of the reactant or product must be identical with the one declared in the Species Block except for the following exceptions.
2OH = H2O2
H + H + M = H2 + MDetails of the reactions with third-body will be given below.
=>Indicates an irreversible reaction, that is, only the forward reaction is considered.
= or <=>Indicates an reversible reaction. The rate constant for the reverse reaction is calculated from the thermodynamic data unless it is specified by using REV keyword.
A + B = C A + B => CRate constant is considered to be independent of pressure.
A + B + M = C + M A + B + M => C + MRate constant is assumed to be in low-pressure limiting region.
A + B (+ M) = C (+ M) A + B (+ M) => C (+ M)Rate constant is in the fall-off region. Auxiliary input is required to specify the formula for the pressure dependence.
A + B (+ M) = C (+ M) 2.3E14 0.0 156.2 LOW/ 6.3E27 -2.6 -54.3 /
A + B (+ M) = C (+ M) 2.3E14 0.0 156.2 LOW/ 6.3E27 -2.6 -54.3 / TROE/ 0.604 6980. 132. /In general, the rate parameters for the low-pressure limit or the low-pressure part of the fall-off region depends largely on the buffer gas. This effect can be specified as an enhancement factor. Here is an example.
A + B + M = C + M 6.3E27 -2.6 -54.3 CO/1.9/ H2/1.7/ CO2/3./ H2O/5./In this example, the low-pressure limiting rate constant is multiplied by 1.9, 1.7, 3., and 5. for CO, H2, CO2, and H2O, respectively. Similar input can be added for the fall-off reactions.
C3H6=C2H3+CH3 5.986E+30 -3.9888 107791. ! HPL PLOG / 0.1 3.075E+69 -15.9470 123807. / ! rrkm2014 PLOG / 1. 1.898E+71 -16.0387 128780. / PLOG / 10. 1.863E+69 -15.1393 131253. / PLOG / 100. 7.007E+61 -12.8256 128945. /
SENS CONP PRES 1.0 TEMP 1000. TIME 2.E-4 DELT 1.E-4 REAC H2 2 REAC O2 1 REAC N2 4 ENDPlace one keyword per line. Lines beginning with '.' (period), '/' (slash), or '!' (exclamation mark) are skipped as comments. Place 'END' indicating the end of input in the last line. Space character cannot be inserted at the beginning of a line.
|CONP||CONstant Pressure & adiabatic|
|CONV||CONstant Volume & adiabatic|
|CONT||CONstant Temperature & constant pressure|
|ICEN||Internal Combustion ENgine (zero-dimensional) – Adiabatic compression and expansion with a constant speed crank-piston mechanism.|
|CGME||Core Gas Model Extention – Core gas model calculation for a rapid compression machine.|
|PRGV*||PRoGrammed Volume & adiabatic|
|VTIM#||Volume as a function of TIMe & adiabatic|
|PRGT*||PRoGrammed Temperature & constant pressure|
|TTIM#||Temperature as a function of TIMe & constant pressure|
|TEMP||Initial temperature [K]|
|PRES||Initial pressure [atm]|
|REAC||Name of the reactant and moles.
May present as many as needed. The name must be registered in the Species Block of chem.inp. The mole fractions will be normalized in senkin.
|TIME||Final time [s] for integration|
|DELT||Time interval [s] for the console and tign.out output.
In save.bin, irrespective of this parameter, results for all integration steps are stored.
The initial condition will be read from the rest.bin. The keywords TEMP, PRES, and REAC are no longer necessary and are ignored if present.
|TRES||Initial time [s] for restart
Usually, the initial time for restart is read from the rest.bin. This may be changed by the 'TRES' keyword.
|ATOL||Absolute tolerance of variables.
It should be noted that the mass fraction of chemical species is integrated in the senkin. Default is 1E-20.
|RTOL||Relative tolerance of variables. (Default : 1E-8)|
|Absolute and relative tolerance of sensitivity coefficients, respectively. (Default : 1E-5)|
|TLIM||Ignition criterial temperature (Default : initial temperautre + DTLM [see below])|
|DTLM||Ignition criterial temperature increment (Default : 400 K)|
ICEN, etc.). The thremodynamics of the mixing process is calculated according to the problem selected. That is, for the volume-specified problems (
VTIM), the internal energy conservation is assumed, while the enthalpy conservation is assumed for the pressure-specified problem (
CONP). For the temperature-specified problems (
TTIM), isothermic mixing is assumed.
|INJL tinj τ φ finj||INJection of Liquid
Inject liquid to reacting gas to simulate the local gas behavior during the spray combustion. The temperature and the composition of the gas are calculated by assuming prompt vaporization of the liquid, according to the problem selected. With this keyword, the time to start the injection (tinj [s]), period (τ [s]), amount of fuel injected in terms of equivalence ratio (φ),function form of the temporal injection rate profile ( finj ) must be specified. The names of the liquid species, corresponding vapor species, and the mole fraction must be specified with the LIQU option described below. The temperature of the liquid can be specified with TLIQ option. Multiple injections can be simulated with multiple INJL option lines. The temporal injection rate profile should be one of the following three. (k = τ −1)example:
REC (RECtangular) : f = k [0, τ)
EXP (EXPonential) : f = k e−k t [0, ∞)
RND (Rise aNd Decay) : f = k 2 t e−k t [0, ∞)
INJL 1e-3 2e-5 0.2 EXP INJL 3e-3 2e-5 0.2 RND
|LIQU Nliq Nvap xm||LIQUid composition
Specify the chemical species name of the liquid component (Nliq) injected by INJL, the species name of the corresponding vapor (Nvap), and the mole fraction of the component (xm). Both species should be declared in theexample-1:
! PRF90 mixture LIQU iC8H18(L) iC8H18 0.888729 LIQU nC7H16(L) nC7H16 0.111271example-2:
! n-heptane LIQU nC7H16(L) nC7H16 1
|TLIQ Tliq||Temperature of LIQuid
Specify the temperature of the liquid (Tliq [K]) injcted by INJL. The default value is 323.15 K when this option is missing.example:
! 50 degree-C TLIQ 323.15
|MIXG tst τ y fmx Nf||MIX Gas
Adiabatically mix a gas mixture with arbitrary composition and temperature. The time to start mixing (tst [s]), period (τ [s]), mass fraction to mix (y), time-function form (fmx), and the name of a senkin binary (restart) file (Nf) must be specified. The information of the gas to be mixed should be prepared in a senkin binary (restart) file. By using multiple MIXG option lines, same or different gas mixture(s) can be mixed multiple times. The function form of the temporal mixing rate fmx can be selected from REC, EXP, and RND similarly to the injection rate function finj in INJL described above. The senkin binary (restart) files can be generated by tools such as sbrest, sbdump, sbgen, sbmod, sbhmix, etc. (See Programs overview for details.)example:
MIXG 2e-3 2e-5 0.1 REC unburntgas.bin MIXG 5e-3 5e-5 0.1 REC burntgas.bin
|CMPR K||Compression Ratio
Ratio of the maximum cylinder volume to minimum volume. Default is 18.4
|RPM N||Rotation speed [rpm] (Default : 1500)|
|LOLR R||Ratio of connecting rod length to crank radius (Default : 3)|
|VOLC Vc||Clearance volume [cm3]
Cylinder volume at the TDC (top dead center). When no heat loss is considered, this value does not affect the calculation essentially, except for the output of the total mass. (Default : 100 cm3)
|DEG0 θ0||Initial crank angle [Unit: degree / TDC = 0] (Default : 180°)|
|ICHT a m n B Tw||Heat loss parameters
Give the coefficients for the relation of Nusselt number with the Reynolds and Prandtl numbers,
Nu = a Re m Pr n
cylinder bore, B [cm], and cylinder wall temperature, Tw [K]. It should be noted that the cylinder surface area is calculate by using Vc.
|CCVF c1 k1 c2 k2 c3 k3||
Parameters for the volume change after the compression
(Core-Gas Model Coefficients for Volume Function)
The virtual volume change after compression by core gas model is approximated by the following empirical equation.
Note that only the relative change of volume is needed and the last term can always be given as unity. The unit of ki is s−1. When the following CCVC option is NOT specified, the calculation starts from the temperature and pressure of the compressed gas specified by TEMP and PRES.
|CCVC t1 V1 t2 V2 t3 V3 t4 V4||
Parameters for the volume change during the compression
(Core-Gas Model Coefficients for Volume Change during Compression)
The virtual volume change during the compression by core gas model is approximated by the following empirical equations.
The parameters for the valume change after the compression (c1 ~ c3, k1 ~ k3) are also used, and should also be specified by the CCVF option.
In these equations, the volume is the core-gas model volume divided by the initial volume before compression. It should be unity (1) at time = 0. The unit of the time t is s [second]. When this option is specified, the initial temperature (TEMP) and pressure (PRES) should be those before the compression.
The profile of the volume change specified by the CCVC and CCVF options is shown in the figure to the right. CCVC option specifies (ti, Vi) pairs at the switching points of the function forms. The time = 0 should be defined so that the V−1 in the first part can be well approximated by a quadratic. In the second and third parts, V and V−1 are approximated by straight lines, respectively. In the fourth part, V−1 is quadratic. After t4, V−1 is approximated by the decay function specified by CCVF.
|VPNT t V||Volume Point
Gives the volume V [cm3] at the time t [s]. The volume profile can be specified by using multiple 'VPNT' options. With PRGV extension, the volume between points are given by linear interpolation. The volume at time = 0 is always one (1) [cm3]. Note that the only relative volume is important for volume change problem. The time t of this option cannot be 0 or negative.
|TPNT t T||Temperature Point
Gives the temperature T [K] at the time t [s]. The temperature profile can be specified by using multiple 'TPNT' options. With PRGT extension, the temperatures between points are given by linear interpolation. The temperature at time = 0 is always the temperature specified by the 'TEMP' keyword. Therefore, the time t of this option cannot be 0 or negative.
===== sb2c (sbin2csv.f) Control file ===== [ TIME OUTPUT CONTROL: (s ms us) atol=# rtol=# mind=# maxd=# sent=# ] us mind=1e-6 maxd=1e-5 atol=1e-15 rtol=.05 [ CONC OUTPUT CONTROL: all selonly none molecules/cc molefrac ] molecules/cc selonly H O OH HO2 H2 O2 [ SENS OUTPUT CONTROL: all none (or species name list) ] H O TEMPIn three blocks (TIME OUTPUT CONTROL, CONC OUTPUT CONTROL, SENS OUTPUT CONTROL), specify the control parameters. The first line and the lines beginning with '[' are comment lines and may be modified, but should not be deleted. Though the keywords are case insensitive, the species names are case sensitive.
The species with mole fractions less than
The output is done when the relative change of the any of the variable exceeds
(Unit: seconds) Irrespective of
(Unit: seconds) Irrespective of
|sent||Time for sensitivity output
(Unit: seconds) Sensitivity output is generated for the all time points that satisfy the other output control options without this option. When this option is specified, the sensitivity output is generated only for the specified time point.
|none||none (output is generated for temperature and pressure)|
|selonly||selected species only|
|all||all the species|
selonlyis specified in the first line. List the name of species delimied by spaces in the second line. In the example above, concentrations of only H, O, OH, HO2, H2, and O2 are output in molecules cm−3 unit.
allas below, or list the variable names delimited by spaces. Variable names are the speceis names or 'TEMP' (temperature). In the example above, sensitivity coefficients are output for the species H and O, and temperature. Though this input is meaningful only when the 'SENS' is specified in senk.inp, but should never be deleted in other cases. (leave 'none', for example.)
|all||output for all the variables|
===== rxnc (rxncntrb.f) Control Input File ===== [ (Time points to be investigated in s) time1, time2, ... ] 2.5e-4 1.78e-4 5e-5 1.e-6 [ (species to be investigated) name1, name2, ... ] H O HO2 [ options (atol, min%, top#, sbin, ocsv) ] atol=1e-20 min%=0.1 sbin=save.binThe third, fifth, and seventh lines specifies the time, species, and option, respectively. In the time specification, the time to be analyzed is specified in the unit of seconds. Multiple values are allowed. In the species line, the names of the chemical species must be listed.
|sbin=file name||specifies the file name of the senkin binary to be read. Default is save.bin.|
|top#=n (integer)||List the top n reactions with highest contribution.|
|min%=r (real)||List the reactions with the contribution no less than r %.|
|atol=ATOL||Input the same number as in the senkin input. Default is the default adopted by senkin, that is, 1E-20.|
|ocsv||When this option is specified, the contribution output is also generated in the .csv files.|
AR 120186AR 1 G 0300.00 5000.00 1000.00 1 0.02500000E+02 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 2 -0.07453750E+04 0.04366000E+02 0.02500000E+02 0.00000000E+00 0.00000000E+00 3 0.00000000E+00 0.00000000E+00-0.07453750E+04 0.04366000E+02 4