Reacting Flows에 대한 7월14일 Webinar 발표자료 입니다.
● Reacting Flows 웨비나 발표자료 | | ● Applications | • Applications
• IC engines
• Fuel synthesis and reforming
• Hot gas generators
• Flow batteries
• Catalytic beds and converters
• Ionized and dissociated gases
Including recombination within gas turbine stages
• Note:
- Intended for system-level energy/mass/species balance
- Most combustion and reactions occur at a single point (lump)
- Can’t model fuel sprays, detonations, nor details within an IC cylinder or combustion chamber | | ● CHGLMP vs. CHGLMP_MIX | • CHGLMP
- Can change one species fraction at a time via XGx
- In a binary mixture of A and B, if XGA = 0.7 …
- then XGB = 1.0-0.7 = 0.3
- In a ternary mixture of A, B, and C, if XGA = 0.7 …
•Then XGBnew = XGBold * 0.3 / (XGBold + XGCold)
and XGCnew = XGCold * 0.3 / (XGBold + XGCold)
• Such that XGBnew+ XGCnew = 0.3 ( = 1.0 - XGAnew)
- If more than 2 species are present, sequential CHGLMP calls just chase a moving target!
• To adjust multiple species simultaneously, use CHGLMP_MIX
- Can also change by mass or mole fraction
- Change by providing an array of target concentrations
• Unnamed species will be prorated, as is done above with CHGLMP
Usually just for boundary conditions (plena) or for initial conditions (tanks)
- Don’t fight with FLUINT by changing tank values during a solution! | | ● HFORM and HSTP: FPROP Data Preparations |
• HFORM: Heat of Formation per unit mass (J/kg or BTU/lbm), not per mole
- The enthalpy to form a substance and take it to standard temperature and pressure (STP: 25°C and 1 atm.)
- In whatever phase it is at STP
- Not the same as “Heat of Combustion!”
- That is a reaction-specific fuel characterization
- HFORM is a function only of the current substance
- Zero for pure substances in their natural state (e.g., O2)
- Must be input even if zero to use chemical reaction tools!
• HSTP: Enthalpy at standard Temp & Pressure
- Rare: just needed if:
- the phase is not correct at STP
- STP is outside of property limits, and extrapolation is not correct
- Example: 8000 or 6000 NEVERLIQ input, but this species is liquid at STP (where HFORM is defined)
- So the handbook value of HFORM isn’t appropriate
- But specifying a different HFORM might confuse a future user
- Basically, HSTP is just a correction to HFORM to improve self-documentation
• This data is built into library fluids, but may be missing from some CRTech-supplied FPROP blocks (whether F-files or R-files) | | ● K or k? |
• Big K: equilibrium constant
- Example: Kp = [P1]n1 [P2]n2 / [P3]n3 (ni are from reaction equation)
- Often expressed by molar concentration (Kc) instead of by partial pressures (Kp)
- These are not “constants” … they are very strong functions of temperature and pressure
- Feeds into the EQRATE utility, described later
- Only valid if the temperatures stay hot enough!
- Your reacting mixture may stray from equilibrium as it cools
• Little k: reaction rate “pre-exponential term”
- ki = Ai*e(-Bi/T)
- Can be difficult to find
- Units vary as a function of each reaction/reagent!
• Current reaction rates (ri) are often a function of both ki and Ki (a per-species equilibrium constant) 
- Feeds into the XMDOTx reaction rate per species x, described later | | ● XMDOT and QCHEM | • Define rate of species creation/destruction within a tank (“XMDOT”): a mass (vs. molar) source/sink term
- Example: “xmdotA100” is the rate of production of mass of species A in tank 100 (negative for consumption)
- Sum of XMDOTs for all species should be zero (or nearly so) within each tank: Σ(XMDOTi) = 0
- Multiple reactions can be modeled within each tank- Sum up XMDOT for each reaction, each species
- XMDOTs are not possible in junctions, and ignored in STEADY
• FLUINT calculates the net heat of reaction (“QCHEM”) and adds it to the tank’s QDOT
- QCHEM = - Σ { XMDOTi* (HFORMi - HSTPi) } | | ● 자세한 웨비나 발표자료 보기 | | pdf로 자세히 보기 |
기타 문의사항은 언제든지 당사로 연락 바랍니다.
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Reacting Flows에 대한 7월14일 Webinar 발표자료 입니다.
● Reacting Flows 웨비나 발표자료
• Applications
• IC engines
• Fuel synthesis and reforming
• Hot gas generators
• Flow batteries
• Catalytic beds and converters
• Ionized and dissociated gases
Including recombination within gas turbine stages
• Note:
- Intended for system-level energy/mass/species balance
- Most combustion and reactions occur at a single point (lump)
- Can’t model fuel sprays, detonations, nor details within an IC cylinder or combustion chamber
- Can change one species fraction at a time via XGx
- In a binary mixture of A and B, if XGA = 0.7 …
- then XGB = 1.0-0.7 = 0.3
- In a ternary mixture of A, B, and C, if XGA = 0.7 …
•Then XGBnew = XGBold * 0.3 / (XGBold + XGCold)
and XGCnew = XGCold * 0.3 / (XGBold + XGCold)
• Such that XGBnew+ XGCnew = 0.3 ( = 1.0 - XGAnew)
- If more than 2 species are present, sequential CHGLMP calls just chase a moving target!
• To adjust multiple species simultaneously, use CHGLMP_MIX
- Can also change by mass or mole fraction
- Change by providing an array of target concentrations
• Unnamed species will be prorated, as is done above with CHGLMP
Usually just for boundary conditions (plena) or for initial conditions (tanks)
- Don’t fight with FLUINT by changing tank values during a solution!
• HFORM: Heat of Formation per unit mass (J/kg or BTU/lbm), not per mole
- The enthalpy to form a substance and take it to standard temperature and pressure (STP: 25°C and 1 atm.)
- In whatever phase it is at STP
- Not the same as “Heat of Combustion!”
- That is a reaction-specific fuel characterization
- HFORM is a function only of the current substance
- Zero for pure substances in their natural state (e.g., O2)
- Must be input even if zero to use chemical reaction tools!
• HSTP: Enthalpy at standard Temp & Pressure
- Rare: just needed if:
- the phase is not correct at STP
- STP is outside of property limits, and extrapolation is not correct
- Example: 8000 or 6000 NEVERLIQ input, but this species is liquid at STP (where HFORM is defined)
- So the handbook value of HFORM isn’t appropriate
- But specifying a different HFORM might confuse a future user
- Basically, HSTP is just a correction to HFORM to improve self-documentation
• This data is built into library fluids, but may be missing from some CRTech-supplied FPROP blocks (whether F-files or R-files)
• Big K: equilibrium constant
- Example: Kp = [P1]n1 [P2]n2 / [P3]n3 (ni are from reaction equation)
- Often expressed by molar concentration (Kc) instead of by partial pressures (Kp)
- These are not “constants” … they are very strong functions of temperature and pressure
- Feeds into the EQRATE utility, described later
- Only valid if the temperatures stay hot enough!
- Your reacting mixture may stray from equilibrium as it cools
• Little k: reaction rate “pre-exponential term”
- ki = Ai*e(-Bi/T)
- Can be difficult to find
- Units vary as a function of each reaction/reagent!
• Current reaction rates (ri) are often a function of both ki and Ki (a per-species equilibrium constant)
- Feeds into the XMDOTx reaction rate per species x, described later
• Define rate of species creation/destruction within a tank (“XMDOT”): a mass (vs. molar) source/sink term
- Example: “xmdotA100” is the rate of production of mass of species A in tank 100 (negative for consumption)
- Sum of XMDOTs for all species should be zero (or nearly so) within each tank: Σ(XMDOTi) = 0
- Multiple reactions can be modeled within each tank- Sum up XMDOT for each reaction, each species
- XMDOTs are not possible in junctions, and ignored in STEADY
• FLUINT calculates the net heat of reaction (“QCHEM”) and adds it to the tank’s QDOT
- QCHEM = - Σ { XMDOTi* (HFORMi - HSTPi) }
기타 문의사항은 언제든지 당사로 연락 바랍니다.