At=mmCd⋅γ⋅ρm⋅Pm⋅(2γ+1)γ+1γ−1cap A sub t equals the fraction with numerator m sub m and denominator cap C sub d center dot the square root of gamma center dot rho sub m center dot cap P sub m center dot open paren the fraction with numerator 2 and denominator gamma plus 1 end-fraction close paren raised to the the fraction with numerator gamma plus 1 and denominator gamma minus 1 end-fraction power end-root end-fraction Cdcap C sub d = Discharge coefficient (typically 0.95 - 0.98) = Specific heat ratio ρmrho sub m = Motive fluid density Pmcap P sub m = Motive fluid pressure 3. Step-by-Step .xls Sheet Architecture
Steam jet ejectors are critical, reliable components used throughout the chemical, petrochemical, power, and oil and gas industries. Because they have no moving parts, they offer exceptional reliability for creating vacuums, mixing fluids, and boosting gas pressures.
By entering these fixed values, the spreadsheet solves the 1-D compressible flow equations to predict the ejector’s performance.
The most critical dimensionless number in ejector design is the Area Ratio ($AR$). $$ AR = \frac\textArea of Mixing Throat\textArea of Nozzle Exit $$ This ratio dictates the operating curve of the ejector.
If your pressure ratio is too high for a single stage, the XLS should flag the need for a multi-stage system with inter-condensers. Finding a Reliable Calculation Sheet ejector design calculation xls fixed
If your spreadsheet is yielding errors or impossible geometries, check for these common issues:
What you are using (Steam, Air, Water, or Gas)? Whether the flow is subsonic or choked/sonic ?
Mastering Ejector Design: A Guide to Using XLS Calculation Sheets
This is the core engine where areas and velocities are calculated using the formulas from Section 2. Calculate sonic velocity ( By entering these fixed values, the spreadsheet solves
The theoretical velocity of the motive fluid leaving the nozzle is calculated assuming isentropic expansion:
Here, we use the Momentum Equation. The spreadsheet solves for the diameter of the mixing throat ($D_throat$). A simplified iteration logic used in spreadsheets is:
The "throat" of the motive nozzle is sized to ensure the steam reaches supersonic speeds (Mach > 1).
Unlike variable-orifice ejectors that use a moving needle to adjust flow, a has a set nozzle diameter and throat area. If your pressure ratio is too high for
Before deploying your fixed XLS sheet to a production environment, verify its outputs against empirical standards:
In practice, industrial spreadsheet design adapts the standards, applying correction factors for molecular weight ( Wmcap W sub m ) and temperature ( Tmcap T sub m 3. Step-by-Step Spreadsheet Architecture
Spreadsheet works for air but gives nonsense for steam or heavy hydrocarbons. Fix: