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| Exp. Ratio | Compr. Ratio (R=0.5) | Compr. Ratio (R=1.0) | | :--- | :--- | :--- | | 10 | 1.8 | 1.2 | | 20 | 2.5 | 1.6 | | ... | ... | ... |
rc=(2k+1)kk−1r sub c equals open paren the fraction with numerator 2 and denominator k plus 1 end-fraction close paren raised to the the fraction with numerator k and denominator k minus 1 end-fraction power ) is the specific heat ratio of the gas. For steam, ; for air, The mass flow rate through the choked nozzle throat ( Atcap A sub t ) is calculated using:
The position of the normal shock wave in the diffuser throat deeply affects compression stability.
⚠️ Excel is ideal for preliminary/sizing calculations. For detailed mechanical design or two-phase flow, use validated commercial tools. ejector design calculation xls
Once you have the mass flows converged, calculate the geometry.
Design a steam ejector to evacuate air from a condenser.
[ ER = \fracP_1P_2 ]
An ejector consists of four main parts:
The area where the low-pressure process gas enters and mixes with the motive steam.
Whether you are designing a steam ejector for a vacuum distillation column, a liquid jet pump for a sump, or an eductor for a chemical reactor, the systematic approach outlined here will serve as your comprehensive blueprint.
Ensure the exit velocity slows down sufficiently to hit the targeted discharge pressure without stalls. 6. Common Design Pitfalls to Avoid in Excel Models
The Entrainment Ratio determines how much motive steam is required to move a specific amount of suction gas. According to the Heat Exchange Institute (HEI) standards, the raw suction mass must be corrected for molecular weight and temperature. This public link is valid for 7 days
Your target (suction, motive, and discharge)?
Unlike centrifugal pumps, ejectors have – but their design is notoriously calculation-intensive. This is where an Ejector Design Calculation Excel Sheet becomes an engineer’s best friend.
Slowly expands the flow area, converting the kinetic energy of the mixed stream back into static pressure (discharge pressure). 2. Key Mathematical Formulations for Ejector Design