Ejector Design Calculation Xls

If calculated P₃ is less than target, adjust:

This iteration is easily automated in Excel using Goal Seek or a lookup table.

Best for gas ejectors (e.g., steam jet vacuum systems). Assumes mixing occurs at constant pressure (ideal for supersonic motive flow).

Key equations in Excel format:

Requirement: Remove 200 kg/h of air (suction) from a vacuum column at 0.3 bar abs, compressing to 1.2 bar abs, using 8 bar g steam. ejector design calculation xls

After running through the Excel tool:

The sheet instantly shows if the ejector is feasible in a single stage or needs multiple stages.

Here is the logic you embed into your Excel sheet:

Calculates the ratio of discharge pressure to suction pressure: $$CR = \fracP_dP_s$$ If calculated P₃ is less than target, adjust:

Excel is excellent for:

For multistage ejectors, condensable mixtures, or non-ideal gases, switch to:

Assume isentropic expansion. For an ideal gas: $$M_m = \sqrt \frac2k-1 \left[ \left( \fracP_mP_s \right)^\frack-1k - 1 \right] $$

In Excel formula (for k=1.4, air): =SQRT((2/0.4)*((P_m/P_s)^(0.4/1.4)-1)) This iteration is easily automated in Excel using

But wait – if $P_m/P_s$ exceeds the critical pressure ratio (approx 1.89 for air), Mach is >1. Most ejectors operate supersonically (M=1.5 to 4.0). Your XLS should cap Mach using the critical ratio.

Before building the spreadsheet, you must define the type of ejector. This guide focuses on the most common industrial application: Single-Stage Steam Jet Ejectors (based on the ASME PTC 24 standards).

Key Inputs:

Key Outputs: