Many simple spreadsheets assume a constant mixing efficiency (e.g., 0.8 or 80%). In reality, efficiency varies with flow rates. A "Fixed" efficiency input allows the engineer to tune the spreadsheet based on historical vendor data, making the tool more accurate for future predictions.
: $$A_t = \frac\dotm_mP_m \times \frac1C_d \times \sqrt \fracR T_mk \left( \frack+12 \right)^\frack+1k-1 $$ Excel Formula (assuming $R=8314/M_m$ and $C_d = 0.95$): =(B11/B2) * (1/0.95) * SQRT( ( (8314/B7)*B5 / B9 ) * ((B9+1)/2)^((B9+1)/(B9-1)) ) ejector design calculation xls fixed
can be used to iteratively find the friction factor or optimal flow rate based on the Darcy-Weisbach or Colebrook-White equations. Resources and Technical Guides Scribd Spreadsheet Guide: Many simple spreadsheets assume a constant mixing efficiency
The following sections outline the typical steps involved in an ejector design calculation XLS fixed: : $$A_t = \frac\dotm_mP_m \times \frac1C_d \times \sqrt
Often called the "back pressure." If the actual back pressure exceeds the design discharge pressure, the ejector will "break" and lose vacuum rapidly. Step-by-Step Design Logic in XLS