Designing an efficient ejector system is a critical task in process engineering, as these devices offer a reliable, low-maintenance way to create a vacuum or pump fluids without moving parts. Using an ejector design calculation xls (Excel spreadsheet) allows engineers to rapidly iterate through various parameters like motive pressure, suction load, and compression ratios to find an optimal configuration. Core Principles of Ejector Design
Ejectors operate on Bernoulli’s Principle: high-pressure "motive" fluid is accelerated through a nozzle to create a low-pressure zone that sucks in a "secondary" fluid. The two streams mix and then enter a diffuser, where velocity is converted back into pressure. Key design variables for your spreadsheet include: Motive Pressure ( Ppcap P sub p ): The high-pressure fluid driving the system. Suction Pressure ( Pecap P sub e ): The pressure of the entrained vapor or gas. Discharge Pressure ( Pccap P sub c
): The final pressure at the exit, often heading to a condenser. Entrainment Ratio (
): The ratio of entrained vapor mass flow rate to motive steam mass flow rate ( Step-by-Step Calculation Logic for Excel
To build a robust ejector design calculation xls, you can follow this 1-D modeling sequence: Graham Manufacturinghttps://graham-mfg.com Steam jet Ejectors
For detailed ejector design calculations, several academic papers and technical resources provide the underlying mathematical models and formulas frequently used in professional Excel (XLS) spreadsheets. Technical Papers and Methodology
The most widely cited paper for steam ejector design calculations is: Evaluation of Steam Ejectors
" by Hisham Al Dessouky, Hisham Ettouney, Imad Alatiqi, and Ghada Al-Nuwaibit (published in Chemical Engineering & Processing, 2002).
This paper provides critical semi-empirical correlations for calculating the entrainment ratio (
) and area ratios for both choked and non-choked flow conditions. Ejector Calculation Formulas ejector design calculation xls
A standard design spreadsheet typically includes the following core components: Entrainment Ratio (
): The ratio of the mass flow rate of entrained vapor to motive steam. For choked flow (compression ratio >1.8is greater than 1.8
is determined using a series of constants (typically A to J) based on expansion and compression ratios. For non-choked flow (compression ratio <1.8is less than 1.8 ): The calculation involves logarithmic pressure ratios. Geometry Sizing: Motive Nozzle Throat Area ( A1cap A sub 1
): Calculated based on motive gas flow rate, pressure, and temperature.
Mixing Section Diameter: Derived from the combined mass flow of motive and entrained fluids. Available XLS and Software Resources
You can find pre-built calculation sheets and software tools at these locations:
Scribd - Steam Ejector Calculations XLS: A document that outlines the structure of a widely used Excel sheet for entrainment and area ratios.
Ezejector Software: Offers specialized design software and demo programs specifically for gas and steam ejector performance prediction.
Cheresources.com: A community forum where chemical engineers often share free Excel spreadsheets for process equipment sizing, including ejectors. Designing an efficient ejector system is a critical
Graham Manufacturing Technical Papers: Technical whitepapers covering the fundamentals of supersonic flow and critical pressure ratios in steam jet ejectors. Steam Ejector Design Calculations | PDF - Scribd
For steam ejector design calculations, several specialized Excel spreadsheets and research papers provide the necessary thermodynamic correlations for entrainment ratios and nozzle sizing. Notable Ejector Design Resources
Steam Ejector Calculation Notes: This is a widely used free spreadsheet on Cheresources based on semi-empirical equations for entrainment ratio. It uses curve-fitting constants for both choked and non-choked flow conditions.
Lempor Ejector Calculator: A specialized calculator for steam locomotive exhaust systems that simplifies complex fluid dynamics into a multi-sheet Excel workbook.
Scribd - Steam Ejector Calculations XLS: This document outlines the specific constants (
) used to calculate mass flow rates of motive steam versus entrained vapor, along with area ratios for the nozzle throat and outlet. Key Design Parameters
Ejector performance is typically calculated using the following variables: Entrainment Ratio (
): The mass flow rate of entrained vapor divided by the mass flow rate of motive steam. Compression Ratio ( ): The ratio of discharge pressure ( Pccap P sub c ) to entrained vapor pressure ( Pecap P sub e ). Choked flow is generally defined as Expansion Ratio ( ): The ratio of motive steam pressure ( Ppcap P sub p ) to entrained vapor pressure ( Pecap P sub e Geometry Sizing: Determining the nozzle throat area ( A1cap A sub 1 ), nozzle outlet area ( A2cap A sub 2 ), and diffuser cross-sections. Foundational Research Papers
If you are looking for the underlying theory to build your own model, the following papers are the industry standard: Worksheet 1: Input Panel
"Evaluation of Steam Ejectors" by Hisham Al Dessouky et al. (Chemical Engineering & Processing, 2002): Provides the empirical constants used in most modern spreadsheets.
"Estimation of ejector's main cross sections..." (Applied Thermal Engineering, 2004): Offers a step-by-step procedure for steam-ejector refrigeration systems.
Lempor Ejector Calculator Beta 1.1 | PDF | Steam Locomotive - Scribd
ER = 7/0.1 = 70Calculate the nozzle throat area: [ A_t = \frac\dotm_1\rho_1 \cdot v_t ] where ( v_t ) is critical (sonic) velocity if the pressure ratio exceeds the critical pressure ratio.
If you do not have access to Steam Table functions in Excel, you can use the HEI (Heat Exchange Institute) empirical curves converted into formulas.
You can program a "Lookup Table" into a separate sheet:
Sheet 3: "HEI Curve Data" Create a table of Expansion Ratio vs. Compression Ratio for various flow ratios ($R = M_s / M_m$).
| Exp. Ratio | Compr. Ratio (R=0.5) | Compr. Ratio (R=1.0) | | :--- | :--- | :--- | | 10 | 1.8 | 1.2 | | 20 | 2.5 | 1.6 | | ... | ... | ... |
Calculation Logic:
VLOOKUP or INDEX/MATCH to interpolate the table.