Ejectors (also called jet pumps or eductors) are fluid handling devices that use the Venturi effect to convert pressure energy of a motive fluid into velocity energy, creating a vacuum that draws in a suction fluid. They are widely used in chemical plants, oil refineries, HVAC systems, and marine applications.
An Excel-based ejector design calculator (.xls) provides engineers with a fast, transparent, and iterative method for sizing ejectors without resorting to expensive commercial software—especially useful for preliminary design, educational purposes, or field troubleshooting.
You have three options:
Warning: Most free XLS files online lack validation. Always test with a known example from a textbook like "Ejectors and Jet Pumps" by G. Krivchenko.
An ejector design calculation spreadsheet (.xls) is a practical, lightweight tool for engineers to quickly size ejectors for gases, vapors, or liquids. While not a replacement for rigorous simulation, it provides reliable first estimates, facilitates design reviews, and serves as an excellent teaching aid. For final detailed engineering, manufacturer validation and CFD are still recommended.
Tip: When building your own XLS, always use absolute pressures for ratios, include steam/air table lookups via VLOOKUP, and add a Goal Seek macro to iterate for target entrainment ratio.
This paper outlines the fundamental mathematical models and design parameters for a Steam Ejector Design Calculation spreadsheet (XLS). It focuses on the 1-D thermodynamic model used to determine the Entrainment Ratio ( and critical geometric dimensions.
Ejectors are passive devices that use high-pressure motive fluid to entrain and compress a lower-pressure suction fluid. This paper details the empirical and analytical formulas required to automate design in Excel, specifically addressing non-choked flow regimes. 1. Nomenclature & Parameters
Successful spreadsheet automation requires defining the following variables based on established research Definition Motive Pressure cap P sub p Pressure of the high-pressure motive steam. Suction Pressure cap P sub e Pressure of the entrained vapor/gas. Discharge Pressure cap P sub c Pressure of the mixture exiting the diffuser. Entrainment Ratio Mass flow of entrained vapor per unit mass of motive steam. Compression Ratio Ratio of discharge pressure to suction pressure ( Expansion Ratio Ratio of motive pressure to suction pressure ( 2. Core Design Calculations 2.1 Entrainment Ratio ( ) for Choked Flow When the compression ratio is greater than
, the flow is typically "choked" at the nozzle throat. The following empirical correlation is used for XLS implementation: ejector design calculation xls
w equals cap A cross cap E r to the cap B-th power cross cap P sub e to the cap C-th power cross cap P sub c to the cap D-th power cross open bracket cap E plus cap F cross cap P sub p to the cap G-th power cross cap H to the cap I-th power cross cap P sub p to the cap J-th power close bracket Constants (A-J):
These are typically derived from curve-fitting manufacturer data. For example, are common in steam applications. Coefficient of Determination ( cap R squared Well-tuned spreadsheets should aim for an to ensure accuracy. 2.2 Nozzle and Mixing Chamber Geometry Nozzle Throat Diameter ( cap D sub t h end-sub
Calculated to pass the required motive steam mass flow at sonic velocity. Diameter Ratio (
The ratio of the mixing chamber diameter to the nozzle diameter typically ranges between for optimal performance. Nozzle Position ( cap L sub g a p end-sub
The distance between the nozzle exit and the mixing chamber inlet, with an optimal ratio between 0.25 to 1.5 3. Implementation in Excel (XLS) An effective spreadsheet should follow this logical flow: Ejector Motive Steam Consumption - Constant Contact
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 Ejectors (also called jet pumps or eductors) are
To build a robust ejector design calculation xls, you can follow this 1-D modeling sequence: Graham Manufacturinghttps://graham-mfg.com Steam jet Ejectors
Ejector design calculation spreadsheets focus on two primary mechanical goals: predicting the Entrainment Ratio (
) and determining the internal geometry (diameters and areas) of the nozzle and mixing sections. These calculations often rely on empirical correlations, such as those derived by Hisham El-Dessouky, which provide high precision (up to ) for steam jet systems. Core Calculation Steps for an XLS Spreadsheet
A standard engineering spreadsheet for ejectors follows these sequential steps: Define Operating Pressures: Motive Pressure ( Ppcap P sub p ): High-pressure steam or fluid entering the nozzle. Suction Pressure ( Pecap P sub e ): Low-pressure entrained vapor. Discharge/Exit Pressure ( Pccap P sub c ): Pressure at the condenser or outlet. Calculate Ratios: Expansion Ratio ( Ercap E sub r = ): Determines how much the motive fluid can expand. Compression Ratio ( Crcap C sub r =
): Identifies if the flow is Choked ( ) or Non-Choked ( ). Determine Entrainment Ratio ( ): Choked Flow Formula: where to are specific empirical constants (e.g., , ).
Non-Choked Flow Formula: Uses logarithmic correlations involving and with a separate set of constants. Geometric Dimensioning: Nozzle Throat Area ( A1cap A sub 1
): Function of the motive mass flow rate, pressure, and molecular weight. Mixing Section Area ( A3cap A sub 3
): Calculated based on the combined flow rate of motive and entrained fluids. Nozzle Outlet Pressure ( P2cap P sub 2 ): Often estimated as . Recommended Resources and Tools
For high-quality templates or verified models, you can refer to these industry sources: Warning: Most free XLS files online lack validation
Scribd Spreadsheet Templates: The Steam Ejector Calculations.xls file provides a comprehensive layout with pre-coded constants for entrainment and area ratios.
Lempor Exhaust Calculator: A specialised XLS tool developed by Richard Stuart for steam locomotive ejectors, focusing on smokebox vacuum and chimney throat area.
Transvac Screening Tools: Transvac Engineers offers online software for preliminary ejector screening that mimics these XLS calculations.
Ezejector Software: A Visual Basic program that handles complex inputs like molecular weight to calculate the best nozzle and mixing diameters. Professional Tip: The "Industry Standard" Lempor Ejector Calculator Beta 1.1 | PDF | Steam Locomotive
Ejectors (also known as jet pumps, eductors, or siphon pumps) are simple yet highly efficient devices that use the Venturi effect to transport fluids, gases, or slurries. Unlike mechanical pumps, ejectors have no moving parts, making them ideal for harsh environments, high-temperature applications, and explosive atmospheres. However, designing an ejector is a delicate balance of fluid dynamics, thermodynamics, and empirical correction factors.
For decades, engineers have relied on specialized software or complex hand calculations. But with the power of Microsoft Excel, you can create a transparent, flexible, and accurate ejector design calculation spreadsheet (.xls). This article provides a comprehensive guide to the theory, step-by-step calculations, and the structure of a professional-grade .xls tool.
$$V_m = M_m \times \sqrtk \cdot R \cdot T_m$$
Then, using continuity: $$W_m = \rho_m \cdot A_n \cdot V_m$$
This allows you to back-calculate required nozzle area if $W_m$ is given.