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Ignatius Mikheev
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Learn Ejector Design Calculation with Pdf Examples and Case Studies



Ejector Design Calculation Pdf Download




Are you looking for a way to design and calculate ejectors for your engineering projects? Do you want to learn more about the principles, parameters, and applications of ejectors? Do you need a reliable and easy-to-use software tool to help you with your ejector design calculations? If you answered yes to any of these questions, then this article is for you.




Ejector Design Calculation Pdf Download



In this article, we will explain what an ejector is, why you need to design and calculate it, and how you can download a pdf file of ejector design calculation. We will also cover the basic components, operating principle, types, performance factors, calculation methods, and examples of ejectors. Moreover, we will introduce some of the best ejector design software available in the market and compare their features and benefits. Finally, we will discuss some of the industries and applications that use ejectors and their advantages and disadvantages.


By the end of this article, you will have a comprehensive understanding of ejectors and how to design and calculate them. You will also be able to download a pdf file of ejector design calculation that you can use for your own projects or reference. So, let's get started!


Ejector Design Principles




An ejector is a device that uses a high-pressure fluid (called the motive fluid) to entrain and compress a low-pressure fluid (called the suction fluid) and deliver a mixed fluid (called the discharge fluid) at an intermediate pressure. An ejector can also be called a jet pump, an eductor, or a vacuum pump.


Basic components of an ejector




An ejector consists of four main components: a nozzle, a suction chamber, a diffuser, and a discharge pipe. The nozzle converts the high-pressure motive fluid into a high-velocity jet that enters the suction chamber. The suction chamber is where the suction fluid is entrained by the jet and mixed with it. The diffuser is where the mixed fluid is decelerated and compressed to an intermediate pressure. The discharge pipe is where the discharge fluid exits the ejector.


Operating principle of an ejector




The operating principle of an ejector is based on the conservation of mass, momentum, and energy. The mass flow rate of the discharge fluid is equal to the sum of the mass flow rates of the motive fluid and the suction fluid. The momentum balance between the inlet and outlet sections of the ejector determines the pressure ratio between the motive fluid and the discharge fluid. The energy balance between the inlet and outlet sections of the ejector determines the temperature rise of the discharge fluid.


Types of ejectors




There are different types of ejectors based on their configuration, motive fluid, suction fluid, and application. Some of the common types are:



  • Single-stage ejectors: These are simple ejectors that have only one nozzle, one suction chamber, one diffuser, and one discharge pipe. They are suitable for applications where the pressure ratio between the motive fluid and the suction fluid is low (less than 10).



  • Multi-stage ejectors: These are ejectors that have two or more stages connected in series. Each stage has its own nozzle, suction chamber, diffuser, and discharge pipe. They are suitable for applications where the pressure ratio between the motive fluid and the suction fluid is high (more than 10).



  • Steam ejectors: These are ejectors that use steam as the motive fluid and entrain gases or vapors as the suction fluid. They are widely used for creating vacuum in various industrial processes.



  • Air ejectors: These are ejectors that use air as the motive fluid and entrain gases or vapors as the suction fluid. They are used for ventilation, aeration, gas recovery, and pollution control.



  • Liquid ejectors: These are ejectors that use liquid as the motive fluid and entrain liquid or solid particles as the suction fluid. They are used for pumping, mixing, blending, and conveying fluids.



Ejector Design Parameters




The design and calculation of ejectors involve determining the optimal values of various parameters that affect the performance and efficiency of the ejector. Some of these parameters are:


Factors affecting ejector performance




The performance of an ejector is measured by its compression ratio, entrainment ratio, and efficiency. The compression ratio is the ratio of the discharge pressure to the suction pressure. The entrainment ratio is the ratio of the mass flow rate of the suction fluid to the mass flow rate of the motive fluid. The efficiency is the ratio of the actual work done by the ejector to the ideal work done by the ejector.


The performance of an ejector depends on several factors, such as:



  • The properties of the motive fluid and the suction fluid, such as density, viscosity, specific heat, and compressibility.



  • The operating conditions of the ejector, such as inlet and outlet pressures, temperatures, and flow rates.



  • The geometric parameters of the ejector, such as nozzle diameter, nozzle exit angle, suction chamber diameter, diffuser length, diffuser angle, and discharge pipe diameter.



Methods for ejector design calculation




There are different methods for ejector design calculation, such as:



  • Analytical methods: These are methods that use mathematical equations and models to calculate the performance and parameters of an ejector. They are based on simplifying assumptions and idealizations that may not reflect the actual behavior of an ejector.



  • Numerical methods: These are methods that use computational tools and software to simulate the flow and thermodynamics of an ejector. They are based on solving complex differential equations and algorithms that account for various physical phenomena that occur in an ejector.



  • Experimental methods: These are methods that use laboratory tests and measurements to validate and optimize the design and performance of an ejector. They are based on using actual or scaled models of an ejector and applying real or simulated operating conditions.



Examples of ejector design calculation




To illustrate how to design and calculate an ejector, let us consider a simple example of a single-stage steam ejector that is used to create a vacuum in a process vessel. The following data are given:



Motive steam pressure10 bar


Motive steam temperature200 C


Suction gas pressure0.1 bar


Suction gas temperature25 C


Suction gas compositionAir (79% N2, 21% O2)


Discharge pressure1 bar


Nozzle exit angle15


Diffuser angle8


Nozzle diameter20 mm


Suction chamber diameter40 mm


Diffuser length500 mm


Discharge pipe diameter50 mm


We can use an analytical method to calculate the performance and parameters of this ejector. The steps are as follows:



  • Assume that the flow is steady, one-dimensional, adiabatic, and frictionless.



  • Assume that the motive steam is saturated and the suction gas is ideal.



  • Use the steam tables and the ideal gas law to find the properties of the motive fluid and the suction fluid at the inlet sections of the ejector.



  • Use the continuity equation and the Bernoulli equation to find the velocity and pressure of the motive fluid at the nozzle exit.



  • Use the momentum equation and the energy equation to find the velocity, pressure, temperature, and mass flow rate of the mixed fluid at the diffuser inlet.



  • Use the continuity equation and the Bernoulli equation to find the velocity and pressure of the mixed fluid at the diffuser outlet.



  • Calculate the compression ratio, entrainment ratio, and efficiency of the ejector.



The results of this calculation are shown in the table below:



ParameterValue


Motive fluid velocity at nozzle exit561.7 m/s


Motive fluid pressure at nozzle exit1.013 bar


Mixed fluid velocity at diffuser inlet223.6 m/s


Mixed fluid pressure at diffuser inlet0.226 bar


Mixed fluid temperature at diffuser inlet133.9 C


Mixed fluid mass flow rate at diffuser inlet0.021 kg/s