Vacuum ejectors ejectors work on the venturi principle. A cfd calculation of the flow of an ejector at high speed. The differential pressure sensor attached between the entry and throat section of the venturi meter records the pressure differencep1p2 which becomes an indication of the flow rate of the fluid through the pipe when calibrated the diverging section has been provided to enable the fluid to regain its pressure and hence its kinetic energy. Ejectors thus have the advantage that they can be driven with waste heat, and used as heat pumps in appropriate cycles to produce heat upgrading, cooling or refrigeration effects, provided that a thermal source is available. Due to the broad range of applications for steam jet vacuum equipment, the units are frequently specified in special alloys and plastics. Since an ejector has no valves, rotors, pistons or other moving parts, it is a relatively lowcost component is easy to operate and requires relatively little maintenance.
Fresh water generator principle, operation and remedies. The working principle of the ejector is based on the expansion of a highpressure. The system consists of two loops, the power loop and the refrigeration loop. Steam jet air ejectors have a low initial cost, so are an economical means and reliable equipment for producing a vacuum. In a steamjet ejector, the suction chamber is connected to the vessel or pipeline that is to be evacuated under vacuum. A jet ejector requires no mechanical drive and has no moving parts. Controlling ejector performance pumps operating on the ejector principle are in use on many processes. The practical application of this principle requires a simple apparatus which essentially consists of only 3 main parts.
Steam ejector design chemical process engineering engtips. Best a generalized ejector model was successfully developed for gas ejector design and performance analysis. Ejector design calculation pdf download anpsortigas. The suction is carried out by the ejector, which is powered by exhaust gases of combustion engine. As a first estimate, a five stage ejector is assumed. Air ejector theory learn how and air ejector works bright. Steamjet ejectors are typically furnished in cast iron or steel with a nozzle of stainless steel. They use kinetic energy of the driving medium to suck in gases, vapors or other liquids and then discharge the resultant mixture against a counter pressure. Functional principle the result of this action is a mixture of the driving and entrained sucked fluids, the velocity of which is reduced and the pressure increased in a second nozzle.
After the cooking process the pressure inside the autoclave was around 3 bar. This change from pressure head to velocity head is the basis of the jetvacuum principle. A jet pump works without a mechanical drive and therefore offers high reliability in continuous operation mode. Air ejector theory learn how and air ejector works. This chapter gives a brief explanation of the ejector working principle and shows. As can be seen below, the total steam required is 500 kghr. A further development by the authors in a separate paper by wang et al. If discharge side of ejector is blocked in and steam is not the steam is going to path of least resistance, back to process. Steam jet refrigeration system seminar report download. In addition to this water ejector, ejector pump, distillate pump, salinity indicator, demister or mesh separator, solenoid valve and water flow meter are also fitted as accessories. It was also used as a base for the creation of a new ejector, which has an increased airflow. Basic constructionejectors are composed of three basic parts. The operating principle of the ejector is the pressure energy in the motive fluid is converted to velocity energy by an adiabatic expansion in the convergingdiverging nozzle. Two mould members form the impression of a mould, namely.
Ejector design software ejector sizing calculation ezejector. The steam jet refrigeration system also known as ejector system refrigeration system is one of the oldest. The term jet ejector describes a device in which a pumping effect is achieved using a motive fluid. The definitions of overall ejector efficiency and ejector component efficiencies in literature are. Working principle of steam ejector power plant tutorials. Jan 28, 2008 a cfd calculation of the flow of an ejector at high speed. Steam jet ejectors offer a simple, reliable, lowcost way to produce vacuum. The basic ejector refrigeration cycle is illustrated in figure 12. In this case, the spindle is essentially changing the dimensions of the. What makes them work all ejectors operate on a common principle.
An ejector dewatering system consists of an array of wells pumped by jet pumps installed at the base of each well up to depths of 150 metres. These systems operate on the ejector venturi principle, which relies on the momentum of a highvelocity jet of steam to move air and other gases from a connecting pipe or vessel. The liquid ejector is designed for both booster and parallel compression systems. Ejector systems gea engineering for a better world. The steam jet refrigeration system also known as ejector system refrigeration system is one of the oldest methods of producing refrigeration effect. The ejector design has basic advantages such as absence of moving parts and simplicity of operation. In such cases, put the starting air ejector in service immediately along with the running main air ejector to prevent a decrease in vacuum. Previous 1d analytical models can be derived from this new. The fluid in the nozzle jet and the entrained liquid are forced through a diffuser where the high throughput velocity creates a turbulent flow. These systems were applied successfully to refrigeration in the early years of this century.
Mathematical model of ejector and experimental verification. One common ejector application is the withdrawal of noncondensible gases from steam condensers. Working principle of jet ejector witte 1969 termed the phenomenon of change from system. Eductor operating principles basic theory an eductor uses a nozzle to produce a high velocity fluid jet to entrain the liquid surrounding the eductor fluid can be either a gas or a liquid. Ejector design software ejector sizing calculation. This paper that based on the working principle of ejector and coefficient of performance indicators, expounds the application of pressure regulator and mixed heater, and recovers steam exhaust of. A created mathematical model describes the flow in the ejector, and was verified by an experiment. Download pdf for free principle and working of aspirator pump definition an aspirator is a type of ejectorjet pump, that produces vacuum by means of the venturi effect. At low temperatures the saturation pressures are low 0. An ejector is essentially a fluidfluid pump that has no pistons, valves, rotors, or other moving parts and works by transfer of momentum from the primary fluid high pressure to the secondary fluid aspirated low pressure. This paper that based on the working principle of ejector and coefficient of performance indicators, expounds the application of pressure regulator. The single stage ejector, in its simplest form, consists of an actuating nozzle, suction chamber and a diffuser. Also known as thermocompressors or vapour compressors, steam jet compressors compress steam flows in various processes in a simple way.
Since the pressure between the first two stages of fourstage ejector or, the firstthree stages of a fivestage ejector is too low to permit condensing, these stages aredesigned as noncondensing with the subsequent stages condensing. Review on ejector efficiencies in various ejector systems. This steam is released in a motive nozzle to bring it up to the maximum speed. Therefore, they react to control impulses in a manner peculiar to their. Ejectors are essentially a fixed capacity device since the diffuser area is constant.
The basic principle of jet pumps consists in the liquid or gas jet being emitted by a nozzle at high speed entraining and accelerating the surrounding liquid, gas or solid matter. The compressed air is supplied through connection a to ejectors. Due to the pressure drop of the motive fluid, it will create a lowpressure zone before the mixing chamber. Simplest procedure of spalding 15 in phoenics software, a general commercial cfd package. Steam jet compressors are part of many process engineering applications. Dec 11, 20 operating principle demo of the tankjet b and bx injectors by. It works on the principle of convergent divergent nozzle as it provides the venturi effect at the point of diffusion as the tube gets narrows at the throat the velocity of the fluid increases and because of the venturi affect it pressure decreases, vacuum will occur in the diffuser throat where the suction line will be provided. This basic principle applies to every jet ejector in different models and ranges of application. On the design and corresponding performance of steam jet. You can also get wet steam into an ejector and this will cause back firing on the ejector also putting material back into process. First, equal steam flow rate is assumed to each stage. Fresh water generator principle, operation and remedies for. The actuating fluid, which may be a gas, vapor or liquid, is expanded from its initial pressure to a pressure equal to that of the secondary fluid.
Pdf investigation of an experimental ejector refrigeration machine. Very often, the motive fluid is steam and the device is called a steam jet ejector. The other conditions will then fall within the performance curve of the larger ejector. Other applications employ ejectors to compress a working fluid, such as vaporcompression refrigeration and vapor compression multipressure humidificationdehumidification desalination 3.
In order to achieve a pumping action, they use the energy from steam at a high level of pressure as the drive medium. Ejector wells work on the same principle as a well point system but allow water to be drawn from deeper in the ground. The ejector performance is affected by either highlow supply steam pressure to the ejector or by high condensate level in the ejector. Principle and working of aspirator pump definition an aspirator is a type of ejectorjet pump, that produces vacuum by means of the venturi effect. Steam jet refrigeration system seminar report download introduction in steam jet refrigeration systems, water can be used as the refrigerant. The core portion of the mould, it forms the internal form of the molding it consists of a core plate and a cavity plate. In an increasing number of applications it is necessary to apply controls. Ejector thermocompressor equirepsa vaccum production. Working principle the basic principle of all lowpressure fresh water generator is that boiling point of water can be reduced by reducing the pressure of the. Ejectors, or jet pumps, utilize the pressure energy of a highpressure fluid stream to boost the pressure andor flow of a lowpressure source. I worked on a project before where a medical waste facility cooked the medical waste in a pressure vessel called an autoclave. The exhaust steam mixes up with the water and condensed. When a high pressure motive fluid steamliquid enters the steam nozzle, this result in a decreasing pressure and increasing velocity of the fluid again the fluid enters in the diffuser which result in a increasing pressure and decreasing velocity of the fluid so due to pressure difference vacuum is created in between the nozzle and diffuser. When a high pressure motive fluid steamliquid enters the steam nozzle, this result in a decreasing pressure and increasing velocity of the fluid again the fluid enters in the diffuser which result in a increasing pressure and decreasing velocity of the fluid so due to pressure difference vacuum is created in between the nozzle and diffuser we can say venture.
Ejector design calculation pdf download 08d661c4be this content was downloaded from ip address 66. Basic ejector components are the steam chest, nozzle, suction, throat, diffuser and they discharge fig. They can operate with either incompressible or compressible fluids as the primary driving and secondary driven flows. Onedimensional model of an optimal ejector and parametric. The overall compression ratio required is approximately 55. The ejector design principles used in the ejector calculations for the program are explained including the ejector energy balance and effects of the ejector flow cones. Apr 26, 2017 i worked on a project before where a medical waste facility cooked the medical waste in a pressure vessel called an autoclave. Ejector working principle mechanical engineering site. Steam jet compressors, jet pump, thermocompressor, ejector. Free demo programs for a short time are offered to let you see how the ejector program works they are not intended for your design work. The principle of this condenser is shown in the figure. Ejectors and steam jet ejectors document library graham. The working principle in the liquid ejector is similar to the gas ejector. The application determines the design of the flow section.
The cavity portion of the mould, which forms the external shape of the molding 2. The operating principle of the ejector is the pressure energy in the motive fluid is converted to velocity energy by an adiabatic expansion in the. They usually save as much as 10% to 20% in motive steam, compared with singlenozzle units designed for the same conditions. Ejector modules featuring econozzle technology for efficient vacuum generation and high suction rate with minimal air consumption.
Due to the lowpressure zone, the suction fluid will start to. In a spindleoperated ejector, the nozzle and tapered spindle work together similar to a needle valve. Steamjet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. Jet pump, ejector, motive media pump, injector many names, same design and working principle. Occasionally an ejector must operate alternately at two or more conditions of load and vacuum. Basic principles of vacuum technology, brief overview festo. Basicprinciplesofvacuumtechnology,briefoverview festo. In an aspirator, fluid liquid or gaseous flows through a tube which narrows then expands in crosssectional area, and thus volume. Boiler steam is used as a motive fluid in steam jet ejector vacuum systems sarevski et al. The basic operating principle of an ejector is to convert the pressure into speed.
Figure 2 illustrates the principle of operation of an ejector based heat pump system. These function according to the venturi principle, i. In the power loop, lowgrade heat, q g, is used in a generator to evaporate. Ejector dewatering systems geoquip water solutions. The main features of an ejector are shown in figure 1. Steam jet ejectors are based on the ejectorventuri principle. Ejector systems ejectors gea engineering for a better world. Using them reduces the energy consumption of the process and cuts the machinerys operational costs sustainably. Water ejectors are vacuum pumps, driven by a high pressure water or similar medium or steam. An ejector cooling system ecs is a mechanical system utilizing the rankine cycle and the gas dynamic effect of an ejector a thermal compression process. How it works working principle hvac industrial engineering phx heat. In this instance the ejector must be designed for the most difficult conditions or the conditions that call for the largest ejector.982 1549 1141 276 201 1438 1228 92 1440 152 1000 1140 502 1516 797 12 840 651 247 1603 1387 543 1400 312 264 639 799 811 1288