Ejector working and principle of VERS Cycle

Presentation On Ejector working on high pressure fluid

Outline of Presentation
 Introduction
 Ejector’s History
 History of Injector /Ejector/Jet pump
 Model of the Ejector
 Introduction to the Ejector
 Ejector nomenclature
 General working principles
 Ejector working processes
 Ejector performance evaluation
 Choice of refrigerant
 Application of Ejectors in different refrigeration system
 Case study
 Conclusion
 References

Introduction
• Normally the compressor, condenser, throttling valve and the evaporator comes in
picture in refrigeration systems.
• In this project our ultimately aim is to increase the COP of the system by inducing
the injector or ejector or jet pump.
• A jet pump/ Injector/ Ejector is better solution to maintain the pressure difference
because it has no moving parts, require low maintenance, do not uses an additional
energy source as it uses energy lost in the cycle.
• In this seminar our main focus is on jet pump ,its principle, working, some
refrigeration system with jet pump or can be say Ejector and in last one case study
on R134a ejector refrigeration cycle.

History
• The injector was invented by Henry Giffard in 1858 for the steam locomotive.
• In this he uses the latent heat of discharging jet of steam and the water from
reservoir.
• In 1860 he published a thesis with entitled “A Theoretical and Practical Paper on
the self acting Injector”.
• For this thesis he get the grand Mechanical prize by France in 1862.
• The Injector was introduced in the United States by Messrs. Wm. Sellers & Co.,
who started its manufacture in 1860 at their works in Philadelphia, with some
improvements.
• In the year 1910, more improvements introduced, American Injectors were
extensively used .
• Now the applications of ejectors comes in several fields like fire extinguishing
purpose, injection of chemicals in Boiler, removal of boiler bottom ash in thermal
power plant ,and the most important i.e. producing vacuum pressure in steam jet
cooling systems.
• Also every injector is an Ejector. From subject point of view, difference in
apparatus arrangement may happen but the principle remains same.
• For the purpose of drawing the steam, the component will be called Ejector, and
the part of component which injects the working fluids into the ejector called
Injector.

Principle of Ejector
Primary Flow High Pressure (P Motive)(Pm)
Secondary flow Lowest pressure ( P Suction )(Ps)
Mixed or Discharge Flow Medium pressure (Pd)

Primary Flow High Pressure (P Motive)(Pm)
Secondary flow Lowest pressure ( P Suction )(Ps)
Mixed or Discharge Flow Medium pressure (Pd)
Principle of Ejector

Variations of pressure/velocity along the Ejector

Ejector performance evaluation
• The most important parameters for assessing ejector performance are the
entrainment ratio μ, defined as the ratio of mass flow rate of the secondary
flow (ṁs) to that of the primary flow (ṁp), and the pressure lift ratio τ,
defined as the ratio of the ejector back pressure(Pb) to the secondary flow
pressure(Ps).

Contd..
• The working processes of the system is generalized as :
1. low grade energy(Qg) is delivered to the generator for vaporization.
2. The high pressure vapor from the generator, i.e. the primary flow,
enters into the ejector nozzle and draws the low pressure vapor from
the evaporator, i.e. the secondary flow. The two flows undergo
mixing and pressure recovery in the ejector.
3. The mixed flow is then fed into the condenser, where it is
condensed by rejecting heat to the environment(Qc).
4. The liquid from the condenser is divided into two parts. One part
goes through the expansion device and then enters into the
evaporator to produce the refrigerating effect(Qe).
5. The rest liquid is pumped back to the generator via the circulation
pump and completes the cycle.

System performance and factors affecting
1. COP …is defined as the ratio of desired effect which is obtained from
evaporator to the work input.
2. Working fluids
 From above equation we can say that the system COP depends on the
entertainment ratio μ and refrigerant properties.
 The working fluid may be dry fluid, wet fluid and isentropic fluid. The
dry fluid is more favorable in the conventional refrigeration system.

Demerits of CERS
• Although the system processes are quite simple it has some demerits:
• In this system ejector geometrical parameters i.e. the area ratio Ar and the
nozzle exit position(NXP) are the most sensitive to the ejector entrainment
ratio μ.
• while the divergent angle of the nozzle and the convergent angle of the
mixing chamber are less sensitive and so error happens in actual reading.
• Also the lengths of the constant-area mixing chamber and the diffuser are
the least sensitive which affects in all the system COP.
• Low COP.

Advanced ejector refrigeration systems
• In the CERS system we get low COP and so the researchers have
developed advanced refrigeration systems with higher COP by means of
simulations and experiments.
• Following changes are done in this refrigeration system
» Changing ejector configurations
» Introducing multi-stage ejectors
» Eliminating the mechanical pump
» Using a regenerator and a pre cooler.

Conclusion
• An ejector is considered as an electricity free compressor. Both the primary flow
and the secondary flow of the ejector can be in any flowing state(liquid, vapor, and
two phase). They can also be pure fluids or mixtures of non-identical fluids.
• It is concluded that the ejector is the key component in these ejector integrated
refrigeration systems. The system performance depends on the type of refrigerant,
the operating conditions and the ejector dimensions. Regarding the ejector
geometry, the area ratio Ar and the nozzle exit position (NXP) are mostly
investigated and closely related to the operating conditions. The optimum ejector
parameters and maximum system performances vary with the operating conditions,
and they are not easily found.
• The conventional ejector refrigeration systems have some remark- able merits, and
consume significantly less electricity than the vapor compression system.
• Advanced ejector refrigeration systems are developed by changing ejector
configurations to increase the ejector efficiency, inventing multi-ejector systems to
improve the system COP, and eliminating the mechanical pump to driven
refrigeration systems.

Reference
1] He S,LiY, Wang RZ. Progress of mathematical modeling on ejectors. Renew
Sust Energ Rev 2009;13:1760–80.
[2] Chunnanond K, AphornratanaS. Ejectors: applications in refrigeration
technology. Renew Sust Energ Rev 2004;8:129–55.
[3] Chen X,OmerS, Worall M,Riffa S.Recent developments inejector refrigeration
technologies. Renew Sust Energ Rev2013;19:629–51.
[4] Zhu Y, Jiang P. Experimental and numerical investigation of the effect of shock
wave characteristics on the ejector performance. Int J Refrig 2014;40:31–42.
[5] Munday JT, Bagster DF. A new theory applied to steam jet refrigeration. Ind
Eng Chem Process Des Dev 1977;16:442–9.
[6] Fillpe Alexandre Ereira Mendes Marques. Study of liquid-vapour ejector in the
context of advanced TPL ejector-absorption cycle.
[7] cunnigham, R.G “Jet pump theory and performance with fluids of high
viscosity.” Trans. ASME,v. 79, pp. 1807-1820,1957.
[8] A. Khalil a, M. Fatouh b, E. Elgendy b, Ejector design and theoretical study of
R134a ejector refrigeration cycle Helwan University, Masaken El-Helmia P.O.,
Cairo 11718, Egypt

Ejector working and principle of VERS Cycle

Ejector working and principle of VERS Cycle

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