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PERFORMANCE ANALYSISAND DEVELOPMENT OF COMPACT

VAPOUR JET REFRIGERATION SYSTEM

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Objectives of the Proposal

• To analyze and optimize the ejector with a single and multiple swirl by keeping the primary nozzle at an angle inclined with the axis of the ejector assembly.

• To provide a complete opening around the circumference of the primary nozzle, instead of a single inlet for secondary jet.

• Flow visualization of entrainment, mixing process, location of both normal and oblique shocks, in ejector with single and multiple swirl and primary nozzle inclined to the reference axes

• Performance analysis with newer working fluids. • To design and fabricate a compact 1 TR vapour jet refrigeration system • To conduct experimentation on the system under simulated conditions

with instrumentation.• To carry out performance analysis through experimentation

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Work carried out (International status)• Bartosiewcz [1] carried out performance analysis of supersonic ejector using CFD

and experimental analysis under different modes, ranging from on-design to off-design conditions has been carried out.

• Cizungu et al. [2] carried out simulation of one-dimensional analysis based on mass, momentum and energy balance and validated the same with experimental results from literature.

• Vargaa [3] investigated six turbulence models namely, standard k-ε, RNG k-ε, realizable k-ε, RSM and two k-ω and compared the results with experimental results from literature. Three-dimensional performance analysis of supersonic air ejector operating with and without secondary flow. Further, it has been recommended that full 3D simulation, would give better prediction of ejector performance compared to 2D axisymmetric domain simulation.

• Il Seoul Park [4, 5, 6], investigated thermal vapor compressor (TVC) used in a multi effect desalination system (MED). Ejector can also be referred as TVC. Author studied the effect of swirl on entrainment ratio for TVC. Compressible, axisymmetric and swirl flow is numerically solved for various swirl to axial component ratio. Improved performance was observed at swirl angle 16.7. Entrainment ratio of the swirled motive flow was observed to increase up to 2 % over the no-swirl case. Also, the author observed evaporator size required gets reduced due to swirling effect of the flow inside ejector.

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Work carried out (International status) contd.,

• Zhu et al. [7] carried out three-dimensional ejector analysis numerically and experimentally to study the entrainment performance and shock wave structures.

• Bouhanguel [8] studied the flow field structure in the ejector mixing using schlieren optical measurements. Two quartz glass windows were installed in the two sides of the mixing chamber for the purpose of observing shock structures. Also they analysed the ejector with four turbulence models viz., standard k–ε, realizable k–ε, RNG k–ε, SST k–ε . Authors observed that among turbulence models, RNG k–ε model agreed well with experimental results.

• Desevaux [9,10] carried out CFD modeling of ejector to investigate the flow regimes with and without secondary choking and validated the same by comparing the numerical results with laser tomographic images. Flow visualization studies on ejector have been carry out by authors to understand the flow patterns, shock patterns, mixing of streams, choking of flows, under various operating conditions.

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Work carried out (National status) • Selvaraju and Mani[11,12] investigated the performance of ejector with different

environmental friendly refrigerants like R134a, R152a, R290, R600a and R717. Based on one-dimensional theory, the authors developed a numerical code for analyzing the performance of ejector and compared the same with experimental investigations. Among the refrigerants selected for analysis, R134a gives a better performance and higher critical entrainment ratio was observed.

• Selvaraju and Mani[13] carried out three-dimensional numerical analysis of ejector based on finite volume method using commercial software FLUENT. The internal flow physics like pressure distribution, temperature distribution, Mach number, shock patterns etc., were studied using CFD, under various simulated operating conditions.

• Sankarlal and Mani [14,15] have designed and developed vapour jet refrigeration system  to operate with ammonia. In this paper, performance of ejector refrigeration system has been experimentally studied with three different area ratio ejectors by varying operational parameters namely generator, condenser and evaporator temperatures.

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Work carried out (National status)• Senthil Kumar [16], studied flash desalination technology, by which fresh water is

produced from sea water by evaporation and subsequent condensation. A two-phase jet pump is designed, developed and tested for such a desalination system to create and maintain vacuum inside the flash chamber. Flow visualization was made experimentally to find jet dispersion in the jet pump which facilitates the determination of the optimum length of the mixing tube for the specified inlet conditions for different orifice diameters and different orifice spacing.

• Kumar and Charan [17] have proposed a Freon ejector refrigeration system operated by solar energy and carried out a thermodynamic analysis of the cycle. They have compared the COP with ammonia, steam and R 11 and reported that COP of R 11 ejector cycle is as good as steam ejector cycle. Since a steam system has got its own limitations, a Freon ejector system is acceptable for low-grade energy applications.

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References1. Y. Bartosiewicz, Z. Aidoun, P. Desevaux and Y. Mercadier, Numerical and experimental investigations

on supersonic ejectors, Int. J. Heat Fluid Flow 26 (2005) 56-70.2. K. Cizungu, A. Mani and M. Groll, Performance comparison of vapor jet refrigeration system with

environmentally friendly working fluids, Appl. Therm. Eng. 21 (2001) 585-598.3. Szabolcs Vargaa, Armando C. Oliveiraa, Bogdan Diaconu, Influence of geometrical factors on steam

ejector performance4. L. Seouk Park, Numerical investigation of entraining performance and operational robustness of

thermal vapor compressor having swirled motive steam inflow, Desalination 257 (2010) 206 – 211.5. S. Park, S. M. Park, J.S. Ha, Design and application of thermal vapor compressor for multi-effect

desalination plant, Desalination 182 (2005) 199–208.6. S. Park, Robust numerical analysis based design of the thermal vapor compressor shape parameters for

multi-effect desalination plants, Desalination 242 (2009) 245–255.7. Y. Zhu, P. Jiang, Experimental and numerical investigation of the effect of shock wave characteristics

on the ejector performance, Int. J. Refrig. 40 (2014) 31-42.8. Ala Bouhanguel, Philippe Desevaux, Eric Gavignet, Flow visualization in supersonic ejectors using

laser tomography techniques, Int. J. Refrig. (2010) 1-8.9. P. Desevaux, A. Mellal, Y. Alves de Sousa, Visualization of secondary flow choking phenomena in a

supersonic air ejector, J. Vis. 7 (2004) 249-256.10. Ala Bouhanguel, Philippe Desevaux, Eric Gavignet, Flow visualization in supersonic ejectors u sing

laser tomography techniques, Int. J. Refrig. 34 (2011) 1633-1640.11. Selvaraju and A. Mani, Analysis of a vapor ejector refrigeration system with environment friendly

refrigerants, Int. J. Therm. Sci. 43 (2004) 915–921.12. Selvaraju and A. Mani, Analysis of an ejector with environment friendly refrigerants, Appl. Therm.

Eng. 24 (2004) 827 – 838.13. Selvaraju and A. Mani, 2005,CFD analysis of an ejector in vapor ejector refrigeration system with

environment friendly refrigerant, Int. Seminar on ejector/jet-pump technology and application, Louvain-la-Neuve, Belgium Paper No. 11.

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References contd.,

14. Sankarlal, T. and Mani, A 2006, ‘Experimental studies on ammonia ejector refrigeration system’, International Communications on Heat and Mass Transfer,Vol.33,pp.224-230

15. Sankarlal, T. and Mani, 2007, A. Experimental investigation on ejector refrigeration with ammonia, International Journal on Renewable Energy, Vol.32, pp.1403-1413

16. Senthil Kumar. R, Kumaraswamy. S, Mani. A, (2007) Experimental investigations on a two-phase jet pump used in desalination systems , Desalination 204, 437–447

17. Kumar, A. and V. Charan, (1981), Refrigerant–11 ejector refrigeration system, Indian society of Mechanical Engineering Conference, University of Roorkee, India

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Methodology

• Analysis and optimization of ejector with a single and multiple swirl• Design and fabrication of altuglas ejector to incorporate swirl • Design and fabrication of stainless steel ejector to incorporate swirl • Design and fabrication of generator, vapour separation tank, vapour collection tank • Design and fabrication of simulator for generator, condenser and evaporator• Design and fabrication of compact condenser, evaporator• Design and fabrication of liquid refrigerant receiver • Selection and procurement of water pump and hermetically sealed centrifugal pump• Selection and procurement of instruments• Flow visualization studies on ejector• Experimentation on ejector with swirl• Design and development of compact vapour jet refrigeration system (VJRS)• Experimentation on VJRS • Experimental performance analysis

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Salient Research achievements

Summary of Progress

(a) One-dimensional analysis

(b) 3D CFD studies with and without swirl

(c) Experimental studies on acrylic ejector with Flow visualisation using PIV facilities (i) without swirl (ii) with swirl with different swirl angles using swirl generator

(d) Experimental studies on ejector working with R134a (i) without swirl (ii) with swirl of different swirl angles using swirl generator

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Studies carried out (a) One-dimensional analysis using MATLAB Ejector geometry working with R134a was arrived by solving the conservation

equations of mass, momentum and energy using MATLAB. Also efficiencies of nozzle, mixing tube, diffuser and frictional losses were included in the coding.

Parametric studies under simulated operating conditions has been carried out.

Fig.1 Effect of condenser temperature on critical entrainment ratio

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Fig.2 Effect of generator temperature on the critical entrainment ratio and COP.

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Fig.3 Effect of evaporator temperature on critical entrainment ratio

Tg= 75oC

Tsh=5oC

Tc=30oC

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One-dimensional studies outputBased on one-dimensional studies, the geometry arrived for 3D-CFD studies is shown in Fig.

Fig. 4 Geometric details of ejector obtained from one-dimensional analysis

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3D Numerical analysis details Solver and turbulence model

• 3D, Compressible and Turbulent flow

• Density based solver with k-ε turbulence model and standard wall function

• Though the steady state is desired, the unsteady terms are conserved, because from numerical point of view, the governing equations are solved with a time marching technique.

• Mesh quality = 0.6 to 0.8

• Aspect Ratio = 10

• Grid independent study has been done and 105 polyhedral cells have been chosen as per the desired accuracy of results and economic aspect of computational costs.

• Convergence criteria for the residuals of mass, momentum, energy, turbulent kinetic energy and dissipation energy are of the order of 10-6

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Fig.5 (a) solid model of swirl generator inside primary nozzle (b) Details of swirl vane

(a) (b)

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Fig.6 Validation of CFD numerical results

Generator temperature : 65C to 80C Condenser temperature : 27C Evaporator temperature : 10C Deviation of entrainment ratio within 10%

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Fig.7 Variation of static pressure along the axis of ejector with and without swirl generator

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Fig. 8 Variation of static pressure along the axis of ejector with and without swirl

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Fig- 9. Variation of Mach number along the axis of ejector with and without swirl

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Fig. 10 Vector representing swirl flow in the cross sectional plane across the swirl generator

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Table 1: Entrainment ratio with primary and secondary mass flow rates

Table 2: Position of swirl generator in ejector

Improvement in ER with swirl is about 6% compared to ejector with out swirl

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Swirl generator at nozzle exit

Fig.11 Contours of velocity magnitude of ejector with swirl generator at the exit of nozzle

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At convergent portion of nozzle

5mm far from convergent portion

10mm far from convergent portion

Fig.12 Mach number variation along ejector axis for various position of swirl generator

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Fig.13 Photograph of acrylic ejector

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Fig.14 Components of acrylic ejector

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Fig.15 PIV experimental setup

05/02/23 28Fig.16 Photograph of compressor and UPS system of air ejector

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Experimental setup of VJRS

Fig. 17 Schematic diagram of experimental setup of VJRS

G- Generator M – Motor BV 1 to 7 - Ball Valve GV 1 - Globe Valve C- Condenser SH –Superheat heat exchanger VFD - Variable Frequency Drive CT - Capillary Tube HSP - Hermetically Sealed Pump VC- Vapour Condenser E – Evaporator T – ThermocoupleNV 1 to 4 - Needle Valve HWS - Hot Water Simulator CWS - Cold Water Simulator FM 1, 2 - Flow Meter EC- Evaporative Coil WP 1 to 3 - Water Pump VST - Vapour Separation Tank LG1,2 - Level Gauge

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Fig. 18 Sectional view of the assembled components of ejector

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Component details of R134a ejector

Fig. 19 Photograph of component details of R134a ejector

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(a) (b)

(c)

Fig.20 Calibration curves for (a) pressure transmitter (b) Thermocouple (c) Flowmeter

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Photograph of VJRS system

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Fig . 21 Photograph of hot water and cold water simulators

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Work element

Period in months

0 -3 4 -6 7- 9 10 -12 13 -15 16 -18

19 -21

22- 24

25 -27

28 -30

31 -33

34 -36

Common

A1

A2

Technical

B1

B2

B3

B4

B5

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The entire project work can be split into the following work elements.

A. Common Work Elements:• A1 Recruitment of personnel• A2 Preparation of project report

B. Technical Work Element for the System:

• B1 Theoretical analysis and design of compact heat exchanger namely generator,

Condenser and evaporator• B2 Design of entraining chamber around the circumference of primary

nozzle, through which secondary vapour jet is entrained.• B3 Analysis and optimization of swirl in the ejector using swirl generator• B4 Ejector modeling based on optimization• B5 Flow visualization system for the flow and mixing process in ejector

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Work element

Period in months

0 -3 4 -6 7- 9 10 -12 13 -15 16 -18

19 -21

22- 24

25 -27

28 -30

31 -33

34 -36

B6

B7

B8

B9

B10

B11

B12

B13

B14

B15

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• B6 Design of simulator for generator, condenser and evaporator• B7 Preparation of fabrication drawings• B8 Procurement of materials • B9 Fabrication of the components• B10 System integration• B11 Instrumentation• B12 Detailed experimentation with swirl in ejector using swirl generator • B13 Experimental studies on compact vapour ejector refrigeration system• B14 Performance analysis• B15 Development of prototype of compact VJRS

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Project Account Summary as on 14/01/2015Project Number : MEE1213295DSTXAMAN Duration :31-07-2012 To 30-07-2015

Sanction Number : SR/S3/MERC-0079/2011 Sanction Date : 28-06-2012Coordinator Name : Mani A

Title : Performance analysis and development of compact vapour jet refrigeration system

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Thank you