Multi-jet Air ImpingementTechnique

Under the Guidance of

Dr. V.R. Kalamkar

By: ARAVIND YADAV

(12MT07HPE002)

Mech. Engineering Department

VNIT Nagpur

INTRODUCTION

Jet impingement is a convective heat-transfer method in which the energy is transported by the bulk motion of the air.

A jet impingement system may consist of a single jet or multiple jets of high velocity that are directed (orthogonally or at another angle) toward the surface of the product.

Jet impingement is one of the very efficient solutions of cooling hot objects in industrial processes as it produces a very high heat transfer rate through forced-convection.

Rapid heat-transfer methods can be used to shorten the process time and increase the production rate.

Continue….

Impinging jets have been widely used and developed to increase heat transfer in areas such as:-

Food industry

Paper industry

Textile industry

Cooling of turbine blade

Cooling electronic components

Anti-ice systems on aircraft

Air quenching of products in the steel and glass industries

LITERATURE SURVEY-1

Flow and heat transfer from multiple slot air jets

impinging on circular cylinders by E.E.M. Olsson, L.M.

Ahrne , A.C. Tragardh published a paper in 2004.

In this paper heat transfer and flow pattern predictions of

single and multiple slot air jets impinging on circular

cylinders using CFD. is studies and they compare the results

Experiment is carried out at domain pressure 0.1 MPa and 2

degree temperature by keeping solid food product at 35

degree.

LITERATURE SURVEY-2

STUDY OF HEAT TRANSFER COEFFICIENT FOR

MULTI-JET AIR IMPINGING COOLING by Mohammad

Khyru Bin Aris published a paper in 2009.

In this paper he analysed the heat transfer coefficient

and temperature distribution through multi jet

impingement for various configurations of jet ,jet to jet

spacing , jet to surface height and Reynolds number.

LITERATURE SURVEY-3

o CFD Analysis of Multi-jet Air Impingement on Flat Plate by Chougule N.K., Parishwad G.V., Gore P.R., Pagnis S., Sapali S.N. (2011)

o In this paper hear transfer coefficient and temperature distribution is analysis by using CFD on the 60mm*60mm plate which produce constant heat flux of 8333 watt/meter square .

o He use four different turbulent model and compare the error with the real results.

o The best result obtained by CFD in SST model with 2.1% error in prediction in Nu.

LITERATURE SURVEY-4

Numerical Simulation for Studying Heat Transfer in Multi Jet Impingement on Dense Pin Fin Heat Sinks by Lakshmi Prasad K, A. Ramakrishna, N.V.S. Shankar .(2013)

In this paper heat transfer coefficient and temperature distribution is analysis 3*3 nozzle by changing fin density of flat plate and Reynolds number .

He observed that the denser design of pin fin heat sinks gives better results.

higher air velocity at lower pressure drop in denser design due to greater restriction of flow in direction perpendicular to the impingement direction

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It is also observed that the heat dissipation is increasing with increase in Re value in designs.

Components

Blower

Flow control valve

Air box

Pipe

Nozzle

Heater

Metal plate

One side open insulated box

Heater power control unit

DAQ system

Schematic Diagram of a Typical MJAIS

Nozzle details

Variable Parameter

Type of surface

nozzle geometry

jet-to-surface spacing

Type of flow

jet-to-jet spacing

Temperature

pressure

REFERENCES

E.E.M. Olsson, L.M. Ahrens, and A.C. Tragardh. Prediction of optimal heat transfer from slot air jets impinging on cylindrical food products using CFD. In: Proceedings of the 9th International Congress on Engineering and Food (ICEF 9), Montpellier, France, 2004.

CFD Analysis of Multi-jet Air Impingement on Flat Plate Chougule N.K., Parishwad G.V., Gore P.R., Pagnis S., Sapali S.N. in World Congress on Engineering 2011 Vol III WCE 2011, July 6 - 8, 2011, London, U.K

Kang, S. H., & Greif, R. (1992). Flow and heat transfer to a circular cylinder with a hot impinging air jet. International Journal of Heat and Mass Transfer, 35(9), 2173–2183.

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