Review of existing electronic product test sites

7.1 FURTHER RESEARCH (A) COMPRESSED AIR

The ability to create compressed air in a rural setting needs more attention to increase the viability of the system. As compressed air has the benefit that it is in itself storage of energy. The basic project objectives can be met with the traditional commercial products. It is our intention that if this application of technologies is economically viable then the innovative spirit will help local communities to better the product for financial gain.

(B) CREATING CLEAN WATER

An additional benefit of temperature drop is the ability to drop the temperature below the dew point and remove the water from the air. The benefit of this is that this water is considered clean. The inlet air conditions are 30⁰C, with relative humidity of 80% and exit conditions of 10⁰C and 0% relative humidity.

(C) REVERSING SYSTEM OF HEAT

The reverse of Ranque-Hilsch phenomenon produces a temperature separation creating a significant heat rise. Laboratory experiments of the dissigno prototype have reached over 80⁰C. This has several practical applications. These high temperatures may be used to reach pasteurization temperatures for water. In addition, the model suggested the vortex tube may need to be occasionally defrosted to maintain the performance. The system could be temporarily reversed to melt any ice in the system.

54 (D) INCREASED VORTEX EFFICIENCY

The vortex is by far the least efficient part of this process and increase its efficiency will dramatically affect the overall efficiency of the system. Vortex performance has been the topic of research to make it more effective as a refrigeration device. Twisted airflow disturbance can be used to increase the cold production. The rigid spiral showed an increase in the refrigeration effect by up to 25%. This increase in the performance would greatly increase the overall efficiency of the system and directly increases the Ice production.

7.2 Future Developments

(A) USE OF SILENCERS AND MUFFLERS:

The experimental investigation shows that the air is leaving the tube with high shrill noise. Using silencer and sound mufflers can attenuate the hissing sound. Such an arrangement while reducing the sound level also increases the temperature of out coming air by increasing its pressure and reducing its velocity. Hence, an effective arrangement optimizing the sound attenuation and lower outer temperature can be developed.

(B) DESIGN OF WARM TUBE END:

A valve is used at the end of warm tube to allow some air to escape as hot air and reversing the direction of remaining air, thus creating forced vortex, i.e. desired cold fraction is achieved by the valve. Different types of valves have been tested and it has been found that they give more or less the same result. However, fixing the desired outlet temperature of the air i.e., Cold fraction and an effective arrangement like fitting a brass can use bush with small orifice to give desired output. Further the elimination of the valve reduces the overall weight of the tube.

(C) DESIGN OF OUTER TUBE:

Outer tube besides holding the whole assembly, also acts as mediator in heat dissipation, hence it should be designed in such a way that it dissipates heat as quickly

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as it can. This can be achieved by drilling the holes on the hot side of the outer tube enhancing the natural circulation. Also water cooling may improve the heat transfer.

(D) THE COLD ORIFICE OR DIAPHRAGM:

When the temperature of air drops down below 0⁰C, the moisture in it gets converted into ice. This may obstruct the flow and can alter the performance. Hence a deep study is needed to be carried out in these regards. Apart from above areas there are more regions of developments one can concentrate on such as relatively high power consumptions, low COP of the system.

Recommendations:

Based on the fact that the device had very poor cooling capacity as compared with industry standard refrigeration devices, it would not be a good substitute for commercial purposes. Significant redesign of the device may in the future better the cooling capacity to a point where it may be usable in the refrigeration industry, but for now, all these devices can be reasonably used for the spot cooling and perhaps providing a quick and simple way to cool or heat a pressure stream.

Since the device has specific length and diameter restrictions, one cannot significantly alter the design of the tube. The reason it has certain length restrictions is that too short of the tube would not give the hot stream enough time to heat up and too long of a length would cause the vortex within the tube to depressurize and collapse.

Likewise, too large a tube diameter will also collapse the vortex flow, so there are tight restrictions on tube design. Increasing pressure will help to enlarge these dimensions, but only slightly and pressurizing the air could get costly depending on the scale up.

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REFERENCES

[1] Vera, G.D. The Ranque-Hilsch Vortex Tube, May 10, 2010.

[2] Nimbalkar S.U., Quantitative observations on multiple flow structures inside Ranque-Hilsch Vortex Tube. Graduate Program in Mechanical & Aerospace Engineering, 2009

[3] N.V. Poshernev and I.L. Khodorkov. Natural-gas tests on a conical vortex tube (CVT) with external cooling. Chemical and Petroleum Engineering, 40(3-4):212–217, March 2004.

[4] R.L. Collins and R.B. Lovelace. Experimental study of two-phase propane expanded through the Ranque-Hilsch tube. Trans. ASME, J. Heat Transfer, 101:300–

305, May 1979.

[5] R.T. Balmer. Pressure-driven Ranque-Hilsch temperature separation in liquids.

Trans. ASME, J. Fluids Engineering, 110:161–164, June 1988.

[6] Smith Eiamsa-ard and P. Promvonge, Numerical simulation of flow field and temperature separation in a vortex tube, International communications in Heat and Mass Transfer, Vol 35, 2008, pp-937-947.

[7] M.H. Saidi, M.S. Valipour: Experimental modelling of vortex tube refrigerator, App. Thermal Engg. April 2003.

[8] Ahlborn B, Groves S. Secondary flow in a vortex tube, Fluid Dynamics Research, Volume 21, 1997, pp. 73-86

[9] C.D. Fulton. Comments on the vortex tube. J. ASRE Refrigerating Engng, 58:984, 1950.

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[10] W.S. Lewellen. A solution for three-dimentional vortex flows with strong circulation. J. Fluid Mech., 14:420–432, 1962.

[11] C.M. GAO, K.J. Bosschaart, J.C.H. Zeegers, and A.T.A.M. de Waele.

Experimental study on a simple Ranque-Hilsch vortex tube. Cryogenics, 45(3):173, 2005

[12] Gao C (2005) Experimental study on the Ranque–Hilsch vortex tube. PhD Thesis, Technische Universiteit Eindhoven.

[13] Soni Y, Thompson WJ (1975) Optimal design of the Ranque–Hilsch vortex tube.

Trans ASME J Heat Transfer 94(2):316–317.

[14] Nellis G.F & Klein S.A. (2002) The Application Of Vortex Tubes to Refrigeration Cycles. Purdue University

[15] M. sssYilmaz, M. Kaya, S. Karagoz & S. Erdogan (2009) A review on design criteria for vortex tubes. Heat Mass Transfer 45:613–632

[16] K. Dincer, S. Baskaya, B.Z. Uysal, I. Ucgul, Experimental investigation of the performance of a Ranque–Hilsch vortex tube with regard to a plug located at the hot outlet, International journal of refrigeration 32 (2009) 87–94.

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