RESEARCH POSTER PRESENTATION DESIGN © 2015 www.PosterPresentations.com Two phase Taylor flow is a flow patterns that has been examined extensively over the past ten years. It is characterised by splitting the fluid stream up into a series of shorter elements or plus. Researchers refer to Taylor flow as plug or segmented flow. A two phase Taylor flow of low viscosity silicone oil-water is illustrated in figure (1). Heat transfer is an important characteristic of liquid-liquid Taylor flow. It has been known that within liquid plugs of segmented flow, internal circulation arise as a results of gas-liquid, or liquid-liquid interfaces. It has been proven by Muzychka et al. (2009) that theses internal circulation explain the thermal enhancement resulting from Taylor flow. Therefore, the application of liquid-liquid Taylor flow in the heat transfer in mini-scale tubes is a promising technique for process optimization due to both fluid segments participating. INTRODUCTION OBJECTIVES Ø Experimental Facilities and Setup An experimental facility for heat transfer and pressure drop characteristics has been assembled in the Micro-fluidics lab at Memorial University, as shown in Fig. (4). METHODOLOGY Ø Benchmark Test RESULTS CONCLUSIONS In this application liquid-liquid Taylor flow are studied the thermal performances of these flows, which can be helpful in understanding the whole process better, including pressure drop and film thickness in this flow regime. The working fluids are water and low viscosity silicone oils. The experimental data is presented using the dimensionless variables for heat transfer, and pressure drop. The results of single-phase flow in a mini- scale tube are used as a reference point to the new two-phase Taylor flow data. The new experimental data for liquid-liquid Taylor flow in straight and curved mini-scale tubes is compared to a model proposed for Poiseuille and slug Graetz flow in a circular tube. The comparison provides validation for the model for predicting convective heat transfer rate and pressure drop in liquid-liquid Taylor flow in mini-scale tubes with different geometries. REFERENCES [1] Adrugi M. A., Muzychka Y. S., and Pope K., “Heat Transfer in Liquid- Liquid Taylor Flow in a Mini-Scale Tube with Constant Wall Temperature”, ASME 2015 13th Int. Conference on Nanochannels, Microchannels, and Minichannels, July 6-9, 2015, CA.,USA . [2] Asthana A., Zinovik I., Weinmueller C., and Poulikakos D., “Significant Nusselt number increase in microchannels with a segmented flow of two immiscible liquids: An experimental study”, Int. J. of Heat and Mass Transfer, 54, p. 1456– 1464, (2011). [3] Eain M. G, Egan V., Punch J. “Review and extension of pressure drop models applied to Taylor flow regimes”, Int. J. of Heat and Mass Transfer, 68, pp. 1-9, (2015). [4] Fischer M., Juric D., Poulikakos D.,. “Large Convective Heat Transfer Enhancement in Microchannels With a Train of Coflowing Immiscible or Colloidal Droplets”, Int. J. of Heat Transfer, 132, 112402-1, (2010). [5] Eain M. G, Egan V., Punch J. “Local Nusselt number enhancements in liquid-liquid Taylor flow”, Int. J. of Heat and Mass Transfer, 80, pp. 85-97, (2015). [6] Muzychka Y. S., Walsh E., Walsh P., “Heat transfer enhancement using laminar gas-liquid segmented fluid stream”, Proceedings of Inter Pack 2009, San Francisco, July 19-23, (2009). [7] Ghobadi M., Muzychka Y.S., Measurement and Analysis of Laminar Heat Transfer Coefficients in Micro and Mini-Scale Ducts and Channels, ASME 2014 4th, Chicago, Illinois, USA, August 3–7 , (2014). [8] Janes N., Muzychka Y. S., Guy B., Walsh E. J., and Walsh P., Heat transfer in gas-liquid and liquid-liquid two-phase plug flow systems. Proceedings of 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, (2010). [9] Malsch D., Kielpinski M., Merthan R., Albert J., K¨ohler J., S¨uße H., Stahl M., Henkel T., “PIV-Analysis of Taylor flow in micro channels”, Chemical Engineering Journal 135S (2008). ACKNOWLEDGEMENTS and CONTACT The authors acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) for providing financial assistance under the discovery grants program. The first author acknowledges the financial support of the Libyan Ministry of Higher Education and Scientific Research. Corresponding author. : Tel:+1 709 864 2050 E-mail addresses: [email protected] (W. Adrugi), [email protected] (Y. S. Muzychka), [email protected] (K. Pope) The main focus in the present research is on modeling of liquid-liquid Taylor flows using experimental method based on the concept of the internal fluid flow and using a dimensionless analysis for reduce experimental data. Ø The following subjects in modeling liquid-liquid Taylor flow will be addressed in this research : ü Measurement of heat transfer in a small scales with types of geometries ü Measurement of pressure drop üMeasurement of film thickness ü Measurements of streaming velocities in plugs using a PIV Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL, Canada, A1B 3X5 Wesam Adrugi, Yuri Muzychka, Kevin Pope Department of Mechanical Engineering Modeling of Liquid-Liquid Taylor Flow in Mini-Scales Channels Fig. 1 - Two-phase Taylor flow of water- 1 cSt oil in mini-channel (D h =1.65 mm) with the water is dyed red for visibility. Discharge Tank Pump A Pump B Camera Pressure Transducer Isotemp. Bath DAQ CPU Ø Create Liquid-Liquid Taylor Flow Two-phase liquid-liquid Taylor flow has been obtained by using T, Y, and X junctions, and junction boxes/segmenters have already been designed, manufactured and examined. Fig 5 - Illustration of segmented flow for (a) variable flow rates of water and constant flow rate of 1 cSt oil (right column), and (b) variable flow rates of 1 cSt oil and constant flow rate of water (left column). Fig. 4 - Schematic of experimental apparatus. Fluid Prandtl # Reynolds # Peclet # Water Dispersed Phase 5.4 50-935 270-5049 0.65 cSt Oil Con/nuous Phase 8.4 59-1188 496-9979 1 cSt Oil 13.8 38-737 524-10,171 3 cSt Oil 38.5 41-705 1578-27,142 Ø Fluid Test Water and three low viscosity silicone oils were used. Ø Analytical Model of Taylor Flow The following expressions are used to validate the results for dimensionless mean heat flux for constant wall temperature, Muzychka et al. (2009) and pressure drop. q For Graetz - Poiseuille flow in a circular tube: q For Graetz - Plug flow in a circular tube: q Pressure drop of liquid-liquid Taylor flow: q Plug * = 1.128 L *1/2 ! " # $ % & −2 + 1 4 L * ! " # $ % & −2 ( ) * * + , - - − 1 2 q Pois * = 1.614 L *1/3 ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ − 3 2 + 1 4 L * ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ − 3 2 ⎡ ⎣ ⎢ ⎢ ⎤ ⎦ ⎥ ⎥ − 2 3 , L e * = L e D Ca 2 cosθ ΔP T * = 16 + 1 L e * ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ , L * = L D 1 Pe ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ 1 10 0.005 0.05 q* L* Water / 3 cSt Oil Taylor Flow Water / 1 cSt Oil Taylor Flow Straight Tube 0.1 1 10 0.01 0.1 1 q* L* Water 0.65 cSt Silicone Oil 1 cSt Silicone Oil Graetz Model 1/4L* 0.01 0.1 1 50 500 f Re Exp. Theory 1 10 0.005 0.05 q* L* R=2 cm, θ=360° R=4 cm, θ=180° Straight Tube 1 10 0.01 0.1 q* L* Long tube (3 cSt oil) Medium tube (3 cSt oil) Short tube (3 cSt oil) 1/4L* Graetz - Plug Flow Graetz - Poiseuille Flow 10 100 1000 0.001 0.01 ΔP* Le* Proposed Model Exp. (α=0.5-0.16) Exp. (α=0.5-0.83) Exp. (α=0.5) Ø Heat Transfer in a Straight Tube Ø Heat Transfer in a Curved Tube Ø Pressure Drop in a Straight Tube Fig. 7 - Comparison of Taylor flow heat transfer data at various flow rates with various lengths channels . Fig. 9 - Non-dimensional total pressure drop, as a function of dimensionless slug length and Capillary numbers compared with the theoretical solution. Fig. 8 - Comparison of Taylor flow heat transfer data in curved tubes with straight tubes at various flow rates with various lengths and curvatures. Fig. 6 - Benchmarking results for heat transfer and pressure drop with 10% & 15% error bar. Ø Mechanism of Heat Transfer Enhancement in Taylor Flow § Using a Taylor flow is another passive way to enhance single-phase heat transfer in small scale tubing. § The internal circulation in Taylor flow effect on heat transfer in a moving slugs. Fig. 3 – Instantaneous velocity vector and streamline in liquid plugs for (a) straight micro-channel, and (b) curved micro-channel (Malsch et al. 2008) Fig. 2 –Temperature field for liquid-liquid Plug flow (Fischer et al. 2010).