### Experimental Study of Forced Convection over Equilateral Triangle Helical Coiled Tubes

#### Abstract

This study presents an experimental investigation of an equilateral triangular cross-sectioned helical tube under uniform heat flux boundary condition. The experiments are carried out for nine helical coiled-tubes of different parameters. Different diameter ratio (D/a) ranged from 6.77 to 15.43 and pitch ratio (P/a) ranged from 1.127 to 3.062 are employed in the present study, The experiments covered a range of Reynolds number from 5.3X10^{2} to 2.2X10^{3}. Uniform heat flux is applied to the inside surface of the helical coil and air is selected as tested fluid. The experimental results obtained from the equilateral triangular cross-sectioned helical tube indicated that the parameters of the coil diameter and pitch of helical coil have important effects on the heat transfer coefficient. The Nusselt number increases with the increase of Reynolds number and coil diameter at constant pitch of the helical coil. Also, Nusselt number increases with the increase of Reynolds number and Pitch of helical coil at constant coil diameter tube. A comparison between the present experimental data with a previous work with circular cross-sectioned helical tubes have the same test conditions was achieved. From this comparison, it is clear that the average enhancement of Nusselt number for equilateral triangular cross-sectioned helical is about 1.12 ~ 1.25 times the circular cross-sectioned helical for all tested conditions. A general correlation of the average Nusselt number as a function in Re, D/a and P/a ratios is obtained to describe the forced convection from the equilateral triangle cross sectioned coiled tube.

** Key words: ** Forced convection; Helical coiled tubes; Coil diameter ratio; Pitch ratio

#### Keywords

#### Full Text:

PDF#### References

[1] Patankar, SV, Pratap, VS, & Spalding, DB. (1974). Prediction of Laminar Flow and Heat Transfer in Helically Coiled Pipes. *J Fluid Mechanical*, *62*, 53–551.

[2] Yang, G., Dong, F., & Ebadian, MA. (1995). Laminar Forced Convection in a Helicoidally Pipe with Finite Pitch. *Int J Heat Mass Transfer*, *38*(5), 853–62.

[3] Rennie, TJ, & Raghavan, GSV. (2002). Laminar Parallel Flow in a Tube-in-Tube Helical Heat Exchanger. *AIC 2002 Meeting CSAE/SCGR Program **at Saskatoon, Saskatchwan* (pp. 14-17).

[4] Inagaki, Y., Koiso, H., Takumi, H., Ioka, I., & Miyamoto, Y. (1998). Thermal Hydraulic Study on a High-Temperature Gas–Gas Heat Exchanger with Helically Coiled Tube Bundles. *Nucl**. Eng**. Des*., *185*(2-3), 141–151.

[5] Prabhanjan, DG, Raghavan, GSV, & Rennie, TJ. (2002). Comparison of Heat Transfer Rates Between a Straight Tube Heat Exchanger and a Helically Coiled Heat Exchanger. *Int Commun Heat Mass Transfer*, *29*(2), 185–191.

[6] Rogrers, G.F.C., & Mayhew, Y.R. (1964). Heat Transfer and Pressure Loss in Helically Coiled Tubes with Turbulent Flow. *International Journal of Heat and Mass Transfer*, *7*(11), 1207–1216.

[7] Manlapaz, R.L., & Churchill S.W. (1981). Fully Developed Laminar Convection from a Helically Coil. *Chemical Engineering Communication*, *9*, 185–200.

[8] Moawed, M. (2005). Experimental Investigation of Natural Convection from Vertical and Horizontal Helicoidal Pipes in HVAC Applications. *Energy Conservation and Management*, *46*(18-19), 2996–3013.

[9] Prabhanjan, D.G., Rennie, T.J., & Raghavan, G.S.V. (2004). Natural Convection Heat Transfer from Helical Coiled Tubes. *International Journal of Thermal Sciences*, *43*(4), 359–365.

[10] Conté, I., Peng, X.F., & Wang, B.X. (2008). Numerical Investigation of Forced Fluid Flow and Heat Transfer from Conically Coiled Pipes. *Numerical Heat Transfer Part A: Applications*, *53*(9), 945–965.

[11] Prabhanjan, D. G., Raghavan, G. S. V., & Rennnie, T. J. (2002). Comparison of Heat Transfer Rates Between a Straight Tube Heat Exchanger and a Helically Coiled Heat Exchanger. *Jnt. Comm. Heat Mass Transfer*, *29*(2), 185 – 191.

[12] Ko, T. H., & Ting, K. (2005). Entropy Generation and Thermodynamic Optimization of Fully Developed Laminar Convection in a Helical Coil. *Int. Commun Heat Mass Transfer*, *32*(1-2), 214–223.

[13] Andrea, C., & Lorenzo, S. (2006). An Experimental Investigation Regarding the Laminar to Turbulent Flow Transition in Helically Coiled Pipes. * Experimental Thermal and Fluid Science* *30*(4), 367–380.

[14] Timothy, A., Rennie, J., & Vijaya, G.S. (2005). Experimental Studies of a Double-Pipe Helical Heat Exchanger. *Experimental Thermal and Fluid Science*, *29*(8), 919– 924.

[15] Comini, G., Savino, S., Bari, E., & Bison, A. (2008). Forced Convection Heat Transfer from Banks of Helical Coiled Resistance Wires. *International Journal of Thermal Sciences*, *47*, 442–449.

[16] Gunes, S., Ozceyhan, V., & Buyukalaca, O. (2010). Heat Transfer Enhancement in a Tube with Equilateral Triangle Cross Sectioned Coiled Wire Inserts. *Experimental Thermal and Fluid Science*, *34*(6), 684–691.

[17] Xia, G.D., Chai, L., Wang, H.Y., Zhou, M.Z., & Cui, Z. Z. (2011). Optimum Thermal Design of Micro Channel Heat Sink with Triangular Reentrant Cavities. *Applied Thermal Engineering*, *31*(6-7), 1208-1219.

[18] Mohsenzedh, A., Farhadi, M., & Sedighi, K. (2010). Convective Cooling of Tandem Triangular Cylinders Placed in a Channel. *Thermal Science*,* 14*(1), 183-197.

[19] Farhadi, M., Sedighi, K., & Korayem, A.M. (2010). Effect of Wall Proximity on Forced Convection in Plane Channel with a Built-in Triangular Cylinder. *International Journal of Thermal Sciences*, *49*(6), 1010-1018.

[20] Mohamed, Ali, Zeitoun, O., & Nuhait, A. (2011). Forced Convection Heat Transfer over Horizontal Triangular Cylinder in Cross Flow. *International Journal of Thermal Sciences*, *50*(1), 106-114.

[21] Wongcharee, K., & Eiamsa-ard, S. (2011). Heat Transfer Enhancement by Twisted Tapes with Alternate-Axes and Triangular, Rectangular and Trapezoidal Wings. *Chemical Engineering and Processing*, *50*(2), 211–219.

[22] Moawed, M. (2011). Experimental Study of Forced Convection from Helical Coiled Tubes with Different Parameters. *Energy Conversion and Management*, *52*(2), 1150–1156.

[23] ANSI/ASME. (1986). *Measurement Uncertainty** *(Part I, PTC 19, 1-1985).

DOI: http://dx.doi.org/10.3968/j.est.1923847920120302.378

### Refbacks

- There are currently no refbacks.

**Reminder**

If you have already registered in Journal A and plan to submit article(s) to Journal B, please click the **CATEGORIES**, or **JOURNALS A-Z **on the right side of the "**HOME**".

We only use three mailboxes as follows to deal with issues about paper acceptance, payment and submission of electronic versions of our journals to databases: caooc@hotmail.com; est@cscanada.net; est@cscanada.org

Articles published in **Energy Science and Technology*** *are licensed under Creative Commons Attribution 4.0 (CC-BY).

* ENERGY SCIENCE AND TECHNOLOGY* Editorial Office

**Address**: 9375 Rue de Roissy Brossard, Québec, J4X 3A1, Canada **Telephone**: 1-514-558 6138 **Website:** Http://www.cscanada.net Http://www.cscanada.org **E-mail**: est@cscanada.net; est@cscanada.org

Copyright © 2010 **Canadian Research & Development Centre of Sciences and Cultures**