Abstract
In this study, effects of geometrical parameters on the average convection heat transfer characteristics in helical square ducts were investigated both experimentally and numerically. The inner wall of the helical square duct was uniformly temperatured, and the top, bottom, and outer walls were adiabatic. The Renormalization Group (RNG) k–ε turbulence model was used to simulate turbulent flow and heat transfer. The governing equations were solved by a finite volume method. Numerical results were found to be in good agreement with the presented experimental data. The new correlation was proposed for the average heat transfer coefficient on the inner wall of the helical square duct. The results showed that the ratio of pitch to coil radius b/R has no obvious effect on the inner wall convective heat transfer coefficient but the ratio of hydraulic radius to coil radius a/R has considerable effect.
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Abbreviations
- A :
-
Surface area [m2]
- A I :
-
Helical coil inner wall total surface area (outer wet surface area of copper pipe) [m2]
- a :
-
Hydraulic radius [m]
- a P :
-
Coefficient of P cell
- b :
-
Helical coil pitch [m]
- C 1ε :
-
Turbulent model constant
- C 2ε :
-
Turbulent model constant
- C p :
-
Specific heat under constant pressure [J/kg K]
- C μ :
-
Turbulent model constant
- c :
-
Constant part of the source term
- D :
-
Outer diameter of the test section [m]
- d h :
-
Hydraulic diameter [m]
- g :
-
Gravitational acceleration [m/s2]
- h :
-
Convection heat transfer coefficient [W/m2 K]
- h fg :
-
Latent heat of vaporization per one kg of condensed vapor [J/kg]
- I :
-
Turbulent intensity \((= u'/\bar u)\)
- k :
-
Turbulent kinetic energy [m2 /s]
- L :
-
Length [m]
- l :
-
Turbulent mixed length [m]
- l ε :
-
Length scale of turbulent kinetic energy dissipation [m]
- l μ :
-
Length scale of viscosity [m]
- m :
-
Mass flow rate of cooling water [kg/s]
- m y :
-
Mass flow rate of condensation [kg/s]
- Nu :
-
Nusselt number
- Nu c :
-
Nu number calculated from the new correlation
- n :
-
Normal direction
- P :
-
Pressure [Pa]
- Pr:
-
Prandl number
- Q :
-
Rate of heat transfer [W]
- q′′:
-
Wall heat flux [W/m2]
- R :
-
Radius of helical coil [m]
- R′:
-
Represents the effect of strain in ε equation [kg/ms4]
- Re:
-
Re number
- Rey :
-
Re number for a cell which has a distance of y from the nearest wall
- S :
-
Modulus of mean rate of strain tensor [1/s]
- T :
-
Temperature [K]
- T ∞ :
-
Mixed mean temperature [K]
- T fl :
-
Film temperature of condensed vapor [K]
- T S1 :
-
The first contact point temperature of outer surface of copper pipe with cooling water [K]
- T S2 :
-
The mid contact point temperature of outer surface of copper pipe with cooling water [K]
- T S3 :
-
The last contact point temperature of outer surface of copper pipe with cooling water [K]
- t :
-
time [s]
- \(\bar u\) :
-
Time averaged mean velocity [m/s]
- u′:
-
Instantaneous velocity component [m/s]
- V :
-
Velocity [m/s]
- y * :
-
Non-dimensional viscous sublayer thickness
- y T * :
-
Non-dimensional thermal sublayer thickness
- α:
-
Under Relaxation Factor
- αε :
-
Inverse Pr number for dissipation rate of turbulent kinetic energy
- α k :
-
Inverse Pr number for turbulent kinetic energy
- α T :
-
Inverse Pr number for turbulent flow
- ΔH :
-
The pressure drop of the test section [mmHg]
- ΔP :
-
The pressure drop of one turn of helical duct [Pa]
- ΔT B :
-
Large temperature difference [K]
- ΔT K :
-
Small temperature difference [K]
- ΔT ln :
-
Logarithmic mean temperature difference [K]
- ε:
-
Turbulent kinetic energy dissipation rate [m2 /s3]
- η:
-
The rate of strain in turbulent flow (= Sk/ε)
- κ:
-
Von Karman constant (=0.42)
- λ:
-
Thermal conductivity [W/m K]
- μ:
-
Molecular viscosity [kg/ms]
- ν:
-
Kinematic viscosity [m2 /s]
- ϕ:
-
The parameter used in conservation of mass, momentum, and energy equations
- ρ:
-
Density of fluid [kg/m3]
- C:
-
Correlation
- eff:
-
Effective
- f:
-
Film
- I:
-
Inner wall
- i:
-
Inlet
- l:
-
Laminar
- nb:
-
Neighbor cell
- o:
-
Outlet
- PE:
-
Polyethylene
- P:
-
P center cell
- r:
-
Radial direction
- S:
-
Surface
- s:
-
Axial direction
- sat:
-
Saturated vapor
- T:
-
Total
- t:
-
Turbulent
- w:
-
Wall
- y:
-
Expresses vapor condensate
References
Rogers GFC, Mayhew YR (1964) Heat transfer and pressure loss in helically coiled tubes with turbulent flow. Int J Heat Mass Transfer 7:1207–1216
Kalb CE, Seader JD (1983) Entrance region heat transfer in a uniform wall-temperature helical coil with transition from turbulent to laminar flow. Int J Heat Mass Transfer 26:23–32
Rao BK (1993) Turbulent heat transfer to viscoelastic fluids in helical passages. Exp Heat Transfer 6:189–203
Guo L, Chen X, Feng Z, Bai B (1998) Transient convective heat transfer in a helical coiled tube with pulsatile fully developed turbulent flow. Int J Heat Mass Transfer 41:2867–2875
Lin CX, Ebadian MA (1997) Developing turbulent convective heat transfer in helical pipes. Int J Heat Mass Transfer 40(16):3861–3873
Li LJ, Lin CX, Ebadian MA (1998) Turbulent mixed convective heat transfer in the entrance region of a curved pipe with uniform wall temperature. Int J Heat Mass Transfer 41:3793–3805
Lin CX, Ebadian MA (1999) The effects of inlet turbulence on the development of fluid flow and heat transfer in a helically coiled pipe. Int J Heat Mass Transfer 42:739–751
Li LJ, Lin CX, Ebadian MA (1999) Turbulent heat transfer to near critical water in a heated curved pipe under the conditions of mixed convection. Int J Heat Mass Transfer 42:3147–3158
Yang G, Ebadian MA (1996) Turbulent forced convection in helicoidal pipe with substantial pitch. Int J Heat Transfer 39(10):2015–2022
Shaukat A (2000) Pressure drop correlations for flow through regular helical coil tubes. Fluid Dyn Res 28:295–310
Bayazıtoğlu Y, Eason RM, Meade A (1994) Enhancement of heat transfer in square helical ducts. Int J Heat Mass Transfer 137(14):2077–2087
Bayazıtoğlu Y, Thomson DL, Meade AJ (1998) Low Dean number convective heat transfer in helical ducts of rectangular cross section. Trans ASME 120:84–91
Thomson David L, Bayazıtoğlu Y, Meade Andrew J Jr (2001) Series solution of low Dean and Germano number flows in helical rectangular ducts. Int J Therm Sci 40:937–948
Bolinder CJ (1995) The effect of torsion on the bifurcation structure of laminar flow in a helical square duct. Trans ASME 117:242–248
Bolinder CJ (1996) First and higher order effects of curvature and torsion on the flow in a helical rectangular duct. J Fluid Mech 314:113–138
Bolinder CJ, Sunden B (1996) Numerical prediction of laminar flow and forced convective heat transfer in a helical square duct with a finite pitch. Int J Heat Mass Transfer 39(15):3101–3115
Thangam S, Hur N (1990) Laminar secondary flows in curved rectangular ducts. J Fluid Mech 217:421–440
Joseph B, Smith EP, Adler RJ (1975) Numerical treatment of laminar flow in helically coiled tubes of square cross section. AIChE J 21(5):965–974
Butuzov AI, Bezrodnyy MK, Pustovit MM (1975) Hydraulic resistance and heat transfer in forced flow in rectangular coiled tubes. Heat Transfer Sov Res 7(4):84–88
Kadambi V (1983) Heat transfer and pressure drop in a helically coiled rectangular duct. ASME Paper 83-WA/HT-1
Holman JP, Gajda WJ Jr (1978) Experimental methods for engineers. Uncertainty analysis, McGraw-Hill, Tokyo
Kaya O (2002) Improvement of heat transfer in plastic pipe extruders. PhD thesis, Mechanical Engineering Department of Yildiz Technical University, Istanbul
Fluent User’s Guide (1998) Fluent Incorporated Centerra Resource Park, Lebanon
Austin LR, Seader JD (1974) Entry region for steady viscous flow in coiled circular pipes. AICHE J 20:820–822
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Kaya, O., Teke, I. Turbulent forced convection in a helically coiled square duct with one uniform temperature and three adiabatic walls. Heat Mass Transfer 42, 129–137 (2005). https://doi.org/10.1007/s00231-005-0656-3
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DOI: https://doi.org/10.1007/s00231-005-0656-3