Prediction Methods for Entry Length Heat Transfer by Combined Laminar Convection in Horizontal Tubes

Numerical prediction methods for calculating velocity and temperature distributions in heated ducts can be made accurately but are time consuming. The paper shows possible simplifications, including the neglect of the buoyancy term, and the resultant accuracy attained. The case studied is for laminar flow, entry length heat transfer in horizontal tubes with constant rate heat flux. Comparison is made between experimental results, a full solution and an approximation based on a series of truncated versions of the fully developed temperature profile. Calculations are made both with and without variation of thermophysical properties with temperature.

Download Full-text

BOUNDARY VORTICITY METHOD FOR CONVECTIVE HEAT TRANSFER WITH SECONDARY FLOW-APPLICATION TO THE COMBINED FREE AND FORCED LAMINAR CONVECTION IN HORIZONTAL TUBES

10.1615/ihtc4.3670 ◽

1970 ◽

Cited By ~ 12

Author(s):

Guang Jyh Hwang ◽

K. C. Cheng

Keyword(s):

Heat Transfer ◽

Convective Heat Transfer ◽

Secondary Flow ◽

Convective Heat ◽

Horizontal Tubes ◽

Laminar Convection

Download Full-text

Computational Methods for Entry Length Heat Transfer by Combined Laminar Convection in Vertical Tubes

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1977_191_007_02 ◽

1977 ◽

Vol 191 (1) ◽

pp. 19-29 ◽

Cited By ~ 6

Author(s):

M. W. Collins ◽

P. H. G. Allen ◽

O. Szpiro

Keyword(s):

Heat Transfer ◽

Computer Time ◽

Vertical Tube ◽

Numerical Techniques ◽

Temperature Dependent ◽

Entry Length ◽

Temperature Distributions ◽

Temperature Dependent Properties ◽

Laminar Convection ◽

Vertical Tubes

Numerical techniques for the calculation of velocity and temperature distributions in heated ducts have proved accurate but expensive in computer time and capacity. It is worth investigating to what extent simplification is possible without loss of accuracy. Entry-length heat transfer to upward laminar flow with combined convection in a vertical tube is taken as typical. Comparison is made between measured values and, first, a full numerical solution for constant thermophysical properties (viscosity and thermal diffusivity), secondly, the same solution but allowing for their individual and combined variation with temperature and, thirdly, a solution which assumes a series of truncated versions of the fully developed temperature distribution to establish corresponding velocity profiles, allowing for temperature-dependent properties.

Download Full-text

Experimental Investigation of Combined Forced and Free Laminar Convection in Horizontal Tubes

Journal of Heat Transfer ◽

10.1115/1.3450343 ◽

1975 ◽

Vol 97 (2) ◽

pp. 212-219 ◽

Cited By ~ 61

Author(s):

S. M. Morcos ◽

A. E. Bergles

Keyword(s):

Heat Transfer ◽

Rayleigh Number ◽

Tube Wall ◽

Steel Tubes ◽

Fully Developed Flow ◽

Transfer Data ◽

Horizontal Tubes ◽

Flow Heat ◽

Laminar Convection ◽

Heated Glass

The present study considers the effects of property variations on fully developed laminar flow heat transfer and pressure drop in horizontal tubes. A facility was developed to test electrically heated glass and stainless steel tubes, with distilled water and ethylene glycol as working fluids. The Nusselt number for fully developed flow depends primarily on Rayleigh number; however, the Prandtl number and a dimensionless tube wall parameter are also required to correlate the four sets of heat transfer data. This correlation agrees well with data of most previous investigations. The friction factor increases with increasing Rayleigh number; data are within the bounds of limiting analytical predictions.

Download Full-text