Heat flux equation software#

The convective heat transfer coefficient is known to be constant such that Stanton numbers and the nondimensional heat transfer coefficient are evaluated as St = 2.5 × 10 − 3 and H = 0.8. Finally, for a simplified analysis, we will assume that the convective heat transfer coefficient, h, between tube wall and fluid is constant, independent of the radiative heat transfer, and known.Ī transparent gas flows through a black tube subject to a constant heat flux. The inner surface of the tube is assumed to be gray, diffusely emitting and diffusely reflecting, with a uniform emittance ϵ. The two open ends of the tube are exposed to radiation environments at temperatures T 1 and T 2, respectively. Over the length of the tube the supplied heat flux q w is dissipated from the inner surface by convection (to the fluid) and radiation (to the openings and to other parts of the tube wall), while the outer surface of the tube is insulated. 8.11, the fluid enters the tube at x = 0 with a mean, or bulk, temperature T m 1. As an example we will consider here the case of a transparent gas flowing through a cylindrical tube of diameter D = 2 R and length L, which is heated uniformly at a rate of q w (per unit surface area).

If the flowing medium is air or some other relatively inert gas, the assumption of a transparent, or radiatively nonparticipating, medium is often justified. All the fluid dynamic and heat transfer parameters are extracted after the hydrodynamic and thermal development of the fluid flow and in this case the entrance length is x/ D=60 beyond which all the measurements are taken.Īs in the case of pure convection heat transfer, it is common to distinguish between external flow and internal flow applications. A constant uniform heat flux of 5000 W m −2 is applied at the wall boundary of the circular tube and fluid is allowed to flow with a plug velocity and uniform temperature of 300 K at the inlet of the tube with an assumption of no slip condition on the tube wall. A turbulent flow through a circular tube of 3 mm diameter and 300 mm length is presented.

Heat flux equation software#

In order to investigate the performance of nanofluid in a circular tube, a numerical study has been carried out by employing commercial computational fluid dynamics software ANSYS Fluent.

Sadrul Islam, in Thermofluid Modeling for Energy Efficiency Applications, 2016 4.4 Physical Model and Boundary ValuesĪ pipe with a constant heat flux applied on its surface can be considered as the simplest case of a heat exchanger to investigate the heat transfer rate and corresponding pumping power requirements.