.BuildingSystems.Fluid.HeatExchangers.BaseClasses.HANaturalCylinder

Information

This model calculates the convection coefficient h for natural convection from a cylinder submerged in fluid. h is calcualted using Eq 9.34 from Incropera and DeWitt (1996). Output of the block is the hA value.

The Nusselt number is computed as

Nu_D = (0.6 + (0.387 Ra_D^(1/6))/(1+(0.559 Pr) ^(9/16))^(8/27))²);

where Nu_D is the Nusselt number, Ra_D is the Rayleigh number and Pr is the Prandtl number.
This correclation is accurate for Ra_D less than 10¹².

h is then calculated from the Nusselt number. The equation is

h = Nu_D k/D

where k is the thermal conductivity of the fluid and D is the diameter of the submerged cylinder.

References

Fundamentals of Heat and Mass Transfer (Fourth Edition), Frank Incropera and David DeWitt, John Wiley and Sons, 1996

Contents

Name	Description
Medium	Medium inside the tank

Revisions

• August 29, 2014 by Michael Wetter:
  Refactored function calls for medium properties.
• May 10, 2013 by Michael Wetter:
  Revised implementation to use hA_nominal as a parameter, and compute the associated surface area A. This revision was required to have a consistent computation of the hA values inside and outside of the coil in the heat exchanger model of the water tank.
• February 26, 2013 by Peter Grant:
  First implementation.