Natural convection from horizontal cylinder

 

The convection coefficient for natural convection from a long horizontal isothermal cylinder can be obtained from:

using the function HorzCylNatNuT( ).

 

Consider a problem in which a specific amount of heat Q_cyl is released per unit length of a long horizontal cylinder, and the temperature of the cylinder T_s is to be determined by satisfying Newton's cooling law:

 

The unknown surface temperature T_s can be determined by the steps:

 

Qcyl=50; D=.01; Tinf=300; % problem parameters

load Air.dat; % avail temperature dependent air properties

h=@(Ts)HorzCylNatNuT(Ts,Tinf,D,Air); % convection coef.

NewtEq=@(Ts)[Qcyl-pi*D*h(Ts)*(Ts-Tinf)]; % Newton's law

Ts=NSolve(NewtEq,350) % rooting finding function to solve equation

Ts = 436.68