This workbook evaluates the efficiency (qactual/qmax) of straight annular fins based on the analytical solution of the governing heat balance equation.   Excel’s intrinsic Bessel functions are invoked in user-supplied VBA functions.   The calculation and the display are only of the “bottom line,” the efficiency of a single annular fin as a function of the fin parameter and the radius ratio (fin tip radius/fin root radius).

 This workbook was developed to verify solutions given by the more general Extended Surface module, The HTTextnd module displays the entire temperature profile in this fin geometry and a myriad of others in addition to the fin efficiency and effectiveness.   Photos of a variety of extended surface configurations, including the straight, annular fin, may be viewed here.