TY - JOUR

T1 - Approximate analytical treatment of annular fins of rectangular profile for teaching fin heat transfer

T2 - Utilization of the mean value theorem for integrals

AU - Campo, Antonio

AU - Acosta−Iborra, Antonio

AU - MASIP MACIA, YUNESKY

PY - 2018/1/1

Y1 - 2018/1/1

N2 - In the teaching of annular fins of rectangular profile, the main obstacle lies in solving the quasi one-dimensional heat conduction equation, the modified Bessel equation of first kind. In the modified Bessel equation, the variable coefficient 1/r multiplying the first order derivative of temperature dT/dr is problematic. The principal objective of the present paper on engineering education is to solve the modified Bessel equation of first kind in approximate analytical form. Specifically, we seek to apply the mean value theorem for integrals to the variable coefficient 1/r, viewed as an auxiliary function in the domain of the annular fin extending from the inner radius r1 to the outer radius r2. It is demonstrated in a convincing manner that approximate analytical temperature distributions having exponential functions are easy to obtain without resorting to the exact analytical temperature distribution embodying four modified Bessel functions of first kind. Furthermore, the easiness in calculating heat transfer rates in annular fins of rectangular profile for realistic combinations of the two controlling parameters: the normalized radius ratio and the dimensionless thermo-geometrical parameter is verifiable.

AB - In the teaching of annular fins of rectangular profile, the main obstacle lies in solving the quasi one-dimensional heat conduction equation, the modified Bessel equation of first kind. In the modified Bessel equation, the variable coefficient 1/r multiplying the first order derivative of temperature dT/dr is problematic. The principal objective of the present paper on engineering education is to solve the modified Bessel equation of first kind in approximate analytical form. Specifically, we seek to apply the mean value theorem for integrals to the variable coefficient 1/r, viewed as an auxiliary function in the domain of the annular fin extending from the inner radius r1 to the outer radius r2. It is demonstrated in a convincing manner that approximate analytical temperature distributions having exponential functions are easy to obtain without resorting to the exact analytical temperature distribution embodying four modified Bessel functions of first kind. Furthermore, the easiness in calculating heat transfer rates in annular fins of rectangular profile for realistic combinations of the two controlling parameters: the normalized radius ratio and the dimensionless thermo-geometrical parameter is verifiable.

KW - analytical temperatures and heat transfer rates

KW - Annular fin of rectangular profile

KW - approximate

KW - mean value theorem for integrals

KW - modified Bessel equation of zero order

KW - transformed ordinary differential equation of second order with constant coefficients

UR - http://www.scopus.com/inward/record.url?scp=85050917975&partnerID=8YFLogxK

U2 - 10.1177/0306419018789336

DO - 10.1177/0306419018789336

M3 - Article

AN - SCOPUS:85050917975

JO - International Journal of Mechanical Engineering Education

JF - International Journal of Mechanical Engineering Education

SN - 0306-4190

ER -