Algebraic evaluation of temperatures and heat transfer rates n simple bodies via a composite lumped model: its connection with the heisler/groeber charts

摘要

Calculations of temperature histories and heat transfer rates in simple bodies (plates, cylinders and spheres) have been traditionally explained in courses of heat transfer by the Heisler and Grorber charts, which are applicable to dimensionless times, tau, greater than 0.2. This imposing restriction, associated with "one-term series solutions", is utilized for their construction. Additionally, the Hesiler charts are difficult to read necessitating skillful "visual interpolation". The central goal of this educatonal paper is to predict the variation of mean, center and surface temperatures as well as heat treansfer rates of basic bodies via a composite lumped analysis with a handful of algebraic equations. These calculations can be done with a calculator and, even more important, they can be extended into the subregions described by dimensionless times less than 0.2.