Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
Thermal-design optimisation is an iterative process which involves the evaluation of many thermo-physical properties that vary with temperature and/or pressure. Therefore, suitable modelling software, such as Engineering Equation Solver (EES) or Mathcad, is usually used. However, such proprietary applications may not be available to many educational institutions in developing countries. This paper presents a case for introducing thermal-design optimisation to engineering students by using Microsoft's Excel as a modelling platform. The design case demonstrates how the principles of thermofluids and economics can be applied so as to find the optimum diameter for an air-conditioning duct. The paper describes the solution steps and provides all the equations needed to solve the case with Microsoft Excel. The paper also highlights the importance of using VBA (Visual Basic for Applications) for developing user-defined functions when repetitive or complex calculations are met. VBA is used to develop a general-purpose function that can be used by Excel users for linear interpolation of tabulated data that depend on a single variable.