Example of Designing for Function-

Consider a power plant engineer charged with designing a cooling tower for water used for cooling the plant. The designer decides, based on a preliminary evaluation, on a wet-type counter-flow forced-convention tower. For this he have to calculate how much heat is needed to be removed per hour. He would then provide for that much water must evaporate per hour. He would then provide for that much evaporation by designing the proper height and cross-section of the tower, the dimensions of the wet-pack, and the optimum shape and size of the fill material. For this he needs knowledge of diffusive and convective mass transfer . he will also require knowledge of thermodynamics and heat-transfer processes. He will also calculate the size and power of the blower or fans require for obtaining the desired rate of air flow.