The control of heating, ventilating, and air conditioning (HVAC) systems is difficult due to the nonlinear nature of the components, the wide range of operating conditions under which they must operate, and the many interactions between them. Accurate models of these loops can be a great tool in evaluating the performance of controllers and their control laws, overall strategies, and tuning techniques. While many models already exist, their accuracy under closed-loop control and varied external parameters is often limited compared with open-loop accuracy due to more variables changing during a closed-loop test. One component in particular, the heat exchanger, is very nonlinear in nature. The general practice of using linear control on this nonlinear component results in sluggish control. The goal of this work is to develop an empirical nonlinear model of a hot-water-to-air heat exchanger loop that could be used in developing a nonlinear control law.

KEYWORDS: calculating, heat exchangers, water air heat exchangers, heating, ventilation, air conditioning, performance, controls, accuracy, water heat exchangers