Fuzzy-Set Based HVAC System Uncertainty Analysis

A fuzzy-set based uncertainty analysis method is employed to study the effects of uncertain parameters on HVAC (heating, ventilation, and air-conditioning) system modeling and describe the associated inaccuracies in HVAC system model predictions. In this study, the uncertain parameters, i.e. the zone cooling loads, heat transfer coefficients, chilled water and condenser water mass flow rate, water temperature at condenser inlet, and mean void fraction in the evaporator are considered and treated as fuzzy parameters. The extended transformation approach is used to evaluate the uncertainties in the model outputs including time history of the zone temperature and humidity, discharge air temperature, temperature of chilled water and condenser water. The upper and lower bounds of these outputs are determined for each alpha-cut level, and the fuzzy description of the outputs are derived as well