Equivalent Room Air Temperature-Based Cooling Load Estimation Method for Stratum Ventilation

Accurately estimating the cooling load is vital for designing and controlling air conditioning systems. However, challenges emerge when dealing with indoor air temperature stratification of stratum ventilation. Many current building simulation tools solely rely on the fully mixed air model, neglecting this stratification. In this chapter, a method is proposed to estimate the cooling load using the concept of equivalent room air temperature, aiming to overcome this limitation and enable accurate estimation using the fully mixed air model for stratum ventilation. The equivalent room air temperature refers to the air temperature that would yield the same cooling load as stratum ventilation when employing the fully mixed air model. To accomplish this, response surface methodology is utilized to establish a mathematical model that correlates the equivalent room air temperature with the supply air temperature, supply airflow rate, and room air temperature. Case studies are conducted using experimentally validated multi-node models to demonstrate the effectiveness of the proposed method. For the constant-air-volume system and the variable-air-volume system, the mean absolute errors under stratum ventilation are 0.02 and 5.78%. Compared to the conventional method, our approach significantly enhances the accuracy of cooling load estimation by 99.94% for stratum ventilation.