Simplified calculation and control method of floor surface temperature for radiant floor and fresh air coupled cooling systems in steady-state

Radiant floor and fresh air coupled cooling systems (RF&FA cooling systems) are increasingly used in practice. Many large space buildings use this type of system in summer to reduce energy consumption effectively, such as the newly completed Beijing Daxing International Airport. Nowadays, many public office buildings in north China are also trying to use "floor heating" to cooling in summer. Using methods of thermal resistance analysis, fixed variable methods, TRYSNS simulation, and data fitting, this paper studies the thermal process of an coupled cooling system, and finds a novel simplified calculation method for floor surface temperature that reduce the variables used in the calculation process to 2. This calculation model greatly reduces the complexity of calculating the floor surface temperature of RF&FA cooling systems. The results are verified by experiments. The maximum absolute error of the average surface temperature is 0.37 degrees C. Based on the theoretical model, an automatic control method is proposed to obtain ideal value of floor surface and indoor air which realizes multidisciplinary innovation. In practice, the conclusion can guide the design and control of radiant floor and fresh air coupled cooling systems.