An integrated experimental and CFD analysis of ceiling-fan-integrated air conditioning system: Indoor air quality and air velocity

The Ceiling-Fan-Integrated-Air Conditioning (CFIAC) represents an innovative HVAC design, which involves directing supply air towards the vicinity of ceiling fans, facilitating the mixture and distribution of air within a room. By eliminating the need for terminal ductwork and diffusers, CFIAC offers an efficient cooling solution for occupants. This study employs experimental and CFD methodologies to assess various parameters, including airflow, air pollution, and temperature related to this system. Experimental tests were conducted in a controlled chamber, with the lowest inlet air velocity and the temperature, where supply air was projected from a high-sidewall vent directly towards a ceiling fan's centerline. Different operational conditions of the ceiling fan were examined (off, Level 2 and Level 4 downwards, and Upwards). Carbon dioxide (CO₂), employed as a tracer gas, was released near a thermal manikin at three distinct locations within the chamber: the middle, lower left, and upper right, and the corresponding CO₂ concentration distributions were evaluated. Additionally, air velocity measurements were collected and analyzed. The effectiveness of ventilation and potential health exposure was quantified using the age of air and intake fraction (IF) metrics. The findings indicate that operating the fan at Level 4 with downward airflow enhances air velocities and heat loss while reducing CO₂ concentrations and age of air by an average of 14 % and 4 min, respectively. Moreover, the IF values for Level 4 operations, both downward and upward, were marginally lower compared to those recorded for Level 2 downward and fan-off scenarios, suggesting a decreased risk of cross-infection.