Empirical modelling of filtration performance for the fibrous air filters with final resistance recommendation

A significant challenge in the filtration applications is the high energy consumption across the air filters, especially with the dust cake formation after a certain period of usage. Therefore, the design of the air filters is important to maintain a good filtration performance with low energy consumption. An accurate setpoint of the final resistance acts as a reference of filter replacement, ensuring the energy-saving of the system and the indoor air quality (IAQ). In the industrial practice, the final resistance is set according to ASHRAE 52.2's recommendation or using the Rule of Thumbs as there is a lack of related literature studies. In this study, a pleated fiberglass air filter is studied to identify the factors affecting filtration performance and formulate the final resistance relationship. The filtration performance parameters, including the initial pressure drop, filtration efficiency, pressure drop across the dust cake and the dust holding capacity of the filter, are studied experimentally. The empirical models of filtration performance parameters are expressed in terms of different contributing factors. The validated empirical models are used for the prediction in the final resistance model in consideration of the filter lifespan and energy cost. The final resistance model developed is FinalResistance=ΔP0ⅇQηTtFRCupDHClnΔPfΔPi where tFR is determined in consideration of the filter's predicted lifespan and energy cost. The proposed filtration performance and final resistance models can provide a reference in giving a better design solution while maintaining the building's IAQ at minimized operation cost.