LAUSR

Abstract Accurate airflow measurement is the key to realize the thermal comfort and energy saving management of VAV air conditioning system, especially for that under low air flowrate conditions. This paper proposed a novel damper torque airflow sensor to solve the problem of low range airflow measurement of VAV terminals. The flowrate model is established based on resistance characteristic analysis and the flow coefficient is studied by CFD simulations and experiments. The simulation and experiment results show that there is a good negative linear relationship between the flow coefficient K ( θ ) and damper opening angle in the range of 10°–50° and the decreasing trend of K ( θ ) is more intense and nonlinear in the range above 50°. Under the general damper opening range (10°–70°), the quadratic fitting equation of K ( θ ) can basically meet the error requirements ±5%, but the error is larger as the opening angle exceeds 70°. As the damper opening increases, the airflow rate increases and the torque changes in a very small range under constant static pressure inlet condition, and the proposed airflow sensor has high measurement range ratio of more than 25:1. The study in this paper is helpful to promote the energy saving and building comfort of VAV system.