A non-iterative method for Testing, Adjusting and Balancing (TAB) air ducts systems: Theory, practical procedure and validation

• The most critical issue about balancing air network is iterativity due to non-linear behavior.
• Iterativity involves high cost in measurement time and operation for balancing procedure.
• We propose an alternative non-iterative method based on the introduction of an inverter control.
• The method is numerically and experimentally compared to the most used.
• The new method has been compared to the most used by definition of a quantitative index named A.

The issue of Testing, Adjusting and Balancing (TAB procedure) of air distribution systems is characterized by growing interest as a result of the increasing use of HVAC systems and the related level of expected performance.The iterative procedure of TAB methods currently used involves several drawbacks. First of all, duration is a priori unpredictable and results are heavily dependent on both operator experience and required tolerances. In this paper a non-iterative TAB procedure, named “progressive flow method” is discussed. A theoretical analysis has been developed to define the procedure further validated both numerically and experimentally through a dedicated test rig which is representative of the most common air distribution network. If the number of flow measurements to be performed is assumed as an effectiveness parameter, results show that, considering a generic system with n terminals and b branches, 2n + b − 1 measurements can be avoided by applying the proposed method compared to a traditional trial-and-error procedure. A deeper analysis reveals that the reduction of the required measurements ranges in percentage between 57% and 67% and that the convenience of the progressive flow methods increases with the number of terminals at fixed number of branches.