An empirical formulation for predicting HVAC system noise in offshore plants using computational analysis

Noise from heating, ventilating and air conditioning (HVAC) systems is normally predicted by the empirical method suggested by the National Environmental Balancing Bureau (NEBB). However, the method suggested by the NEBB for ducts used in architecture is not suitable for large size ducts usually used in ships and offshore plants. In this paper, to predict noise from an offshore plant HVAC system, empirical formulas for attenuation of sound pressure level in large ducts are derived using the boundary element method (BEM). Further, regeneration noise caused by air flow in ducts with stiffeners inside is analyzed using computational fluid dynamics (CFD). Break-out noise is also analyzed by BEM and finite element method (FEM). Utilizing the results of this study, an integrated HVAC noise analysis program has been developed and the results obtained from the program were compared with measured data. The efficiency and validity of the formulas are shown.