Design and verification of an acoustic mitigation intervention for an air-cooled inverter heat pump: a case study

An acoustic mitigation intervention with reference to an air conditioner outdoor fan motor (heat pump and liquid chiller) CLIVET WSAN-XIN 141 is explored. On the basis of a measurement session conducted ante operam, the paper focuses on the phases of design activity of an innovative structure aimed at reducing the equivalent sound pressure level on the façade to the most sensitive receiver, according to the current Italian legislation. In these cases, resistive or dissipative silencers with a circular or rectangular duct, internally lined with sound absorption material, are widely used, but the axial fan under examination has a residual prevalence very low to allow the installation of suitable silencers. So in order to guarantee adequate airflow to the radiator heat exchanger along the lateral surface of the heat pump, avoiding the reduction of the efficiency of the system, an original structure of appropriate geometry, able to achieve high-performance sound mitigation, is presented. The phonometric campaign post operam shows the results achieved at the end of the realization of the proposed acoustic mitigation intervention and this approach may be adopted as a guideline by the practitioner.