Noise Impact of Absorption Machines for Civil Applications Franco Cotana, Andrea Nicolini Università degli Studi di Perugia, Dipartimento di Ingegneria Industriale, Via G. Duranti 67, Postal Code 06125, Perugia, Italy cotana@unipg.it Abstract. Absorption Machines (AM) are known as low noise devices; thus, they are employed when silence requirements are very severe as like hotel rooms, hospital rooms, etc. Big size AM noise emissions may be anyway re- markable. This work deals with an experimental investigation aimed to deter- mine the characteristics of AM noise emissions on nominal working conditions. Measurements have shown that AM power spectrum is mainly characterized by frequency components equal and higher than 400 Hz. Noise abatement solu- tions have been proposed and discussed. 1 Introduction Heat and electricity generation for civil applications is today obtained by single low power wall-boilers and solar panels. Fuel cells will be employed in the next future jointly with refrigeration machines. Thus, wide interest is given to Absorption Ma- chines (AM) for cooling and heating civil applications. In fact, AM are characterized by low noise emissions with respect to the Compression Machines (CM) ones; elec- trical and mechanical devices such as electrical engines, compressors and pumps are not used to get an absorption refrigeration cycle [1]. However, noise levels caused by a high power AM may be particularly annoying. A measurement campaign has been carried out to individuate noise emissions characteristics of a commercial AM; the refrigerant-absorbent mixture is H 2 O-LiBr, which is the most common mixture for building refrigeration applications [2]. Measurement results have shown very low noise power levels with respect to a same power CM. Noise abatement solutions have been proposed in compliance to machine geometrical configuration and noise power spectrum distribution. 2 Absorption Machine Characteristics Measurements have been carried out on a single stage no-sheltered AM (Yazaki, model WFC 5) connected to a custom refrigerating plant which has been realized at the Perugia University Thermophysics Laboratory [3]. The system scheme is shown in Fig. 1.