Submitted by Maria.Kapsalaki on Wed, 04/17/2019 - 11:16
The AcouReVe Project aimed to improve the knowledge and the quality of acoustic calculation in ventilation ductworks. Such calculations are based on simplified models and the main issue is the input data. For each component of the ductwork, acoustic insertion loss and/or sound generation due to air velocity has to be known. Some components are well described by manufacturers, such as terminal devices, silencers, but others are not known. Sometimes, literature exists and can help to assess the input data, but the values may be out of date or no longer reflect current practices.
Submitted by Maria.Kapsalaki on Tue, 04/16/2019 - 08:56
Noise remains a major concern for building occupants, both in their home and workplace. Ventilation system is one of the noise sources in buildings. Usually, the main issue is the resulting noise level in the room. It is generated by the fan and the ductwork components, travels inside ducts, and is then radiated into the room by air diffusers, air inlets, and air outlets. But ducts also go through other indoor spaces. Airborne noise will pass through the duct wall and radiate in the surrounding space. This can be an issue for occupants.
Submitted by Maria.Kapsalaki on Thu, 11/23/2017 - 12:24
Noise from domestic ventilation systems is currently a little understood problem in the UK. Other European countries that have a longer history of using mechanical domestic ventilation systems have introduced noise limits for these systems. Without mandatory limits for noise in UK, noise is not a factor that is often considered during the design. However, noise can be a significant constraint to the use of ventilation systems. Research is reviewed from across Europe and North America that indicates residents turn off ventilation equipment with objectionable noise.
Submitted by Maria.Kapsalaki on Thu, 11/23/2017 - 12:21
Where residential developments rely on opening windows to control overheating, there can be a compromise between allowing excessive noise ingress with windows open, or excessive temperatures with windows closed. This problem is exacerbated by the move towards better insulated, more airtight buildings and the need, particularly in urban areas, to consider development on noisier sites. A working group has been formed by the Association of Noise Consultants to provide guidance on acoustic conditions and design when considering both the provision of ventilation and prevention of overheating.
Submitted by Maria.Kapsalaki on Thu, 02/25/2016 - 13:53
The quality of indoor environments influences satisfaction, health, and work performance of occupants. Additional understanding of the theoretical and practical value of individual indoor parameters in relation to health and performance aids indoor climate designers to obtain desired outcomes. This also results in expenditure savings and increased revenue as well as health care and improved productivity. This paper reports on two experiments that investigated how heat, cooling strategy and background noise influence performance in a full-scale classroom mockup setting.
Submitted by Maria.Kapsalaki on Fri, 10/25/2013 - 17:53
The fan is one of the major noise sources of an air conditioner. Because of the presence of other components in the fan assembly, such as the bell-mouth, outlet grille and compressor chamber, the ingested and discharged flow fields around the fan impellers are distinctly different from those in a free field. Therefore, the noise generation mechanisms become much more difficult to analyze and model. This paper concentrates on understanding the generation mechanism and evaluating the noise in the fan system of a split-type air conditioner.
Fan is a source of noise in ventilation and air conditioning systems. The article provides information about noise emission from different types of fans and the ways to attenuate it, using different types of silencers, including passive and active silencers, or combination of both.
This article describes the physical mechanisms leading to broadband noise from axial fans. It gives the results of a literature survey about the semi-empirical correlations available to predict this noise and their application to two examples : a low pressure fan and a high pressure fan.
In this paper, a literature survey on rectangular and round ventilation ducts is presented. The comparison is based on two important aspects: pressure drop and noise radiation. The pressure losses in the ductwork should be kept as low as possible without jeopardizing proper control of the flow rates in the system. Pressure loss through a rectangular duct is significant higher than a volumetrically equal round one. The higher the aspect ratio, the higher-pressure loss in the rectangular system.