Sonobex has been working on the development of a new acoustic solution for low-frequency noise problems, this blog is part two of the development story.
Sonobex and Merford cabins reduce the sound level in operator cabins
Computer models show the air stream and velocity in the HVAC of an STS cabin.
Merford Cabins is the global market leader in STS cabins. This cabin model was designed for large quay cranes that load and unload container ships. Our STS cabins are mostly standardized and comply with the applicable port processes and the demands of time. Throughout the years our engineers researched, tested and implemented an impressive number of optimizations. One of our most recent projects: new air ducts in the cabin that reduce the needed counter pressure and required energy, while the noise level is lower as a result of a decreased airspeed. Merford Cabins' sister organisation Sonobex, a young British research company specialized in noise control, played an important part in this project.
OVERPRESSURE AND NOISE NUISANCE
Most of our STS cabins are fitted with an Industrial Climate Unit (also called HVAC). This HVAC provides the operator cabin with a pleasant working temperature, regardless of the outdoor climate. Another task of the HVAC is to fill the cabin with an overpressure, to reduce the likeliness of polluted air or dust entering the cabin. The full process of moving air is quite complex and consists of parts where the air clashes with other airflows, has to make U-turns, or gets detained. Sound is air in motion. Depending on the intensity, this motion could result in critical noise pollution.
Sonobex made simulations to get an idea of the airflows in the cabin. This helped us to locate the weak spots in the process. With the data achieved, adjustments were made to the HVAC and the layout of the cabin to properly suppress the noise pollution. For instance, a void was discovered with a high density of airflows, that increased the counter pressure more than necessary. We secluded this spot with insulation material to help the airflows find their way better. Second, the air inlet was enlarged to reduce the airspeed of the air entering the HVAC, after which it goes past sound absorbing sheets. Third, we upgraded the sytem for the heated air flowing underneath the floor of the cabin to demist the front window. Thanks to the improvements described, the HVAC fan can reach the same goal with less rotations. This results in a reduction of noise and required energy.
Merford Cabins benefited greatly from the knowledge of the Sonobex team and the simulations they use to map sound. Based on these calculations, almost all components in the HVAC, such as the heat block, the fan and the compressor, could be adjusted so that the sound level values meet general noise standards, regardless of the speed of the fan. Moreover, thanks to the measures taken, the cab can be produced more efficiently, the energy consumption is reduced and – perhaps most importantly – the operator will hardly be impeded in his or her work due to noise pollution.
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