Noise is one of the key performance metrics for transport equipment and manufacturers of vehicles, tail lifts, roll cages, trailer floors and refrigeration equipment as noise generated is an irritant to both drivers and the public. Manufacturers are also obliged to target noise reduction in their designs as Low Emission Zones, where engine emissions and noise can be regulated, are being established in many European cities. Thermo King believes that improvements can be made in this area in order to reduce noise pollution and improve environmental performance.
Noise measurements are most commonly expressed as either sound power or sound pressure. The former quantifies the rate at which acoustic energy is emitted from a source. To determine sound power, a series of measurements is taken on a hemispherical surface around the source so that the power radiating from the source can be summed. Sound power is an independent property of the acoustic source and is not influenced by the surroundings or the measurement locations. The labeling of equipment introduced by European Directive 2000/14/EC shows what the manufacturer asserts is the maximum sound power generated.
Most of us are more familiar with sound pressure measurements. In contrast to sound power, sound pressure is dependent on the distance of the measurement position from the source, becoming weaker as this distance increases.
The SLX is significantly quieter than its predecessor and several factors contribute to achieve this. Substantially larger condenser and evaporator coils coupled with more efficient air movement enable the engine, compressor and fan speeds to be reduced without adversely affecting performance. This reduction in speed has a major impact on the reduction of sound levels.
In addition, the layout of the SLX is acoustically favourable, offering fewer paths for the noise to escape. The SLX, as a one-piece, easily installed unit delivers substantial noise reduction without having to resort to complex and costly solutions such as split units with under-mounted engines.
The values quoted on the maximum sound power labels on the SLX and predecessor SL ranges are shown below:
While objective measurement of noise levels is necessary for legislative and comparative purposes, the reaction of the human ear is what ultimately determines the success or failure of a noise-reduction technology. Feedback from recent SLX field trials confirms that the measured differences can really make a difference to operators:
“Stefan Nyman, Chief Executive of Erling Anderson: “Benefits include noticeably reduced fuel consumption, minimal noise and a very easy to use display.”
“Juha Kotka, Managing Director of Kulijetus K ja J Kotka Oy: “My overall impression of the SLX range is that it is very powerful, yet completely silent.”
“Günter Dieker, Director of Gunter Dieker Kühltransporte GmbH: “The system is quiet and the diesel consumption is lower than with our SL-200.”
“Jordi Cuesta, Manager of Pickingmed: “The SLX field trial has been extraordinary. We saw a great improvement in the area of noise, but the most impressive aspect of the new Thermo King SLX units is their power – even when the outside temperature exceeds 25°C, they can cool a semi-trailer in a matter of minutes.”
“Antton Larzabal, Technical Director of the Olano Group: “It’s a remarkable success and it’s going to cause quite a stir in the refrigerated transport market. Its low-level noise, two-fold increase in power and the fact that it consumes barely two litres of fuel an hour are strong benefits.”
“Josef Klausling, deputy workshop manager at Overnight Tiefkühlservice GmbH: “The driver is very complimentary – he tells us that the SLX runs much more quietly than comparable front-mount units.”
From the start of the SLX development project, a key deliverable was reduction of environmental impact. The design team conducted a life-cycle assessment of the SL range to identify areas where the greatest gains could be achieved without compromising the cost of ownership or performance. The result is a substantially reduced carbon footprint in manufacturing, operation & end of life disposal as well as impressive gains in noise reduction.
For more information about the SLX visit www.slx.thermoking.com
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