Drives and Controls Magazine

Enclosure cooling system slashes energy use by up to 70%

21 April, 2011

Rittal has launched a new generation of energy-saving enclosure cooling systems following pilot installations in the automotive sector which demonstrated energy savings of up to 70% compared to earlier systems. The company has also been developing other cooling technologies, including frequency-controlled chillers which, it claims, could halve energy costs.

In one 11-month pilot trial, at a Daimler plant in Germany, the new Blue e enclosure cooling system used up to 70% less energy than a standard Rittal cooling system with the same output. The new equipment, which looks similar to the earlier TopTherm system, has a 42% higher coefficient of performance (COP) – up from 1.2 to 1.7. It covers cooling outputs from 500–4,000W.

One way this has been achieved is to use efficient, electronically commutated, external-rotor fan motors, instead of the traditional mechanical pole-reversal machines. The new motors have dynamically balanced rotors and use Hall sensors to record the rotor position.

Other improvements include switching off the fans automatically when they aren’t needed, and optimising the design of key components such as condensers, evaporators, cooling fins and pipework.

The new frequency-controlled chillers (shown above) offer cooling outputs from 1–6kW (with versions up to 16kW on the way), and can deliver savings of up to 50% compared to systems using hot gas bypass control. Even in systems with two-point controls, savings of more than 30% are possible.

Hot gas bypass systems are often used in applications such as machine tools where the frequent switching can shorten compressor lives. However, says Rittal, this represents an artificial burden on the compressor and part of the cooling output is “destroyed”. The new TopTherm Inverter Chillers adapt the motor speed to the load to provide the exact cooling output needed – to an accuracy of ±0.1K – especially at part-loads. Other advantages include longer component lives, lower start-up currents and reduced noise and vibration.