New technology often takes time to overcome teething trouble and ‘bed in’ to become an industry standard. Steve Warnock, md of the Coolmation Group, argues that the Turbocor compressor chiller has now come of age, offering higher efficiency, lower carbon emissions and reduced fuel costs
WHEN Turbocor compressor chillers were launched a few years' ago they offered contractors and end-users a highly efficient chiller that could significantly cut both carbon emissions and fuel costs in one fell swoop.
Their introduction was timely with the acr industry facing increasing pressure from EU regulations, including the F-Gas, as well as a raft of building legislation.

The Turbocor compressor was a huge technological leap, so it was not surprising that the technology took time to overcome teething problems and took time to produce the optimum relationship between chiller and compressor.
This refining process has now resulted in proven Turbocor chiller technology which offers all the efficiencies that the prototype compressor promised.

According to recent data from BSRIA the compressor market is currently in a state of flux with the sector continuing to experience shifts in compressor type, refrigerant and size. However, BSRIA has also noticed growth in recent technologies such as the Turbocor.

This is being driven by a number of factors including: the existence of proven Turbocor chiller technology, energy efficiency regulations; and the desire to reduce carbon emissions.

In its target capacity range, there is no other compressor currently on the market that produces better efficiency in operation.

The Turbocor, oil-free compressor incorporates an inverter-driven, permanent magnet motor and magnetic bearings. Within the compressor, efficiency is affected by the compressor's isentropic efficiency (the efficiency of the impellers), the motor and the bearings.

Typically, traditional induction motors of this size are in the 92% efficiency range. The Turbocor compressor's permanent magnet DC motor, with its completely integrated variable-speed drive, provides an efficiency of between 96 to 97%.

The variable-speed drive (VSD) varies the frequency between 300 and 800Hz, providing a compressor-speed range from 18,000 to 48,000 rpm and at the same time eliminating the need for an energy consuming gear set.

Efficiency is further enhanced by the use of magnetic bearings which avoid the friction typically associated with traditional oiled bearings. In fact, magnetic bearings have over 500 times less frictional losses than conventional bearings.

The frictionless bearings reduce the starting current to just 2A removing the transient starting spikes frequently associated with screw compressors and the need for expensive soft start arrangements, as well as eliminating the risk of penalty charges for exceeding maximum power demands.

Coolmation launch
Coolmation has launched Rhoss' new series of Eurovent-certified Turbocor R134A cooled chillers which are available from 150kW to 2,100kW and have been developed through a partnership between Rhoss and the University of Udine.

The result is that Coolmation's Turbocor chillers include features, which complement the Turbocor compressor to offer even higher efficiencies.

Turbocor chillers, such as Coolmation's range, now offer significantly higher operating efficiencies than chillers using scroll, screw or reciprocating compressors. Compared with screw compressors, Coolmation's Turbocor range has an EER of up to 4.0 at full load conditions and in excess of 8.0 at part load, representing an efficiency increase of 10% and more than 100% respectively.

These efficiencies are due to a number of new chiller design elements which complement the Turbocor compressor. Features include: electronic expansion valves, innovative heat exchange technology, highly intelligent control systems; and micro channel, parallel flow, air-cooled condenser coils.

Increased performance
For instance, the micro channel, parallel flow, air-cooled condenser coils are designed to increase performance by up to 45%, making it possible to significantly reduce condenser dimensions for a given capacity. Constructed entirely of aluminium, the coils' weight is also reduced by as much as 45% while the manufacturing method reduces the potential for refrigerant leakage.

These factors not only make the chillers easier to install but the high standard of workmanship means that the reduction in potential refrigerant leaks makes it easier for end-users to comply with the F-Gas Regulation.

Other benefits of micro channel condenser coils include a reduction in coil depth, which reduces air pressure drop providing further energy savings through reducing the capacity or number of fans required to create the design air flow rate.

The smaller coils also result in a 30% reduction in the refrigerant volume and a reduction in refrigerant pressure drop across the coil of 65%, enhancing energy efficiency still further.

In addition, the condenser fans feature low noise sickle blades which are arranged so that when the Turbocor compressor cycles off, they have the ability to reverse, to blow out dust which has gathered on the coil surfaces. This feature helps to maintain coil efficiency and overall energy consumption.

Flooded type evaporator
Another benefit of the new generation of Turbocor chillers is a flooded-type evaporator which is more efficient than a shell and tube, direct expansion evaporator.

The flooded type is designed and optimised specifically for R134A featuring specially finned tubes along with a cleverly sited refrigerant level sensor, which makes it possible to take full advantage of the total heat exchange surface area. This helps to create higher saturated suction gas temperatures and higher EER values while lowering energy consumption.

Meanwhile, a patented heat exchange device further increases the overall energy performance levels by interchanging heat between the saturated suction gas and condensed liquid refrigerant, raising the temperature of the suction gas while sub cooling the liquid, improving the cooling efficiency and EER values.

Low maintenance
Low maintenance is another key feature of this type of chiller which is partly due to the simplicity of the compressor - it comprises only one moving component - the compressor shaft.

Magnetic bearings keep this high-speed shaft suspended in the air and frictionless, so reducing wear, extending the chiller's lifetime and keeping maintenance to an absolute minimum.

The compressors are also oil-free. This not only helps to keep maintenance costs down but is also the key to sustainability by improving heat exchange performance through the elimination of oil film between the coolant and heat exchange surfaces.

Oil management, particularly in relation to the lubrication of compressor bearings, is always a critical issue in refrigeration system design. But with magnetic bearings, this issue is effectively eliminated.

Avoiding oil management systems also avoids the capital cost of oil pumps, sumps, heaters, coolers, and oil separators, as well as the labour and time required to perform oil-related services.

Turbocor compressors are manufactured from aircraft grade aluminium castings with high strength thermoplastic electronics enclosures.

Designed to operate at very low sound levels, the low noise frequency is possible owing to zero-vibration, even at start-up, and the elimination of the tonal problems typically found in screw compressor chillers.

Coolmation Group
01425 478971