Data Centre CRAC unit efficiency improvements

Jun 15, 2017

One of the main types of project Munters look at is energy efficiency improvements within the thermal management side. One of the easiest changes that can be made is swapping out the old AC powered motors for EC powered impellors. the reductions in energy is considerable, with some older belt drive unit changes measuring a saving of over 60% this is due to the design of the new impellors and the remarkable efficiency of the EC motor.

By David Bennett, Service Sales Manager, Munters

EC fans

They use less energy to produce the same amount of power. The use of EC fans does not affect the air volume produced, only the positive effect of lowering the power consumption of the unit. They are able to produce the same air flow through the unit, but at a lower RPM, meaning less energy is consumed to produce the same air flow.

In depth about EC fans compared to belt drive and plug fans 

EC motors and matching impellors are currently the most efficient type of fan arrangement for the air movement needed in CRAC units. They utilise the most modern manufacturing techniques used to produce the impellors, they are generally a polymer based injection moulded component, which means more efficient designs can be made without the need to individually shape the impellor blades, and weld them into place. The metal impellor fabrication had to allow tolerances for the construction methods used. With the improvements gained in impellor design and manufacture, the EC motors attached to them could provide the maximum energy savings. The new impellors can deliver the same air flow as the older fans, but at a slower speed, this reduction in speed gives efficiency improvements, as well as motor efficiency being improved upon. These two areas are where we see the energy savings. Multiply the savings from each fan, into a complete data centre and the savings become obvious. 

Why are the new fans and motor assemblies so much more efficient? 

EC fans do not need an inverter to control their speed; instead a 0-10 volt signal (normally sent to an inverter) is sent directly to the motor, resulting in no controls efficiency losses, these signals control the speed of the fan, either through commissioning or by demand based control. 

What effect does the fan speed have elsewhere in the system – Like chiller power consumption? 

None. It is often thought that the reduction in motor power and fan speed will cause the chillers to work harder, as the flow rate will need to increase to allow for the lower air flow. This is incorrect, the air flow remains the same as before, as the design of the impellor and motor mean it provides the same air flow but at a lower speed. 

Can this upgrade be completed on direct expansion CRAC units? 

Yes, the air flow needs to be controlled to prevent the evaporator coil inside the CRAC unit from freezing. If it is a mechanical change out at the same air flow as the original, then there is no need to consider this. 

Can these upgrades be carried out on non-Emerson products? 

Should you have other manufacturers products installed, we are able to carry out these works to upgrade them too. It doesn’t matter who’s name is on the front, we can upgrade them, and probably already have somewhere in the UK. 

How do we know the energy saving potential of these upgrades? 

We monitor installations and provide energy usage data of before and after installations. These figures allow us to confidently provide payback periods and expected energy savings. The new fan and motor assemblies we use are vigorously tested during lengthy R&D tests, to ensure that the data provided is 100% accurate. Once we know your cost per kW/Hr we can work the energy cost savings. We generally provide a payback in less than two years, and in some cases much quicker. 

Can this upgrade be offered on more than just CRAC units? 

YES!

We provide EC fan upgrades for the axial fans installed on chillers for the condenser fans and some dry coolers. The saving can be just as impressive on the chillers, and should be considered. The additional savings are very good, for minimal outlay. We have a range of fans specifically designed to retro fit on to condensing coil fans. We can apply the same technology to all chillers. 

We are also able to offer EC fan upgrades on comfort cooling Air Handling Units (AHU’S) too; we often see older belt drive fans in these units. The process is basically the same as it is for a CRAC unit, only the fans are usually larger.

 

Read more about Munters fan upgrades

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