This case study outlines how ebm-papst, Cinque Energy Solutions and Stulz are working together to provide energy saving solutions to their customers.
In this example, one of the UK’s leading scientific organisations dramatically reduced their cooling energy consumption by simply upgrading their existing air conditioning equipment to use ebm-papst’s EC fans.
The inception of the project was mid 2012 when Stulz requested ebm-papst UK to carry out a site survey for upgrading some of their computer room air conditioner units. Normally this type of unit is used for datacentre cooling but in this case the equipment was being used to cool electronic equipment rooms around the perimeter of the Diamond Light Source synchrotron in Didcot.
Phase 1 of the project was to upgrade 27 CCD900CW Stulz downflow CRAC units from their traditional AC forward curved centrifugal blowers to EC backward curved impellers.
The initial site survey was carried out to ascertain what the current solution delivered in terms of power draw and performance. Suitability for upgrade also had to be considered. The blowers would be replaced by EC backward curved impellers but due to the limitation of the scoop which feeds the air into the room, the EC solution had to be mounted within the CRAC unit enclosure rather than below.
The proposed solution was to use the latest RadiCal 560mm impeller from ebm-papst, which offers excellent energy efficiency. The fans would be mounted into bespoke metalwork frames to angle the airflow to assist with the air delivery into the room. The metalwork and assembly were all carried out at ebm-papst UK Ltd where there is a dedicated production area capable of offering custom solutions.
An initial survey was carried out and the results presented to Stulz and the end client, with a view to carry out a single unit trial to prove the concept.
Unit type: Stulz CCD900CW chilled water CRAC
Number of units: 27
% energy saving: 39%
Trial and Energy Analysis
In January 2013, the trial installation of one air conditioning unit was carried out by Cinque Energy Solutions. The aim of the trial was to confirm the bespoke design and prove the potential energy saving and benefits to the customer.
Initial results showed a 43% improvement in kVA compared with the original AC fans. For the trial, the CRAC unit was not physically modified, which allowed the potential to revert back to the original set up if desired. It was agreed that for the complete upgrade the floor of the CRAC unit would be opened up further to allow the new EC fans a less restrictive system resistance to increase efficiency further.
The main measured perimeter important to the client was the temperature at rack level in the room. The trial unit airflow was adjusted to match the previous ambient conditions. Due to the simplicity of the control of EC fans, a simple manual 0-10v controller was fitted to the CRAC unit to allow each unit to be tuned to the room requirements. Over the course of a few months the maintenance team was able to adjust the fan speed to optimise the solution even further.
The upgrade of the 27 air conditioning units was scheduled to be completed during a shutdown period in August 2013. The complete upgrade had to be finished within a two week window so two teams from Cinque Energy Solutions were deployed to work on units simultaneously. All 54 fans were delivered to site and positioned near the units to cut down on delays during the conversion.
Step 1: Remove the original AC fans and motor system.
Step 2: Enlarge the outlet holes in the floor void to maximise airflow with the EC fan solution.
Step 3: Fit new EC fans and frames.
Step 4: Reconnect supply to fans and fit manual speed controller.
As well as the significant energy saving achieved by converting to EC fans, other benefits also came out of the conversion, which proved to be as important for the customer. Due to the sensitivity of the equipment being used in the synchrotron, noise and vibration reductions from using EC fans was also an advantage. The other benefits from the upgrade include:
1. Extended fan life
2. Extended unit life
3. Reduced maintenance - no belts
4. Reduced maintenance contract with supplier
5. No belt dust being blown into the equipment rooms
6. Controllability of cooling capacity
7. Greater flexibility for capacity management
The successful completion of phase 1 of the EC upgrade has led to a 55% energy saving and an annual carbon reduction of 46 tonnes. It has brought a £32k energy saving per annum* as well as significantly reducing noise and vibration from the units being transmitted into other parts of the building. It will also reduce maintenance costs on the units going forward. *Based on an industry average of 10p/kWh
Phase 2 of the project, to convert the remaining Stulz cooling units, is scheduled for upgrade at the next shutdown period.
The customer commented: “As a scientific organisation, the project appealed to us on several levels. Obviously the financial savings from reduced energy consumption and increased reliability were of great importance. Other key benefits from the modifications ebm-papst offered were the reduction in both noise and vibration. These can affect our operations significantly. Following the change of fans, one operator stated he now had to give a unit the ‘cuddle test’ to confirm it was running following the significant reduction in noise and vibration!”