Edenaire delivers track side cooling solution for Network Rail
As part of an overall upgrade of the infrastructure of the UK’s rail network, Edenaire in partnership with Network Rail has developed a cooling solution for unmanned trackside signalling and control cabins, Relocatable Equipment Boxes (REBs).
Network Rail runs the network infrastructure and is responsible for its operation including all plant and equipment. Track side this includes all the REBs which contain a diverse range of equipment depending on location, for controlling crossings and CCTV, signalling, telephone networks.
The REB varies in size from 10- 60 feet long and contains switch gear, electro-mechanical equipment and UPS units. High heat gains are a major problem with vast quantities of heat generated by UPS’ and transformers. In addition the REBs are usually situated in open and exposed areas and subject to all that the weather can throw at them. In the winter months this is not a problem but in the summer months the units are also susceptible to heat gain from the sun. Some are brick built as opposed to the majority which are fibreglass construction which also impacts heat gains.
The worst scenario is that an REB may in the summer months have its longest side south facing, therefore it will be in the sun all day and heat gains become a serious problem” says Andy Merritt “Equipment failure could cause delays in specific areas and affect level crossings, track changes, year round reliability is paramount.”
Currently a cooling environment of 21°C is delivered to the REBs by split systems that were the most appropriate solution at the time. However as most of these are now coming to the end of their expected life span, Network Rail took the opportunity to look at alternative solutions.
“The split systems are more suitable for comfort cooling but were all that were available in their day. We also have a number of ‘window’ rattlers - through the wall single DX units - that will need to be replaced.”
As a result of its successes with its eBTX and CTXe units developed for BT and other telecoms suppliers in exchanges and data switching centres, Edenaire was invited to apply its skills and design a solution to tackle the heat loads generated by the REBs.
But, heat wasn’t the only factor that had to be considered. The boxes are located throughout the south east region which includes Sussex, Wessex, Kent, Great Eastern, West Anglia and north London lines. Geographically the area reaches from Kings Lynn down to Exeter.
Network Rail also specified its own essential criteria including reliability, performance, energy efficiency and ease of maintenance as many units are not easily accessible.
With 24/7 operation required and variable cooling loads required depending on the equipment in the REB, standard units were not an option. Units based on Edenaire’s successful CTXe were used as a template from which customised units were developed for Network Rail Two types pf unit were developed delivering 16-19°C for signalling equipment and 16-24°C for the rest.
In line with Network Rail’s energy strategy, free cooling was a pre-requisite and a number of modifications incorporated to meet the rail operator’s own specific requirements. For example the way in which the doors hang, there was also a preference for components that were tried, tested and known to be reliable rather than the latest high tech alternative.
Specific controllers were also requested in addition to bespoke software. The basic indicators inside each REB duplicate the traffic light settings familiar to all engineers and eases fault diagnostics.
Most REB units are being fitted with single units but some may require double units depending on the cooling capacity required.
Prototypes were built and piloted in East Anglia where the first of the aged split systems were due to be replaced. Ransome Engineering carried out the installations.
The trials threw up some interesting unforeseen hurdles. Some of the areas are quite rural which causes a significant problem in August when crops are harvested and the ensuing dust can clog the filters which never occurred on the split systems as they were not free cooling. Filters on rural units therefore need to be maintained more frequently and any maintenance is scheduled to coincide with harvesting. Coastal units also came with their own unique set of problems typically associated with a salt-laden and corrosive environment. The possibility of track and brake dust being kicked up by passing trains and getting into the AHUs filters was reduced by ensuring that all units were mounted on the back of the REBs.
To date 17 REB have been refurbished with the units. With a further 1500 across the network waiting to be replaced as they age and become uneconomical and reliable to maintain, it is estimated that the project will take some 10 years to complete.