CASE STUDIES
CASE STUDIES
Specialist VRF system meets Crossrail underground needs
A
specialist VRF air conditioning system has been developed for the Crossrail project, in order to provide high resilience cooling for its new underground facilities.
The system was developed by a project team made up of representatives from Toshiba Air Conditioning UK and Crossrail engineering staff, which provided the solution for contractor Laing O’Rourke.
It will be used to provide a high quality temperature-controlled environment in ticket halls, station control centres and equipment rooms.
Significant design challenges included the need to meet London Underground’s strict fire safety requirements, as well as the necessity of integrating refrigerant leak detection and management systems to ensure the safety of workers and the public.
Similarly vital was the cability to deliver fine control of temperatures in order to ensure a stable environment for both people and equipment, with low power draw on equipment start-up.
64 April 2018
After analysing the required specification and identifying variances with existing standard air conditioning systems, the partners developed and tested a bespoke system to meet the precise requirements.
The London Underground fire-prevention code places strict limits on the use of plastics below ground. The team carried out a detailed evaluation of all components in Toshiba’s indoor units.
It resulted in the drain pan being replaced with an all-metal version, and several other components – such as fans, motors, controls and insulation – being replaced with non-plastic alternatives.
The system is equipped with Toshiba’s new integrated LD2 refrigerant leak detection and management technology, which constantly monitors refrigerant charge in relation to performance. In the unlikely event that a leak should occur, an alarm signal is sent and the site of the leak is automatically isolated, thus preventing further loss.
Low power draw on start-up is ensured by the use of Toshiba’s inverter system, which allows
the system to be controlled in fine increments of just 0.1Hz.
With the use of Toshiba’s twin rotary compressors, this also enables the system to operate at very low loads, when cooling demand is low.
This suits the demand profile of the equipment rooms in which the systems are installed, which was a focus of Crossrail’s engineering team. The equipment was tested and certified to CE standard at a third party facility. What has resulted is a VRF system suitable for use in underground and sensitive applications.
In the Crossrail project, the VRF condensing units can be connected to bespoke floor/wall- mounted and ceiling-suspended indoor units. Toshiba is supplying 30 of these specialist units to Laing O’Rourke, which will then be installed by contractors Conair UK and Skyline Air Conditioning.
The system is believed to be the only VRF air conditioning system currently available that meets the strict requirements for use on London’s Underground.
www.acr-news.com
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