Seventy-metre pipe runs on Cool-Therm’s chiller installation at Swansea Civic Centre claims record for Turbocor-based air conditioning project
The installation at Swansea Civic Centre uses two 420 kW ‘split’ Turbomisers connected to two air-cooled condensers some 70 m away on the rooftop. Cool-Therm’s Wales branch installed the system, which was designed and project-managed by Swansea council’s in-house mechanical and electrical design and maintenance department.
The Turbomisers replaced a pair of conventionall Carrier chillers based on R22. To avoid disruption, it was necessary to use some of the existing refrigeration pipe work, said Dave Blackmore, Cool-Therm director. “The internal building pipe work runs through library archives, risers and ceilings, and into office spaces. Replacing it would have been complex and expensive, and would have caused considerable upheaval for the building. The project manager was understandably keen to retain it and replace the outdoor condensers and chillers in the plant room, resulting in minimal disturbance to the operation of the building.”
This aim posed a number of design and installation challenges, as the original chillers were based on different pipe sizes to those on the Turbomisers. In addition, the original dual-circuit Carrier system had four pipes running through the building per chiller, two liquid and two discharge pipes, compared with Turbomiser’s single circuit. To overcome this, Cool-Therm designed and manufactured its own bespoke Refnet Y-joint pipe connecting system.
The design for the new chiller system itself posed a particular challenge due to the complex configuration, Mr Blackmore said: “We needed to make sure there was no excessive pressure drop across any specific component or pipe length, in order to deliver the correct cooling capacity at the flooded evaporator,rather than in the pipework.This entailed a forensic focus on pipe sizing, vertical and horizontal pipe lengths. The evaluation had to be right first time, there was no margin for error. Calculations had to take account of all system pressure drops, factoring in bends and 45 degree angles, all components and the properties and behaviour of refrigerant via psychrometric charts.”
A further issue arose due to the oil-free nature of the Turbomiser chillers, as the previous chillers, based on reciprocating compressors, used conventional lubricant and therefore the pipework incorporated oil traps. This meant that all oil residues in existing pipe work had to be flushed out and thoroughly cleaned prior to installation.
“We couldn’t allow any oil to remain in the system. This required removing all the oil traps and blowing the pipes out with oxygen-free nitrogen (OFN). As a back-up, we also ran a separate recovery rig with an oil accumulator in series with the chiller to catch any residual oil that remained after treatment with OFN.”
Swansea Civic Centre is located 20 m from the seafront and thus exposed to salt and sand and corrosive sea breezes. To protect against this, the aluminium micro-channel condensers were treated with an anti-corrosion coating to protect them from the elements.
Cool-Therm fitted new refrigerant leak detection and emergency extract ventilation in the plant room to comply with current F-Gas regulations.
Turbomiser chillers are based on the Turbocor oil-free compressor, which uses virtually frictionless magnetic bearings to produce the most energy efficient product of its type on the market, Cool-Therm said. Turbomiser chillers reduce energy costs by up to 50 per cent compared with traditional chillers based on screw or reciprocating compressors.