Retrofit Turbocor project overcomes challenges

Cool-Therm, Turbocor chiller, air conditioning
A familiar sight on a rooftop, but these air-cooled condensers are some 70 m away from the Turbomiser chillers they serve.

A replacement installation of Turbomiser chillers at Swansea Civic Centre is believed to have the longest pipework run ever used on a Turbocor-based air-conditioning project. The project uses two 420 kW ‘split’ Turbomisers installed by Cool-Therm in the building’s plant room. They are connected to air-cooled condensers some 70 m away on the roof.

Designed and managed by the council’s M&E design and maintenance section, the installation replaced a pair of aging chillers using R22. To avoid disruption, it was necessary to use some of the existing refrigeration pipework with R134a.

Dave Blackmore, a director with Cool-Therm, explains, ‘The internal building pipework runs through library archives, risers and ceilings, and into office space. 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 condenser and chillers in the plant room, resulting in minimal disturbance to the operation of the building.

There were several design and installation challenges. The original chillers were based on different pipe sizes to those on the Turbomiser chillers. Integrating the two required careful design and installation on site.

In addition, the original dual-circuit system has four pipes per chiller running through the building — two each for liquid and discharge. Turbomiser chillers have a single circuit. This problem was overcome by Cool-Therm making a bespoke Refnet Y-joint pipe-connecting system.

Very accurate assessment of pipe sizes and pressure drops was crucial to ensuring the correct cooling capacity at the flooded evaporator.

Turbomiser chillers do not need oil, so all traces of lubricant in existing pipework had to be removed.

The old chillers were broken down and taken out in manageable sections through public access areas in the civic centre. Likewise, the modular Turbomiser chillers were delivered in the same way and rebuilt in the plant room.

Cool-Therm fitted new refrigerant leak detection and emergency extract ventilation to comply with current F-gas regulations.

The condensers have micro-channel coils, which reduces refrigerant charge and increases heat-exchange efficiency. Swansea Civic Centre is just 20 m from the seafront, so the condensers were treated with an anti-corrosion coating.

To enable an extended warranty to be provided in such a harsh location, the condensers were galvanised and then epoxy coated. Copper pipework was insulated with pipe insulation billet topped with a galvanised wrapping.

For more information on this story, click here: Feb 2014, 120
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