University of Manchester

The Jodrell Bank Observatory is part of the department of Physics and Astronomy at The University of Manchester. The Observatory is home to the Lovell Radio Telescope and the MERLIN/VLBI (Very Long Baseline Interferometry) National Facility which is operated by the University on behalf of PPARC (The Particle Physics and Astronomy Research Council). It is a place of learning, teaching and research for the many astronomers, students and engineers who develop and use the facilities there.

MERLIN is an array of seven radio telescopes distributed over central England and is one of the world's major astronomical instruments which has an enormous impact on fields as diverse as galactic star-formation and stellar evolution, distant starburst systems, galactic evolution and cosmology.

The observatory also operates smaller higher frequency radio telescopes, which are sited at a high altitude observatory on Mount Teide, Tenerife, to reduce the atmospheric contamination of their data as a result of water vapour in the lower area part of the Earth's atmosphere.

The VSA (Very Small Array) telescope detects the cosmic background radiation to support research into the nature of the universe a few tenths of a second after the Big Bang.

The construction of this array provides a unique radio telescope designed explicitly to image the background anisotropies of cosmological origin. The instrument has sensitivity and a range of resolutions unmatched by any other telescope in the world. The VSA provides direct, fundamental information on topics ranging from the origin of galaxies to unified theories of particle physics.

Objective

• To cool eight water cooled cryogenic helium compressors, sited in Izana, Tenerife, each dissipating 3.3 KW, requiring a total water/glycol (30%) flow rate of 4.9m3/hr with a temperature rise from 10°C to 15°C through the equipment.
• The heat load calculated as 26.4 KW and design ambient temperature determined as 30°C dry bulb at an altitude of 2400m.

Solution

Sealed and pressurised closed circuit water cooling system.

The system comprised:

• 2 air cooled water chillers
• Air blast radiator, having two 0.85 KW fans drawing air over the aluminium finned copper tubes. This was fitted with two fan control thermostats and an air sensing thermostat. Designed to dissipate 26.4 KW when cooling 4.9m3/hr, 30% glycol solution from 25°C to 20°C in design ambient 16°C dry bulb
• Self acting 3-way diverting valve
• Dual pump module, fitted with two 2.2 KW pumps (1 duty, 1 Standby) and flow monitor
• Pressurisation set with manual fill and sight glass
• Electrical control panel for duty/standby pumps including automatic changeover on duty pump failure and pressure set pump

A specific design consideration was the wide range of ambient temperatures from -10 to +35C, very high winds containing fine saharan sand and the low density of air at 2400 m above sea level. A set of assembly and electrical drawings, together with an installation and maintenance manual, translated into Spanish, were also provided upon completion of the order.

Result

• Guaranteed cooling of compressors, day and night to achieve physical temperatures within the cryostats of 15 Kelvin (ie 15°C above absolute zero) providing very low internal noise generation and hence the highest possible sensitivity to enable detection of weak signals.
• Improved reliability by keeping the helium compressors at a constant temperature inspite of wide varying ambient conditions.
• Free-cooling air blast units virtually free to operate, so costs are kept to a minimum, important for remote locations.

This was a cooling system for a new telescope, with run and standby pumps and run and standby chillers to guarantee cooling.

The radiator was installed as a "free cooler" to save energy as the ambient at the observatory, which is at 8,000 ft, is low enough during the night-time and for the whole of the Winter season to operate and make considerable energy savings.

Endorsement

Colin Baines, Receiver Operations Engineer, University of Manchester says 'Stadco Cooling's consultancy and design capability was exceptional. They provided a bespoke, designed for purpose, location and cost effective technical solution, meeting all of our needs for such a sophisticated requirement, especially being based at Mount Teide in Tenerife!'