05 July 2000

Can solar water heaters win UK's biggest engineering prize?

A solar water heater so efficient it can serve a weather station in Antarctica has been shortlisted for this year's £50,000 Royal Academy of Engineering MacRobert Award, the UK's most coveted prize for engineering innovation. Thermomax Ltd, based in Blackwood, South Wales, and Bangor, Northern Ireland, manufactures vacuum tube solar water heaters, which can halve heating bills. Sharokh Sabba, Dr Vahid Tabatabai and Trevor Griffiths have developed the ideal solar power system for cloudy climates.

No longer do you need desert conditions to use solar power, thanks to this innovative water heating system. The company uses a completely different technology to the conventional solar panels that require permanent sun to be effective. Instead they use a series of long glass tubes, each containing a closed-loop copper "heat-pipe" attached to an absorber plate with a photovoltaic coating. This collects both direct and indirect solar radiation, heating up both the heat-pipe and the fluid (usually methanol) inside it. Evaporation and condensation enables the heat-pipe to act as a heat exchanger to the property's hot water circuit. The greatest benefit is in completely evacuating the glass tubes of air - this insulates the system on cold days and protects it from moisture and condensation, which could corrode it.

The system continues to heat up the water supply until a pre-set maximum temperature is reached - about 95ºC for domestic applications. A memory metal spring seals off the heat exchange at this point and prevents the water supply overheating.

About 20,000 European homeowners are buying the system every year. "Our system works well even in cold and cloudy conditions," says Executive Director Dr Vahid Tabatabai. "The tubes last about 25 years and the whole system only costs about £2,000 to install, so it saves people money as well as being environmentally friendly. We expect the European market to grow by about 20 per cent every year."

About 100,000 of the UK's 18 million homes already use conventional flat plate solar panels to take advantage of sunny days. The Thermomax system is far more compact than flat panels. "A family of four would need four or five square metres of solar panels to get the same output as 20 of our tubes, which take up about two square metres," says Chief Executive Sharokh Sabba

Thermomax produces three solar tubes with different temperature cut-offs, the highest being at 180ºC, but the team is now working on even higher temperatures for use in solar air conditioning and seawater desalination - a joint project with the University of Athens.

Sadly, the man who actually invented this technology died last year, aged 54. Dr Framarz Mahduri founded Thermomax Ltd in 1980 to develop his idea for the solar tube, conceived while he was head of energy research for Phillips Aachen.

ends

Notes for editors

1. The Royal Academy of Engineering MacRobert Award is Britain's premier prize for engineering. It is given annually for outstanding innovation of benefit to the community. First presented in 1969, the award consists of a solid gold medal and £50,000 prize.
   
2. The outright winner of the 2000 Award will be announced in November 2000.
   
3. The four finalists will receive certificates from the Academy president, Sir David Davies, at the Academy's AGM on Monday 10 July 2000.
   
4. The three other finalists this year are BAE Systems in Edinburgh for the ECR-90 radar for Eurofighter, NXT plc in Huntingdon for the first flat panel loudspeaker, and Johnson Matthey in Royston for the CRT™ continuously regenerating trap to control diesel pollution.
   
5. The Royal Academy of Engineering aims to pursue, encourage and maintain excellence across the whole field of engineering in order to promote the advancement of the science, art and practice of engineering for the benefit of the public. The Academy comprises the UK's most eminent engineers and is able to use their combined wealth of knowledge and experience to meet its objectives.

For more information please contact:

Jane Sutton at the Royal Academy of Engineering
tel: 020 7227 0536 (direct), email: jane...@...org.uk

Links:

www.thermomax.com

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