Miniaturized low gas flow rate measuring
When the bus in front of us bellows out black fumes, we know that
the air is polluted. Often, however, we are oblivious to the potential
health risks. Assessing pollution levels calls for accurate measurements.
Part of the problem has been the lack of reliable flowmeters to
determine air volumes precisely. As this is the basis of air pollution
evaluation, the MILOGAS project developed a prototype flowmeter
that is portable, precise, energy-efficient and robust. At last,
a solution that yields trustworthy results on which to base atmospheric
We all enjoy a breath of fresh air. But just how fresh is the air around us? At times it is patently obvious that something is wrong, often it is not. Increasingly, people in large cities choose to wear face-masks to protect them from air pollution. Atmospheric contamination is a major environmental and health hazard that adversely affects us daily. The result is decreased productivity and spiralling healthcare costs.
To accurately assess the extent of pollution it is fundamental that test results are accurate. After all, if the basic measurements are unsound how can we detect and then reduce pollutants?
One vital aspect of atmospheric testing is accurate flow rate measurement in the sampling systems. Until now, no cheap, precise, low flow rate measuring device existed. A considerable oversight: large airflows are costly to measure as they need large expensive power-hungry pumps. This gap in the market provided a stimulus for the MILOGAS project to investigate the possibilities of developing an accurate low flow rate flowmeter.
Flow of information
The principal partner, Algade, specialises in making measuring instruments for pollution monitoring especially in uranium mines. Their previous work centred on hot-wire flowmeters - an adaptation from earlier applications in 19th century anemometers and later in aerodynamic studies. Through the company's years of experience, they realised that improvements in the measurement of the sampled volume of air were the only realistic way to progress. Algade saw that an electronic thermal sensor would be the key to future designs. Here, flow rate is determined by measuring the temperature difference between the sensor and an integrated heater.
The necessary recipe for success required two missing ingredients: IPHT, experts in sensor technology; and ENEA, skilled in environmental testing. With funding from the European Commission, the project took off.
A lot of hot air?
The partners set out to produce a sensor capable of operating accurately yet independently of a wide range of environmental conditions. IPHT used their accumulated wisdom of thermal sensor design to propose three possible solutions. Bringing these sensors to life depended on IPHT's expertise in production and thermal simulations.
Once these sensors had been incorporated into different packaging arrangements, ALGADE conducted aerodynamic tests to select the best design that would work. ENEA simultaneously tested the equipment against its behaviour in different environments. By combining the results the team could steadily refine the sensor to near
The results far exceeded expectations: compared with current commercial sensors, sensitivity increased 30-fold and the
operational flow rate became 25 times greater. The sensors' tolerance of high temperatures greatly exceeded that of its competitors. Not only did performance improve; adopting this chip will allow the price of air flow meters to drop by a factor of ten.
This development gave the flexibility required to build a light, compact prototype that could operate independently for long periods of time. Although not completely innovative in design, the air flow around the sensor incorporates other improved aspects. The details of this improved prototype cannot be described here for reasons of confidentiality.
The success extends beyond the new flowmeter. Algade, being the major partner, will capitalise on the success of the project by developing flowmeters based on the sensor. For IPHT, this project reinforced the idea of the benefits of EU-supported research and technological development. As part of former East Germany, this was their first direct experience of a European project. It gave them the opportunity to put their theory into commercial practice. Finally, ENEA will have copies of the sensor and this will allow them to deepen their knowledge of environmental testing. Bringing partners from different countries and cultures together brought the best out in each and enabled the project to exceed its own expectations.
Which way now?
At present the project is applying for a European patent. Initially, IPHT will produce a small number of sensor chips. As demand increases, the technology will transfer to a local SME for mass production.
The chip will be incorporated into the flow meter which Algade will produce and market. Initially, work will concentrate on delivering a practical dosimeter for miners exposed to uranium - an area that relies on flowrate meausurement and that Algade knows well. At first, this might seem a small market but remember, it is not only uranium miners that face exposure to radioactivity. Natural background radiation is a problem that miners around the world must contend with.
This market is expected to be between 3,000 and 10,000 units over the next three years, with each unit being sold at 200 ECU. From these humble beginnings, further modifications will improve performance and the diversity of potential applications. The sensor's versatility will allow it to be launched in most other fields of pollution measurement: from the flues of power plants to aeroplane exhaust plumes, from medical equipment to sick buildings. The equipment will find applications wherever flow rate needs to be examined. New and replacement equipment will provide larger market opportunities.
In short, we may soon be breathing a sigh of relief for cleaner air, thanks in part to this novel device.