Early Warning System for gas leaks - Dr Martin Lloyd & Robert Cameron

Gas leakages from commercial refrigeration systems are an environmental hazard and can prove costly for food retail outlets and cold storage facilities. A new generation of low cost, micro miniaturised sensors currently being developed to detect these emissions early is proving to have equal relevance for aerospace and other industry sectors.

The enticing display of fresh produce in your supermarket’s chiller cabinets is kept in peak condition by a complex refrigeration system that uses refrigerant gases as a cooling agent. As much as 60% of the gas can leak before its loss is noticed – even a minor leak can result in the loss of up to 20% of refrigerant gas if nothing is done about it. Hence 70% of gas sold to retailers is used for ‘topping up’ their systems. This leakage is a matter of concern for a number of reasons, not least because the quality and safety of the produce is compromised. From an environmental point of view there’s the damage the emissions do to the ozone layer, while the financial consequences can significantly affect a food retailer’s or manufacturer’s bottom line. Energy consumption increases to maintain the refrigeration equipment’s cooling capacity; in a worst case scenario the system may break down altogether, resulting in down time, spoilt food and maintenance costs. It is estimated that as much as £40 million per annum could be saved on energy costs by reducing leakage levels.

On-The-Spot Solution
Constant monitoring enables a leak to be detected at an early and manageable stage, before too much damage is done. While the commercial refrigerant gas detectors currently on the market can detect minute traces of gas and generally do a good job, they are cumbersome, very expensive and complex to install. They typically consist of a central control roombased chamber which sucks in air samples via a network of hundreds of metres of tubes from different parts of a supermarket or cold store and analyses and measures the gas in the sample.

The consortium collaborating on Eureka project E! 1811 Euroenviron Pampas, an acronym for Practical Applications of Micro-Miniaturised Photoacoustic Sensors, identified commercial opportunities in Europe and the US for a new generation of improved refrigerant gas detectors which they believed would be less expensive and much easier to use. Their solution was elegantly simple: a ‘point sensor’ which could be installed in a plant control room or, if sufficiently inexpensive, plugged into individual chiller units rather like a domestic smoke alarm, eliminating the need for an intricate network of sample collecting tubes.