Research funds well spent

Press, 27 July 1989, Page 27

Research funds well spent

Innovations, introduced in all good faith by their developers or manufacturers as being beneficial to the human race, can sometimes turn out to have a less desirable effect.

Take catalytic converters, for instance. Hailed as the answer to increasing air pollution caused by exhaust emissions from petrol powered cars, three-way catalytic converters are mandatory on all new cars in the United States. The European Commission is also considering following suit to making them compulsory on all new vehicles in Europe. But recent research carried out in Sweden and France has found that while the converters can

eliminate up to 80 per cent of pollutants such as hydrocarbons, carbon monoxide and nitrogen oxides, they also produce increased levels of nitrous oxide, a gas which contributes significantly to the warming of the world through the greenhouse effect.

However, little is known about the chemical processes by which nitrous oxides are produced within the converters, so they cannot yet be modified to prevent the gas from forming.

Although a setback for the car industry and the world’s clean air hopes, the news about the efficacy of converters did not come as a total surprise to one Auckland company.

Five years ago, when

looking for ways to develop a cleaner burning heater, woodstove manufacturer Kent Heating, Ltd, was faced with a choice. It could either fit a catalytic combustor into the heater’s flue or outlet, as most of its United States competitors had done, or it could look for a completely new way of reducing emissions. “Fortunately,” said the product approval manager for Kent, Mr Graham Walker, “we chose the latter. Our research at the time showed there was strong consumer resistance to the converters, even though they had been compulsory on new United States vehicles for some years.

“Also independent tests had shown that catalytic

combustors do not perform as well in the field as was first claimed because of technical problems.

“If coated nails, paint, glossy magazines, printers ink, coal, driftwood and so on are burned on the fire they will quickly destroy the chemical activity at the surface of the catalytic combustor which is the key to its performance,” Mr Walker says. “Or, if the catalytic combustor comes into the path of direct flame this will also burn off the coat of metals at its surface, once again making it useless.

“Once its chemical coating is destroyed, the combustor will make the heater less efficient and cause its emissions to be

worse than if there was nothing there at all.

“In short we believed they were an expensive and unreliable method of reducing emissions.” Long regarded as a world leader in high technology wood heating, Kent chose the hard way out instead. It decided to develop a high technology firebox in which combustion temperatures were increased, thereby reducing emissions. “Historically,” says Mr Walker “the firebox has been a bare metal box in which heat transfers rapidly away and the temperatures maintained are not always very high. We needed to increase the combustion temperature. “Other manufacturers

had chosen to do that by placing fire bricks inside the firebox. But the bricks had a lot of disadvantages. They are very thick, up to 80mm which reduces the volume of the firebox quite substantially, and they are limited in strength and design shapes. “We set out to find a material which would give us improved thermal insulation properties without significantly reducing the size of the firebox. “About two years ago we found a ceramic that could be moulded and pressed to fit the curves of our firebox design while still providing a high degree of thermal insulation,