There is still huge potential for energy saving through waste heat recovery in industrial spaces and processes. They create a lot of heat, which could be recovered and utilized. Many times, this is not case, though waste heat recovery and re-use would increase energy efficiency and create cost savings.
There are special requirements for using heat recovery equipment in industrial environment. They need to be durable and easy to keep clean. In industrial spaces, the exhaust air often contains different kinds of impurities, such as dust, oil mist or small metal flakes. These cause fouling in the heat transfer surfaces of the heat exchanger and thus reduced energy efficiency. Even a thin layer of dirt significantly diminishes the heat transfer capacity and the device may operate on a notably lower level of efficiency than originally planned.
Fouling in waste heat recovery is a problem, resulting in investment, energy and maintenance costs. The loss in annual efficiency rate may be as high as 10 % if there if there is fouling in waste heat recovery. This decreases the annual efficiency rate in ventilation by 8%.
The dirtier the heat exchanger gets, the more work it requires to get it clean. Designing the heat exchanger so that it easier to clean, usually results either in an increase in size or decrease in efficiency at the time. This obviously increases the investment / operating costs. These are factors, which should be considered when choosing and dimensioning the heat exchanger. The working life of the device is also something to keep in mind. A more durable device, which is easy to keep clean, will return the original investment through longer working life, through smaller maintenance and operating costs and through minimal down-time.