During the past winter, we developed a new type of rotary heat exchanger that, in tests conducted down to –20°C, could completely eliminate the need for additional methods for heating the supply air.
We were able to cover 100 % of the energy requirement for heating to +1°C when the exhaust air temperature was above +4°C, the outdoor air temperature was above –20°C, and the air flows were the same on both sides. Since delta-T becomes higher between exhaust air and outdoor air the colder it is outdoors, the rotor will be able to provide more energy since the exhaust air can be cooled more at colder outdoor temperatures.
This means that the solution can be used even at temperatures below –20°C.
”Rotary heat exchangers are a fantastic invention, and with our unique selection of materials and in-house control technology, we are also able to avoid the rotor icing over even in extreme cold and with 100% relative humidity in the exhaust air,” says Tomas Bolsöy, innovator and owner of EOL Vent Mining.
In the described tests, the heat exchanger delivered with a temperature efficiency of 87%. In most cases, temperature efficiency is a good indicator of a heat exchanger’s efficiency. In mining ventilation, however, the supply air usually only needs to be heated to just above freezing to prevent the water from turning to ice in the shafts. A better KPI for showing the heat exchanger’s efficiency is therefore to calculate the energy efficiency in different operating conditions.
So far, and in the temperature conditions of winter last year, we have managed to show 100% energy efficiency.
In order to maintain a high seasonal efficiency over time, the system needs to both provide good output at different temperature intervals and be able to defrost efficiently. When the large masses of exhaust air meet the cold outdoor air, condensation forms, and there is a risk that ice will build up in the rotator. We eliminate ice formation using sensor technology that in less than two minutes reduces the rotation speed until the ice no longer forms and the condensation water drains as usual.
”We are very proud of the results we have documented and that we are now taking even more sustainable technology to the market,” says Samuel Kaartokallio, Project Manager at EOL Vent Mining.
In addition to the heat exchanger we are now launching, we have also worked on the development of related condensation-resistant silencers for exhaust air. This technology is sustainable and is based on smart design and recycled materials. It features both high sound-absorbing properties and high moisture resistance. We look forward to sharing more about this technology in the fall.
We spend a lot of time every day adapting our products to each unique delivery.
This leads to many strong customer relationships and a high degree of knowledge sharing. We are grateful for this, and in addition to providing us with friends all over the Nordic region and the world, it also gives us the opportunity to continue to innovate and offer products that strengthen the mining industry.
Tests show that our new rotary heat exchanger for mines is able to cover 100 % of the power requirements for heating at down to –20°C outdoor temperatures without ice build-up, even at 100 % relative humidity in the exhaust air.