Many building owners and contractors have been seeking ways to improve indoor air quality (IAQ) by controlling airborne particulates while also saving on operational costs.
One solution gaining popularity around the world is the counterflow plate heat exchanger. It has already proved successful in places where cross-contamination of intake and exhaust air is unacceptable, such as in hospitals, industrial buildings, and laboratories.



One solution, multiple benefits

Counterflow plate heat exchangers can solve both the energy problem and cross-contaminated airflow at once.  Spikes in power bills are most common in winter and summer. During these seasons, plate heat exchangers can offer significant advantages, recuperating heat energy at 90% efficiency. In the winter, they recover heat energy loss, and in the summer, they help retain low-temperature air.At the same time, two airstreams are fully separated between the plates that exchange heat. As a result, the fresh outdoor air can enter the system, while the foul indoor air gets exhausted.  Before I get into design features of a plate heat exchanger and its impact on indoor air quality, let’s cover why this even matters in a broader sense.

Why indoor air innovations matter

The coronavirus outbreak and a continuous need for increased energy efficiency have put new pressures on the HVAC industry to innovate, increase efficiency, and improve health conditions. Residential and commercial buildings can make up a significant amount of a country’s annual energy consumption. According to the US Energy Department, when electrical system losses are included, both these sectors accounted for about 21% and 18% respectively (39% combined) of total nation’s energy consumption in 2019. Emerging government stimulus packages in response to the COVID-19 pandemic offer new financing options for buildings that adopt energy-saving technologies. 

Energy-efficient building certifications like the  Eurovent’s ECC are increasingly important. They serve as market viability indicators across well-informed customers who are increasingly knowledgeable about IECC and ASHRAE indoor air standards. Heat exchangers can help to visibly reduce the consumption of operational energy used for heating and cooling.

And in terms of health improvements, airtight counterflows can prevent airborne particles and pollutants from recirculating. HVAC solutions and materials compliant with VDI 6022 –just as Swiss Rotors’ heat exchangers–guarantee to fulfill the strictest hygiene requirements. They undergo extensive testing to prove that they can’t provide a growth base for pathogens–helping to protect the health of individuals staying in the ventilated rooms.

Heat exchange basics–and what airtightness brings

The desired outcome of recuperation systems is to recover heat energy and avoid loss. Counterflow exchangers allow airstreams to pass between alternating plates so that they enable heat transfer to take place.  Outdoor air comes in through filters to remove microbes, microparticles, dust, pollen, and pollutants. Simultaneously, indoor gasses are exhausted. Both airstreams pass through the heat exchanger between alternating plates but almost never cross-contaminate due to airtightness. 

Designing plate heat exchangers for maximum airtightness

Advances in material sciences and automated manufacturing have made these products more commercially viable than previously possible. Guided by the global EN 308 standard, here are some of our top priorities that go into the design engineering of plate heat exchangers.

  • Plate crimping and edge sealing. Plates are mounted with double-folded edges in aluminium HEX to ensure exchanger rigidity and minimise leakage. Complete airtightness is maintained with double-folded edges for aluminium or ultrasonic welding in polymer exchangers. Plates are sealed to the casing with a flexible compound to avoid any leakage.
  • Plate design and material choices. At Swiss Rotors, we design plates for efficiency and stability to provide minimal pressure loss. Operation ranges from 150-250 Pa are considered highly efficient, and our maximum differential pressure between supply and exhaust airflow is 800 Pa. We manufacture both aluminium and plastic polymer plates and encase them in Aluzinc for optimal performance and manufacturing ease.
  • Automated manufacturing. At Swiss Rotors, we have automated manufacturing and production, which offers the benefits of enhanced product quality and fast lead times.
  • Testing. We rigorously test 100% of our exchangers for airtightness based on leading European standards (EN 308).

Engineers and manufacturers need to be aware of what technologies are now available and why these solutions can make a difference. Let’s talk if you share a passion for HVAC product engineering or want to learn more about modern IAQ design.

About the author: Sebastian Wejchert, product engineering manager with over 8 years of experience in the HVAC industry. In his work, he always follows the market’s best practices but also leaves some room for intuitive creativity.