Applying Automation to Reduce Illness

The demand for ventilation systems that can limit virus spread by increasing the indoor flow of fresh air from outside continues to rise in the U.S. and around the world as a direct result of the COVID pandemic. The U.S. Government, for example, has approved an $80 million funding program for upgrades of older ventilation systems in schools and other buildings to new ones that have correct filtering, extremely precise humidity levels and can distribute large volumes of outdoor air inside buildings.

CaptiveAire designs and manufactures systems that can transmit up to 100% fresh air through its Paragon ventilation equipment. The company, founded in 1976 and is headquartered in Raleigh, N.C., maintains a network of more than 90 sales offices in the U.S. and Canada. It also operates six manufacturing plants in North Carolina, Iowa, Oklahoma, California, Pennsylvania and Florida.

The Paragon ventilation system CaptiveAire is well known for employs technology called DOAS (dedicated outdoor air system). It brings outside air inside and filters, conditions and delivers it with minimal energy use. Paragon’s rare earth magnet inverter scroll compressor eliminates excessive cycling, premature unit aging, inefficient hard starts and unnecessary energy consumption.

DOAS systems can reduce the risk of infection in facilities where many people gather. Not surprisingly, demand for the company’s ventilation solutions has risen since the COVID-19 pandemic emerged and is currently 150% above pre-COVID levels.

Danfoss’s work with CaptiveAire

Danfoss supplies a number of components for the Paragon system, including variable speed scroll compressors with built-in VLT drives. The drive and compressor in the Paragon system react instantly to the ever-changing cooling loads throughout the day as well as seasonal loads.

Danfoss variable speed compressor designed into the CaptiveAire RTU unit.

Neil Evans, key account manager at Danfoss, explains, “Unlike constant-speed systems, variable-speed systems can run between 20% and 100% capacity, effectively matching HVAC load to a building’s actual demand. And as opposed to the on/off operation method of their fixed-speed counterparts, variable-speed systems operate continuously, providing a steady stream of conditioned air to the space.”

The company is also working with CaptiveAire to review the addition of heat exchangers, filter driers, and pressure and temperature sensors.

Danfoss tests its components for optimized system performance at its cooling and air-conditioning development center in Tallahassee, Fla. “Our Application Development Center is a great resource for us,” says Danfoss engineer Jordan Ross. “We’ve performed several stress tests of CaptiveAire’s system. At one point, we even had snow inside the test chamber.”

Danfoss components are designed to enable the end-user to always obtain correct temperatures with minimal energy-use. Along with other system components, they also help ensure optimal humidity levels and fresh air. The latter two are key—particularly when you want to prevent virus-spread.

COVID-19 and its variants need a carrier to transport them through air. People produce such particles when they breathe and cough. Big particles—droplets—fall to the ground and the viruses in them are killed when disinfectant is applied to tables and other surfaces. The smallest particles—aerosols—travel through air. And if the air is dry, they shrink and may become small enough to travel through some filters. That’s why it is key to constantly keep humidity at a level where aerosols remain big enough for air filters to catch them.

Some aerosols will remain at a size where they can pass through inadequate filtration. This can be countered by constantly adding fresh air into the ventilation system, thereby sending the remaining aerosols outside.

“Traditional ventilation systems recirculate inside air, but we constantly add large amounts of fresh air from the outside. We also filter and control humidity throughout the system. This places us among the best worldwide at preventing virus-spread,” claims Brandon Hafner, CaptiveAire’s vice president of construction and facilities.