Air-Soarer: A constant air speed device that realizes a variable air volume Coanda air conditioning system

In any office of a certain size, ducts are essential to deliver conditioned air to the entire space - but now a new technology has been developed that overturns this conventional wisdom. Airflow from the wall-mounted outlets, which have an autonomous opening and closing mechanism, creeps along the ceiling and moves forward, reaching the back of the room. Even with a reduced air volume, a uniform air conditioning effect can be achieved, which not only saves energy by reducing the power required to transport air, but also makes it possible to reduce floor height and costs by eliminating the need for ductwork above the ceiling. This will expand the possibilities for streamlining equipment and spatial design.

When the space becomes large, air conditioning technology installs ducts to distribute the air outlets and prevent the conditioned air from stagnating locally, creating a uniform environment. However, is there a way to create a uniform air environment by only blowing air from one wall without using ducts? This is where we turned our attention to a principle called the "Coanda effect." This is the phenomenon in which the trajectory of a jet of gas or liquid is attracted to a nearby wall. By blowing air near the ceiling surface, the airflow crawls along the ceiling, preventing it from falling, and is sent to the back of the room. However, there is one problem. If you reduce the air volume to lower the air conditioning capacity, the wind speed will decrease and the Coanda effect will not be able to maintain it, and the air will immediately fall near the outlet.

Therefore, a device called "Air-Soarer" was developed as a technology to keep the wind speed constant regardless of the air volume. The basic principle is to narrow the outlet when the air volume decreases, and widen it when the air volume increases. Moreover, it operates gradually and smoothly. It is possible to use a sensor to measure the air volume and automatically control the shape of the outlet electrically, but the greatest feature of this device is the simple mechanism that does not use such an exaggerated system. It uses movable blades made of metal plates, weights, and a rotating shaft. When conditioned air hits the weighted blades that block the outlet, the air pushes the blades down and the mouth opens. The more the air volume increases, the wider the outlet opens. Will the blades drop accurately with even the slightest difference in air volume? Will it operate smoothly? These were tested, and the optimal materials and construction method were obtained. By using a mechanical mechanism that does not use IT at the heart of the system, we have reduced failures and improved maintenance performance.

Air quality verification

We carried out actual measurements to verify how well the air conditioning was being achieved. Using a model space with a 13m span, the size of a medium-sized office, we installed the system and blew out cold air from one side, measuring the room temperature and wind speed during air conditioning. Assuming the occupied area is 1.7m above the floor, the temperature in that area was kept below 26.5°C (yellow-green). The cold air slowly descends along the ceiling to a height of about 4m, providing air conditioning up to a depth of 13m.

We also found that a square shape for the opening of the air outlet helps maintain the wind speed without drawing in the surrounding air. Therefore, we limit the width of the air outlet to 500mm and increase the number of them side by side.