Case History 2- Project: High Velocity Hand Dryer

Objective : Our client was designing a new revolutionary hand dryer using a very high velocity air stream to achieve drying in 1/3 the usual time.

Challenges : For the product to deliver its full promise the pressure drop from the heater had to be close to negligible. There was very little space available for the heater since the air path from the blower to the exhaust had to be minimal. Low product cost and very easy assembly were very important.

Solutions and their impact :

• We designed a very open heater with little pressure drop.
• Space in the direction of air flow was very limited. So, we designed the heater to occupy a minimal .375" distance in the duct length. Even though the heater circuits fill this compact space so efficiently, we were still able to integrate two over-temperature protectors into this small package.
• The heater had to be very open and low mass but, it also needed to be stout to withstand the force of the high velocity flow. So, we made a frame around the heater which adds much strength but produces little profile to the air-stream. The structural frame is made of mica which also acts as a stand-by heat shield lining the plastic housing.
• This frame has another function as well. It permits the heater to be self positioning as it is inserted blindly into the duct. This makes assembly very efficient. One end of this frame doubles as the mounting plate which attaches to and seals to the duct.