Specifications
Devatech as a Company wants to meet the Users requirement as exact and as precise as possible.This technology, as expected, has not only demonstrated an effective means of reducing energy cost and heating and cooling loads, but has allowed for the scaling down of equipment. Additionally, this system will allow for the indoor environment to maintain a relative humidity of an appealing 40% to 50% range. This range can be maintained under essentially all conditions. The only energy penalty is the power needed for the blower to overcome the pressure drop in the system.
The rotating wheel heat exchanger is composed of a rotating cylinder filled with an air permeable material resulting in a large surface area. The surface area is the medium for the sensible energy transfer. As the wheel rotates between the ventilation and exhaust air streams it picks up heat energy and releases it into the colder air stream. The driving force behind the exchange is the difference in temperatures between the opposing air streams which is also called the thermal gradient. Typical media used consists of polymer, aluminum, and synthetic fiber.
The Enthalpy Exchange is accomplished through the use of desiccant. Desiccants transfer moisture through the process of adsorption which is predominately driven by the difference in the partical pressur of vapor within the opposing air-streams. Typical desiccants consist of Silica gel, and moiecular sives.
Enthalpy wheels are the most effective devices to transfer both latent and sensible energy but there are many different types of construction that dictate the wheel's durability. The most common type of wheel is constructed of polymer (plastic) and can be plagued with high pressure drop and shorter life. Alternatives to plastic wheels include aluminum and fiberglass which have been shown to have a much longer life, often with a much lower pressure drop.
When using rotary energy recovery devices the two air streams must be adjacent to one another to allow for the local transfer of energy. Also, there should be special considerations paid in colder climates to avoid wheel frosting, systems can avoid frosting by modulating wheel speed, preheating the air or stop/jogging the system. Some systems offer equal sensible and latent energy transfer which greatly decreases the chance for frosting. Cross-contamination of the contaminants via the desiccant is also a concern and can avoided through the use of a selective desiccant like a molecular sieve.
