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Bernoulli’s Theorem |
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Daniel Bernoulli (1700-1782) was a genius of a mathematician, born into a family
of leading mathematicians. His brothers Johann II and Nicolas II were mathematicians,
as were his uncle Jacob and father Johann. In 1738 Daniel published the book
Hydrodynamica, in which most of his findings relevant to our field occur, including
principles of the conservation of energy.
One of the applications of Bernoulli’s Theorem that we see every day is in aircraft flight:
- Where there is decreased flow, you will find increased pressure.
- Where there is increased flow, you will find decreased pressure.
- The air flowing over the upper curved surface of an aircraft wing moves faster than
the air beneath the wing, so that the pressure underneath is greater than that on the
top of the wing, causing lift.
Another example is the showerhead. In massage mode, you are moving a small amount of
water fast. If you removed the head, you would be moving a lot of water slowly. It takes
the same amount of energy to move a little water fast as it does to move a lot of water
slowly. The amount of energy you have available is due to your water pressure. The small
holes in the showerhead create a pressure point in your water line, which makes the water
moving through that pipe have a high pressure and low velocity. When it leaves the
showerhead, the flowing water is no longer under pressure, so the velocity increases.
This is basically how the airflow works with the Hi-Velocity Systems.
Our air handler pressurizes the ductwork just like the water pipe of your shower. Our
compact 2" vent outlets act like the holes in the showerhead to convert the pressure to
velocity, and deliver the conditioned air into your home. Unless part of your showerhead
is plugged with scale, you will get equal water flow from all the small jet holes. Since
airflow and water flow follow the same principles, you will get equal airflow from all the
Hi-Velocity vents in your home. This holds true from the first branch duct to the last one,
and is modified only due to friction from longer lengths of branch ducts.
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The Venturi Effect |
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Giovanni Battista Venturi (1746-1822) wrote a book on the history of optics, and
published valuable works on Leonardo da Vinci and Galileo. His research into the
physics that fluid pressure drops as fluid flow increases sees more applications than
just airflow with our Hi-Velocity Systems. People familiar with the workings
of the internal combustion engine will know that the venturi effect is what causes the
fuel air mixture to draw properly through the intake manifold of the car.
The Venturi Effect is the increase in the velocity of a fluid stream as it passes
through a constriction in a channel, pipe, or duct. Calculated by the Continuity Equation,
or Q = VA where Q is the volumetric flow rate, A is the Area of flow, and V is the fluid
velocity. Because Q does not change, as A gets smaller then V must increase.
In simpler terms, if the duct gets smaller, then the air at that point will move
faster than when the air was in the larger duct. Airflow can be considered energy in
motion. The airflow must maintain a relationship between its velocity and its pressure
so that when one increases, the other will decrease. It doesn't matter if it's air
entering a carburetor or air leaving a duct, this energy in motion will have an effect
on its surroundings.
When the higher-pressure air leaves the vent of Hi-Velocity Systems, it
expands rapidly and causes a lower air pressure around the vent. This causes the room
air to be drawn toward the airstream leaving the vent. This application of the Venturi
Effect is what causes the thorough mixing of room air in a home that has the Hi-Velocity
Systems installed.
It doesn't matter if the vents are located in the floor, ceiling, or wall; this
complete mixing will always occur due to the Venturi Effect. With other air systems
that operate with less pressure, this effect does not occur to any appreciable amount.
This is why stratification of "lazy air" can occur.
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Inventing Hi-Velocity Systems |
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Calvin Dodd MacCracken (1920-1999) can be credited with building the first higher
pressure, high velocity style air handler. He earned his first patent during World
War II when he worked for General Electric to reduce the size of a British design for
a jet engine to be used in the XP-59a. After the war, he founded Englewood, N.J.-based
Jet Heet Inc., now called Calmac Inc., and served as its president for 50 years. Some
of his other works ranged from electric hot dog cookers to space suit components used
by the astronauts on the Apollo missions.
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He helped in the development of several hundred products and has 80 patents to his
name. The first product marketed by Jet Heet was a residential forced-air oil furnace,
which was based on some of his findings from his jet engine research, and was the
forerunner to Hi-Velocity Systems.
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MacCrackens Jet Heet system used small, insulated ducts to deliver air of a higher
than "normal" temperature and pressure into a structure. This was found to be very
interesting to the public in 1946, and he even had a very successful article written
about it in the December, 1946 issue of Life magazine. As the popularity of the Jet
Heet system grew, Space Conditioning Inc, a company involved in the HVAC field, picked
up the line. As the Jet Heet system evolved, one of the primary markets developed was
for retrofit cooling installations into homes that had little room for ductwork, or in
which architectural changes were undesirable.
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Today, while the Hi-Velocity System is still used in that market, it was
found to be much more versatile. With the compact size of the ductwork, and the superb
airflow patterns from the vents, Hi-Velocity Systems is used extensively in
new construction and old to provide quality heating, cooling, filtration, humidity control,
and fresh air make-up. This system can provide all of these items (important for superior
Indoor Air Quality) without sacrificing indoor comfort.
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Call us to discuss your
application today! 1-888-652-2219 |
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