Leader in Misting & Temperature Control Systems


A) TECHNOLOGY

The “MISTER” system consists of an arrangement of atomizing nozzles, whose
function is controlled by a central control module. The control module maintains
the required system operating pressure, filters the water supply, and activates
the operation of the nozzles based on signals received from a sensor, which is
specified according to the application.

The “MISTER” system uses ordinary water that has been treated, filtered, and
pumped up to between 600 and 1000 psi. It is then delivered down a ½”
stainless steel tube or flex hose. Unique “MISTER” nozzles are placed at various
distances along the tubing. These nozzles atomize the water into billions of
micron sized particles which cool the surrounding air, as well as increasing its
relative humidity.

B) CONTROL MODULE

The two major components of the control module are a positive displacement
pump and motor. Both of these are thermally protected by a dump valve that
releases if the temperature exceeds 140 F. A pressure gauge and solenoid
valves regulate both the inlet and outlet water flow. The inlet water must reach a
pressure of 10 psi before the solenoid valve is opened. Likewise, the outlet
water flow to the nozzles must reach a pressure of 100 psi before the solenoid
opens. The pressure gauge has a six second delay feature.

C) NOZZLES

“MISTER” unique atomizing nozzles offer low flow rates as well as a high rate of
forward discharge velocity. This results in high turbulence and therefore,
extremely uniform particle distribution. Each nozzle includes a non-corrosive
stainless steel orifice and internal components. A special O-ring seal design
requires only finger tightening for a completely watertight seal.

Nozzle orifice diameters range from 0.006″ to 0.40″, which corresponds to
maximum flowrates ranging from 0.0121 to 0.1486 USGPM. These maximum
flowrates are based on a 1000 psi operating pressure. Lowering the operating
pressure of the system results in lower nozzle flowrates.

Droplet sizes that were produced by different MEC nozzles were measured
using Laser Doppler Anemometry by Aeromatics (Sunnyvale, California). Laser
Doppler Anemometry (LDA) measures the scatter of laser-light from individual
droplets to yield the size of the droplet as well as its velocity. The results
showed that MEC’s nozzles produced a broad spectrum of droplet sizes ranging
from 1 to 50 microns. A majority the droplets, on a Sauter mean basis, were in
the range of 2 to 10 microns in diameter. Also, it was known that nozzle size and
operating pressure have only a minor effect upon droplet size distribution.

D) NOZZLE LINE

1) Stainless Steel

Stainless steel performs well under oxidizing conditions (e.g. acidic or alkaline
solutions), since resistance depends on an oxide film on the surface of the alloy.
It is easily fabricated into complex shapes and can withstand temperatures up to
1500 F.

2) Flexhose

MEC Systems Inc. uses a ¼” diameter flex hose for specific applications where
stainless steel would be impractical.

E) WATER SUPPLY

In all atomization systems, one must pay close attention to supply water quality.
MEC’s nozzle designs include very small diameter orifices and very narrow
passages. Water with Total Dissolved Solids (TDS) counts exceeding 300 PPM
or with high calcium of pH levels should be treated in order to prevent excessive
nozzle blockages and/or excessive filter cartridge maintenance. If the water
quality is in question, a water analysis report should be obtained.

The “MISTER” system is provided with four stages of water filtration: 25 microns,
10 microns, 5 microns, and 1 micron. This will aid in the prevention of nozzle
plugging.

BASIC FUNDAMENTALS

A) VAPORIZATION

The conversion of a liquid to its vapor is called vaporization. Heat must be
absorbed by the liquid for this process to occur. For instance, in order for 1 mol
(18 g) of liquid water to be completely vaporized at 20 C, 44.10 KJ (41.80 BTU)
of heat energy must be absorbed. The amount of heat required to convert one
mole of liquid into one mole of vapor at a given temperature and constant
pressure is called the latent heat of vaporization.

H2O (1) +44.1 KJ H20(g)

It always requires heat to vaporize a liquid because of the greater magnitude of
the force of attraction between the molecules in the liquid state as compared to
the gaseous state. Energy must be supplied to overcome the force of attraction
between molecules in the liquid, to pull them apart and increase the distance
between the molecules. The energy supplied increases the potential energy of
the molecules.                                                                 
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“MISTER”™ unique system is one of the first around, using atomizing nozzles and flash evaporation to effectively
manage odours, moisture and temperatures.
B) FLASH EVAPORATION
evaporation of liquid H20. This is the change that occurs when a liquid under
pressure passes through a nozzle to a pressure low enough that some of the
liquid vaporizes or “flashes”, producing a two phase stream of vapor and liquid
in equilibrium.

Water is first filtered, and then pumped to as much as 1000 psi. The water is
then sent to “MISTER” unique atomizing nozzles. When the water passes
through these nozzles, flash evaporation occurs. The energy required for this
vaporization to occur is provided from the surrounding air in the form of heat,
thus cooling the surrounding air.

C) IMPACT

The impact of MEC’s high pressure spray is given by the following formula:

Impact = Mass per Unit Time x Spray Velocity

The variables affecting the impact of a spray are flow rate, spray angle,
concentration of the spray, operating pressure, and air friction. These variables
will either affect the mass per unit time or the velocity and this affects impact.
The flow rate is, of course, essentially the mass per unit time. The drop sizes
affect the velocity in that smaller drops lose velocity due to air friction more
rapidly than the larger ones.
Total impact of the nozzles should be distinguished from the impact per unit
area. The total impact of two nozzles may be the same, but the impact per unit
area can be entirely different. The spray angle and the concentration of the
spray does not directly affect the total impact but does affect the impact per unit
area. The smaller the spray angle and the more concentrated the spray pattern,
the higher the impact per unit area is.

POLLUTION CONTROL

A) PARTICULATE EMISSIONS

Particulates may be defined as solid or liquid matter whose effective diameter is
larger than a molecule but smaller than approximately 100 m. Particulates
dispersed in a gaseous medium are collectively termed an aerosol. Particular
types of aerosols include: dust, smoke, fog, and haze.

The adverse health effects of particulates depend not only on their amounts but
also on their chemical and physical properties. Particle size limits access to the
lungs. Those reaching the lungs by mouth are usually less than 15 m and by
nose, less than 10 m. Fine aerosol particles, 2 m or smaller, ultimately reach the
lung’s fine structures, the individual alveoli. The effects produced depend on
chemical properties such as toxicity, acidity, and solubility.

The “MISTER” system removes particles from gas by capturing the particles in
water droplets and separating the droplets from the gas stream. The droplets
act as conveyors of the particulate out of the gas stream. The three main
mechanisms utilized in capturing particulates include:

I) Inertial Interception

On approaching a collecting body, a particle carried along by a gas stream
tends to follow the stream but may strike the obstruction because of its inertia.

ii) Brownian Diffusion

Smaller particles, particularly those below about 0.3 m in diameter, exhibit
considerable Brownian movement and do not move uniformly along the gas
streamline. These particles diffuse from the gas to the surface of the collecting
body and are collected.

iii) Flow-line Interception

If a fluid streamline passes within one particle radius of the collecting body, a
particle travelling along the streamline will tough the body and may be collected
without the influence of inertia or Brownian diffusion.

These mechanisms cause the tiny pollutant particles to be lodged inside the
collecting droplet. The larger droplet is then separated from the gas stream by
gravity. Because of the minute size of fog droplets produced, the “MISTER”
system is best suited for the elimination of very fine particulates.
                                                     
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Copyright © 2017 MEC Systems Inc.
*Unit size & structure may vary depending on application requirements