HEV Static Mixer Bulletin0 pages

Kenics HEV High Efficiency
Static Mixer
The ideal solution for turbulent flow applications

The patented Kenics High Efficiency
HEV Static Mixer gives you pressure
drops drastically lower than any other
static mixer available today and can
be applied to any turbulent flow mixing
problem regardless of line size or shape.
Typical applications for the HEV include
all low viscosity liquid–liquid blending
problems, as well as gas–gas mixing. It
is offered in unlimited sizes and mixes
in the shortest possible pipe length for
applications having space restrictions.

HEV Technology
University studies of turbulence led
to the understanding of fluid flow
phenomena that made the development
of the HEV Static Mixer possible. Years
of research have gone into defining the
patented element geometry parameters
to maximize conversion to fluid energy
into efficient mixing. The length, width,
and attack angle of the HEV mixing
elements have been optimized for
mixing performance while limiting
pressure drop.
To create mixing action the mixing
element must impart momentum to
the fluid stream. The level to which this
momentum is converted to effective
mixing versus wasted turbulence
determines the mixer efficiency.
Because the HEV is configured to
promote a “natural” mixing pattern, the
redirection of the flow stream results in
virtually no loss of pumping energy. The

benefit you gain is minimum pressure
loss and significant energy savings
compared to static mixers using more
disruptive-type mixing elements.
The HEV mixing element consists
of special patented trapezoidal tabs
mounted at an acute angle relative to
the downstream surface of the mixer
housing. As the process stream strikes
the base of the tab, it is deflected up
the angled incline creating a pressure
gradient between the upstream and
downstream surfaces of the tab. This
pressure differential causes the fluid to
flow around the opposite sides of the
tab generating alternating tip vortices
having their axes of rotation oriented in
the direction of the main fluid flow. The
alternating rotations of the tip vortices
induce vigorous cross-stream mixing
which results in rapid uniformity of the
process components.
Full-scale mixing tests have confirmed
the performance of the HEV and have

resulted in highly accurate equations
for predicting uniformity levels. These
equations evaluate various parameters
such as side-stream ratio and injection
techniques that are influential to the
process performance of the mixer.
Control of these parameters allows
the HEV to be applied with complete
certainty.

Uniformity Criteria
Comprehensive testing of the HEV mixer
using tracer injection techniques has
quantified its mixing performance. Multipoint sampling probes were utilized
to generate stream uniformity data.
Statistical analysis applied to this data
resulted in the equations that predict
mix quality as a function of the inlet and
outlet coefficient of variation (CoVo and
COV, respectively). By knowing the inlet
stream conditions any desired level of
uniformity can be achieved by adjusting
the design of the HEV.

Typical Mixing Performance of HEV
.100

.010

CoV/(CoV)o

HEV4

CoV = Coefficient of Variation mixer exit
σ σ = Standard Deviation
CoV = —
x x = Mean Concentration
of added component
(maximum .50)
(CoV)o = Coefficient of Variation
at mixer entrance
1-Va
(CoV)o = —— 1/2 Va = Volume
Va
fraction
added

.001

.0001
1.0E+03

1.0E+04
1.0E+05
Reynolds Number

1.0E+06