Danfoss Heat Exchangers Service guide
Fitters’ Notes Heat Exchangers
Contents
MicroChannel Heat Exchanger – Construction ........................................................................................................ 2
MicroChannel Heat Exchanger – Cleaning Procedure .......................................................................................... 4
Micro Plate Heat Exchanger – MPHE Instructions ................................................................................................... 5
MicroChannel Heat Exchanger – MCHE Instructions ............................................................................................. 7
Troubleshooting Refrigerant Systems Using Plate Heat Exchangers ............................................................... 9
DKRCC.PF.000.G1.02 / 520H6410
Exchangers
Heat
1
Fitters’ Notes Heat Exchangers
MicroChannel
Heat Exchanger –
Construction
The fi gure on the right represents the basic
structure of a MicroChannel heat exchanger.
The actual design depends on the specifi ed
application.
Flow arrangement
The MicroChannel condenser is often designed
with multiple passes (parallel fl ow) with fewer
tubes in each successive pass.
Accidentally connecting the outlet tube to
the outlet header of the MCHE will result in
excessively high refrigerant-side pressure loss
and poor heat exchanger performance.
End plate Side plate Fin Tube
B a ffl e
Manifold
Inlet
Many
tubes
The inlet and outlet tubes are designed only
for connection and to support their own weight.
Unfortunately they locate where handles would
be, and often look like handles. Never lift an
MCHE by the inlet and outlet tubes.
Mounting
The MicroChannel heat exchanger must
be mounted with at least some fl exible
brackets, so movement is possible without
applying unnecessary stress/tension to the
heat exchanger or its connections.
It is preferable for the mounting brackets
of the MCHE to touch only rubber or plastic
grommets, washers, bumpers, etc. Direct
contact with metal fasteners and/or frames
can result in galvanic corrosion unless
appropriate steps are taken to prevent it, e.g.
careful alloy selection, paints/coatings, etc.
To meet customer-specifi c requirements,
diff erent mounting types are available.
Outlet
Few
tubes
Mounting bracket
2
DKRCC.PF.000.G1.02 / 520H6410
Fitters’ Notes Heat Exchangers
MicroChannel
Heat Exchanger –
Construction
Inlet/outlet connections
Inlet/outlet connections should be designed
so the stress from thermal expansion will not
be transferred to the tubing.
Inlet/outlet connections should also be
supported/designed so brazed joints are
not exposed to stress/ tension.
To avoid damaging or collapsing the thin-
walled aluminium inlet/outlet tubes,
mating tubes should be pre-bent/prepared
so no bending/forcing is needed during
installation.
When copper and aluminium tubes are joined
together, galvanic corrosion of the aluminium
can result. To prevent this the joint is protected
with paint, resin or a plastic heat shrink tube.
Avoid stress/ collapse of tube
Allow some
movement due
to thermal
expansion
To protect the Cu-Al brazing and shrink tube,
the tube length after the joint on inlet/outlet
pipes should be longer than 70 mm. When
brazing the coil into your system, additional
protection can be obtained by dry nitrogen
purging and/or wrapping the copper stub tube
with a wet cloth. The aluminium inlet/outlet
tube on the MCHE must also be at least 70 mm
long to protect the tube-header braze joint.
The pipe length after the brazing joint should be longer than 70 mm.
≥70 mm
≥70 mm
Exchangers
Heat
DKRCC.PF.000.G1.02 / 520H6410
3
Fitters’ Notes Heat Exchangers
MicroChannel Heat
Exchanger – Cleaning
Procedure
Compared with fin & tube heat exchangers, MicroChannel coils tend to accumulate more dirt
on the surface and less dirt inside, which can make them easier to clean.
Step 1. Remove surface debris
Remove surface dirt, leaves, fibres, etc., with a vacuum cleaner (preferably with a brush or other
soft attachment rather than a metal tube), compressed air blown from the inside out, and/ or a soft
bristle (not wire!) brush. Do not impact or scrape the coil with the vacuum tube, air nozzle, etc.
Step 2. Rinse
Do not use any chemicals (including those advertised as coil cleaners) to wash MicroChannel
heat exchangers. They can cause corrosion. Rinse only.
Hose the MCHE off gently, preferably from the inside out and top to bottom, running the water
through every fin passage until it comes out clean. MicroChannel fins are stronger than those of
traditional fin & tube coils, but must still be handled with care. Do not bang the hose into the coil.
We recommend putting your thumb over the end of the hose rather than using a nozzle end
because the resulting spray is gentler and impact damage is less likely.
Step 3: Optional blow dry
MicroChannel heat exchangers, because of their fin geometry, tend to retain water more than
traditional fin & tube coils. Depending on the specific design and installation of your coil,
it may be beneficial to blow or vacuum out the rinse water from your unit to speed drying and
prevent pooling.
Warning!
While it is possible to carefully clean with a pressure washer, it is also possible to totally destroy
a coil with a pressure washer. We therefore do not recommend their use.
4
DKRCC.PF.000.G1.02 / 520H6410
Fitters’ Notes Heat Exchangers
Condensers
Q1
Q2Q3
Q4
Condensers
Evaporators
Q1
Q2
Q3
Q4
Q5
Q6
Q1
Q2Q3
Q4
Q1
Q2
Q3
Q4
Q5
Q6
Q1
Q2Q3
Q4
Q1
Q2Q3
Q4
Micro Plate Heat
Exchanger – MPHE
Instructions
General information
Store dry at 17 °C (62 °F) to 50 °C (122 °F).
The performance of Danfoss MPHEs is based on
their installation, maintenance and operating
conditions being in accordance with the manual.
Danfoss cannot assume any liability for MPHEs
that do not meet these criteria. Mount MPHEs
vertically (see figs. right).
Condensers
Connect the refrigerant (gas) to the upper left
connection, Q4 (Dual circuit: upper left, Q4,
and right, Q6), and the condensate to the lower
left connection, Q3 (Dual circuit: lower left, Q3,
and lower right, Q5). Connect the water/ brine
circuit inlet to the lower right connection, Q2,
and the outlet to the upper right connection,
Q1 (Dual circuit: inlet lower middle, Q2, and
outlet upper middle, Q1).
Evaporators
Connect the refrigerant (liquid) to the lower left
connection Q3 (Dual circuit: lower left Q3 and
lower right Q5) and the refrigerant (gas) outlet to
the upper left connection Q4 (Dual circuit:
upper left Q4 and upper right Q6). Connect
the water/brine circuit inlet to the upper right
connection, Q1, and the outlet to the lower right
connection, Q2 (Dual circuit: inlet upper middle,
Q1, and outlet lower middle, Q2).
Strainer
If any of the media contain particles of 1 mm
or larger, we recommend that a strainer
(16–20 mesh) be installed before the MPHE.
IMPORTANT:
MPHEs have sharp edges. Their surfaces can be
very hot or cold. Media they contain may be at
high pressure. For product information, refer to
the product label.
Condensers
Dual Circuit
Condensers
Evaporators
DKRCC.PF.000.G1.02 / 520H6410
Dual Circuit
Evaporators
Exchangers
5
Heat
Loading...