Submittal Sheet

Data sheet Thermostatic expansion valves, type TUA/TUAE and TCAE
24 DKRCC.PD.AG0.A4.22 / 520H8945
TU operation and function
(continued)
Subcooling ∆t
sub
Subcooling is dened as the dierence between
the liquid refrigerant temperature and its
saturation temperature. Depending on system
design, subcooling may be necessary to prevent
ash gas from forming in the liquid line. If ash
gas forms in the liquid line, the capacity of the
expansion valve will be greatly reduced.
Superheat-subcooling relationship
Superheat
Superheat is the controlling parameter of the
valve. Superheat, measured at the evaporator
outlet, is dened as the dierence between
actual bulb temperature and the evaporating
temperature at the saturation point. In other
words, vapor is said to be superheated if its
temperature is higher than the saturation
temperature corresponding to its pressure.
In order to prevent liquid refrigerant from
entering the compressor, a certain minimum
superheat must be maintained. Liquid entering
the compressor causes serious damage.
When discussing superheat, the following terms
are used with respect to valve operation:
Static Superheat
Static superheat, SS, is superheat above which
the valve will begin to open.
Opening Superheat
The opening superheat, OS, is the amount of
superheat above static superheat, SS, required to
produce a given valve capacity.
Operating superheat
The operating superheat, SH, is the sum of the
static superheat, SS, and the opening superheat,
OS.
Danfoss
68U63.11
F-bulb charge
The F-bulb charge is designed for refrigeration
applications where low superheat is required.
Valves with this charge are delivered with an
optimized static superheat setting which allows
for installation with minimal eld adjustment
of superheat. F-charge valves also include the
Danfoss Marinit Anti-Hunt (MAH) function,
which reduces valve hunting during evaporator
load changes, helping maintain stable system
superheat and improved system performance.