Quantech QTC40160, Установка, эксплуатация и обслуживание

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Quantech
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Section 9 - Maintenance
Form QTC4-NM2
Issue date: 05/12/2023
7. Continue removing refrigerant until liquid is no
longer observed flowing in the manifold hoses.
8. Once the liquid is removed and no longer visible
in the hose, the remaining gas can be pumped out
with the recovery unit while the pressure is al-
lowed to drop to 0 psig (0 barg).
Checking and trimming the refrigerant
charge
Important: The amount of chiller refrig-
erant charge must be verified to meet the
specified amount as found in the chiller
nameplate or chiller FOF. Reference this
document of the unit sales order screen
on the chiller control panel to determine
the amount of charge required based on
the chiller rating.
During operation, the refrigerant charge level is correct
when the evaporator approach (STD), subcooling are
at the design values for the condition. For new sales,
these design values are included as part of the FOF. For
units where they are not seen on the FOF, they can be
provided upon request from the chiller sales engineer
from the chiller rating program. These depend on tube
selection, chilled fluid type, operating head, and op-
erating conditions. For QTC4 Chillers, a typical way
to verify correct charge amount in the system is when
evaporator sight glass is half-full.
The following equations define these parameters.
Condenser subcooling is calculated and the condenser
drain valve is controlled to the programmed setpoint by
the chiller control logic:
• Evaporator approach = (LCHLT) -
(EST)
• Discharge superheat = (DT) - (CST)
• Subcooling = (CST) - condensed
refrigerant liquid temperature
(from condenser outlet)
Definitions
• EST = Evaporator saturation temperature: can be
calculated from saturated suction pressure on the
panel.
• LCHLT = Leaving evaporator liquid temperature
• DT = Compressor discharge temperature: shown
on the chiller panel.
• CST = Condenser saturation temperature: can be
calculated from saturated condenser pressure on
the panel.
You can view the parameters on the chiller control cen-
ter. The chiller must be at full load design operating
conditions so that the correct refrigerant charge level
can be correctly determined, when operating. When
correct condenser level is maintaining the design
subcooling, the evaporator approach and discharge su-
perheat are a function of the amount of charge that is
now maintained in the evaporator. To lower evapora-
tor small temperature difference and compressor dis-
charge superheat, add the refrigerant charge is added
to the system. If additional details are needed, contact
product technical support (PTS) for guidance.
Checking the refrigerant charge
during unit shutdown
Because QTC4 uses a hybrid falling film technology,
there are no reliable means to evaluate the refrigerant
charge when the chiller is not running.