Thermo King 098916, Руководство по обслуживанию

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Operating Theory
113
(compressor pumping time) in the duty cycle
equals the cooling capacity percent required to
meet the current load demand.
Remember that the percent ON time defines the
time the compressor is engaged. The compressor
is engaged (pumping) when the Compressor
Digital Control valve is closed (OFF). Therefore,
a duty cycle of 100 percent means the compressor
is pumping 100 percent of the time and the
Compressor Digital Control valve is ON (open) 0
percent of the time. A 60 percent duty cycle
means the compressor is pumping 60 percent of
the time and the Compressor Digital Control valve
is ON (open) 40 percent of the time.
Economizer System
An economizer heat exchange system replaces the
conventional heat exchanger. The economizer
system subcools the liquid refrigerant before it
reaches the evaporator expansion valve.
Subcooling liquid refrigerant increases the
cooling efficiency and capacity of the evaporator.
Figure 60: Economizer Heat Exchanger
A vapor injection line tee is located in the liquid
line between the filter drier/in-line filter and the
economizer heat exchanger. A vapor injection
valve controls refrigerant flow through the vapor
injection line to the economizer expansion valve.
When this normally closed valve is energized
(open), a portion of liquid refrigerant flows
through the economizer expansion valve and
evaporates in the inner coiled tube of the
economizer. This cools the rest of the liquid
refrigerant that flows past the tee and through the
economizer to the evaporator coil.
The economizer suction gas continues through the
vapor injection circuit and returns to the
intermediate suction port of the scroll compressor.
Injecting the economizer suction gas into the
compressor downstream from the suction port
prevents the gas from affecting the suction
pressure or cooling capacity of the evaporator
coil. However, the economizer suction gas adds
its heat and volume to the condenser side of the
refrigeration system, increasing the discharge
pressure.
Because the economizer system increases system
cooling capacity, the vapor injection valve is
energized (open) continuously when the
compressor duty cycle (ON time) is 100 percent
(Full Cool). High compressor discharge
temperature may cause the vapor injection valve
to energize (open) but only while the Compressor
Digital Control valve is not energized (closed).
Data Recording and
Downloading Data
The MP-3000a data logger can record sensor
temperatures as well as loss of power, alarms,
sensor failure, setpoint change and unit shutdown
events. All data logs include the time and date;
setpoint temperature; supply, return, ambient,
USDA1, USDA2, USDA3 and cargo sensor
temperatures; and humidity sensor. All
temperature logs can be viewed from the
controller’s LCD message display.
Data logging intervals are selectable for 30
minutes, 1, 2 or 4 hours.
When a 1 hour logging interval is selected, the
data logger memory can store approximately 680
days of information. The logging of USDA
sensors is fixed at 1 hour intervals to comply with
USDA requirements. A logging test of USDA
sensors at 1 minute intervals is possible for 72
minutes. USDA data can not be downloaded
during the logging test and can only be viewed on
screen. After 72 minutes, controller returns to
previous logging interval and clears USDA test
data from data logger memory.
If the unit power supply is disconnected, the data
logger will continue to register 120 temperature
logs (except humidity sensor) when battery
voltage is above 11.4 volts. These will be
maintained until the unit is re-connected to power,
and the battery automatically recharged.
Trip data can be retrieved (but not erased) from
the data-logger memory using a LOGMAN
handheld data retriever, LOGMAN PC used on a
AXA0427