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• 452000 cycles (start-ups) with a maximum difference of 6 K between two neighboring points in the vessel, based
on 6 start-ups per hour over 15 years at a usage rate of 57%.
Corrosion allowances:
Gas side: 0 mm
Heat exchange fluid side: 1 mm for tubular plates in lightly alloyed steels, 0 mm for stainless steel plates or plates
with copper-nickel or stainless steel protection.
8.2.1 – Water side exchanger
30XQ water side exchanger is designed with a flooded multi-tube cooler. The water circulates in the tubes and the
refrigerant is on the outside in the shell. One vessel is used to serve both refrigerant circuits. There is a centre tube
sheet which separates the two refrigerant circuits. The tubes are 3/4" diameter copper with an enhanced surface
inside and out. There is just one water circuit, and depending on the size of the chiller, there may be one, two or
three water passes.
The cooler shell has a thermal insulation of 19 mm thick polyurethane foam, an aluminum sheet and a water drain and
purge. It has been tested and stamped in accordance with applicable pressure codes for the design pressure of
2100 kPa refrigerant side and 1000 kPa water-side.
The water connection of the heat exchanger is a Victaulic connection. As an option the evaporator is available with
frost protection (evaporator frost protection option).
The products that may be added for thermal insulation of the containers during the water piping connection
procedure must be chemically neutral in relation to the materials and coatings to which they are applied. This is also
the case for the products originally supplied by Carrier.
8.2.2 - Oil separator
In these units, the oil separator is a pressure vessel that is mounted under the outside vertical condenser coils.
Discharge gas at the compressor outlet is directed towards the bottom of the oil separator ring and most of the oil
separates from the gas by strong deceleration and by gravity. The gas then flows through a wire mesh screen where
the remaining oil is separated by coalescence and flows to the bottom of the ring. The gas is now free from oil and
leaves the ring at the top towards the condenser.
The oil separator is equipped with a trace heater regulated by the control. This heater is equipped with an internal
thermostat that disconnects the power supply when the temperature reaches 85° C and automatically resets when
the temperature again falls to a normal value. The products that may be added for thermal insulation of the vessels
during the water piping connection procedure must be chemically neutral in relation to the materials and coatings to
which they are applied. This is also the case for the products originally supplied by Carrier.
8.2.3 - Economizer function
The economizer function includes a liquid line valve, a filter drier, two EXVs, a plate heat exchanger as well as
protection devices (fuse or valve).
At the condenser outlet a part of the liquid is expanded via the secondary EXV in one of the heat exchanger circuits
and then returns as gas at the compressor economizer. This expansion permits increase of the liquid sub-cooling of
the rest of the flow that penetrates the evaporator via the principal EXV. This permits increasing the cooling capacity
of the system as well as its efficiency.
8.2.4 – Receiver
Receiver is taken on to hold redundant refrigerant at heating mode. When unit operate at cooling mode, much more
refrigerant is circulating in system than at heating mode.
8.2.5 – Accumulator
Heat pump operates at defrost period, especially at changeover period from defrost to heating, a large amount of
liquid refrigerant will rush to suction pipe. It will be a risk if liquid refrigerant enters into compressor directly. And it
maybe leads to compressor damage. Accumulators play a roll of preventing liquid refrigerant sucking into compressor
and ensure pure gas compression.
Carrier Yileng - Shanghai, China
39
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