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Large Tonnage ChillerAC Screw
Content• Mechanical System
• Key Components
• Control Logic
• Application
2
Mechanical System
3
Layout
4
Control panel
High Efficiency Shell & Tube Cooler
Condenser fans
Layout
5
Screw Compressor
Pressure gage
Condenser coils
Easily Accessible Filter Drier
Refrigerant System
6
Model:380, 500, 900, 1000
7
Model:600, 720, 1200, 1420
Key Components
8
Compressor
9
Compressor
10
Compressor
11
Hermetic Semi-Hermetic Open
Compressor
12
Item Open Hermetic Semi-Her.
MaintenanceEasy
Break the shell or change new one.
Easy
Leakage
Likelihood of Refrigerant and oil leakage, and it have to be charged.(Y brand)
Motor and rotors are in one shell, no leakage.
Shaft seal Yes, maintenance No
Mechanical room Motor heat reject out of compressor, it
need ventilation/cooling system. (e.g. 550RT chiller with input power 370kW, so motor heat 37kW have to taken by a 15HP AC.)
Just ventilation for flash air.
Compressor
13
Open Hermetic Semi-Her.
Cooled Air Refrigerant
Noise High Lower Low
Application Few and refrigeration Few More
Brand York DB The others
Compressor
14
Compressor
15
Single Twin Triple
FeaturesMain rotor(metal) and dual gaterotor (Non-metal, GR 1750RPM),tooth ratio 6:11 ,fitting complicated, flow losses.
Metal tooth ratio 5:6 fitting without flow losses.
Balanced rotor geometry and shorterscrew lengths
Efficiency Low efficiency, especial in low speed. Higher Higher
Parts
The higher speed, the less flow losses, so increase the friction loss, the gaterotor have to be replaced regularly.
No No
Oil - -Less
Brand Mcquay(Daikin) Midea and the others Carrier 23XRV
Compressor
16
Air cooled — OpenRefrigerant cooled — Semi-/Hermetic
Features
1. Motor efficiency increase 3%;2. High maintenance cost;3. Need ventilation/cooling system, increase initial cost.4. Does not recharge refrigerant when burnout.
1. Better cooled efficiency;2. Longer operation life;3. Burnout can cause catastrophic damage to a chiller. The entire chiller must be cleaned, and the refrigerant replaced.
ProtectionWiring high temperature, current overload( Midea: 1. PTC sensors in each motor winding coil; 2. Current overload in
MIC; 3. Overload relay.)
CompressorSuction valve Wiring box
Rotors
Discharge valve
Inner Check valve
Relief valve
Oil separator
10um Oil separator
Closed bearingOil heater
Oil server valve
Oil level switch
Motor
Gas filter
Overview
18
Compressor
Throttle
19
EEV TEV Capillary Orifice Butterfly valve
Throttle
20
Item EEV TEV Capillary Orifice Butterfly valve
Components
Valve, controller,
sensor
Valve, bulb,
capillary tubeCapillary tube
Stainless steel
plate
Valve, driver, liquid
level sensor
Sensitivity
Precise flow regulation;
bi-flow operation as well as solenoid tight shut-off;
Wide range control.
Hysteresis but
stable
superheat.
Narrow range
control.
Narrow range
control.
Precise flow regulation,
bi-flow operation as well as solenoid tight shut-off
Wide range control
Price More expensive Benchmark Cheaper Cheap Most expensive
Throttle
21
Throttle
22
Control Logic
23
Capacity ControlCR2/Y2CR1/Y1
CR4/Y4CR3/Y3
24
Capacity Control
Discharge GasOil Pressure
Eco
CR4
CR2
Suction Gas CR1
CR3
25
Capacity control
Compression process Capacity Control
26
Fan control
27
Fan controlDischarge (bar)
Fan Quantity
The higher/ lower
discharge pressure , the
more/less fans On.
28
Applications
29
Air side(T1/T3)
30
Note: 100% load condition.
Cooler entering/leaving temperature difference at full loadMin~ Max 3~8C
Cooler LWT °C
Am
bie
nt
T °
C
Normal unit
High Ambient unit
Free cooling
31
NEW
4 Piping(Cooling/Heating/Hot water)
32
NEW
33
34
Thank You!