TURBOCOR COMPRESOR CHILLERS General Description Microprocessor controlled, water chiller using HFC 134a refrigerant, two stage centrifugal oil free variable speed compressor's and electronic expansion devices. Quality Assurance The unit shall be rated in accordance with AHRI Standard 550/590 and construction shall comply with relevant Australian codes, vessels shall be manufactured in accordance with ASME code or AS1210. Chiller Manufacturer should have been manufacturing chillers utilizing magnetic bearing, oil free technology for more than 10 years. Equipment Factory assembled, package liquid chiller with modular compressors, fitted with all factory wiring, piping and controls. Compressors Construction shall utilize a two-stage, variable speed, centrifugal compressor design requiring no oil for lubrication. The motor rotor and impeller assembly shall be the only major moving part. Compressors shall be designed for use with HFC 131a. 1. Construction shall utilize a two-stage, variable speed, centrifugal compressor design requiring no oil for lubrication. 2. The motor rotor and impeller assembly shall be the only major moving part. 3. Compressors shall be designed for use with HFC 134a, - The compressor should be provided with radial and axial magnetic bearings to levitate the shaft during rotation, thereby eliminating metal to metal contact, and thus eliminating Friction and the need for oil. - The magnetic bearing system shall consist of front, rear and axial hearings. Roth the front and the rear bearings are to levitate the shaft at X and Y directions, and the axial at Z direction. - The rotor shaft of the compressor shall be sensed by position sensors, and the bearings shall provide real time repositioning of the rotor shaft, controlled by onboard digital electronics
- When the compressor Is not under operation (not rotating), the rotor shall be supported by touchdown bearings made from durable materials - Each compressor shall have a bank of capacitors used for energy storage and filtering DC voltage fluctuation. In case of power failure, the capacitors shall continue to provide power to the bearings to keep them levitated, allowing the motor to turn into a generator and to power itself clown to a stop. - Equal capacity compressors are allowed on single chiller for equal loading. 4. Capacity Control - The compressor shall have an integrated Variable Speed Drive (VFD) for linear capacity modulation, high part-load efficiency, and reduced in-rush starting current (under 2 amps at 380V). - It shall include IGBT (Insulated Gate Bipolar Transistor) type inverter that converts the DC voltage to an adjustable three-phase AC voltage. - Signals from the compressor controller shall determine the inverter output frequency, voltage and phase, thereby regulating the motor speed. - Compressor speed shall be reduced as condensing temperature and/or heat load reduces, optimizing energy performance through the entire range from 100% to 25% or below of full load capacity of each compressor given ARI unloading conditions. Capacity shall have infinite modulation as motor speed is varied across the range of operation - Inlet Guide Vanes (IGV) shall be built-in to further trim the compressor capacity in conjunction with the variable speed control, to optimize compressor performance low loads 5. Compressor Motor - The compressor shall be provided with a direct drive, high efficiency permanent magnet synchronous motor, powered by pulse width modulating (MAW) voltage supply. - The motor shall be compatible with high-speed variable frequency operation that affords high speed efficiency, compactness and soft start capability. - Motor cooling shall he by integrated liquid refrigerant injection, 6. Compressor Electronics - The compressor shall include a microprocessor controller capable of controlling magnetic bearings and speed control. - Controller shall be capable of providing monitoring including commissioning assistance, energy outputs, operation trends, and fault codes via an interface,
Evaporator/Cooler The Evaporator shall be horizontal flooded shell and tube type. The Evaporator tubes shall be mechanically cleanable. Evaporator/Cooler shall be tested and stamped in accordance with ASME code or AS1210 for a refrigerant side working pressure of 1300 kpa and shall be tested for a maximum waterside pressure of 1000 kpa. Evaporator Shell shall be insulated with 38 mm closed-cell, foam (max K factor of 0.28) and fitted with a vapour barrier. The Evaporator shall have a cooler drain and vent. A copy of the as built drawings shall be included in each Operating and Maintenance manual. Condenser (Water Cooled) The Condenser shall be shell and tube type. The Condenser tubes shall be mechanically cleanable. Condenser shall be tested and stamped in accordance with ASME code or AS1210 for a refrigerant side working pressure of 1300 kpa arid shall be tested for a maximum water-side pressure of 1000 kpa. The Condenser shall have a drain end vent. Refrigerator Components Refrigerant circuit components shall include the following requirements; 1. Pressure relief devices shall be fitted to both the Evaporator and Condenser Pressure vessels. 2. Each compressor shall be equipped with adequate Discharge and Suction line shutoff valves for completion refrigerant isolation during servicing. 3. The Evaporator shall have a sight glass installed. 4. The unit shall be fitted with Electronic expansion valves. 5. Complete operating charge of refrigerant HFC 134a. 6. Check valve shall be installed on the discharge port of the compressor to protect against liquid migration back to the compressor during off cycles. 7. The evaporator and the condenser must be able to be individually isolated. 8. Dedicated economizer for each compressor would be required for optimized operation of chillers.
Controls, Safety and Diagnostic The Chiller shall be controlled by a real time, embedded microprocessor, which shall control and monitor the Magnetic Bearing, Oil Free compressors. The chiller controller also shall gather information from external inputs and monitor internal sensors, switches and safeties, controlling the entire chiller, compressors and auxiliary equipment at the most optimum point to realize higher energy efficiency from the chillier package. Unit controls snail Include the following minimum components: 1. Microprocessor control with non-volatile memory 2. Power and control circuit terminal blocks 3. Temperature sensors installed to measure cooler and condenser entering and leaving fluid temperatures 4. Sensors for suction and discharge pressures 5. An Operator Interface The operator interface shall consists of a colour Touch Screen, to allow the operator to navigate through the menus via built in, user friendly menu tabs which are specific to the application. The interface shall display all key operational data: compressor data, external resets and input/output status of the Chiller. Messages generated by the controller shall be "real" alphanumeric text for simple system interrogation. The interface shall allow the adjustment of user set points and options, arid shall provide alarm descriptions. The Interface shall include the following parameters: General Operational Data: Entering and leaving chilled water temperatures, Chilled water set point, Entering and leaving Condenser water Temperatures (Water Cooled Chillers). Time and Date, Active timers, System Demand, Chiller status, Active faults and alarms Compressor Data:
Communication integrity, Active faults/ alarms, Actual compressor(s) demand, Speed, IGV Position, Pressure Ratio, Suction pressure, Discharge pressure, Power input, Desired Power input, 3 phase Amps. Surge RPM, Choke RPM Trending Data, comprising of: Entering and leaving Chilled water temperatures. Entering and leaving condenser water temperatures Standard Controller Functions and Features Unit controls shall include the following functions as standard: 1. Capacity control based on leaving or entering chilled water temperature with set point offset load compensation 2. Rate of change control at startup to prevent overshoot 3. Incremental control of condenser fans (air cooled models) to control head pressure 4. Auto-restart after power failure 5. The controller shall include contacts for interfacing to the building management system for the following functions: Summary fault Star /stop Chilled water flow interlock. Condenser water flow interlock. The chiller controller shall consist of an adaptive control strategy, controlling the necessary number of compressors and operate the chiller at the most efficient point, based on the building load and external conditions. The controller shall monitor key parameters such as pressure and compressor amperage to allow the chiller to continue to run at a reduced demand when the chiller approaches the boundary of predetermined limits. Fault points shall also be provided such that if they are reached and the controller cannot take any further corrective action, the controller shall stop the chiller. The controller shall provide High Level interface to the EMS via Modbus or BacNet. Safeties Unit shall be equipped to provide the following protection: 1. Loss of refrigerant charge
2. Low chilled water temperature 3. Power supply error 4. Compressor motor thermal or electrical overload 5. Phase Loss 6. Hig h p re ss u re 7. L o w pre s s u re 8. L oss of chilled water flow (Interlock to external flow switch) 9. Loss of condenser water flow (interlock to external flow switch) Electrical 1. Unit primary electrical power supply shall enter the unit at a single location 2. Unit will be provided with a main power disconnects 3. Unit shall operate on 3-phase voltage (400V/50Hz) and shall be designed to operate within ± 10% of the rated voltage 4. Control voltage shall be 24 Vac. 5. Unit shall be shipped with factory control and power wiring installed. 6. Power factor shall be greater than 0.9 (compressors only) at full design toad.