York Screw Chiller

Unit characteristics

Efficient, reliable, safe and durable

The world-famous industrial twin-screw compressor. York is a famous product of the world's industrial screw compressor unit

Brand, its rich design experience and advanced manufacturing equipment make the charm of industrial compressor products enduring. Its high-efficiency and long-life characteristics have been extensively proven in practice.

Stepless adjustment to reduce energy consumption. York water-cooled screw compressor adopts slide valve type unloading device, which can reach 100%-

Stepless adjustment within 20% load range, fully matching the actual load, effectively improving partial load efficiency, and greatly reducing operating costs.

High-efficiency heat exchanger, excellent performance. The heat exchanger adopts the latest high-efficiency heat exchange copper tube, which makes the heat transfer efficiency best and has a compact structure. The water side and the refrigerant side enhance heat transfer, reducing unit energy consumption and pipe fouling.

High-efficiency oil separator with excellent performance. Use high-efficiency oil separator to limit the carrying degree of lubricating oil below 500ppm. Lubricating oil is extremely important for the lubrication of the screw compressor, the sealing and cooling of the rotor. However, the lubricating oil in the evaporator may cause a decrease in heat transfer effect and system performance. Therefore, the efficient oil separator allows the lubricating oil to circulate only in the lubricating oil circuit, so that the heat transfer efficiency is better.

Superior part load performance significantly reduces operating costs. Since most of the operating time is in non-design conditions, attention should be paid when selecting a chiller: it not only needs to meet the design requirements of full load, but also can operate effectively at lower loads and when the cooling tower water temperature is low. For chillers with the same full-load energy efficiency ratio, the operating costs under partial load sometimes differ by more than 10%.

The part-load performance index can be conveniently and accurately calculated by the computer. Because it is very important to the user's operating budget. This performance index has been standardized according to the requirements of ARI, including the integrated value of part load (IPLV) and the non-standard value of part load (NPLV). All York's selection documents will provide NPLV values for customers to check.

Environmentally friendly refrigerant

R134a refrigerant is a green refrigerant that has no destructive effect on the global ozone layer and meets the requirements of the Montreal Protocol. At the same time, R134a is also one of the safest refrigerants in the world.

Factory inspection, easy installation

Each chiller is tested for trial operation before leaving the factory to ensure the reliability of the unit.

Unit model representation

Mechanical characteristics

Drive device

Use high-efficiency industrial semi-hermetic twin-screw compressor, high-precision processing, unique structure, high efficiency and reliability.

The compressor adopts a cast iron shell and a forged steel rotor. The rotor gap is small but does not touch. The supporting surface ensures that the rotor maintains precise positioning at various pressure ratios, reduces wear, prevents leakage, and prolongs life.

The compressor adopts a full anti-wear bearing design to reduce energy consumption and improve reliability. The roller bearing is subjected to radial load at four corners, and the ball bearing is subjected to axial load. There is an oil storage tank inside the compressor, which can guarantee the supply of lubricating oil to the bearing at any time. The check valve is combined with the compressor frame to prevent the rotor from reversing when it is stopped.

Two-pole continuous operation squirrel-cage motor uses suction cooling (semi-enclosed design). The full load current of the motor under design conditions will not exceed the nameplate current (FLA) of the unit. The motor is used in conjunction with a specific type of starter.

Heat exchanger

Shell — The shells of the evaporator and condenser are coiled and welded with carbon steel plates. The carbon steel pipe plate is drilled and reamed to take over and welded to the end of the shell. The working pressure on the refrigerant side is 1.62MPa, which meets the requirements of international or Chinese standards.

The heat exchanger adopts the most advanced high-efficiency heat exchange copper tube bundle, and the inner and outer walls have enhanced heat transfer to obtain the best performance. The wall thickness of the copper tube at the support part is increased (the wall thickness can be up to twice the original), and it has not been hardened, thereby extending the life of the heat exchanger. Each heat transfer tube is expanded in the tube sheet to avoid leakage; each tube can be replaced individually.

Evaporator—Using York’s patented hybrid falling film evaporator technology, the refrigerant is first evenly distributed to the falling film heat exchange area by spraying, naturally descends to form a film, and realizes film heat exchange with the heat exchange tube. The heat transfer coefficient is greatly improved. At the same time, the refrigerant charge required by the system is significantly reduced, which helps to meet the standards.

Condenser — Shell and tube type, with exhaust baffle to prevent gas from directly impacting the tube bundle at high speed. It can also distribute the flow of refrigerant gas reasonably to maximize the heat exchange efficiency. The subcooler is located at the bottom of the condenser, which effectively subcools the liquid and improves the circulation efficiency.

Compact water chamber — The detachable compact water chamber is made of steel pipes and has a design working pressure of 1.0 MPa. The steel partition is welded in the water chamber according to the required process. The standard water pipe connection provided by the factory adopts HG20615 flange connection. The water chamber of each evaporator and condenser is equipped with a 20mm drain and vent pipe.

Capacity control

The twin-screw compressor uses slide valves for capacity control, which can be steplessly adjusted within 100% to 20% load. The spool valve driven by the system pressure difference is controlled by the external solenoid valve of the control center.

Lubrication system

Sufficient lubricating oil can be supplied to the compressor at any time. When the unit is running, the positive pressure difference of the system is used to transport lubricating oil. The immersed oil heating (temperature driven) can effectively separate the refrigerant from the oil during shutdown. The external oil filter and manual isolation shut-off valve can be easily overhauled, and the oil filter core can be replaced. The automatic oil return system recovers the lubricating oil left in the evaporator and makes it flow back to the compressor. The oil separator is a vertical structure with no moving parts. After entering the oil separator, the refrigerant gas enters the heat exchanger after the steam and oil are separated. Liquid refrigerant injection can be used to maintain satisfactory oil temperature and allow the unit to operate above full load conditions.

The condenser shell tube can store the refrigerant amount of the entire system during maintenance. The service valve can easily discharge the refrigerant from the system.

The unit is equipped with a suction filter to prevent external debris from entering the system during maintenance and overhaul. The motor cooled by the refrigerant must be protected with a filter or screen to protect the motor and prolong its service life.

Evaporator factory insulation

The factory attaches 19mm thick soft closed-cell plastic to the evaporator shell, end plate, suction nozzle and auxiliary pipe (if necessary) as anti-condensation and thermal insulation. Water chamber and water pipe joints do not belong to the factory's thermal insulation range. The 19mm thick insulation layer generally prevents condensation on the surface under environmental conditions of 75% relative humidity and 10-32°C dry bulb temperature. When the relative humidity is as high as 90% and the dry bulb temperature is 10-32℃, a 38mm thick insulation layer can be used to prevent frosting.

Unit size

On-site construction, unit commissioning

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