Quick-frozen foods, low-temperature cold storage, low-temperature chemical crystallisation, pharmaceutical low-temperature storage — these applications often call for evaporating temperatures as low as -20°C or below. The challenges that medium-to-low temperature conditions pose to a compressor are direct: suction density falls, the pressure differential grows, discharge temperature rises, and lubrication conditions worsen. If a compressor is not designed specifically for such conditions, both efficiency and reliability are clearly compromised.
The Fusheng CSRL/SRL series screw refrigerant compressor is a refrigeration compressor dedicated to the medium-to-low temperature field, meeting application requirements from 7.5°C to -45°C. It uses a 5:6 asymmetric rotor profile, combined with a capacity-control slide valve and VSD capability, with displacement covering 85-472 m³/hr and suitability for refrigerants such as R22, R404A, and R507.
In medium-to-low temperature applications, a compressor faces a set of interlinked difficulties: a low evaporating temperature increases suction specific volume and lowers refrigerating capacity per unit volume; the larger pressure differential between condensing and evaporating raises the compression ratio, and discharge temperature rises with it; at the same time, oil viscosity and flow characteristics change at low temperature, making oil return and lubrication harder. The CSRL/SRL series is designed specifically for these characteristics, including specially optimised cooling passages and a dedicated oil circuit design, to widen the application range and ensure stable operation while reducing operating noise.
The rotor profile is the foundation of a screw compressor. The 5:6 asymmetric profile is a mature, widely proven geometry in the industry, balancing sealing, efficiency, and manufacturability through optimised tooth count and tooth-surface shape. The CSRL/SRL rotors are precision-formed with high tooth-surface accuracy, which helps reduce gas leakage and raise compression efficiency. This design is also one of the foundations for the series' ability to maintain high performance across a wide range of medium-to-low temperature conditions.
The load on a refrigeration system is never constant. Ambient temperature and cooling demand change through the day and across the year. CSRL/SRL uses a capacity-control slide valve mechanism to precisely regulate the capacity the system requires, with a choice of four-step or stepless design, and optional built-in volume ratios to suit different refrigerant conditions; it also supports VSD applications, with a frequency-lowering range of 20-60Hz and a frequency-raising range of 20-80Hz. Only when refrigerating capacity follows the load can pointless energy consumption — a big machine doing a small job — be avoided.
The series supports parallel operation of multiple units to meet high cooling demand — when one unit is not enough, expanding through paralleling is more flexible than replacing it with a larger model, and it also allows staged investment on demand. For running protection, the compressor has a built-in PTC thermistor together with an upgraded protection module, able to monitor motor coil temperature precisely and reflect motor operating status in time, adding a layer of protection for long-term operation.
| Item | Specification |
|---|---|
| Displacement | 85 ~ 472 m³/hr |
| Refrigerants | R22 / R404A / R507 |
| Application temperature range | 7.5°C ~ -45°C |
| Rotor profile | 5:6 asymmetric rotor profile |
| Capacity control | Capacity-control slide valve (four-step / stepless) |
| VSD range | 20 ~ 80 Hz |
| Expansion capability | Multiple units can be paralleled for high cooling demand |
With medium-to-low temperature refrigeration, the real fear is not failing to achieve it, but achieving it unstably and at high power cost. From rotor profile and cooling passages to oil circuit design, capacity control, and motor protection, the Fusheng CSRL/SRL series brings a whole set of dedicated design work to medium-to-low temperature conditions. For refrigeration applications in the 7.5°C to -45°C range, it is a choice that balances professionalism against flexibility.
| Fusheng 5 | 6 asymmetric rotor profile, machined on HOLROYD rotor machining centres from the UK and finished on KAPP and KLINGELNBERG precision rotor grinders from Germany, then inspected on ZEISS and LEITZ coordinate measuring machines. |
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