The
Screw Condensing Unit is a high-efficiency core refrigeration equipment based on the vapor compression refrigeration cycle. With a screw compressor as its power core, it achieves heat transfer through refrigerant phase change, making it widely suitable for the continuous and stable operation needs of large-scale refrigeration scenarios. Founded in 1995, Zhejiang Kaidi Refrigeration Equipment Co., Ltd. (hereinafter referred to as Kaidi) has been deeply engaged in the refrigeration field for nearly 30 years. Leveraging its 100,000-square-meter production base and high-standard testing laboratory, Kaidi's R&D and produced Screw Condensing Units cover a cooling capacity range of 100KW-4180KW, a chilled water outlet temperature range of 15℃~-35℃, and an IPLV (Integrated Part Load Value) of over 5.6, fully complying with the energy-saving requirements of the "14th Five-Year Plan for Industrial Green Development". It has become the preferred refrigeration equipment for many well-known enterprises worldwide.
I. Core Working Principle
The working logic of the Screw Condensing Unit is based on the vapor compression refrigeration cycle, consisting of four key processes:
- Compression Process: Low-temperature and low-pressure refrigerant gas is sucked into the screw compressor and compressed into high-temperature and high-pressure gas through the meshing of male and female rotors. Kaidi adopts a 5:6 asymmetric twin-screw compressor, whose volumetric efficiency is 8% higher than that of conventional models.
- Condensation Process: High-temperature and high-pressure gas enters the shell-and-tube condenser, completes heat exchange with cooling water, and condenses into high-pressure liquid. Kaidi's condenser uses imported 316L stainless steel plates, whose corrosion resistance is twice that of ordinary steel.
- Throttling Process: High-pressure liquid is throttled and depressurized through an electronic expansion valve, converting into a low-pressure and low-temperature gas-liquid mixture to ensure stable and efficient evaporation.
- Evaporation Process: The low-pressure and low-temperature mixture absorbs heat from the secondary refrigerant in the evaporator and vaporizes, cooling the secondary refrigerant to the set temperature. The vaporized refrigerant re-enters the compressor to complete the cycle.
Through independently developed high-efficiency oil return system (oil separator oil return + high-pressure ejector oil return) and Siemens S7-200 SMART PLC control system, Kaidi realizes stepless regulation of the unit from 10% to 100%, with a temperature control accuracy of ±0.5℃, adapting to dynamic refrigeration needs under complex working conditions.
II. Product Performance Comparison (Including Kaidi Core Parameters)
| Comparison Dimension |
Screw Condensing Unit (Kaidi) |
Reciprocating Condensing Unit |
Centrifugal Condensing Unit |
| Cooling Capacity Range |
100KW-4180KW |
10KW-100KW |
300KW-5000KW |
| Energy Efficiency Level (IPLV) |
Up to 6.0 (Inverter Model) |
3.5-4.5 |
4.8-6.2 |
| Regulation Method |
10%-100% Stepless Regulation |
Cylinder Unloading Step Regulation |
20%-100% Regulation (Prone to Surge) |
| Core Advantages |
Stable Operation, Low Noise & Vibration, Low Maintenance Cost |
Low Cost, Mature Technology |
Large Single Unit Capacity, Oil-Free Compression |
| Application Scenarios |
Large Cold Storage, Industrial Process Cooling, Pharmaceutical Cold Chain |
Small Shops, Civil Refrigeration |
Super Large Building Air Conditioning, Chemical Plants |
Data Source: Kaidi Laboratory Test Report, 2025 Industrial Refrigeration Equipment Industry Evaluation Data
III. Typical Application Cases
Relying on its full-chain capabilities of "R&D + Production + Service", Kaidi's Screw Condensing Units have been widely applied in core scenarios of various industries:
- Cold Chain Logistics: Providing continuous refrigeration for large cold storages of enterprises such as GLP, Shunfeng, and JD.com. The unit's COP value remains stable above 2.8 under -35℃ low-temperature working conditions, meeting the long-term fresh-keeping needs of cold chain goods.
- Food Processing: Adapting to the process cooling links of food enterprises such as Wufeng and Ligao, with a temperature control accuracy of ±0.5℃, ensuring stable food quality during production.
- Pharmaceutical Cold Chain: Serving the refrigeration projects for drug storage and transportation of Shanghai Pharmaceuticals and China National Pharmaceutical Group. It uses the environmentally friendly refrigerant R134a with an Ozone Depletion Potential (ODP) of zero, complying with the compliance requirements of the pharmaceutical industry.
- Industrial Manufacturing: Providing cooling for high-temperature environments in petrochemical, nuclear energy material production and other scenarios. The unit's pressure resistance level reaches 1.6MPa, adapting to complex industrial working conditions.
IV. Professional Maintenance Guidelines
Daily Maintenance Points
- Keep the condenser and evaporator clean to avoid dust accumulation or scaling affecting heat exchange efficiency. It is recommended to clean the fin surface once a month.
- Check the oil level to ensure it is within the range of 1/2-2/3 of the oil sight glass, and the oil pressure is 0.15-0.2MPa higher than the suction pressure.
- Monitor operating parameters: control the condensation temperature at around 40℃, maintain the cooling water inlet/outlet temperature at 32℃/37℃, and the chilled water inlet/outlet temperature at 7℃/12℃.
Regular Maintenance Specifications
- Inspect the oil filter after the unit's first 500 hours of operation, and replace it every 2000 hours or when the pressure difference exceeds 2.1bar thereafter.
- Conduct refrigerant leakage detection and replenishment once a year, with the charging error controlled within ±1%.
- Drain the water in the heat exchanger or add ethylene glycol antifreeze during winter shutdown to prevent equipment freezing and cracking.
Kaidi After-Sales Support
Kaidi has branches in Beijing, Guangzhou and other cities, as well as the Shanghai Hongqiao R&D Center. The after-sales team's response time is ≤24 hours, providing full-cycle services such as on-site commissioning, troubleshooting, and spare parts replacement. Relying on its global service network, Kaidi ensures the long-term stable operation of the unit.
V. Frequently Asked Questions (FAQ)
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What are the core advantages of the Screw Condensing Unit?
Answer: Core advantages include 10%-100% stepless regulation (high part-load efficiency), few components and wearing parts, low vibration and noise. Kaidi's models are additionally equipped with a high-efficiency oil return system and intelligent control system, adapting to long-term continuous operation scenarios.
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Compared with reciprocating condensing units, which projects are screw condensing units more suitable for?
Answer: More suitable for medium and large-scale projects with a cooling capacity of over 100KW, such as large cold storages, industrial workshop cooling, and large-scale food processing. Kaidi's units have been verified for their adaptability to high-capacity and high-stability requirements in large cold chain projects such as GLP and Shunfeng.
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How to plan the unit's maintenance cycle?
Answer: Daily maintenance is required once a month, the oil filter is replaced every 2000 hours, and comprehensive inspection and maintenance are conducted annually. Kaidi can customize an exclusive maintenance plan according to the customer's usage scenario and provide on-site services.
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Is the refrigerant used in the unit environmentally friendly?
Answer: Kaidi's Screw Condensing Units uniformly use the environmentally friendly refrigerant R134a with an ODP of zero and a Global Warming Potential (GWP) lower than that of traditional refrigerants, complying with international environmental standards and adapting to industries with strict environmental requirements such as pharmaceuticals and food.
02 Nov,2026
