How Is A Scroll Compressor Cooled?

The cooling mode of scroll compressor is mainly divided into internal cooling and external cooling. The specific method depends on the compressor's power, operating conditions and energy efficiency requirements. Here are the details:
I. Internal Cooling: direct reduction of the Compression Chamber Temperature
How it works: The heat generated during compression is absorbed directly by the refrigerant itself or by an external cooling medium (e.g. oil) in direct contact with the compression chamber.
1.Refrigerant injection cooling (common in medium to Large Scroll Compressors)
Structure: Install a nozzle at the suction port or intermediate pressure point of the compression chamber to inject cryogenic liquid refrigerants (e.g. R410A, R134a) directly into the chamber.
Function:
Cooling: Liquid refrigerants absorb heat during evaporation, reduce the temperature of the compression chamber temperature (which can be lower than the ambient temperature), and reduce gas leakage and overheating.
Lubrication: Some models use the refrigerant spray to transport lubricant and improve lubrication between moving and stationary scroll plates.
Application Scenarios: High ambient temperature (e.g. outdoor facilities) or high compression ratio conditions (e.g., refrigerant evaporation temperature below -20°C).
2.Oil Cooling (commonly used in High Pressure Ratio or Variable Speed ​​Scroll Compressors)
Structure: The compressor has an internal oil circulation system, and oil pump carries the lubricant to the compression chamber or bearing surface.
Function:
Heat Dissipation: Oil absorbs heat, which is then released into the environment through an oil cooler (air or water).
Seal: The oil film fills the gap between the scroll plates, reduces gas leakage and improves volumetric efficiency.
The Danfoss Turbocor series variable speed rolling compressor uses oil cooling technology and can operate at ambient temperatures between -40 and 55 degrees Celsius.
ii. External Cooling: indirect control the Compressor Housing Temperature
Principle: using external media such as air or water to indirectly cool compressor housing, reducing the internal temperature.
1.Air Cooling (Standard Configuration)
Structure: compressor housing has a fin tube and is equipped with a forced air-cooled fan (such as an axial fan or centrifugal fan).
Function:
Convective Heat Dissipation: Air flows over the fin, taking heat with it; shell temperatures are usually 10-15 degrees Celsius above ambient temperatures. Dustproof Design: Some models are equipped with filters or air deflectors to prevent dust from entering the compressor chamber.
Optimization Directions:
Variable speed fan: According to compressor load dynamic adjustment fan speed, reduce energy consumption.
Reverseflow design: Optimize airflow structure, ensure full contact between air and compressor housing, and improve heat dissipation efficiency.
2. Water Cooling (efficient but costly)
Structure: compressor casing is equipped with a water jacket and circulating cooling water (e.g. ethylene glycol solution) flows through the housing to absorb heat.
Function:
High cooling efficiency: Water cooling efficiency is 3-5 times higher than air cooling, and compressor housing temperature is kept below 40°C.
Suitable for high temperatures: Desert, tropical temperatures above 40C.
Typical applications: Data centers, industrial cooling, and other applications that require extremely stable temperatures.
III. Comparison and selection of cooling methods
Typical Scenario Model of Cooling Method forHeat Efficiency
High Refrigerant Injection (Direct Cooling), medium high temperature/High Compression Ratio Emerson ZPK Series
Oil Cooling High (Indirect Cooling) High Variable Frequency/Wide Temperature Range Danfoss Turbocor
BorgWarner ZR Series Air Cooling, Low and Medium Standard Operating Conditions
Water Cooling Very High Very High High Temperature/High Precision Bitzer CSH Series
IV. INTRODUCTION Guide: Introduction to the Design Point of Cooling System Design
Temperature Monitoring: Installation of a temperature sensor at the compressor outlet to trigger an alarm or shutdown protection if the temperature exceeds the set value (e.g. 120°C).
Flow control: Water cooling system requires a flow switch to ensure that the flow of cooling water does not fall below the design value (e.g. 3 L/min) to prevent local overheating.
Antifreeze Protection: At low temperatures, ethylene glycol antifreeze is added to water cooling system to prevent the water jacket from freezing and cracking.
Maintenance Cycle: Clean air-cooled filters every 3 months, replace coolant every year and clean the scale of water cooling system.
V. Real-World Application Case Study
Commercial Building Air Conditioning: The BorgWarner ZR series of air-cooled scroll compressors operate efficiently and energy-efficient through variable speed fans, keeping summer shell temperatures below 60 degrees Celsius. Refrigerated transport vehicles: Equipped with Emerson ZPK series liquid-cooled scroll compressors to maintain stable refrigeration performance even at minus 30 degrees Celsius.
Data center precision air conditioning: The The Bitzer CSH series water-cooled scroll compressors and closed-loop cooling water systems ensure that the compressor casing temperature remains constant at 35°C.