Types of Environmental Test Chamber Cooling Systems

Environmental test chamber cooling systems are critical for achieving and maintaining precise temperature conditions during testing. The two primary types of chamber cooling systems are expendable refrigerants and mechanical refrigeration systems.

Selecting the right environmental test chamber cooling system directly impacts temperature range, cooling performance, system efficiency, and overall complexity.

Expendable Refrigerants in Environmental Test Chambers

Expendable refrigerants are liquid gases used in environmental test chamber cooling systems to rapidly remove heat. These refrigerants can be injected directly into the chamber or into a heat exchanger.

As the liquid refrigerant enters the chamber (either directly or through a fin coil), it absorbs heat and rapidly evaporates into a gas. The gas is then vented out of the environmental test chamber and must be properly ducted outdoors.

The most commonly used expendable refrigerants include:

Liquid nitrogen (LN2)
Liquid carbon dioxide (CO2)

Temperature Capabilities of Expendable Refrigerants

LN2 can achieve cryogenic temperatures down to -184°C (-300°F)
CO2 can achieve temperatures down to -68°C (-90°F)

Safety Considerations for Expendable Refrigerants

Both LN2 and CO2 are environmentally safe and can be vented to the atmosphere. However, proper ventilation is critical.

Because these gases displace oxygen, environmental test chambers using expendable refrigerants must be vented outdoors to prevent asphyxiation risks.

When to Use Expendable Refrigerants

Expendable refrigerants are commonly used in environmental test chambers for:

Rapid cooling applications
Cryogenic temperature testing
Test conditions requiring extremely low temperatures

Mechanical Refrigeration Systems for Environmental Test Chambers

Mechanical refrigeration systems are widely used environmental test chamber cooling systems. These systems operate similarly to standard refrigeration systems and use a compressor to circulate refrigerant through a closed-loop system.

The required low temperature in the environmental test chamber determines which type of mechanical refrigeration system is needed.

Single-Stage Refrigeration Systems

Single-stage refrigeration systems are a common type of mechanical refrigeration system used in environmental test chambers. These systems use a single refrigeration loop and typically achieve temperatures down to:

-34°C (-30°F)

Some environmental test chamber manufacturers rate single-stage systems to reach -40°C (-40°F). However, due to refrigerant limitations, there is very little cooling capacity available at this temperature, making it difficult to achieve and maintain.

For continuous operation at -40°C and below, most environmental test chamber applications require a cascade refrigeration system.

Cascade Refrigeration Systems

Cascade refrigeration systems are designed for environmental test chambers that require lower temperature performance. These systems use two independent refrigeration systems working together to achieve deeper cooling.

The first stage cools and condenses the refrigerant in the second stage
The second stage circulates refrigerant through an evaporator inside the environmental test chamber

Temperature Capabilities of Cascade Systems

Down to -73°C (-100°F)
Up to -85°C for industrial freezer models

Considerations for Cascade Refrigeration Systems

Increased system complexity
Higher maintenance requirements depending on the application

Cascade refrigeration systems are commonly used in environmental test chambers requiring continuous operation at temperatures below -40°C.

Tundra® Refrigeration System

The Tundra® refrigeration system is a patented, single-stage environmental test chamber cooling system designed to provide improved efficiency at lower temperatures.

Performance of the Tundra System

Capable of cooling down to -45°C (-50°F)
Designed for continuous operation at -40°C

Advantages of the Tundra Refrigeration System

Uses up to 40% less energy than cascade refrigeration systems
Lower system complexity compared to traditional cascade systems
Fewer components, resulting in reduced maintenance and utility costs

Application Benefits

Because many environmental test chamber applications operate at -40°C, the Tundra refrigeration system provides an efficient alternative to cascade systems.

At higher temperatures, this environmental test chamber cooling system can also handle large live load conditions generated during electronic testing.