Extraction Chiller, Circulator Chiller, Chiller System: What’s the Difference?

October 8, 2024

When diving into extraction processes, the terminology around chillers can feel overwhelming. Here’s a breakdown to help clarify the differences and guide you in selecting the right chiller system for your needs.

Terminology

• Chiller / Refrigerated Circulator / Recirculating Chiller: These terms are often used interchangeably to describe devices that circulate a cooled liquid to maintain specific temperatures in extraction systems.

Key Considerations for Your Extraction System Chiller

1. Equipment Compatibility: Determine which equipment you’ll pair the circulator chiller with. For example, if you’re using a fully jacketed column, that influences your choice.
2. Liquid Capacity: Assess the liquid capacity your equipment can hold to ensure adequate circulation.
3. Desired Temperature: Identify the target temperature you need to achieve for your extraction process.
4. Heat Load: Consider whether your extraction method generates a heat load. For instance, when dewaxing, there might not be significant heat added since solvents aren’t evaporated.

Types of Chillers

1. Vapor Absorption vs. Vapor Compression

• Vapor Absorption: Utilizes heat to move a cooling agent through the system.
• Vapor Compression: Uses an electro-mechanical compressor to circulate the refrigerant.

2. Air vs. Water Chillers

• Air Chillers: Use air to remove heat; typically require more energy due to the fan system but are easier to install.
• Water Chillers: Use water for heat dissipation, which is more energy-efficient due to water’s high heat capacity. They generally have a longer lifespan compared to air chillers.

Specific Chiller Applications

Rotovap Chillers

• Cooling Capacity: Rotovaps produce significant heat during solvent evaporation, necessitating a high cooling capacity. Maintaining temperatures close to 0°C is ideal, but anything up to 15°C is also acceptable.

Factors to Consider When Shopping for a Chiller

Chilling Fluid & Tubing

• Fluid Selection: Choose a chilling fluid based on the temperature range required. For example, Dynalene HC-50 is low-toxicity and suitable for temperatures not colder than -50°C. Ethanol can be used for lower temperatures but is highly flammable, requiring careful handling.
• Tubing Compatibility: Ensure that the tubing is chemically compatible with the chilling fluid and rated for the maximum pressure of your system. Insulated hoses can help reduce thermal losses.

Heating Considerations

• When to Use a Heater: In some applications, particularly during recovery, heating might be more straightforward than chilling. A chiller with a wide temperature range (like the Polyscience 15L AD) can effectively manage both heating and cooling needs.
• Heating Fluid & Tubing: Similar to chillers, select heating fluids based on the desired temperature. Silicone-based fluids are common for high-temperature applications. Ensure the tubing is compatible with the heating fluid and rated for the required pressure.

Recommended Chiller Pairings

• When pairing chillers with your extraction system, consider both your chilling and heating needs. For instance, if your process requires maintaining specific temperatures across different stages, opt for a versatile chiller that can accommodate a broad temperature range.

By addressing these key aspects and understanding the different types of chillers available, you can make informed decisions that enhance the efficiency and effectiveness of your extraction processes.