Types Of Chillers: How To Select A Chiller For Extraction
, by Avery Benitez, 9 min reading time
This guide gives an overview of chillers and how to select the right one for your specific application. Also included is a list of recommended chiller/equipment pairings.
Extraction Chiller, Circulator Chiller, Chiller System...What’s the Difference?
When you’re new to extraction, it feels overwhelming enough to discover that you may need a chiller system—let alone that there are a whole bunch of different types of chillers available for purchase. To start, it helps to know that the words “chiller,” “refrigerated circulator.” and “recirculating chiller” virtually mean the same thing. Determining the right one for your needs can be as simple as asking yourself a few starter questions:
- What type of equipment am I pairing the circulator chiller with?
- How much liquid capacity does my equipment hold?
- What temperature do I need to reach?
- How much of a heat load will my equipment put on the chiller?
Let’s find your answers together.
Considerations For Your Extraction System Chiller
The temperature you’re trying to reach and the capacity of your system are large factors in determining the kind of extraction chiller needed. Consider that you’re looking to dewax solvent with a 4" x 24" fully jacketed column.
Heat Load
Will there be any heat load on the chiller from this application? The answer is no: the solvent is not being evaporated so there is no heat load to the recirculating chiller.
Temperature Range
When dewaxing, you’re looking to achieve the coldest temperature possible. Because you own a fully jacketed column, a chiller like our AD 15L—instead of something like a 6160—would be your best bet. That’s because its temperature range is -30℃-200℃. That means that you should be able to reach as low as -30℃ since there’s no heat load.
Capacity
Use the volume capacity of the jacket to select an extraction chiller that’ll hold about twice as much liquid volume. This should ensure that enough cold liquid is circulating throughout the column so it reaches the correct temperature sooner.
If you’d also like to use a chiller for a solvent tank, use the same calculation to find the jacket or internal coil volume: whichever the cold liquid will circulate through. This number should tell you whether your chiller has enough fluid capacity and a low-enough temperature range to cool a solvent tank too.
Types of Chillers
Vapor Absorption vs Vapor Compression
Chiller systems can work by using either vapor absorption or vapor compression. Vapor absorption chillers run on heat to maneuver a cooling agent across the system, while vapor compression chillers rely on an electro-mechanical compressor to do so.
Air vs Water Chillers
The two types of vapor compression chillers are air chillers and water chillers. Here, air and water are used respectively to remove heat from the chiller system. The fan of an air chiller takes more energy to blow air on the condenser tubes than a water chiller would, but it’s an easy stationary installation job.
In a water chiller, water is pumped throughout a cooling tower by a sealed condenser. Dissipating heat via evaporation takes less energy because water has a high heat capacity. In general, a water recirculating chiller should outlast an air chiller.
Rotovap Chillers - High Cooling Capacity
Rotovaps need circulator chillers to maintain certain temperatures and recover solvents. During the evaporation of solvents in a rotovap, the solvent vapor will be quite warm. This means there’ll be a larger heat load on the chiller than with other applications, so it’ll require a high cooling capacity. Because of this, it’ll probably have a smaller temperature range, which isn’t necessarily a bad thing. Maintaining 10℃ is much easier than maintaining -40℃.
When using a rotovap, the goal is to be as close to 0℃ as possible, although anything up to 15℃ will work. Applications with larger heat loads will require higher cooling capacities. Most chiller manufacturers provide cooling capacities at different set temperatures which can be used to compare and select the correct chiller for your application.
Things to Consider While Shopping For A Chiller
Chilling Fluid & Chiller Tubing
When deciding what type of fluid to buy for your extraction chiller, start with the temperature range that matches up with it. We always recommend Dynalene HC-50 for its low toxicity and non-flammability. HC-50 will start to congeal around -50℃. It’s a good choice for applications that don't need to get colder than this.
If you need lower temperatures—go with an ethanol mixture. Although ethanol won’t freeze until -173℉: it’s highly flammable. Extreme caution should be taken while using it as a chilling fluid. When selecting chiller tubing, look at your chiller’s pump specifications. That’ll give you a good idea of the pressure the pump is putting behind the liquid.
Ensure the tubing selected by chemical compatibility with the chiller fluid being used, temperature range of the application, and pressure rated higher than the max operating pressure of the chiller. Failure to pair the correct tubing will cause the tubing to burst immediately or over a longer period of time. If you are operating at low temperature, there are insulated hoses that can reduce thermal losses to ambient exposure. Condensation forming on the tubing or the jacket of a column are signs that there are thermal losses in your setup and it requires insulation. Insulating all components that will be chilled increases efficiency of the chiller to reach the desired temperature.
What About Heaters?
For certain recirculating chiller system applications, we might only really need a heater. An example of this would be when you’re heating a jacketed base during recovery. Heating is simpler to figure out because it’s much easier to heat a liquid than cool it while at room temperature. You’ll notice some of the extraction chillers we’ve already discussed, such as the Polyscience 15L AD, have a large temperature range. This one heats up to 200℃. This means you could use this chiller for both heating and cooling.
During the recovery process the evaporation of solvent creates a cooling load on the internal components of the vessel, this is known as evaporative cooling. This puts a cooling load on the heater and will lower the temperature. Having a higher heating capacity will help you maintain the temperature and speed up the recovery process.
Heaters can also be used in the decarboxylation and distillation process. Under both of these processes a cooling load may be minimal or not present at all depending if solvent is still present. For these applications a higher temperature range heater is needed. If the reactor is larger, more heating capacity is needed at the desired temperature. Distillation temperatures are higher, but the heater still acts as a means of condensing hot vapors. Some heater manufacturers also provide cooling capacities at higher temperatures. However, if this is not available then the correct heater can be selected by temperature range and heating capacity.
Buying just a heater will always be more affordable than a chiller. However, if you have multiple applications requiring both heating and cooling, it’s better to buy a chiller with a large temperature range to achieve both.
Heating Fluid & Heating Tubing
When deciding what type of fluid to buy for your heater, start with the desired operating temperature that will be used in your application. The most common fluid used for heaters operating over 100°C are silicone based. BVV also provides Therminol XP Heat Transfer Fluid for high temperature applications. The reason these fluids are used is because of their specific heat. Specific heat is a measurement that measures the amount of energy required to raise the fluid temperature by 1°C. If the heater requires less energy to raise the temperature, then the more efficient it will be to reach and maintain those temperatures. Make sure you are also using an approved fluid by the heating circulator manufacturer. Fluids may be corrosive or too thick for the heater pump.
Ensure the tubing selected by chemical compatibility with the heating fluid being used, temperature range of the application, and pressure rated higher than the max operating pressure of the heater. Failure to pair the correct tubing will cause the tubing to burst/melt immediately or over a longer period of time. If you are operating at high temperature there are insulated hoses that can reduce thermal losses to ambient exposure. Insulating all components that will be heated increases efficiency of the heater to reach the desired temperature.
Recommended Chiller Pairings
Shop all these recommended chillers and more at BVV.
- 2L Rotovap: Polyscience LS -20℃ to 40℃ 1/2HP Chiller w/ Turbine Pump
- 5L Rotovap: Polyscience LS -20℃ to 40℃ 1/2HP Chiller w/ Turbine Pump or Polyscience 6160 -10℃ 4.2L 1HP Chiller w/ Turbine Pump
- 10L Rotovap: Polyscience 6160 -10v 4.2L 1HP Chiller w/ Turbine Pump or Polyscience DuraChill -10℃ to 80℃1.5HP Chiller w/ Turbine pump
- 20L Rotovap: Polyscience DuraChill -10℃ to 80℃ 1.5HP Chiller w/ Turbine Pump
- 30L Rotovap: Polyscience DuraChill -10℃ to 80℃ 1.5HP Chiller w/ Turbine Pump
- 50L Rotovap: Polyscience DuraChill -6℃ 42L 5HP Chiller w/ Displacement Pump
- 2L Short Path: Polyscience 7L MX Heated Circulator or Polyscience 7L MX Refrigerated Circulator or Polyscience 7L Standard Digital Refrigerated Circulator or 7L Advanced Digital Refrigerated Circulator
- 5L Short Path: Polyscience 7L Standard Digital Refrigerated Circulator or Polyscience 15L Advanced Digital Heated Circulator or 7L Advanced Digital Refrigerated Circulator
- 10L+ Short Path: Polyscience 15L Advanced Digital Refrigerated Circulator or Polyscience 15L Advanced Digital Heated Circulator
- 10L Glass Reactor: Polyscience 15L Advanced Digital Refrigerated Circulator or Thermo Scientific Glacier Series G50 Ultra-Low Refrigerated Circulator
- 20L Glass Reactor: Polyscience 28L Advanced Digital Refrigerated Circulator or Thermo Scientific Glacier Series G50 Ultra-Low Refrigerated Circulator
- 50L+ Glass Reactor: Polyscience 45L Advanced Digital Refrigerated Circulator or Thermo Scientific Glacier Series G50 Ultra-Low Refrigerated Circulator
- 50L Stainless Steel Reactor: Polyscience 45L Advanced Digital Refrigerated Circulator or Thermo Scientific Glacier Series G50 Ultra-Low Refrigerated Circulator
- 1LB Fully Jacketed Columns: Polyscience 15L Advanced Digital Refrigerated Circulator or Polyscience 7L Advanced Digital Refrigerated Circulator
- 2LB Fully Jacketed Columns: Polyscience 15L Advanced Digital Refrigerated Circulator
- 5LB Fully Jacketed Columns: Polyscience 28L Advanced Digital Refrigerated Circulator or Thermo Scientific Glacier Series G50 Ultra-Low Refrigerated Circulator
- #25 Fully Jacketed Stainless Steel LP Tank: Polyscience 7L Advanced Digital Refrigerated Circulator or 7L Standard Digital Refrigerated Circulator
- #50 Fully Jacketed Stainless Steel LP Tank: Polyscience 15L Advanced Digital Refrigerated Circulator
- #100 Fully Jacketed Stainless Steel LP Tank: Polyscience 28L Advanced Digital Refrigerated Circulator
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