Temperature Control for External Applications, What to Look For
What is an external temperature application?
There are two main types of temperature applications: internal and external. In an internal application, whatever you want to heat or cool is placed directly into the temperature controller’s bath tank. With an internal application, the temperature control unit (TCU) serves as the vessel for heating and cooling. With an external application, temperature application is taking place away from or outside the TCU itself.
External applications can take many forms, including, but not limited to:
- Heating or cooling samples in an external vessel, such as glass reactors & bioreactors
- Simulating temperatures or heating/cooling objects in vacuum chambers or other vessels
- Removing heat generated from chemical or biochemical processes or equipment
Equipment & Processes that Use External Temperature Control
Various equipment and chemical/biochemical processes require careful temperature monitoring and management. For example, a process such as fermentation generates additional heat during the metabolic stages, and that heat needs to be removed to protect the sample environment and process. Additionally, equipment such as large-scale industrial lasers also generate excess heat that has to be removed to preserve the stability of the beam itself.
At JULABO USA, we help scientists, engineers, and manufacturers find the temperature control equipment they need to master their external applications. JULABO units have been used for various external applications, processes, and equipment cooling.
TCUs pair with various types of equipment for external temperature control, including:
- Lasers
- Fermenters
- Vacuum chambers
- Refractometers
- Polarimeters
- Rotary evaporators
- Spectrometers
- Electrophoresis
- Reaction calorimeters
- Extruders
- Molding machines
- And more
A variety of chemical and biochemical processes may require external temperature control, including:
- Fermentation
- Distillation
- Condensation
- Flow Chemistry
- Material testing
- Component testing
- Sub-assembly testing
- Solvent evaporation
- Viscosity testing
- Dissolution testing,
- Crystallization
- And More
External Temperature Control Equipment, What to Look For
Choosing a TCU for an external application requires specific considerations. Many basic chillers, heating or refrigerated/heating circulators operate on internal temperature control. Internal temperature control units use a temperature sensor inside the TCU to measure and achieve the target temperature. However, these types of controllers aren’t recommended for external applications. Why? Because the actual temperature in the application can differ significantly from the displayed internal temperature measurement. Various factors contribute to this, including tubing length, insulation, etc. Using a TCU with internal-only temperature control can lead to a lot of trial and error, longer processing timelines, and poor results.
Consideration #1: Does the TCU have Pt100 & External Sensor Capabilities?
There’s one simple thing to look for when sourcing a TCU for external temperature control. Can you easily connect an external sensor such as a Pt100 sensor or thermocouple? For example, JULABO’s TCUs incorporate a LEMOSA 4-pin outlet for Pt100 sensors. The outlet allows you to plug one end of the Pt100 sensor into the TCU and place the other end (the end with the sensor) directly into the application, providing you with an accurate measurement within the application itself. The TCU will then be able to control and monitor the application from the external Pt100 sensor. This eliminates any heat loss via tubing/plumbing, ensuring that the application reaches the required temperature.
Ideally, the manufacturer of the TCU should also be able to provide or help you source the Pt100 sensor or external sensor that’s recommended for your application. For instance, JULABO offers several external Pt100 sensor options in stainless steel or PTFE-coated stainless steel. We can also custom source sensors of varying dimensions and materials of construction, including Hastelloy. For applications that require small sensors like thermocouples, we offer the TCCB (ThermoCouple Converter Box), which adapts mini-connecter type J, K, or T thermocouples to the LEMOSA 4-pin outlet.
Consideration #2: Band Limits
TCUs optimized for external temperature control also provide an additional feature for band limit. If the application has a limitation on the temperature delta (ΔT) between the fluid temperature and the application temperature, setting a band limit protects the application from thermal stress. For example, most jacketed glass reactors have a maximum temperature differential across the internal glass wall ranging from 50 K to 80 K. JULABO units have a band limit value available to set appropriately for heating and cooling. Another way to visualize, think of band limit as thermal cruise control. The TCU will not exceed the band limit value (the internal and external temperature difference), thus protecting the application from thermal stress. All JULABO units have default band limits set to 200 K; therefore, we highly recommend adjusting these values before operation.
Legend:
- Internal Bath
- External System
- Upper Band Limit
- Lower Band Limit
Upper bandlimit active while heating; lower bandlimit active while cooling.
Consideration #3: Workflow & Operational Capabilities
As with any temperature control equipment you select, you’ll also want to consider how that unit fits into your workflow and operations.
- Can you operate the TCU remotely using a computer?
- What are the data capture, graphing, and management capabilities?
- What type of safety features does the TCU have?
- How much space does the TCU require?
- Can the TCU operate more than one application?
- How will the TCU integrate with other equipment and systems? Can it be placed directly next to other units or applications?
- Can it help reduce operational costs such as energy and water consumption?
Next Steps: Equipment Selection and Expert Support
JULABO specializes in external temperature control. Our PRESTO line of highly dynamic temperature control systems incorporate a closed design ideal for external temperature control. We also offer recirculating chillers that can replace water cooling methods, which can be both expensive and wasteful. In addition, we have several benchtop to larger-scale heating and refrigerated heating circulators, chillers and cryo-compact circulators.
Our external temperature control units offer the workflow enhancements, accuracy, connections, and accessories you need to take control of your external application. For assistance finding a TCU to heat or cool your external process, contact your local JULABO USA account manager.
