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Heat Flux Monitor & Control


Heat Flux Monitor & Control

AccuFlux is the only technology that provides heat flow monitoring and control— including direct measurement of Kv and mass flow—throughout the entire freezing and primary drying processes. Millrock Technology has pioneered the use of heat flux sensors to measure and control the heat transfer dynamics of the freeze drying process using real measurement in real time. This technology is designed to obtain a precise direct reading of thermal transfer to the vial. Knowing the energy transfer allows the process to be verified, optimized, repeated and controlled without the use of thermocouples or other invasive measurement techniques.



  • Know that your product has nucleated properly
  • Know when your product is fully frozen
  • Know when your product has stabilized at its annealing temperature
  • Know if there are any material changes to your freeze drying process
  • Monitor and Control the Freezing process
  • Monitor and Control Primary Drying Dynamics
  • Know the amount of water removed
  • Optimize your freeze drying process
  • Know that the product was processed as expected
  • Transfer protocols to production the first time
  • Have a real time tool for predicting process time
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Learn more about AccuFlux Technology

  • True PAT measurement for Lyophilization
  • QbD Tool—Ability to develop Design Space in a single run
  • Eliminates the need for thermocouples in the vial
  • Continuous monitoring for both freezing and drying
  • Non-Invasive and non-interruptive
  • Batch size independent
  • Works in both the lab and production
  • Localized measurement instead of batch average
  • Extreme sensitivity and stability
  • Develop cycles in the lab for transfer to production
  • Measure equipment performance changes
  • Measure product container variations

During freezing the product may not change temperature, such as during removing latent heat in the freezing step. Although the product temperature doesn’t change, there is a significant heat transfer event taking place. Post nucleation latent heat removal (the speed of heat transfer), has a major impact on ice crystal size, orientation and distribution.

The ice crystal structure dramatically influences the drying performance and final product appearance. Measuring the heat flow provides feedback for shelf temperature control during the freezing process to control the crystal structure.

  • The Kv is used to verify that there is no material change in heat transfer between batches
  • The shelf temperature can be adjusted to maintain a constant heat flow
  • During freezing the heat flux will reach zero when the vial has reached equilibrium

AccuFlux measurement information is used to produce a cycle optimization design space. Product temperature isotherms, along with shelf temperature isotherms, can be plotted on a mass flux versus chamber pressure diagram. The resulting information can be used to select the optimum shelf temperature and chamber pressure for highest throughput possible in a specific freeze dryer. This quality by design approach maximizes process and product understanding with a minimum of experimentation.

  • Monitor Primary Drying dynamics
  • Control the rate of drying by adjusting the shelf temperature to control the heat flux

Imagine being able to reproduce the conditions in your production freeze dryer in your laboratory system. Using the AccuFlux measurement, the shelf temperature can be dynamically adjusted to control the energy transfer to simulate your production system, allowing you to produce a protocol that is fully transferrable to production the first time.

  • Measure the Kv under various vacuum level in a Single Run
  • Calculate Mass Flux based on Heat Flux measurement
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Your Freeze Drying Partner

When you purchase a Millrock product, you get more than a freeze dryer. You get a long-term partner delivering industry-changing innovations, high-performing products, and on-call expert support.

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