Refrigerated Circulating Baths

Proper fluid selection and maintenance for heat transfer applications

Whether your temperature control unit (TCU) is a water bath, refrigerated/ heated bath circulator, cooling/heating recirculating chiller or recirculating chiller, a fluid will have to be selected. If you are operating between approximately 5 ºC and 95 ºC, then water seems the likely choice. You might find yourself close to a source of tap water, filtered water, distilled water, reverse osmosis (RO) water, or deionized (DI) water. However, just using the nearest convenient source may not be the right choice. While these water types all have their uses, not all are suitable for your TCU needs. Regardless of how it has been treated, all water starts out with the same basic properties, advantages and disadvantages. 

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I plan on using my bath circulator for external circulation only. Should I get a large reservoir that can absorb the heat for more stability?

No. A large bath reservoir is not an indication of increased cooling capacity or better temperature stability. Cooling capacity is based on setpoint temperature and compressor size. Temperature stability is affected by two things: the consistency of the heat load from your application, and how precisely the heating and/or cooling is controlled by the bath circulator.

The best selection for you would be a bath circulator with the smallest possible bath reservoir that still meets your setpoint temperature and cooling capacity requirements. This will lower the load when changing from one setpoint to another, improving your time to temperature.

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Optimizing the selection of a recirculating chiller

A recirculating chiller is used to supply a steady flow of temperature-controlled fluid to an application. The fluid temperature coming from the chiller could be used to cool, maintain or even increase the temperature of the application. Five criteria must be defined in order to select the correct refrigeration, circulation, and control systems for your recirculating chiller.

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How do I select an energy efficient refrigerated bath circulator? Is it simply based on the selection of energy efficient components? 

Selecting energy efficient components does help with overall energy efficiency. However, the most efficient refrigerated bath circulators control temperature differently compared to standard refrigerated bath circulators. Through a special energy savings mode, they are able to further reduce the power usage under low demand situations without reducing performance during high demand operations. 

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With the rising cost of municipal water supply and sewer disposal, along with corporate initiatives and municipal laws aimed at reducing water usage, how will the cost of purchasing and running a recirculating chiller or bath circulator affect my bottom line?

First calculate the annual water usage and the cost of purchasing and disposing of that water. Then calculate the cost of purchasing and operating a chiller or circulator. Depending on what you pay for water, sewer and electricity in your community, you may be surprised how little a chiller or circulator actually costs. In fact, you may discover that using a chiller or circulator may save you money and pay for itself over time.

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