Why is Stirling Cooling so Great for Portable, Ultra-Low Temperature Freezers?

By Norman Quesnel, Senior Member of Marketing Staff
Advanced Thermal Solutions, Inc. (ATS) 

The VOSTOK portable, ultra-low temperature (ULT) freezer features a lightweight, non-powered cooling system. When it comes to providing low temperatures, it is as capable as larger cabinets, easily reaching down to -86°C (-123°F).

Why is Stirling Cooling so Great for Portable, Ultra-Low Temperature Freezers?
Portable Ultra-Low
Temperature FreezerPortM80

This is achieved by using Stirling engine technology in place of more common compressor systems (too big, heavy) or using dry ice (not cold enough for many requirements). At just 30 lbs (13.5 K), the portable VOSTOK cooler, PortM80, is one-third lighter than many other portable coolers.

Stirling engines provide a sound method of energy conversion with useful qualities like high efficiency, high reliability, and easy and quiet operation. Stirling technology uses environmentally safe helium as its refrigerant. It has a linear motor and thermosiphon system that minimize moving parts and maximize reliability and working life. Its moving parts don’t wear out because gas bearings eliminate internal friction. The two moving parts, the piston and the displacer, expand and compress helium in the engine, absorbing heat from the thermosiphon, keeping the cabinet cold. They don’t wear out because the inert gas bearings eliminate internal friction.

Because of the unique Stirling technology, the PortM80 freezer easily absorbs vibration and transportation bumps. It can be equipped with multiple Stirling coolers. During pre-cooling, multiple Stirling coolers can be started at the same time to achieve shorter pre-cooling time, and during normal operation, it can be put into a multi-prepared mode.

Thanks in large part to Stirling cooling the PortM80 freezer is a very useful method for keeping Pfizer’s COVID-19 vaccine in its safe storage temperature. It safely keeps the vax that way when it’s transported to locations where large cabinets can be used.

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