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Paragon Space Development, a supplier of environmental control systems to NASA, and partner SunDanzer Refrigeration, a specialist in off-grid refrigeration, recently were awarded a research contract worth about $150,000 by the U.S. Special Operations Command to design the medical field fridge.

Not your granddad’s icebox, the refrigerator-freezer must be portable, crate several cooling zones and be able to operate for hours without an outside power supply.

“It’s much more high-tech than a regular refrigerator,� said Grant Anderson, president and CEO of Paragon.

Paragon is leading the research effort and will collaborate with SunDanzer on components including advanced compressors and ice-pack material that freezes at a higher temperature than water to last longer essentially by absorbing more heat.

The companies said their proposed solution will entail a hybrid cooler concept that harnesses passive insulation, thermal storage and heat transport technology as well as an active refrigeration cycle for “recharging� once supplied with power.

Both companies have years of experience under research and development contracts with the Department of Defense, as well as NASA.

SunDanzer, founded in 1999 by David Bergeron — who also has worked for Paragon — has developed a line of high-efficiency, battery-powered and battery-free refrigerators.

“It’s great to be working with SunDanzer and Dave,� Anderson said. “They seemed like a logical fit, because they’re top in the market for refrigerators for places without infrastructure.�

Stemming from Bergeron’s work as head of a NASA program to develop advanced refrigeration technologies, the company’s fridges combine refrigeration components capable of working with off-grid solar power with super-insulation and proprietary phase-change materials.

SunDanzer has built thousands of solar-powered vaccine refrigerators for the United Nations Children’s Fund at its small factory on Tucson’s south side. The company also has been working with the Army for several years to demonstrate highly efficient field coolers and freezers in 20-foot metal shipping containers.

The Special Operations Command is asking the companies to design a compact refrigeration unit with three cooling zones, including one that can keep blood at an optimal temperature between about 34 and 42 degrees Fahrenheit, Anderson said.

The unit must be able to run on regular house-rated 110-120 volt AC current, with 12-volt DC power or a 24-volt NATO standard, with backup battery power for six hours and insulated drawers that can keep stuff cold for six to 12 hours.

The SpecOps units must be small — 32 inches high, 22 inches wide and 13 inches long — weigh 70 pounds or less and be portable by one person.

The companies already have deep experience with some of the critical technologies.

For example, once their ice packs are frozen, SunDanzer’s UNICEF fridges can keep vaccines at their safe temperatures for three days in 100-plus-degree heat, said Bill Barg, vice president of engineering for SunDanzer.

Paragon has a long history of research and development and holds several patents related to cooling technology from its work designing environmental and other systems for NASA spacecraft.

Other requirements are tricky, for example, one that calls for a unit that can operate in both horizontal and vertical positions.

Barg said typical compressors typically must be operated upright to keep the oil inside lubricating the mechanism.

One solution the researchers will look at, he said, are so-called “oil-free linear compressors,� which instead of traditional cylindrical electric motors use linear motors that use electrical fields to create motion along a straight line.

“Because it doesn’t need oil, it can be oriented in almost any position, and it’s low-wear because its linear,� Barg said.

Paragon’s Anderson said the researchers also are looking at “heat pipe� technologies — used to cool some microelectronics — that use thermal conductivity along with traditional refrigeration.

Work under the Small Business Innovation Research Phase I field fridge research contract is expected to be completed in the fourth quarter of this year. Any Phase II contract would focus on building a working prototype.

The companies could patent any inventions that spring from the research, Anderson said.

“We’re not all space,� he said of Paragon. “One thing we’re excited about with this contract is that it shows we play across all fields.�