RD Fresh - Refrigeration Dehumidifier


RD Fresh Validation

The effectiveness of natural refrigeration dehumidifiers has been verified by independent testing:


  • As noted by the U.S. Department of Energy "Desiccants can work in concert with chillers… by allowing chillers To cool low-moisture… In some applications, desiccants can cut cooling loads and peak demand by as much as 50 percent"

  • As noted by the British Zeolite Association "nearly every application of zeolites has been driven by environmental concerns, or plays a significant role in reducing waste and energy consumption."

  • As noted by the Food Engineering Directorate, U.S. Army Research, Development and Engineering Center "It is clear from these studies that ethylene absorber filters … should be used in all fruit and vegetable storage areas in order to ensure maximum shelf life at an affordable cost."


The U.S. Army study excerpted below shows the effectiveness for other fruits and vegetables as well as the economic benefits, using a mineral mix very similar to RD FRESH.



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U.S. Army Research, Development and Engineering Command


John A. Ayoub, Dr. Margaret G. Driver, Dr. Irwin A. Taub

Nature of the Problem:

Ethylene is a natural plant hormone produced by metabolism in most fruit. It initiates and accelerates the ripening of fruit and causes vegetables to deteriorate. This unavoidable process is a major problem, since in almost all applications noncompatible fruits and vegetables (i.e., ethylene emitters and ethylene sensitive items) are stored and/or shipped in the same container. If we could keep the level of ethylene as low as possible, we would be able to slow the maturation of the fruits, protect the vegetables, and reduce spoilage to a minimum. Technical Strategy: One of the simplest ways to remove ethylene from the atmosphere is to absorb it.

Field Test II(Korea by Surface Vessel)

This test was the most controlled of all the field tests to date. In cooperation with DSR-PAC in Alameda, CA, we set up a three-week shipping test to South Korea. Large lots of FF&V were split and placed into two identical 40 ft. sea vans, one with and one without absorber filters placed near the air inlet to the cooling system operation at 36°F. The produce was inspected by a Quality Assurance Specialist from DSR-PAC and a Natick Project Officer before loading in Alameda and after unloading from the container ship in Pusan, South Korea. The atmosphere in each van was also sampled for the concentration of ethylene. Upon arrival in Pusan, the atmosphere in the test van with the absorber filters had an ethylene concentration of 1.8ppm, while the atmosphere in the control van had 29ppm (more than 16x the concentration). The fruits and vegetables in the absorber-protected van were in excellent condition. In the control van, many of the green leaf vegetables were completely spoiled and most of the fruits were ripe enough for immediate use.

Product Test VAN Control VAN
Kiwi fruit
Fresh, crisp, good green color  
Fresh, crisp, 3% decay-tops
Fresh, green, <1% rot
Some decay at tips
Mostly Firm
Mostly Hard
Mostly firm, 1% decay
Yellowish green, 11% decay
100% rot surveyed
Fresh, green, 14% rot, mold
100% decay surveyed
Firm to ripe, many ripe
Mostly hard to firm, 13% decay
Mostly ripe, 2% decay

Comparative Economic Aspects:

In order to know the overall economic benefits of using ethylene absorbers, you have to determine the savings due to reduced spoilage and compare it to the cost of absorbers required. Using the example of the shipment to South Korea, the estimated savings due to a reduction in spoilage at destination was $928 while the cost of the absorbers was $160, thus a net benefit of $768 (A 480% Return On Investment)

U.S. Department of Energy



Thermally Activated Technology: Desiccant Dehumidifiers

The desiccant process involves exposing the desiccant to a high relative humidity air stream- allowing it to attract and retain some of the water vapor-In some applications, desiccants can cut cooling loads and peak demand by as much as 50 percent, with significant cost savings.

Market Potential
Desiccants can stretch the capacity of existing chillers by increasing system efficiency, potentially eliminating the need to replace a functioning chiller with a larger unit.

Environmental Benefits
Reduce condensation on equipment and humidity levels, eliminating growth of mold, mildew, and bacteria.

BZA Logo

"Zeolites contribute to a cleaner, safer environment in a great number of ways. In fact nearly every application of zeolites has been driven by environmental concerns, or plays a significant role in reducing waste and energy consumption."

"Zeolite exhibits a large adsorption capacity with respect to substances of relatively small molecular weight such as ethylene gas. Activated carbon is excellent in its adsorption capacity of substances having relatively large molecular weight. Montmorillonite is capable of adsorbing water and carbon dioxide gas besides gases such as ethylene generated from vegetables and fruits in their ripening process."

Industry is just now moving forward...
"Some manufacturers offer models that use enhanced carbon filters. Some use a carbon-zeolite mix. This provides protection where greater adsorption is required for ethylene, ammonia and volatile organic compounds."

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