DewRight: Invention could reduce producers’ storage losses

'DewRight' significantly improves measurement of relative humidity

The DewRight, center, surrounded by earlier prototypes. Behind the devices are (l to r) Ralph Shepard, director of business development at Vermont Energy Control Systems, which has licensed and is commercially developing the product, UVM Extension assistant professor Chris Callahan, who invented the device, and Bill Kuhns, director of product development at VECS. (Photo: Brian Jenkins)

BURLINGTON, Vt. — A University of Vermont Extension professor has invented a $300 device that could save produce growers an average of $6,500 annually in improved storage conditions. The device could also save artisanal cheese and meat producers up to $10,000 a year in higher yields during processing.

The invention, called a DewRight, modernizes 250-year-old technology to more accurately measure temperature and relative humidity.

The savings come from reduced spoilage and increased yield, increased quality, improved recipe repeatability and labor savings, said its inventor, Chris Callahan, an assistant professor of agricultural engineering at UVM Extension.

In the high humidity environment of a storage room, off-the-shelf equipment that is now used can be off by as much as plus-or-minus 6 percent relative humidity, Callahan said. The new device reduces that to plus-or-minus 2 percent relative humidity, a 67 percent improvement.

Unlike off-the-shelf versions, it also functions accurately at lower temperatures that food storage and processing facilities often require and does not fail in the continuous high humidity environment, as conventional versions do over time.

Measuring relative humidity

The device makes use of “wet bulb” psychrometry, developed in the late 18th century, where an ordinary thermometer and one that is enclosed by a wet wick are spun in the air by the user.

The difference in temperature between the two — the wet one will show a lower temperature as the evaporating water cools it — indicates the amount of moisture in the air, its relative humidity.

Callahan’s innovation was to make an electronic version of the mechanical device with improved accuracy in temperature measurement. The DewRight also automates the measurements, removing human error.

Idea from farm research

An earlier, on-farm research project of Callahan’s — a experimental system that allowed farmers to remotely monitor temperature and relative humidity in storage facilities — led Callahan to the need to better measure relative humidity.

“The monitoring and communication electronics in that application did what they were supposed to do, but we were using off-the-shelf sensors to measure relative humidity. They weren’t accurate and eventually failed completely in the high humidity, low temperature conditions,” he said.

The new technology could also have application for other fields where measuring relative humidity accurately is important, in art museums and conservation spaces for examples, or in semiconductor manufacturing.

For now, though, Callahan said he plans to focus on growers and artisanal food producers.

“This is a market we know, and the space we know that has an immediate need,” he said.

A growing market

Callahan is optimistic that the product will find success. His analysis also shows both strong and sustained growth of cold storage space for produce in the region and nation (by at least 25 percent per year for both) and increasing production of artisanal products — both of which require careful control of temperature and humidity.

“There is pent-up demand for a device like this,” he said.

The new technology has been licensed and is being commercially developed, with assistance from UVM Ventures and the Vermont Agency of Commerce and Community Development, by Vermont Energy Control Systems of North Ferrisburgh, Vermont, which has added monitoring, data logging, and control technology to Callahan’s device that will automate operation and allow remote access .

“Right now, there is no cost-effective solution for small farms and artisanal cheese producers who need to accurately measure temperature and humidity in their storage and production facilities,” said Bill Kuhns, director of product development at Vermont Energy Control Systems.

“It’s a natural fit with our existing data logging and control products. There’s an international need for this capability, especially for the smaller operations that the farm-to-table movement is supporting.”


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