Tag Archives: DEVap

NREL’s “DEVap” The Future of Cooling!

Picture Courtesy Larry Page

The Dog Days of Summer are on us already and the heat is climbing everyday. It is a tough choice between deciding whether to switch the Air Conditioner on or keep the windows open which would be the green thing to do. When the heat gets unbearable it is difficult to not reach for the thermostat and switch on the Air Conditioner.

Air Conditioners also mean heftier power bills it climbs up in to the 100$ plus range and one is left wondering what to do to keep oneself cool without spending so much energy and money. MIT’s Technology review states it well “When it comes to home comforts, few inventions can beat the air conditioner for its ability to help us tolerate the dog days of summer. The problem is, when it comes to energy-guzzlers, few inventions can beat the air conditioner”.

A soothing solution is on the way! for both our wallets and our homes.The NREL has built on the basic concept of the swamp cooler to make it effective and efficient to solve our cooling issues.

The U.S. Department of Energy’s National Renewable Energy Laboratory has invented a new air conditioning process with the potential of using 50 percent to 90 percent less energy than today’s top-of-the-line units. It uses membranes, evaporative cooling and liquid desiccants in a way that has never been done before in the centuries-old science of removing heat from the air.

What are Evaporative Coolers?

Evaporative coolers or Swamp coolers have been used for many many years all over the world to cool rooms during the dog days of summer. They basically use evaporating water to cool the air around. They are referred to as Swamp coolers in the US probably due to the swamp like smell the algae assocaited with earlier products. Swamp coolers are perfect for areas with high heat and low humidity. In dry, arid climates, the installation and operating cost of a swamp cooler can be much lower than standard conditioning, often by 80% or so. However, swamp cooling and vapor-compression air conditioning are sometimes used in combination to produce optimal cooling results.

Swamp coolers are being used world over in tropical countries as a cheaper alternative to Air-conditioning and are typically referred to as desert coolers. The filters which the hot air passes through is made of hay/other fibrous substances which soak in water and let air pass through. the filters are cleaned in regular intervals to keep it algae free.

Like mentioned earlier the thing to watch out for is humidity which works against the cooler as adding more water to the already humid air just makes it more sticky and not cool.

The Coolerado cooler is a unique cooler which uses indirect evaporative systems use a purge air stream that removes heat from the product or supply air stream that is then directed into a building. This still does not help in humid conditions.

NREL’s DEVap The Future of Cooling!

The DEVap solves that problem. It relies on the desiccants’ capacity to create dry air using heat and evaporative coolers’ capacity to take dry air and make cold air.

“By no means is the concept novel, the idea of combining the two, But no one has been able to come up with a practical and cost-effective way to do it. The idea is to revolutionize cooling, while removing millions of metric tons of carbon from the air,” NREL mechanical engineer Eric Kozubal, co-inventor of the Desiccant-Enhanced eVaporative air conditioner (DEVap), said.

Most people know of Desiccants as the small sachets which come with shoes etc to keep them dry. NREL uses syrupy liquid desiccants – highly concentrated aqueous salt solutions of lithium chloride or calcium chloride. They have a high affinity for water vapor, and can thus create very dry air. Desiccant based cooling systems in use were very complex and hence used only for industrial purposes.

NREL uses thin membranes that simplify the process of integrating air flow, desiccants, and evaporative cooling. This results in an air conditioning system that provides superior comfort and humidity control.

The membranes in the DEVap A/C are hydrophobic i.e. means water tends to bead up rather than soak through the membranes. Imagine rain falling on a freshly waxed car. That property allows the membranes to control the liquid flows within the cooling core. “It’s that property that keeps the water and the desiccant separated from the air stream,” Kozubal said.

Picture Source NREL

NREL senior engineer Eric Kozubal examines a prototype air flow channel of the DEVap air conditioner, which he co-invented. The graph superimposed on the photo shows shows how hot humid air, in red, changes to cool dry air, in blue, as the air passes through the DEVap core.

The Devap A/C’s desiccant and evaporative cooling effect work together to create cold-dry air.

What makes it Green and Wallet friendly?

  • DEVap uses 50 percent to 90 percent less energy than top-of-the-line refrigeration-based air conditioning.
  • DEVap uses salt solutions rather than refrigerants, there are no harmful chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) to worry about.
  • A standard A/C uses around 13pounds of refrigerant which is equivalent to burning more than 1,300 gallons of gasoline, or driving over 60,000 miles in a 2010 Toyota Prius.
  • Traditional air conditioners use a lot of electricity to run the refrigeration cycle, but DEVap replaces that refrigeration cycle with an absorption cycle that is thermally activated. It can be powered by natural gas or solar energy and uses very little electricity.

When one sees what it can do it means that DEVap could become the most energy efficient way to cool your house irrespective of where you live; Phoenix, New York, or Houston.

NREL has patented the DEVap concept, and Kozubal expects that over the next couple of years he will be working on making the device smaller and simpler and perfecting the heat transfer to make DEVap more cost effective.

Eventually, NREL will license the technology to industry, “We’re never going to be in the air conditioner manufacturing business”, said Ron Judkoff, Principle Program Manager for Building Energy Research at NREL. “But we’d like to work with manufacturers to bring DEVap to market and create a more efficient and environmentally benign air conditioning product.”

Hoping the day comes soon when the DEVap is available as a Green and wallet friendly cooling solution on the market. Live Green!

Sources :

NREL article by Bill Scanlon and the picture.

MIT’s Technology Review where I read it first

The Wikipedia for info on Swamp coolers