Summer’s finally here! Today will be another sunny, breezy and hot day. High temperatures will be in the upper 80s to near 90 degrees. Winds will be out of the southeast at 10-20 mph.
So, now after worrying about heating the house without breaking the bank for the last 5 months, we’re all hoping to stay as cool as possible, as cheaply as we can. And your government has found a way to help with that.
As you probably already know, Cooling comes in two forms. The first is sensible cooling, which is drop the ambient temperature, and latent cooling, which pulls the moisture out of the air.
One intriguing product already on the market in arid, temperate climates never increases the moisture content of the supply air. It provides cool air through indirect evaporative cooling.
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. That way, it can cool the air all the way to the wet-bulb temperature.
The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) in Golden CO has invented a new air conditioning process with the potential of using 50 percent to 90 percent less energy than today’s highly efficient units.
Using membranes, evaporative cooling, and desiccants in a way that has never been done before in the centuries-old science of removing heat from the air.
Here in the front range we’ve all seen evaporative coolers that are a lower-cost alternative to A/C in dry climates that don’t get too hot or humid like Boulder & Denver, but not Phoenix or Miami. Water flows over a mesh, and a fan blows air through the wet mesh to create humid, cool air.
In humid climes, adding water to the air creates a hot and sticky building environment. Furthermore, the air cannot absorb enough water to become cold.
In places like the deserts of Arizona, the evaporative cooler can bring down the temperature, but not enough to make it pleasant inside on a 100-degree day.
The cooling bumps up against the wet bulb temperature, the lowest temperature to which air can be cooled by evaporating without changing the pressure. Typically, evaporative coolers only can bring the temperatures about 85 percent of the way to the wet bulb level.
So, for most of the country, refrigeration-based air conditioning is the preferred way of keeping cool.
The air is cooled and dried from a hot-humid condition to a cold and dry condition all in one step. This all happens in a fraction of a second as air flows through the DEVap air conditioner. The result is an air conditioner that controls both thermal and humidity loads.
DEVap helps the environment in many ways. DEVap uses 50 percent to 90 percent less energy than top-of-the-line refrigeration-based air conditioning.
Because DEVap uses salt solutions rather than refrigerants, there are no harmful chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) to worry about.
A pound of CFC or HCFC in refrigerant-based A/Cs contributes as much to global warming as 2,000 pounds of carbon dioxide. A typical residential size A/C has as much as 13 pounds of these refrigerants.
The release of this much refrigerant is equivalent to burning more than 1,300 gallons of gasoline, or driving over 60,000 miles in a 2010 Toyota Prius.
The traditional, refrigerating 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.
This means that DEVap could become the most energy efficient way to cool your house whether you live in Phoenix, New York, or Houston.
NREL has already patented the DEVap concept, and 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.