Monday, May 22, 2006

New Technology for Air Conditioning



Every few years I hear of a new technology that simply amazes me. One such technology is the refrigeration known as R718 or simple water vapor.

How does it work? Is it efficient? Why doesn’t everyone use it? I asked myself when I first heard of it.

It turns out R718 has been around for a long time. In Europe they have used it for years, primarily driven by their high energy prices. R718 can be more efficient than our current refrigerants (R134A for example), but it takes a special type of compressor to make it work. The compressors used in Europe have titanium turbines. The expensive titanium is used because they have to spin very fast to get the right pressures and in Europe where the energy costs are relatively high, it makes good economic sense. The titanium compressors are too expensive to use in the United States - it takes too long to recover the initial expense through energy savings. That is ’till now.

(Editor’s note: I am working on the development of a novel R718 air conditioner, I have submitted for some funding so what you read is not entirely impartial)

The Stratos Company LLC (of which I am president) is working with Prof. Norbert Muller of Michigan State University on the development of a novel R718 air conditioner that is very inexpensive. The key to success has been the development of a special turbine that is made in a very cleaver way such that you can substitute relatively cheap carbon fiber plastic for titanium! The text below is from a grant application.

Air conditioning systems consume roughly 11% of the energy used in US buildings, and are the main contributors to peak demand in summer months leading to brown-outs and black-outs of the electric grid. What's more, air conditioning loads are increasing. In 1997, 52% of homes with central air conditioning report using it "all summer long, an increase from 33% in 1981. In 2005 air conditioning accounted for 3.07 quads of energy use which resulted in 187,784 thousand metric tons of CO2, 1,069 thousand metric tons of SO2 and 3,600 kilograms of mercury pollution in the atmosphere.

Most HVAC units use HFC-134a or HCFC-123 as their refrigerant. HFC-134a can achieve relatively high energy efficiency and is almost 100% ozone-safe (ODP=0.000014), but HFC-134a is a relatively potent greenhouse gas which is directly linked to global warming (GWP=1320). HCFC-123 can achieve high energy efficiency and is not a potent greenhouse gas (GWP=76), but it does have an ozone-depleting potential (ODP=.012). Neither of these refrigerants is environmentally benign and both of them will be phased out after the year 2020 when provisions of the Montreal Protocol regarding HCFC usage is enacted.

To address this problem the Stratos Company LLC is developing a very innovative water based vapor compressor system that will yield major air conditioning energy improvements of 30%. Our novel system will achieve these improvements in efficiency by utilizing refrigerant R718, which is simply water vapor. Benefits derived from our energy efficient technology include reduced green house gas emissions by 22 billion metric tons per year, a reduction in mercury emissions of 128 Kg per year, reduced dependence on imported fuels, and a reduced load on the electric grid. (These numbers are based on average emissions per unit of energy use and do not take into account additional benefits of reducing peak demand.)

I will be updating this weblog on R718 from time to time.

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