8/8/2019 US DoE Unveils a New Efficient Air Conditioner
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US DoE unveils a new efficient air conditioner system
The US Department of Energys National Renewable Energy
Laboratory (NREL) has invented a new air conditioning process that
has the potential to use 50-90% less energy than todays
top-of-the-line units.
The idea is to revolutionise cooling, while removing millions of
metric tonnes of carbon from the air,NREL mechanical engineer Eric
Kozubal, co-inventor of the Desiccant- Enhanced eVaporative air
conditioner (DEVap) said. As cooling is one of the largest energy
consumers in the data center, a lot of
attention is focused on increasing energy efficiency.
Wed been working with membranes, evaporative coolers and
desiccants, explains Kozubal. We saw an opportunityto combine them
into a single device for a product with unique capabilities.
NREL has patented the DEVap concept, and Kozubal expects that
over the next couple of years he will be working onmaking the
device smaller and simpler, and perfecting the heat transfer to
make DEVap more cost effective. The DEVaprelies on the desiccants
capacity to create dry air using heat and evaporative coolers
capacity to take dry air and makecold air. By no means is the
concept novel, but no one has been able to come up with a practical
and cost-effectiveway to do it, Kozubal said.
The kind of desiccants that NREL uses are syrupy liquids highly
concentrated aqueous salt solutions of lithiumchloride or calcium
chloride. They have a high affinity for water vapour and so create
very dry air.
To solve the problem of complexity, the NREL device uses thin
membranes that simplify the process of integrating air flow,
desiccants and evaporative cooling. The membranes in the DEVap A/C
are hydrophobic, which means water tendsto bead up rather than soak
through the membranes.
That property allows the membranes to control the liquid flows
within the cooling core. Its that property that keeps the
water and the desiccant separated from the air stream, Kozubal
said.
We bring the water and liquid desiccant into DEVaps heat-mass
exchanger core. The desiccant and evaporativecooling effect work
together to create cold dry air.
ENVIRONMENTAL PROTECTION
Apart from using less energy, DEVap uses salt solutions rather
than refrigerants, so there are no harmfulchlorofluorocarbons
(CFCs) or hydrochlorofluorocarbons (HCFCs) to worry about. A pound
of CFC or HCFC inrefrigerantbased A/Cs contributes as much to
global warming as 2,000 pounds of carbon dioxide.
Traditional air conditioners use a lot of electricity to run the
refrigeration cycle, but DEVap replaces that cycle with
anabsorption cycle that is thermally activated. It can be powered
by natural gas or solar energy and uses very littleelectricity.
HPC APPLICATION
We asked Robert Tozer, an independent mission critical
facilities consultant, for his view on applying desiccanttechnology
to data centres.
Reduced capital cost will always increase feasibility, however,
we should be mindful that we need a heat source in theorder of 50C
(122F) to regenerate the desiccant, which could be an interesting
opportunity for HPC applications, Tozer said.
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