The Montreal Protocol, crafted in 1987 and signed by 191
countries as of 2007, put the hot iron to the cooling industry. It has seen
several revisions since 1987 and some of its strictures affect industry as a
whole while others involve mainly cooling and refrigeration.
The ultimate goal of the protocol is to reduce the amount of
several ozone-depleting chemicals used by industrialized nations to zero. Most
CFCs (chlorofluorocarbons) were to be phased out of use by 1996; other less
dangerous CFCs and chemicals are to be phased out by 2010; HCFCs
(hydrochlorofluorocarbons) are on a longer leash, and have cease and desist
date of 2030, 2020 in developed nations.
Unfortunately for the air-conditioning and refrigeration industries, this means
an industry-wide change in practice, as HCFCs are commonly used as refrigerants
in modern cooling machines. There are several technologies that cool without
the use of these refrigerants, but until recently, they have been utilized
mostly only in large-scale applications. Absorption chillers are used in many
industries, from commercial to machinery cooling.
Absorption chilling differs from standard mechanical air conditioning in that
it doesn't use an active force, such as a compressor, to condense the coolant
chemical, but rather uses heat to drive a circulatory system. Many absorption
chillers are utilized in areas where ample amounts of waste heat are available
(turbine power or water heating systems are common sources). This allows them
to make use of waste heat for a secondary purpose, thereby making the entire
system more efficient and cost-effective.
This nearly century-old technology has not been widely used in consumer arenas
like home cooling as the heat needed to power the system would cost more than
the typical compressor-driven air-conditioning unit and there are not usually
readily available sources of waste heat powerful enough to harness. Professor
Marcelo Izquierdo of the Universidad Carlos III of Madrid and his group of
researchers are aiming to put
this technology into homes, however, with a little help from a very large
furnace – the sun.
Izquierdo's team built an absorption chiller unit that closely resembles a
typical exterior air-conditioning unit, and it works by capturing solar energy
and residual heat to provide the impetus for the system's circulation. The
device uses a refined lithium bromide-based coolant process – most absorption
chillers use either an ammonia, hydrogen and water or a lithium bromide
solution and water system – and is capable of cooling water to a temperature of
7C to 18C with an ambient temperature of 33 to 43C. The machine can produce
enough chilled water to cool a 120 cubic meter area via a water-to-air heat
exchanger.
Neither the lithium-bromide solution nor the more common ammonia and hydrogen
systems are ozone depleting. This makes them a viable alternative to the HCFC
refrigerants used in modern compression systems. In the very near future,
consumer-grade absorption chiller units could become common in many regions
that experience high temperatures during one or many seasons. Using the Big
Heater in the Sky itself to power the cooling units is an ironic twist and one
definitely worthy of more research.