A History Of Modular Chillers
Like a lot of advancements in engineering, the modular chiller
is an outcome of our desire to control the environment around us.
As one of the top ten engineering achievements of the 20th century,
the air conditioner is a consequence of our search for a way to
keep things cool independently of the surrounding environment. Beyond
mere convenience, air conditioning not only protects food and medicines
from bacterial decay, it protects electronics, and plays an important
role in the delivery of health care. Air conditioning has its roots
in the principles of mechanical refrigeration which can be traced
to our efforts to cool things like food. In ancient times we collected
snow and ice and stored it in caves and cellars to refrigerate food.
In the 18th century we collected ice in the winter, packed it in
salt wrapped it in strips of cloth and put it into icehouses or
cellars to keep it frozen until the summer. In America we stored
blocks of ice in wooden "ice boxes" lined with tin or zinc and insulated
with various materials including cork and sawdust.
Mechanical Refrigeration
It wasn't until the industrial revolution of the 17th and 18th
centuries that our search for a method of refrigeration starts to
coalesce around several poplular theories. Mechanical refrigeration
is the culmination of several competing methods: vapor evaporation
or, absorbtion, compression and cold-air systems like the first
ice machine built and patented in 1851 by the American Dr. John
Goorie.
Five Basic Refrigeration Techniques:
- Ice box (or dry ice box)
- Cold air systems
- Vapor-compression: the current standard method of refrigeration
- Vapor-absorption: the Electrolux refrigerator with no moving
parts
- Thermoelectric
If we start with the thermometer by Galileo in 1597, the development
of the temperature scale in 1709 by Gabriel Fahrenheit, and the
separation of gases in 1773 by Joseph Priestly, we can see the early
stages of mechanical refrigeration. Once natural philosophers noticed
things like the ability of ether to freeze water when it evaporates
and that you could absorb heat by applying pressure to certain gases,
the basis for the refrigeration research was set in stone.
Pioneers in refrigeration included people like Dr. William Cullen
(1748), who developed the method of evaporative cooling where heat
is aborbed by the process of water or vapor evaporation. Other inventors
like Oliver Evans (1805) designed the first closed circuit refrigeration
machine, while Jacob Perkins (1834) and the famous chemist Michael
Farady (1824) discovered that you could absorb heat by pressurizing
a gas like ammonia into a liquid. German engineer Carl von Linden
patented the process of liquifying gas in 1876 setting the stage
for the modern refrigerator, freezer, air conditioner and dehumidifier.
Very little ice was actually produced until the early 1890s. The
first mechanical refrigerator appeared around 1910. J.M. Larsen
produced a manually operated machine in 1913. By 1918 Kelvinator
introduced the first automatic refrigerator for the American market.
They sold 67 models that year. Frozen food was here to stay in 1923
marking the beginning of the frozen food industry.
Mechanical refrigeration uses the method of evaporative cooling.
We are all familiar with the cool feeling we get when we put water
on our skin. As the water evaporates, it absorbs heat, creating
a feeling of coolness. Other fluids like rubbing alcohol can absorb
more heat because it evaporates at a lower temperature. In a classic
refrigeration system, when a liquid or refrigerant like ammonia
or freon is compressed into a gas, heat is released which is condensed
into a liquid by a condenser. This liquid enters the refrigerator
and passes into an evaporator, where it's allowed to expand into
a gas and it absorbs heat from its surroundings. The gas then returns
outside the refrigerator to repeat this cycle over and over again.
There are four basic parts of the mechanical refrigeration system:
Compressor - compresses the refrigerant vapor.
Condensor - releases heat from the refrigerant.
Expansion Valve - releases vapor refrigerant when needed.
Evaporator - cold liquid from the expansion valve absorbs
heat.
Very little has changed in the refrigeration industry since vapor
evaporation and gas compression systems became the norm. Most of
the work in the 20th century has concentrated on refining the closed
cycle of evaporation, compression and condensation, i.e, finding
the most efficient refrigerant, developing better compressors, and
working out the most efficient arrangement of components and pressures
for the desired operating temperatures.
For more information about refrigeration:
History
of Sealed Refrigeration Systems
How
Refrigerators Work
Refrigerators
- The Physics Handbook
The
History of the Refrigerator
The
Impact of Refrigeration
Air Conditioning
1902 - Willis Haviland Carrier (the father of air conditioning)
figures out the relationship between temperature, humidity and dew
point while contemplating the fog on a train platform in Pittsburgh.
1906 - Stuart Cramer is the first to use the phrase "Air
Conditioning". Carrier patents his first device "An Apparatus
for Treating Air' (U.S. Pat# 808897).
1911 - air conditioning becomes a recognized branch of
engineering. Carrier presents his basic Rational Psychrometric Formulae
to the American
Society of Mechanical Engineers. Industries flourish with the
new ability to control the temperature and humidity levels during
and after production. Film, tobacco, processed meats, medical capsules,
textiles and other products acquired significant improvements in
quality with air conditioning.
1915 - Carrier and six other engineers form the Carrier
Engineering Corporation with a starting capital of $35,000 (Sales
in 1995 exceed $5 billion).
1920 - air conditioning is achieved by using larger sizes
of extended surface fin and tube heating elements or coils with
cold well water to cool theatres and department stores.
1921 - Carrier patents the centrifugal refrigeration machine.
The centrifugal chiller was the first practical method of
air conditioning large spaces. Previous refrigeration machines used
reciprocating-compressors (piston-driven) to pump refrigerant. Carrier's
solution was a centrifugal-compressor similar to the centrifugal
turning-blades of a water pump. The result is a safer and more efficient
chiller.
1922 - movies are watched for the first time in an air
conditioned movie theatre.
1930 - General Electric manufactures and sells 30 self-contained
room air conditioners.
1931 - Freon-12 is registered as a refrigerant
1938 - the centrifugal compressor is introduced
by Trane. This
was the forerunner of the modern water chiller which combined a
centrifugal compressor, condenser, and evaporator into a single
unit.
1945 - Refrigerant R-13 is registered.
1950 - sales of room air conditioners surpass 100,000 and
never looks back. Refrigerant R-500 is introduced and the father
of air conditioning Willis Carrier dies.
For more information about air conditioning:
History
of Air Conditioning
Greatest
Achievements - 10. Air Conditioning and Refrigeration
Air
Conditioning and Refrigeration Institute - Air Conditioning
North American Technician
Excellence
ARTI 21CR: HVAC/R
Research for the 21st Century
How
an Air Conditioner Works
Refrigeration Service
Engineers Society
Chilling
Like the household refrigerator, the chiller is based on a method
of compression. When a refrigerant is compressed, its state will
change to either liquid or vapor. This change in state causes the
refrigerant to absorb or discharge heat. This gives the chiller
system two pressure points: the evaporation (low pressure) and condensing
(high pressure) point. Chillers are categorized according to size
(portable, central) and by condenser (air or water). At the center
of any chiller is the compressor which is either a reciprocating,
scroll or screw compressor.
1950 - the first industrial chiller is designed for use
in the plastics industry.
1957 - the first rotary compressor is manufactured replacing
the less efficient reciprocating compressor allowing for the construction
of small, lighter and quieter chillers.
1959 - the American Society of Air Conditioning Engineers
merges with the American Society of Refrigeration Engineers to form
ASRHAE.
1963 - York installs a central chilling system in the Library
of Congress which supplies chilled water totaling 17,000 tons of
refrigeration.
For more information about chillers:
American Society
of Heating, Refrigeration and Air Conditioning Engineers
Modular Chilling
The modular chiller solves several overwhelming concerns in modern
day air conditioning. Research has shown that most existing chiller
installations are far from energy efficient. Most are at least 30%
oversized or more which results in higher than necessary power and
energy consumption per ton of cooling delivered, increased maintenance
cost and, ultimately, a shortened chiller operating life. The problem
is that most of these existing installations are in hard-to-reach
areas making maintenance and repair difficult in older deteriorating
buildings where footprint space is at a premium.
These problems called for an energy efficient system of air conditioning,
that could be installed in hard-to-reach places, was reliable, easy
to repair, required a small footprint, and made future expansion
easy.
The concept of modular cooling was instigated by the concept of
modular heating with modular boilers supplying hot water heating
to hi-rise residential buildings where the upper and lowest floors
had the maximum heat loss.
1992 - a new filtration system is designed in response to
the problem of fouling caused by the use of CBEs (Compact Brazed
Heat Exchangers).
2000 - while existing modular chillers are "modular"
in the sense that they can be delivered in sections and assembled
on site, they guarantee uninterrupted operation by installing additional
modules that will back up the system in case one of its individual
modules fails or breaks down. This solution is expensive and wasteful
compared to a modular chilling system where it is possible to "pull"
a component from the system (in order to fix it) and "plug"
it back into the system without shutting down the system.
2004 - Tandem Chillers designs the first true modular chiller
where it is possible to remove an individual component to fix it
and "plug" it back in without shutting down the balance
of the system - in a matter of a few hours.
Contact us today:
Tel: 1.877.513.8330
Email: sales@tandemchillers.com
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