I was out tonight visiting with my friends Lucky and Saskia. Lucky is a passionate flamenco enthusiast and theoretical physicist. We were enjoying an evening of live music and talking about advances....

Precursers to the Industrial Revolution.

Tin and Napoleons Buttons, Grey tin and white tin.

Stirling invented the Stirling Engine. And Stirling cycle.

He wanted to control the air in the room where his patients were. He made an enclosed room with an intake pipe > He created a machine that acted. Refrigeration unit that is an air conditioner. His patients did do better. Not because  but befcause he put mosquito nets around their beds.

This machine . The waste product or side product was ice. Which was a valuable commodity to he used it to make ice. Around of the times of the gold rush. 1890. Malaria. Wanted to lower the temperature of

Carl Von Linde of Germany invented the Fridge obtaining a
patent in 1876 for it from the German Imperial Patent Office

Carl von Linde, German
engineer whose invention of a continuous process of liquefying gases in large
quantities formed a basis for the modern technology of refrigeration. Refrigeration is chiefly used to store foodstuffs at low
temperatures, thus inhibiting the destructive action of bacteria, yeast, and
mold.

Before mechanical refrigeration systems were introduced, people
cooled their food with ice and snow, either found locally or brought down from
the mountains. The first cellars were holes dug into the ground and lined with
wood or straw and packed with snow and ice: this was the only means of
refrigeration for most of history.

Refrigeration
is the process of removing heat from an enclosed space, or from a substance, to
lower its temperature. A refrigerator uses the evaporation of a liquid to
absorb heat. The liquid, or refrigerant, used in a refrigerator evaporates at
an extremely low temperature, creating freezing temperatures inside the
refrigerator. It's all based on the following physics: - a liquid is rapidly
vaporized (through compression) - the quickly expanding vapor requires kinetic
energy and draws the energy needed from the immediate area - which loses energy
and becomes cooler. Cooling caused by the rapid expansion of gases is the
primary means of refrigeration today.

Refrigerators

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© 1998-2008 by Glenn Elert -- A Work in Progress

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Discussion

introduction

A refrigerator is any kind of
enclosure (like a box, cabinet, or room) whose interior temperature is kept
substantially lower than the surrounding environment.

The term
"refrigerator" was coined by a Maryland engineer, Thomas Moore, in
1800. Moore's device would now be called an "ice box" -- a cedar tub,
insulated with rabbit fur, filled with ice, surrounding a sheet metal
container. Moore designed it as as a means for transporting butter from rural
Maryland to Washington, DC. Its operating principle was the latent heat of
fusion associated with melting ice.

The term
"air conditioning" was coined by Stuart Cramer in 1905 to describe
his system for regulating the temperature and humidity inside a textile factory
in the South (the humidity regulation was seen as more important than the
temperature regulation). Willis Carrier also designed climate control systems
for industry.

One of the
first uses of air conditioning for personal comfort was in 1902 when the New
York Stock Exchange's new building was equipped with a central cooling as well
as heating system. Alfred Wolff, an engineer from Hoboken, New Jersey who is
considered the forerunner in the quest to cool a working environment, helped
design the new system, transferring this budding technology from textile mills
to commercial buildings.

In 1906,
Stuart Cramer first used the term "air conditioning" as he explored
ways to add moisture to the air in his southern textile mill. He combined
moisture with ventilation to actually "condition" and change the air
in the factories, controlling the humidity so necessary in textile plants.

An early
pioneer who did much to promote "controlled air" was Willis Carrier,
a mechanical engineer who worked at the Buffalo Forge Company in Buffalo, New
York. Subsequent subsidiary companies carrying his name helped conquer the
temperature-humidity relationship, marrying theory with practicality. Starting
in 1902, he designed a spray-type temperature and humidity controlled system.
His induction system for multi-room office buildings, hotels, apartments and
hospitals was just another of his air-related inventions. Many industry
professionals and historians consider him the "father of air
conditioning."

There are
several basic refrigeration techniques:

1.    
ice box (or dry ice box)

2.    
cold air systems

3.    
vapor-compression: the current standard method of refrigeration
used in home refrigerators, home air conditioners and heat pumps (Kelvin's
idea, refrigerate the environment in the winter, store "cold" in the
ground for use in the summer)

4.    
vapor-absorption: the Electrolux refrigerator with no moving parts

5.    
thermoelectric

cold air refrigeration

Physician Dr.
John Gorrie, Apalachicola, Florida, 1849. Rapidly expanding gases are cooled.
Intended to cool hospital wards. Hot air was considered "bad", was
thought to be the origin of tropical diseases, thus the name
"malaria". Died before commercial models could be made. Design
improved by William Siemans of Germany. Dr. Gorrie may have also invented the
ice cube tray in its current form.

By widening
the vessel … from the bottom upward the removal of the block of ice
is … rendered more easy ….

To further
facilitate the removal of the ice from the vessels [they are] made a little
smaller at the bottom than at the top ….

schematic
diagram

indicator
diagram

vapor compression refrigeration

In 1834 an
American inventor named Jacob Perkins obtained the first patent for a
vapor-compression refrigeration system, it used ether in a vapor compression
cycle.

• Joule-Thomson
  (Kelvin) expansion
• Low
  pressure (1.5 atm) low temperature (-10 to +15 °C) inside
• High
  pressure (7.5 atm) high temperature (+15 to +40 °C) outside

[magnify]

Follow along
with this discussion using vapor-compression.pdf.

Note: liquids
are not ideal gases, liquids are nearly incompressible.

1.    
compressor

cold vapor from the evaporator is compressed, raising it temperature and
boiling point

adiabatic compression

T, b.p. ~ P

work done on the gas

2.    
condenser

hot vapor from the compressor condenses outside the cold box, releasing latent
heat

isothermal, isobaric condensation (horizontal line on PV diagram)

high temperature

T (hot)

latent heat of vaporization Q (hot)

3.    
expansion valve (throttling
valve)

hot liquid from the condenser is depressurized, lowering its temperature and
boiling point

adiabatic, isochoric expansion (vertical line on PV diagram)

T, b.p. ~ P

no work done W = 0

4.    
evaporator

cold liquid from the expansion valve boils inside the cold box, absorbing
latent heat

isothermal, isobaric boiling (horizontal line on PV diagram)

low temperature

T (cold)

latent heat of vaporization Q (cold)

indicator
diagram

vapor absorption refrigeration

Oliver Evans,
USA, 1805, proposed but not built, evaporated sulfuric acid absorbed by water.

The first
absorption machine was developed by Edmond Carré in 1850, using water and
sulphuric acid. His brother, Ferdinand Carré developed the first ammonia/water
refrigeration machine in 1859. Ferdinand Carré, France, ammonia absorption
refrigerator, 1859. Established commercial success in the Confederate States
during the US Civil War, since Union ice was not being transported to the
South.

vapor
absorption refrigerators can be powered by any heat source: natural gas,
propane, kerosene, butane?

schematic
diagram -- vapor-absorption-fridge.pdf

1.    
generator

ammonia-water solution heated to generate bubbles of ammonia gas

2.    
separator

ammonia gas bubbles out of solution

3.    
condenser

ammonia gas condenses

4.    
evaporator

ammonia liquid evaporates

5.    
absorber

ammonia gas absorbed by water

indicator
diagram

performance

not
efficiency, but coefficient of performance

Carnot diagrams for refrigerators of increasing performance. [magnify]

refrigerants

These notes
are a disaster.

The first
true refrigerator (as opposed to an icebox) was built by Jacob Perkins in 1834.
It used ether in a vapor compression cycle. The first vapor absorption
refrigerator was developed by Edmond Carré in 1850, using water and sulfuric
acid. His brother, Ferdinand Carré, demonstrated an ammonia/water refrigeration
machine in 1859. Since 1834 more than 50 chemical substances have been used as
refrigerants including …

• amines
  
• methyl
  amine
• ethyl
  amine

• chlorides
  
• ethyl
  chloride
• methyl
  chloride / methylene chloride

• ethers
  
• nitrous
  ether
• sulfuric
  ether / sulfuric (ethyl) ether

• halocarbons

The current standard refrigerants since the 1940s. See comments below.

• chlorofluorocarbons
  (CFCs)
• hydrochlorofluorocarbons
  (HCFCs)

• hydrocarbons

In Europe, and particularly in Germany, simple hydrocarbon compounds are
used in small quantities for domestic refrigerators. Due to their
flammability and explosive potential, they are not suitable for
applications requiring larger cooling capacities.

• propane
  
• butane
  / isobutane

• sulfur
  compounds
• sulfur
  dioxide

  Sulfur dioxide is a heavy, colorless, poisonous gas with a pungent,
  irritating odor familiar as the smell of a just-struck match.

• sulfuric
  acid

• miscellaneous
  
• ammonia

  Prior to the 1930s and 1940s, ammonia was the primary working fluid for
  vapor compression refrigeration. Largely abandoned for home use due to
  its toxicity, but still in widespread use in industrial applications.
  Also used in vapor-absorption refrigerators.

• carbon
  dioxide

Used under higher pressure than the other fluids.

The first
mechanical refrigerators had to be connected to the sewer system to dispose of
the refrigerant on a regular basis. In the 1930s and 1940s the halocarbon
refrigerants (commonly known by such trade names as "Freon,"
"Genetron," "Isotron," etc.) were developed, giving the
industry a strong push into the household market because of their suitability
for use with small horsepower motors.

The most
important members of the group have been

• trichloromonofluoromethane
  (R-11)
• dichlorodifluoromethane
  (R-12)
• chlorodifluoromethane
  (R-22)
• dichlorotetrafluoroethane
  (R-114)
• trichlorotrifluoroethane
  (R-113)

pause

• appropriately
  volatile
• low
  boiling points
• low
  surface tension
• low
  viscosity
• non
  reactive (stable)
• non
  toxic (vapor may be irritating, however)
• non
  corrosive
• non
  carcinogenic
• non
  flammable

Stable? Yes.
Too stable! Stays around and accumulates in the atmosphere. Shifts the
equilibrium between O₂ and O₃ in the stratosphere.
global warming. Production of chlorofluorocarbons (CFCs) ended in 1995 in
developed countries.

Production of
R-12 was halted by the Clean Air Act on January 1, 1996. Today the remaining
supplies are product which has been recovered and reclaimed back to a
Chemically Pure State in accordance to ARI - 700 Standard. The ARI Standard is
basically a virgin specification. Persons arguing that the supply of virgin
product is still available is probably unrealistic, since most of the reserves
were depleted in the 1st year. DoD Public Law prohibits the purchase of R-12
except for existing systems, when retrofit has been determined by technical
staff to be prohibitive. Senior or Executive approval of this product to be
purchased is required.

Summary

• A
  refrigerator is any kind
  of enclosure (like a box, cabinet, or room) whose interior temperature is
  kept substantially lower than the surrounding environment.
• Types
  of Refrigerators
• non-mechanical
  
• for
  example: ice box, root cellar, wine cellar
• are
  not often considered true refrigerators

• mechanical
  
• vapor
  compression
• vapor
  absorption
• multievaporator,
  cascade
• gas
  cycle, air cycle
• pulse
  tube
• thermoacoustic
  

• electronic
  
• thermoelectric
  
• magnetic,
  magneto-calorific

• An
  air conditioner is a mechanical system in a room, building, or vehicle for
  controlling …
• temperature
  (by providing cool air),
• humidity
  (by providing dry air),
• and
  ventilation (by providing fresh air).

• A
  heat
  pump
  is a device for moving heat mechanically.
• A
  heat pump can move heat against the temperature gradient (from cold to
  hot).
• Refrigerators
  and air conditioners are examples of heat pumps.
• In
  common usage, the tem heat pump often refers to air conditioners that can
  be run …
• "forward"
  to cool a building in summer by extracting heat from the building and
  depositing it in the environment (refrigerating the building and heating
  the environment) or
• "backward"
  to warm a building in winter by extracting heat from the environment and
  depositing it in the building (refrigerating the environment and heating
  the building).

• Energy
  is conserved in the operation of a heat pump.
• The
  heat extracted from the cold reservoir (Q_c) plus the work
  done by the system (W) is equal to the heat deposted in the hot
  reservoir (Q_h).

• The
  coefficient
  of performance
  (COP) is the ratio of the useful energy output of a system to the
  mechanical work required to operate it.
• The
  COP is a measure of the effectiveness of a mechanical device or system at
  performing some task.
• The
  COP of a heat pump used as …
• an
  air conditioner or refrigerator is the ratio of the heat extracted
  to the mechanical work required to operate it.
• a
  heater is the ratio of the heat deposited in the room to the
  mechanical work required to operate it.

Problems