Terms And Scientific Principles Applied To Cryogenic Equipment Flashcards
Atmospheric Pressure
- Pressure exerted by the weight of the weight of the atmosphere
- Standard atmospheric pressure 14.696 PSIA
- Equivalent to 29.92 inches of mercury at sea level
Fahrenheit
- 32 degrees Fahrenheit is the freezing point of the water
- 212 degrees Fahrenheit is the boiling point of the water
Rankine
- Thermometer scale based on absolute zero of the Fahrenheit Scale
- 492 degrees Rankine freezing point of water
- 672 degrees Rankine boiling point of water
- also known as Fahrenheit Absolute Scale
Kelvin
- thermometer scale based on absolute zero of the Celsius scale
- 273 degrees Kelvin freezing point of water
- 373 degrees Kelvin boiling point of water
- also known as International-Practical Scale
British Thermal Unit (BTU)
The amount of heat required to produce a temperature rise of 1 degree Fahrenheit in one pound of water
Refrigeration Ton
Removal of heat at the rate of 288,000 BTU’s in 24hrs or 12,000 BTU’s in one hour
Latent Heat
Heat that is given of or absorbed by a substance while it is changing state without changing temperatures
Latent Heat of Vaporization
Change state from a liquid to vapor without a change in temperatures
Latent Heat of Condensation
Change of state from vapor to a liquid without a change in temperatures
Latent Heat of Fusion
Change the state from a liquid to a solid (freezing) or from a solid to a liquid (melting)
Saturation Temperature
The temperatures at which a liquid boils under a given pressure
Conduction
A transfer of heat from one body to the another when the two bodies are in physical contact
Convection
The transfer of heat by the circulation of a liquid or gas such as air
Radiation
The transfer of heat in the form of waves similar to light and radio waves, without physical contact between the emitting and the receiving regions
Relative Humidity
The ratio of the weight of water vapor in a quantity of air to the weight of water vapor which that quantity of air would hold if saturated at the existing temperature
Velocity
Speed in definite direction
Cryogenics
Temperatures below -150 degrees Fahrenheit (-101 degrees Celsius)
Fractional Distillation
- The process used to separate the components of a substance through differences in physical or chemical properties
- In cryogenics, liquefying air and then separating the resulting distillate into its individual components due to the fact that each component has its own specific boiling point
Reflux
The process in which liquid moves down a distillation column and comes into close contact with vapors rising up the column, thereby stripping them (the vapors) of their less volatile components
Cavitation
Formation of a gas pocket in the inlet chamber of a cryogenic pump resulting when the temperature of the pumped liquid rises above its boiling point
Lined Cycle
- A method of liquefying air, employed in all shipboard air separation plants that use Joules-Thompson expansion, heat exchange, and auxiliary refrigeration
- High Pressure Cycle means the same thing as Linde Cycle
Joule-Thompson Expansion
Expansion of high pressure gas through a valve or orifice to reduce its temperature, as in the Linde Cycle
Claude Cycle
A method of liquefying air involving compression of the air and expansion portion of it through an expansion engine
Absorbent
A material that has the ability to soak up or extract certain substances from a liquid or a gas with which air is in contact, without causing change to the fluid passing around the material
Adsorbent
A material that has the ability to cause molecules of gases and liquids to adhere to its external surfaces, possibly causing a physical or chemical change in the fluid passing around the material
Standard Air
- Air at 68 degrees Fahrenheit
- 14.7 PSIA
- a relative humidity of 36 %
- weight density of 0.0075 pounds per cubic foot
Oxygen (O2) Gaseous
- Colorless and odorless
- it’s not flammable
- supports and rapidly accelerated the combustion of all flammable material
Oxygen (O2) Liquid
- Pale blue, transparent fluid
- (-297 degrees Fahrenheit) boiling point
- 1.14 specific gravity at atmospheric pressure
- 1 gallon liquid oxygen weighs 9.53lbs
Nitrogen (N2) Gaseous
An inert has, slightly lighter than air, it does not form flammable or explosive mixture with air or oxygen, nor will it support combustion or respiration
Nitrogen (N2) Liquid
- A colorless, transparent fluid
- (-320 degrees Fahrenheit) boiling point
- 0.808 specific gravity at one atmosphere absolute (14.7 lbs/in2)
Purity
The percent by volume of the major constituent in a gas
Boyle’s Law
The volume of any dry gas varies inversely with the applied pressure, provided the temperature remains constant
Charles’ Law
The volume of any dry gas varies directly with the applied temperature, provided the pressure remains constant
General Gas Law
By combining Boyle’s Law and Charles’ Law, a single expression can be derived which includes all the information contained in both
Dalton’s Law of Partial Pressures
The pressure exerted on the inner walls of a vessel is the sum of the pressure that each gas would exert if it were present alone
Bourbon Tube Pressure Gauge
A thin walled tube bent into the shape of a “C”, which tends to straighten out when pressure is exerted
3 Methods of Refrigeration
- Mechanical Refrigeration
- Joules-Thompson Refrigeration Effect
- Claude Cycle Refrigeration Effect
Mechanical Refrigeration
A mechanical system or apparatus that transfers heat from one substance to another
Joules-Thompson Refrigeration Effect
Expansion of a high pressure gas through an expansion valve to reduce temperature
Claude Cycle Refrigeration Effect
A method of liquefying air by compressing the air and then expanding it through an expansion engine
