29 Questions
What is the primary method to provide mechanical cooling?
Vapour compression refrigeration
In compression refrigeration cycles, what advantage do highly compressed fluids at one temperature have?
They tend to get colder when expanded
What advantage do vapour-compression refrigeration cycles have regarding thermal energy?
They exploit the large thermal energy required to change a liquid to a vapour
What is the benefit of the isothermal nature of vaporization in vapour compression refrigeration?
It allows extraction of heat without raising the working fluid temperature to that of what is being cooled
What is the main challenge in refrigeration and air conditioning systems?
Removing heat from a low temperature source and dumping it at a higher temperature sink
Why do compression refrigeration cycles take advantage of highly compressed fluids?
To get colder when allowed to expand
What did Carrier present in an ASME meeting?
Rational Psychrometric Formulae
When did air conditioning for comfort begin in motion-picture theatres?
1920 in Chicago
What is the working substance under study in air conditioning?
Moist air
Is moist air considered a pure substance?
Only when moisture does not condense or evaporate
Which gases make up the fixed part of moist air?
Oxygen and nitrogen
In what kind of laws can perfect gas laws be applied?
To both dry air and water vapor
What are the four basic components of all vapor compression systems?
Evaporator, Condenser, Compressor, Expansion Valve
What is the purpose of the expansion valve in a vapor compression system?
Control the flow of condensed refrigerant back into the evaporator
Why is the Carnot vapor compression cycle not suited for practical refrigeration systems?
It involves wet compression of the refrigeration vapor
What is the purpose of a throttle valve in a vapor compression system?
Throttle the refrigerant from high to low pressure regions
Why is wet compression undesirable in a refrigeration system?
It requires two different fluid phases to be compressed
Which component is responsible for raising the pressure of the refrigerant in a vapor compression system?
Compressor
What component controls the flow of condensed refrigerant back into the evaporator?
Expansion Valve
Why is an isentropic expansion preferred over throttling in a vapor compression cycle?
Isentropic expansion produces more work output
What happens during wet compression in a vapor compression cycle?
The liquid droplets react with the lubricant in the compressor
In which path of the Carnot vapor compression cycle does dry compression occur?
1-2-3-4
What is the main reason the Carnot vapor refrigeration cycle is not suitable for use in refrigeration systems?
Low efficiency
In a vapor compression refrigeration cycle, what process is used to achieve the desired expansion from state 4 to state 5?
Throttling in an expansion valve
How does a vapor absorption system differ from a vapor compression system?
Use of absorbent and generator
What is the function of the absorbent in the absorber of a vapor absorption system?
Drawing (or sucking) the refrigerant vapour
In a lithium bromide absorption system, what is used as the absorbent?
Lithium bromide
What function does the generator perform in a vapor absorption system?
Heating the absorbent
Who is known as the 'Father of Air Conditioning'?
Carrier
Explore the differences between vapour absorption and vapour compression refrigeration systems. Learn about the heat operation, similarities, and challenges of these systems.
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