Podcast
Questions and Answers
What did Carrier present in an ASME meeting?
What did Carrier present in an ASME meeting?
When did air conditioning for comfort start in motion-picture theatres?
When did air conditioning for comfort start in motion-picture theatres?
Can moist air be considered a pure substance?
Can moist air be considered a pure substance?
Which part of moist air is considered the fixed part?
Which part of moist air is considered the fixed part?
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Why can perfect gas laws be applied to dry air and water vapor?
Why can perfect gas laws be applied to dry air and water vapor?
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What properties can be established using Gibbs-Dalton laws?
What properties can be established using Gibbs-Dalton laws?
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What is a key similarity between vapour absorption refrigeration and vapour compression refrigeration?
What is a key similarity between vapour absorption refrigeration and vapour compression refrigeration?
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What advantage do vapour-compression refrigeration cycles have over other refrigeration cycles?
What advantage do vapour-compression refrigeration cycles have over other refrigeration cycles?
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What happens to the compressed gas in a vapour compression system when it is allowed to expand?
What happens to the compressed gas in a vapour compression system when it is allowed to expand?
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What role does the large thermal energy required to change a liquid to a vapor play in vapour compression refrigeration?
What role does the large thermal energy required to change a liquid to a vapor play in vapour compression refrigeration?
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Why is an isothermal process beneficial in vapour compression refrigeration?
Why is an isothermal process beneficial in vapour compression refrigeration?
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What is the primary method used to provide mechanical cooling according to the text?
What is the primary method used to provide mechanical cooling according to the text?
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What is the main reason the Carnot vapor refrigeration cycle is not suitable for refrigeration systems?
What is the main reason the Carnot vapor refrigeration cycle is not suitable for refrigeration systems?
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In a vapor absorption system, what function does the generator perform?
In a vapor absorption system, what function does the generator perform?
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Why does the absorbent solution need to be heated in the generator in a vapor absorption system?
Why does the absorbent solution need to be heated in the generator in a vapor absorption system?
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Which component replaces the compressor in a vapor absorption system?
Which component replaces the compressor in a vapor absorption system?
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What distinguishes ammonia absorbent systems from lithium bromide absorption systems?
What distinguishes ammonia absorbent systems from lithium bromide absorption systems?
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Who is known as the 'Father of Air Conditioning'?
Who is known as the 'Father of Air Conditioning'?
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What purpose does a shell and tube heat exchanger serve in a vapor absorption system?
What purpose does a shell and tube heat exchanger serve in a vapor absorption system?
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Why does the refrigerant operating temperature in a lithium bromide absorption system's evaporator have to be above 0°C?
Why does the refrigerant operating temperature in a lithium bromide absorption system's evaporator have to be above 0°C?
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What role does the absorbent play in an absorber of a vapor absorption system?
What role does the absorbent play in an absorber of a vapor absorption system?
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What does an expansion valve do in a refrigeration system?
What does an expansion valve do in a refrigeration system?
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Which component of a vapor compression system is responsible for raising the pressure of the refrigerant?
Which component of a vapor compression system is responsible for raising the pressure of the refrigerant?
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In a vapor compression system, what is the function of the expansion valve?
In a vapor compression system, what is the function of the expansion valve?
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What happens during the throttling process in a vapor compression system?
What happens during the throttling process in a vapor compression system?
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In a Carnot vapor compression system, what is the primary issue with achieving isothermal compression?
In a Carnot vapor compression system, what is the primary issue with achieving isothermal compression?
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What is the main drawback of wet compression in a vapor compression system?
What is the main drawback of wet compression in a vapor compression system?
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Why is the Carnot vapor compression cycle not suitable for practical refrigeration systems?
Why is the Carnot vapor compression cycle not suitable for practical refrigeration systems?
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Which component of a vapor compression system functions by absorbing heat while evaporating the refrigerant?
Which component of a vapor compression system functions by absorbing heat while evaporating the refrigerant?
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Study Notes
Vapour Absorption Systems vs. Vapour Compression Systems
- Vapour absorption refrigeration is a heat-operated system similar to vapour compression systems.
- Both systems have evaporators and condensers, but the method of creating pressure levels and refrigerant circulation differs.
Vapour Compression Systems
- The primary method of providing mechanical cooling.
- Takes advantage of the idea that highly compressed fluids will tend to get colder when expanded.
- Exploits the thermal energy required to change a liquid to a vapour, allowing for efficient heat removal.
- Has two additional advantages:
- The isothermal nature of vaporization allows for fast heat transfer without raising the working fluid temperature.
- Large thermal energy is required to change a liquid to a vapour, enabling efficient heat removal.
Limitations of Carnot Vapour Compression Systems
- Although the Carnot vapour compression cycle has the highest COP, it is not suitable for practical refrigeration systems.
- Isothermal compression from state 2 to state 3 is virtually impossible to achieve in a finite time interval.
- Dry compression is desirable, but wet compression is highly undesirable due to the presence of liquid droplets.
Vapour Compression Cycle
- Consists of four basic components: evaporator, condenser, compressor, and expansion valve.
- The evaporator and condenser are heat exchangers that evaporate and condense the refrigerant while absorbing and rejecting heat.
- The compressor raises the pressure sufficiently for the vapour to condense in the condenser.
- The expansion device controls the flow of condensed refrigerant back into the evaporator.
Air Refrigeration Introduction
- The art of air conditioning developed gradually from the predecessor arts of cooling, cleaning, heating, and ventilating.
- W.H. Carrier is known as the "Father of Air Conditioning" for his contributions to the field.
- The first year-round air-conditioning system provided for the four major functions of heating, cooling, humidifying, and dehumidifying.
Working Substance in Air Conditioning
- The working substance in air conditioning is moist air, a mixture of two gases: dry air and water vapour.
- Moist air is not a pure substance, as it consists of two parts with different properties.
- Dry air is a mixture of permanent gases, while water vapour can be considered as a perfect gas.
- Gibbs-Dalton laws for non-reactive mixtures of gases can be applied to the dry air part to obtain its properties as a single pure substance.
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Description
Explore the differences between vapour absorption and vapour compression refrigeration systems in this quiz. Learn about the heat operations and challenges involved in each system.
