Introduction to Refrigeration

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What is the primary purpose of refrigeration and air-conditioning?

To adapt to unpredictable variations in the environment

To control the environments of living and non-living subjects (correct)

To maintain a temperature higher than the surroundings

To extract heat from the surroundings for energy conservation

Why is adaptation to unpredictable environmental variations not feasible for living and non-living beings?

It allows for longer lives of the beings

It increases efficiency in performing tasks

It is impossible to adapt to unpredictable variations

It hinders efficiency and performance (correct)

What does refrigeration achieve in terms of temperature relative to its surroundings?

Maintains a temperature lower than its surroundings (correct)

Controls the humidity levels in its surroundings

Maintains the same temperature as its surroundings

Maintains a temperature higher than its surroundings

Which important environment variables are mentioned in the text as constantly changing?

Temperature, humidity, pressure, and air motion Signup and view all the answers

What does refrigeration achieve by extracting heat from the space under consideration?

Maintains a lower temperature than the surrounding atmosphere Signup and view all the answers

Why is control of the environment essential for living and non-living beings?

To provide comforts for better performance and longevity Signup and view all the answers

What was the working fluid used by Jacob Perkins in his hand-operated refrigeration system?

Ether Signup and view all the answers

Who obtained the first American patent for a cold air machine to produce ice?

Dr. John Gorrie Signup and view all the answers

In the 19th century, what was developed to replace natural ice?

Artificial ice producing machines Signup and view all the answers

What was the purpose of the vapor-absorption refrigeration system developed by Ferdinand Carre?

To meet the demand for ice during the civil war Signup and view all the answers

What was the heat source used to separate ammonia vapor in Ferdinand Carre's refrigeration system?

A burner Signup and view all the answers

What was the world's first installation of a refrigeration machine used for brewery?

James Harrison's system Signup and view all the answers

In which century were large-sized refrigeration machines developed?

20th century Signup and view all the answers

Who developed the first two-stage modern compressor in 1915?

Dr. John Gorrie Signup and view all the answers

What method was used to keep water outside homes overnight in ancient India and Egypt to produce ice?

Evaporation in cool, dry air with radiative heat transfer Signup and view all the answers

Who is credited with obtaining the first British Patent for a refrigeration system in 1790?

Thomas Hariss and John Long Signup and view all the answers

What is the precise meaning of air conditioning?

Controlling temperature, humidity, cleanliness, and air motion Signup and view all the answers

Why is external power always required in air conditioning systems?

To pump out or in the heat Signup and view all the answers

In the winter air conditioning system, what is added to the space being conditioned?

Extra moisture Signup and view all the answers

What does comfort air conditioning primarily deal with?

Residential buildings and offices only Signup and view all the answers

Which parameter is NOT considered essential for the comfort of human beings in air conditioning?

Air pressure Signup and view all the answers

What role does a dehumidifier play in summer air conditioning?

Removing extra moisture from the space Signup and view all the answers

Why is air motion considered essential for comfort in air conditioning?

To distribute conditioned air evenly Signup and view all the answers

What distinguishes industrial air conditioning from comfort air conditioning?

Includes control of air pressure Signup and view all the answers

What is the primary difference between summer and winter air conditioning systems?

Heating versus cooling the space Signup and view all the answers

What happens to the humidity levels during rain in Delhi and Kolkata?

Humidity decreases in Delhi but increases in Kolkata. Signup and view all the answers

What was the most important development in refrigeration systems after the 1920s?

Invention of new refrigerants like chlorfluor hydrocarbons Signup and view all the answers

What was a major advantage of chlorfluor carbons as refrigerants compared to NH3 and SO2?

Non-toxicity Signup and view all the answers

Which specialized field of refrigeration involves removing heat from substances in chemical, petroleum, and petrochemical plants?

Industrial refrigeration Signup and view all the answers

What are some examples of applications of air conditioning mentioned in the text?

Treating air to control temperature, humidity, cleanliness, and distribution Signup and view all the answers

Why is cooling required in buildings even in places where temperatures remain normal?

To remove heat generated internally by people and equipment Signup and view all the answers

What is the main purpose of comfort air conditioning in residential and official buildings?

To maintain comfortable conditions for people Signup and view all the answers

What role does air conditioning play in hospitals and medical buildings according to the text?

To maintain humidity levels and cleanliness Signup and view all the answers

In what way does spot heating differ from spot cooling?

Spot heating is more practical in cold weather while spot cooling is more effective in hot weather. Signup and view all the answers

What is the primary function of air conditioning in environmental laboratories?

To control humidity and cleanliness of air Signup and view all the answers

What is the purpose of maintaining a high temperature and humidity in one laboratory?

To study the behavior of animals in tropical climates Signup and view all the answers

In the printing industries, what problems arise if humidity is not properly maintained?

Curling or buckling of paper Signup and view all the answers

Why are textiles sensitive to changes in humidity and temperature?

To prevent rust formation Signup and view all the answers

How does air conditioning help in the manufacturing of precision metal parts?

Maintain uniform temperature to avoid expansion and contraction Signup and view all the answers

What is a major contributor to the cooling load in vehicles like planes, trains, and ships?

Heat from solar radiation Signup and view all the answers

What is the purpose of using a vapour compression cycle in air refrigeration systems?

To improve the efficiency of cooling systems Signup and view all the answers

What is the standard unit of refrigeration used?

Ton refrigeration Signup and view all the answers

Why do raw photographic materials deteriorate quickly in high humidity and temperatures?

Because of high humidity and temperatures Signup and view all the answers

What is the role of air conditioning in computer rooms?

Control temperature, humidity, and cleanliness of the air Signup and view all the answers

How does refrigeration help extend storage life for perishable food products?

By maintaining low temperatures above freezing point Signup and view all the answers

What is the purpose of the expansion valve in a refrigeration system?

To allow the liquid refrigerant to pass at a controlled rate after reducing its pressure and temperature Signup and view all the answers

What is the role of the condenser in a vapor compression refrigeration system?

To cool and condense the high pressure and temperature vapor refrigerant Signup and view all the answers

At what stage of the theoretical vapor compression cycle does the liquid refrigerant evaporate in a refrigeration system?

Expansion process Signup and view all the answers

What happens to the refrigerant in the condenser of a vapor compression refrigeration system?

It is cooled and condensed from a high pressure and temperature vapor to liquid Signup and view all the answers

What is the function of the receiver in a vapor compression refrigeration system?

To store the condensed liquid refrigerant before supplying it to the evaporator Signup and view all the answers

During which phase of the vapor compression cycle does no heat absorption or rejection occur by the liquid refrigerant?

Expansion process Signup and view all the answers

What happens to the pressure of the vapor refrigerant during isentropic compression in a vapor compression cycle?

Pressure increases Signup and view all the answers

How is the condensed liquid refrigerant supplied to the evaporator in a refrigeration system?

Through the receiver output valve Signup and view all the answers

What happens to the medium when liquid-vapor refrigerant evaporates in an evaporator?

The medium absorbs heat from the evaporating refrigerant Signup and view all the answers

Which part of a vapor compression cycle stores the high pressure and temperature vapor refrigerant before being condensed?

Receiver Signup and view all the answers

What is one of the main benefits of superheating the suction vapour in refrigeration systems?

Ensures complete vaporization of the liquid in the evaporator Signup and view all the answers

What role does superheating of the suction vapour play in modulating the capacity of the expansion valve?

Increases the capacity of the expansion valve Signup and view all the answers

For which refrigerant is the maximum Coefficient of Performance (COP) obtained with superheating of the suction vapour?

Freon 12 Signup and view all the answers

What is the primary effect of superheating the suction vapour in refrigeration systems in terms of specific volume?

Increase in specific volume of suction vapour Signup and view all the answers

Compared to the decrease in evaporator pressure, what is noted about the effect of an increase in condenser pressure on refrigerating capacity and power consumption?

It is less significant Signup and view all the answers

What is the equation for the refrigerating effect (RE) during evaporation?

RE = h1 - hf3 Signup and view all the answers

What does the Coefficient of Performance (C.O.P.) represent in a refrigerating system?

Ratio of refrigerating effect to work done Signup and view all the answers

How does a decrease in suction pressure impact the Coefficient of Performance (C.O.P.) of a refrigerating system?

Decreases the C.O.P. Signup and view all the answers

What is the net effect of a decrease in suction pressure on the refrigerating capacity of a system?

Decreases refrigerating capacity Signup and view all the answers

How does a decrease in evaporator pressure affect the reciprocating compressor's capacity?

Decreases compressor's capacity Signup and view all the answers

What is the consequence of a decrease in evaporator temperature on a reciprocating compressor?

Decreases volumetric efficiency Signup and view all the answers

How does an increase in condenser pressure affect refrigeration capacity?

Decreases refrigeration capacity Signup and view all the answers

What happens to the Coefficient of Performance (C.O.P.) with decreasing evaporator pressure?

Decreases C.O.P. Signup and view all the answers

What effect does increasing condenser pressure have on power consumption?

Increases specific work Signup and view all the answers

What is the main reason for a decrease in refrigeration capacity due to an increase in condenser pressure?

Decrease in refrigerating effect Signup and view all the answers

What is the primary purpose of refrigeration according to the text?

Cooling down a space where heat is unwanted Signup and view all the answers

Why does the temperature inside a refrigerator decrease when food products are kept inside?

Unwanted heat from the food products is removed Signup and view all the answers

In the context of refrigeration, why do air-conditioned cars have to reject heat to the surroundings?

To lower the temperature inside the car by removing heat Signup and view all the answers

What is one of the main reasons for using refrigerators in homes and canteens?

To slow down bacterial growth in food products Signup and view all the answers

Why is it necessary for a refrigerator to transfer unwanted heat from food products to the surrounding environment?

To maintain a lower temperature inside the refrigerator Signup and view all the answers

What role does a heat pump play in maintaining comfortable temperatures in different seasons inside a car?

It rejects heat in hot seasons and absorbs heat in cold seasons Signup and view all the answers

What distinguishes refrigeration from natural heat flow processes according to the text?

Heat flow in refrigeration is always from high to low temperatures Signup and view all the answers

How does refrigeration influence the temperatures inside a car during summer?

By rejecting heat from inside, lowering internal temperature Signup and view all the answers