Multiple-Choice Questions or Objective-Type Questions on Refrigerants [PDF Included]

Hello Readers! In this article, I will discuss a few numbers of Multiple-Choice Questions or Objective-Type Questions on Refrigerants along with some Interview questions or Viva Questions on Refrigerants. First, I will display the short questions and next, you will find the MCQ Questions.

These questions may be asked by the Interviewer when you go for a job interview. Also, it may be asked during the semester viva examinations. Also, you may download this MCQ sheet or this Short Question sheet by clicking on the pdf downloadable button that you will find at the end of this article.

So, without wasting your time, let us start the interview questions or short questions on refrigerants.

Interview Questions or Short Questions on Refrigerants

What do you mean by the Dielectric Strength of refrigerants?

Insulating materials block the electric charge to flow. The capability of these insulating materials is known as dielectric strength.

In hermetically sealed compressors, refrigerant vapor comes in touch with motor windings. As a result, short circuits may occur. In these cases, the dielectric strength of the refrigerants should be very high to prevent short circuits.

What is a secondary refrigerant?

In large refrigerant plants, secondary refrigerant is used. The primary refrigerant need not flow into the main concerned zone. There is a heat exchange between the primary refrigerant and secondary refrigerant. Then secondary refrigerant does the necessary work on behalf of primary refrigerant. As a result, the cost of primary refrigerant and the pressure drop is reduced.

Some examples of secondary refrigerants are chilled water, brines, glycols, some hydrocarbons, etc.

What are the desirable properties of a secondary refrigerant?

The desirable properties are:

• Low freezing point
• Low viscosity
• Non-flammability
• Good stability
• Low vapor pressure

What is an Azeotropic refrigerant?

An azeotropic refrigerant is a mixture of two or more refrigerants that have the same boiling and condensing temperature. Some examples of azeotropes are R500 (R12+R152a), R502(R22+R115), R503(R23+R13).

What is Raoult’s law?

The vapor pressure of a solution at a given temperature is equal to the product of the mole fraction of the solvent and the vapor pressure of the solvent.

What is a minimum boiling azeotrope?

The azeotropes boil at a lower temperature than that of the boiling temperature of the components when they are in a pure state. Suppose, two components A and B have boiling temperatures as X and Y when they are in a pure state. They form an Azeotrope AB that has a boiling temperature of Z. If  Z< X and Y, then AB is a minimum boiling Azeotrope.  It shows a positive deviation of Raoul’s Law. It has a lower latent heat of vaporization.

What is a maximum Boiling azeotrope?

The azeotropes boil at a higher temperature than that of the boiling temperature of any one of the components when they are in a pure state. Suppose, two components A and B have boiling temperatures as X and Y when they are in pure state form an Azeotrope AB that has a boiling temperature of Z. If  Z> X or Z> Y, then AB is a maximum boiling Azeotrope.  It shows a negative deviation of Raoul’s Law. It has a higher latent heat of vaporization.

How can you detect the leak of the refrigerants in the refrigeration system?

There are two methods to detect the leakage of refrigerants: Halide Torch Method and Soap Bubble Method.

How can you get the chemical formula of a refrigerant?

Ans:  For saturated hydrocarbons, the representation will be R(C-1)(H+1)F and for unsaturated hydrocarbons, it should be represented as R-1(C-1)(H+1)F where the chemical formula in both cases is C_CH_HF_pCl_q.

Find out the chemical formula of R134a.

Ans: here, (C-1)=1 => C=2

(H+1)=3 => H=2

P=4

Hence, the chemical formula is: C₂H₂F₄

What are the desirable properties of a Refrigerant?

• Low boiling point and low freezing point
• High latent heat and low specific heat
• Low operating pressure
• High critical pressure and temperature
• Low specific volume
• High thermal conductivity
• Low viscosity
• Non-flammable, non-explosive, non-toxic, non-corrosive
• Ease of leak detection
• High miscibility with lubricating oil

What is the chemical formula of R717?

Ans: NH₃

What are the chemical formulas of the following refrigerants: R-12, R-22, R113, R11, R114?

Ans: R12 is CCl₂F₂ Difluoro dichloro methane

R-22 is CHClF₂ Difluoro monochloro methane

R113 is Trichloro trifluoro ethane

R11 is CCl₃F

R114 is C₂Cl₂F₄

MCQ Questions on Refrigerants

• Name the secondary refrigerant used in milk chilling plants.

1. Ammonia solution
2. Sodium silicate
3. Brine
4. Propylene glycol

Ans: (3)

• The leakage of a Freon-based refrigeration system can be detected by:

1. Oxy-acetylene torch
2. Halide torch
3. Sulphur torch
4. Blue litmus paper

Ans: (2)

• An azeotrope is:

1. A refrigerant dissolved in ammonia
2. A refrigerant that is non-halogenic
3. An eco-friendly refrigerant
4. A mixture of refrigerants without phase separation

Ans: (4)

• Selection of refrigerant for a vapour–compression system depends on:

1. Toxicity
2. Saturation pressure-temperature relationships
3. Environmental effect
4. All of the above

Ans: (4)

• Here is one fluid whose properties of all the phases are useful in thermodynamics. The fluid is:

1. Ammonia
2. Freon-22
3. Water
4. Helium

Ans: (3)

• In which of the following refrigeration system, the oil separator is not required?

1. Refrigerant and oil are miscible at condensation pressure and temperature
2. Refrigerant and oil are miscible at all temperature and pressure.
3. Refrigerant and oil are immiscible at condensation pressure and temperature
4. Refrigerant and oil are immiscible at condensation pressure and temperature

Ans: (1)

• R718 is:

1. Carbon-di-oxide
2. Water
3. Ammonia
4. Methane

Ans: (2)

• R744 is:

1. Carbon-di-oxide
2. Water
3. Ammonia
4. Methane

Ans: (1)

• The pipes and fitting in an ammonia refrigeration system should be made of:

1. Copper
2. Aluminium
3. Cast steel or wrought iron
4. Naval brass

Ans: (3)

• For detecting the leakage of ammonia, which of the following system is used?

1. Halide torch test
2. Sulphur candle test
3. Soap and water test
4. Ammonia swab test

Ans: (2)

• For detecting the leakage of Halocarbon Refrigerants, which of the following system is used?

1. Halide torch test
2. Sulphur candle test
3. Soap and water test
4. Ammonia swab test

Ans: (1)

• For detecting the leakage of Propane, which of the following system is used?

1. Halide torch test
2. Sulphur candle test
3. Soap and water test
4. Ammonia swab test

Ans: (3)

• For detecting the leakage of Sulpher dioxide, which of the following system is used?

1. Halide torch test
2. Sulphur candle test
3. Soap and water test
4. Ammonia swab test

Ans: (4)

• Which one of the following refrigerants has the highest critical temperature?

1. Carbon-dioxide
2. Water
3. Freon
4. Ammonia

Ans: (2)

• The significant advantage of using ammonia refrigerant is:

1. Its odour
2. High latent heat
3. Solubility
4. Inflammibility

Ans: (2)

• The color of the flame of Halide torch, in a case of leakage of Freon refrigerant, will be converted into:

1. Yellow
2. Red
3. Bright green
4. Orange

Ans: (3)

Conclusion

I feel that you like this article especially the “Multiple-Choice Questions on Refrigerants” along with the “Interview Questions on Refrigerants”. Be in touch with this site. I will bring a lot of articles on Mechanical Engineering. Some articles will help you in your semester examinations and some will help you in the Gate examination. Stay happy and fit. Best wishes!