Power Engineering 4th Class Ch 114
b
A refrigerant in the "B" Group that is used more than others in its group in refrigeration systems is: Choose one answer. a. R-290 b. Ammonia c. R-134a d. R-22 e. CO2
c
R-134a is non-toxic and non-flammable. Which of the following groups does it belong to? Choose one answer. a. Group A2 b. Group B4 c. Group A1 d. Group A3 e. Group B2
b
The enthalpy of a vapour is a. Sensible heat of a liquid b. Sensible heat of a liquid plus latent heat of evaporation c. Latent heat of evaporation
d
Which of the following is not a physical property of refrigerants Choose one answer. a. Toxicity b. Odour c. Leakage tendency d. Corrosiveness e. Miscibility
d
Which one of the following should a ideal refrigerant should NOT have? a. A low boiling point at atmospheric pressure b. A high latent heat capacity: that is, it should require a large amount of heat to convert it from a liquid to a gas after its boiling point has been reached c. A fairly low condensing pressure d. An offensive odour e. A nonpoisonous nature f. A noncorrosive action on metals g. A nonflammable and nonexplosive nature when mixed with air h. A reasonable price
c
Group "A" refrigerants are: Choose one answer. a. Non-flammable b. Low-flammable c. Low-toxic d. Low-toxic and flammable e. High-toxic and flammable
e
Leakage tendency is determine by: a. Operating pressure b. Viscosity c. Density d. Molecular mass e. All of the above
e
R-22 refrigerant is: Choose one answer. a. Not miscible with oil b. Mostly used in packing plants c. Corrosive on copper d. Corrosive on aluminum e. A heat transferring medium
a
R-22: Choose one answer. a. Is non-toxic b. Has a strong, pungent odour c. Is explosive when mixed with air d. Is highly toxic e. Is not an ozone-depleting substance
e
The ability of a refrigerant to be dissolved into oil and vice versa is called a) moisture reaction b) enthalpy c) density d) leakage tendency e) miscibility
a
The amout of liquid that may flash into vapour can be as high as? a. 30% b. 40% c. 50% d. 60% e. 70%
d
The ideal refrigerant should: Choose one answer. a. Have a low latent heat capacity b. Have a high boiling point c. Have high condensing pressure d. Be environmentally friendly e. Be easily detected because of its strong odour.
b
The larger the difference between the temperature of the liquid refrigerant entering the evaporator and the actual evaporator temperature: a. The larger the refrigerating effect will be b. The smaller the refrigerating effect will be c. The larger the latent heat will be d. The smaller the latent heat will be e. The smaller the senible heat will be
b
The latent heat of fusion of ice is: Choose one answer. a. The sensible heat required for melting ice b. 335 kJ per kg c. 335 kJ per ton d. The latent heat required for evaporation of ice e. 4.2 kJ per gram
b
The molecular mass of a refrigerant is a factor in which of the following refrigerant characteristics? Choose one answer. a. Miscibility b. Leakage tendency c. Toxicity d. Flammability e. Explosiveness
d
The property which has to be known for the calculation of the size of control valves and piping etc. is: Choose one answer. a. Specific gravity b. Enthalpy c. Refrigerating effect d. Density e. Boiling point
e
The refrigerant R-11 belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
a
The refrigerant R-142b belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
a
The refrigerant R-152a belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
c
The refrigerant R-290 belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
c
The refrigerant R-600 belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
d
The refrigerant R-717 belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "B2" e) group "A1"
b
The refrigerant R-764 belongs to the following group a) group "A2" b) group "B1" c) group "A3 d) group "2B" e) group "A1"
a
The refrigerating effect of a refrigerant is: Choose one answer. a. Equal to its latent heat of vaporization b. Greater than its latent heat of vaporization c. Less than its latent heat of vaporization d. Equal to its specific heat capacity e. Less than its net-refrigerating effect
b
The standard refrigeration cycle is used to compare refrigerants and machines operating under comparable conditions. These standard conditions are: Choose one answer. a. 1030 kPa and atmospheric pressure b. 30°C condensing and -15°C evaporating c. 30 kPa and atmospheric pressure d. -30°C condensing and 15°C evaporating e. 30 kPa and atmospheric temperature
b
What is the name of the refrigerant that has the following characteristics? It is non-flammable, odourless, non-toxic, it does not have a corrosive effect on metal if water is present and at atmospheric pressure it has a boiling point of approximately -40.6°C. Choose one answer. a. Ammonia b. R-22 c. R-744R d. R-134a e. R-290
a
Which of the following characteristics is common in all of the group B refrigerants? Choose one answer. a. High toxicity b. High flammability c. Non-toxic but highly flammable d. Low Toxicity e. Low flammability
e
Which of the following has the highest boiling point at atmospheric pressure? Choose one answer. a. Ammonia b. Freon 12 c. Freon 22 d. Freon 113 e. Water
e
Which of the following is a thermodynamic property of heat? a) entropy b) enthalpy c) density d) volume e) all of the above
d
Which of the following is not a physical property of refrigerants? a) Toxicity b) Odour c) Leakage tendency d) Density e) Explosiveness
c
Ammonia is explosive in concentrations between? A. 5 to 10 % b. 11 to 14 % c. 16 to 25 % d. 26 to 31 % e. 32 to 40 %
c
Ammonia is the only commonly used refrigerant which has the physical property of a) miscibility b) enthalpy c) flammability d) density e) low condensing pressure
d
Ammonia refrigerants: Choose one answer. a. Have high sensible heat capacity b. Mix well with oil c. Are very expensive d. Are well suited for industrial refrigeration e. Are ideally suited to copper piping system
c
Ammonia, as well as being toxic, is also : Choose one answer. a. Miscible b. Odourless c. Flammable d. Dense e. A low pressure refrigerant