MCQ: SUPER HEATING AND SUB COOLING

 MCQ: SUPER HEATING AND SUB COOLING

Super heating as well as sub-cooling takes place at constant pressure. Super heat is applicable to the vapor phase. The sub cooling is applicable to liquid phase.

Super heat

Use of degree of super heat is with
(a) Solids
(b) Liquids
(c) Vapors
(d) None
(Ans: c)

Standard degree of super heat is
(a) 3⁰C
(b) 7⁰C
(c) 5⁰C
(d) None
(Ans: c)

Super heating of the vapor takes place

(a) at Constant entropy

(b) At constant volume

(c) at constant pressure

(d) None

(Ans: c)

Increase of super heat beyond 5⁰C

(a) increases the COP

(b) Decreases COP

(c) COP remains same

(d) none

(Ans: b)

Degree of super heat is the temperature difference

(a) between the actual temperature and the boiling temperature

(b) between the actual and the dew point  temperature

(c) Between the dry bulb temperature and the wet bulb temperature

(d) None

(Ans: a)

Due to super heating, entropy

(a) increases

(b) decreases

(c) Remains the same

(d) None

(Ans: a)

For a saturated vapor, what is degree of super heat

(a) >0

(b) < 0

(c) = 0

(d) None

(Ans: c)

For a wet vapor, what is degree of super heat

(a) >0

(b) < 0

(c) = 0

(d) None

(Ans: c)

Subcooling

Use of degree of sub-cooling is with
(e) Solids
(f) Liquids
(g) Vapors
(h) None
(Ans: b)

Standard degree of sub-cooling is
a) 3⁰C
(b) 7⁰C
(c) 5⁰C
(d) None
(Ans: c)

 

Sub cooling of the liquid takes place

(a) at Constant entropy

(b) At constant volume

(c) at constant pressure

(d) None

(Ans: c)

 

Increase of sub cooling beyond 5⁰ C

(a) increases the COP

(b) Decreases COP

(c) COP remains same

(d) none

(Ans: a)

 

Degree of sub cooling is the difference

(a) between the dry and wet bulb temperatures

(b) Between the actual temperature and the condensing temperature

(c) between the actual and the boiling temperature

(d) None

(Ans: b)

 

Due to sub cooling, entropy

(a) increases

(b) decreases

(c) Remains the same

(d) None

(Ans: c)

 

For a wet vapor, what is degree of sub cooling

(a) >0

(b) < 0

(c) = 0

(d) None

(Ans: c)

 

For a saturated vapor, what is degree of sub cooling

(a) >0

(b) < 0

(c) = 0

(d) None

(Ans: c)

For a saturated liquid, what is degree of sub cooling

(a) >0

(b) < 0

(c) = 0

(d) None

(Ans: c)