# A condenser of a refrigeration system rejects heat at a rate of 120 KW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system would be

1.  1/4

2.  4

3.  1/3

4.  3

4

3

Explanation :
No Explanation available for this question

# One kilogram of water at room temperature is brought into contact with a hight temperature thermal reservoir. The entropy change of the universe is

1.  Equal to entropy change of the reservoir

2.  Equal to entropy change of water

3.   Equal to zero

4.  Always positive

4

Always positive

Explanation :
No Explanation available for this question

# Consider the following two processes; a. A heat source at 1200 K loses 2500 KJ of heat to a sink at 800K b. A heat source at 800K loses 2000Kj of heat to a sink at 500K Which of the following statements is true

1.  Process I is more irreversible than process II

2.  Process II is more irreversible than process I

3.  Irreversible associated in both the process is equal

4.  Both the processes are reversible

4

Process II is more irreversible than process I

Explanation :
No Explanation available for this question

# If the air has to flow from station P to station Q, the maximum possible value of pressure in KPa at station Q is close to

1.  50

2.   87

3.   128

4.  150

4

87

Explanation :
No Explanation available for this question

# If the pressure at station Q is 50 KPa, the change in entropy (SQ - SP) in KJ/KgK is

1.  -0.155

2.  0

3.  0.160

4.  0.355

4

0.160

Explanation :
No Explanation available for this question

# An ideal gas of mass m and temperature T1 undergoes a reversible isothermal process form an initial pressure P1 to final pressure P2. The heat loss using the process is Q. The entropy change S of the gas is

1.  mR 1n (P2 /P1)

2.  mR 1n (P1 /P2)

3.  mR 1n(P2 /P1) – Q/T1

4.  Zero

4

mR 1n (P1 /P2)

Explanation :
No Explanation available for this question

# The pressure temperature and velocity of air flowing in a pipe are 5 bar, 500 K and 50 m/s, respectively. The specific heats of air at constant pressure and at constant volume are 1005 KJ/KgK and 0.718 KJ/KgK, respectively. Neglect potential energy. If the pressure and temperature of the surroundings are 1 bar and 300 K, respectively, the available energy in  KJ/Kg of the air stream is

1.  170

2.   187

3.  191

4.   213

4

187

Explanation :
No Explanation available for this question

# In air – standard Otto cycle the terminal pressure at the end of compression, heat release and expansion are respectively P2, P3 and P4. If the corresponding values are P21  P31 , and P41  , taking into account the effect of variable specific heat and dissociation of the working fluid, then

1.  P2 < P21 and P3 > P31

2.  P3 < P31 and P4 > P41

3.  P2 > P21 and P3 > P31 and P4 < P41

4.  P2 > P21, P3 > P31

4

P2 > P21, P3 > P31

Explanation :
No Explanation available for this question

# An air – standard diesel cycle consists of:

1.  Two adiabatic and two constant volume processes

2.  Two constant volume and two isothermal processes.

3.  One constant pressure, one constant volume and two adiabatic processes.

4.  One constant pressure, one constant volume and two isothermal processes

4

One constant pressure, one constant volume and two adiabatic processes.

Explanation :
No Explanation available for this question

# The theoretical mechanical efficiency of a jet engine (neglecting frictional and thermal losses), when driving a vehicle has its maximum

1.   Only when the vehicle moves at sonic velocity

2.  When outlet gases approach zero absolute velocity

3.  When the vehicle speed approaches the magnitude of the relative velocity of gases at nozzle exit

4.  Only when the relative velocity at nozzle exit is at its maximum

4