250+ TOP MCQs on Mass Balance and Energy Balance in a Simple Steady Flow Process and Answers

Thermodynamics Multiple Choice Questions on “Mass Balance and Energy Balance in a Simple Steady Flow Process”.

1. Equation of continuity comes from
a) conservation of energy
b) conservation of mass
c) conservation of work
d) conservation of heat
Answer: b
Clarification: w1=w2 i.e., we get (AV/v)1=(AV/v)2 and this is called equation of continuity(where w1 & w2 are mass flow rates).

2. In a flow process, the work transfer may be of which type?
a) external work
b) flow work
c) all of the mentioned
d) none of the mentioned
Answer: c
Clarification: Flow work is the displacement work and external work mostly comprises of shaft work.

3. The total rate of flow of all energy streams entering the control volume must equal to that of leaving the control volume.
a) true
b) false
Answer: a
Clarification: Given statement is true by the conservation of energy.

4. Which of the following represents the steady flow energy equation?
a) Q+Wx=(h2-h1)-(V2-V1)(V2+V1)/2+g(Z2-Z1)
b) Q+Wx=(h2-h1)+(V2-V1)(V2+V1)/2+g(Z2-Z1)
c) Q-Wx=(h2-h1)-(V2-V1)(V2+V1)/2+g(Z2-Z1)
d) Q-Wx=(h2-h1)+(V2-V1)(V2+V1)/2+g(Z2-Z1)
Answer: d
Clarification: This equation is the general form of SFEE and it involves conservation of mass and energy.

5. When more than one fluid stream is in a control volume, which of the following is more convenient?
a) energy flow per unit time
b) energy flow per unit mass
c) all of the mentioned
d) none of the mentioned
Answer: a
Clarification: It makes calculations less difficult.

6. In the differential form, the SFEE becomes
a) dQ+dW=dh+VdV+gdZ
b) dQ-dW=dh+VdV+gdZ
c) dQ+dW=dh-VdV-gdZ
d) dQ-dW=dh-VdV+gdZ
Answer: b
Clarification: This equation is the differential form of SFEE.

7. The steady flow energy equation is applied to which of the following processes?
a) pipe line flows
b) heat transfer processes
c) combustion processes
d) all of the mentioned
Answer: d
Clarification: These are the applications of SFEE.

8. When more than one fluid stream enters or leaves the control volume, which type of balance is taken?
a) mass balance
b) energy balance
c) mass balance and energy balance
d) none of the mentioned
Answer: c
Clarification: Both energy and mass balance are considered here.

9. What are the different kinds of external work?
a) shear work
b) electrical work
c) all of the mentioned
d) none of the mentioned
Answer: c
Clarification: Given two kinds of external work are important.

10. The flow work is the displacement work done by the fluid and is given by
a) -pvdm
b) pvdm
c) pvdm or -pvdm depending on whether it is inlet or exit
d) none of the mentioned
Answer: c
Clarification: At inlet, flow work=-pvdm and at exit, flow work=pvdm.