ect- exam (practice 2- sv) 2014-2015(2)

8/18/2019 ECT- Exam (Practice 2- SV) 2014-2015(2)

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School of Engineering

and Built Environment

Department of Engineering

SESSION: 2014/2015

Sample: EXAM PRACTIC (MOCK EXAM PAPER)

Energy Conversion Technologies

Level: 3

Module Code: M3J923150

Module Leader: Prof M El-Sharif

DATE: 2015 DURATION: 2 Hours

Time:

CANDIDATES SHOULD ATTEMPT FOUR QUESTIONS – TWO FROM

SECTION A AND TWO FROM SECTION B

All Questions Carry Equal Marks

PLEASE READ THE QUESTIONS CAREFULLY

MATERIALS TO Lined Examination Script BooksBE SUPPLIED/ALLOWED:

Unlined Examination Script Books

Question Paper (Supplied)

Thermodynamic Tables (Attached)

Key Formulae Sheet (Attached)

Dictionary (Allowed)

Calculator (Allowed)



SECTION A

Attempt TWO Question

Q1. Consider a steam power plant that operates on the ideal regenerative Rankine cycle

with a closed feedwater heater as shown in Figure Q1. The plant maintains the turbine

inlet at 3000 kPa and 350°C; and operates the condenser at 20 kPa. Steam is extracted

at 1000 kPa to serve the closed feedwater heater, which discharges into the condenserafter being throttled to condenser pressure. Assume that the isentropic efficiency of

the turbine is 90% before and after steam extraction point.

a) Show the cycle on a T-s diagram with respect to saturation lines.

b)

Determine:

i.

the specific work produced by the turbine;

ii.

the specific work consumed by the pump; iii.

the thermal efficiency of the cycle.

.

Figure Q1: Steam power plant

Data and Formulae related to Q1 :

h1 = 251.42 kJ/kg v1 = 0.001017 m3/kg

h3 = 763.53 kJ/kgh4 = 3116.1 kJ/kg

h5s = 2851.9 kJ/kg

h6s = 2221.7 kJ/kg

h7 = 762.51 kJ/kg

,efficiencyturbineIsentropic64

64

54

54

s s

T hh

hh

hh

hh

Condenser

Turbine

Closed

FWH

Boiler

Pump

2

1

3

4

5

7

6(1-y)

(y)

Throttle valve



Q.2 The gas-turbine cycle shown in Figure Q2 is used as an automotive engine. In the first

turbine (Tur 1), the gas expands to pressure P5, just low enough for this turbine to drive

the compressor. The gas is then expanded through the second turbine (Tur 2)

connected to the drive wheels. The isentropic efficiency of the compressor is

82% and both turbines have efficiencies of 87%. The regenerator effectiveness is

70%. Using data shown in Figure Q2 and assuming no pressure drop in regenerator

and burner, determine:

i.

the air temperature leaving the compressor T2

ii. the net specific work output of the engine,

iii. the mass flow rate through the engine.

iv. the specific enthalpy of the exhaust stream h7

v. the thermal efficiency of the engine.

Figure Q2

DATA:

h2s = 501.74 kJ/kg

h6s = 1088.63kJ/kgTABLE A-22 Ideal Gas Properties of Air (attached)

Formu lae related to Q2 :

26

23 ess,effectivenrRegeneratohh

hhreg

s

T hh

hh

65

65 ,efficiencyturbineIsentropic

,efficiencycompressor Isentropic12

12

hhhh s

c



Q.3 Figure Q3 provides steady-state operating data for a well-insulated device having

steam entering at one location and exiting at another with a mass flow rate of 10kg/s.

Neglecting kinetic and potential energy effects, determine:

i.

the direction of flow;

ii. the power output or input, as appropriate, in kW.

Figure Q3

Formu lae related to Q3 :

system gen

ou t in J J

J S smmT

Q

s0

balance.rateentropyvolumecontrolstate-Steady

iieieCV CV z g C C hhmW Q e

22 z)(2

1

state.steadyat balancerateEnergy

Saturated vapour

P =1.0 bar

P =1 MPa

T = 320oC



SECTION B

Attempt TWO Question

Q4.

a.

What is the definition of the coefficient of performance, Cp, of a wind turbine? [2 marks]

b. With the aid of a sketch, explain how the lift and drag forces on an aerofoil are generated.

[5 marks]

c.

On a particular wind turbine, a blade is travelling with an angular velocity of 3 rad/s. If the

incident air velocity is 6 m/s and the inflow factor can be taken as 0.01, what is the relative

wind speed at a blade radius of 10m? [5 marks]

d.

If the pitch angle of the blade described in part c is 2o; calculate the angle of attack.

[3 marks]

e. The distribution of wind speeds over a year at a location 20m above ground level are found

to be as follows:

6 hrs/day at 4m/s

6 hrs/day at 7.5m/s

6 hrs/day at 0m/s

6 hrs/day at 2m/s

i)

Calculate the root mean cube speed URMC. [5 marks]

ii) Calculate the annual average power available in the wind; assume the density of air

is 1.2 kg/m3. [3 marks]

iii)

What is the annual energy production potential at this location? [2 marks]



Q5.

a) What forces influence the generation of tides on earth? [2 marks]

b) Will an estuary which has a length of approximately 100 km and an average depth of 25 m

experience a resonance effect? [2 marks]

c) When considering tidal range power generation, what factors determine the potentialenergy available? [4 marks]

d) Sketch a typical layout for a turbine within the setting of a tidal barrage and label the

important components. [5 marks]

e) Describe the four steps of the operating cycle for Ebb generation for a tidal barrage scheme;

use a series of sketches to illustrate your description. [12 marks]



Q6.

a.

Name the two kinds of particle that are at the centre of an atom and give nature of the

charge of each. [4 marks]

b. What is meant by the term mass defect ? [1 mark]

c. If the element boron is written as B105 , what do the values 10 and 5 represent?

[2 marks]

d. At the atomic scale; what is the unit for energy and what is its value in Joules [2 marks]

e. Name three nuclear decay modes. [3 marks]

f.

Draw a sketch of a boiling water reactor and label the major components [10 marks]



Data Q2: TABLE A-22 Ideal Gas Properties of Air (attached)

ect- exam (practice 2- sv) 2014-2015(2)

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