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Universiti Tenaga Nasional

Mechanical Engineering Department

Thermodynamics II, MEHB312

Semester 1, 2013/2014

Assignment on Combustion

This is an individual assignment which carries 15% of the total assessment for this course. This

assignment is to meet the Course Outcome 7 of this course which is; able to derive combustion

equation at a given fuel composition and air fuel ratio as well as determination of energy andpollutants released as a result of combustion.

Course Outcome 7 is mapped to Program Outcome 3 which is; Design solutions for complex mechanical

engineering problem that meet specific needs with appropriate consideration for public health and

safety, culture, society, and environment.

For this assignment,

a) Write in not less than 3 pages, the effects and hazards of combustion in transport, utility andindustry to the health, safety, culture, society and environment.

b) 100 kg of coal is burned steadily in a power plant boiler. This coal has an ultimate analysis bymass of consists 39.25% Carbon, 6.93 % Hydrogen, 41.11% Oxygen, 0.72% Nitrogen, 0.79%

Sulfur and 11.20% ash (non-combustible). This coal is burned with 30% excess air in the boiler.

The coal and air enter this boiler at standard conditions (1 atmospheric pressure and 298K) and

the products of combustion are released through the chimney at 400 K.

I. Utilizing the conservation of mass principle, derive the chemical reaction equation forthis combustion process by balancing the no. of atoms of each element.

II. Determine the mole number of each component in the products.III. Calculate the amount of heat released in KJ/kmol of fuel for this combustion process.

Use the mini property table below for the enthalpy of substance at different states:

Substance fo

in kJ/kmol 298K in kJ/kmol 400K in kJ/kmol

O2 0 8682 11,711N2 0 8669 11,640

H2O (g) -241,820 9904 13,356

CO2 -393,520 9364 13,372

SO2 -297,100 SO2= 400K - 298K = 4253 kJ/kmol

IV. Identify and list the products in this combustion process that cause problems to theenvironment.

V. What are the problems caused by these products of combustion?VI. If Nitrogen monoxide and Nitrogen dioxide (NOx) and Carbon monoxide(CO) are present

in the products of this combustion process, what problems would NOx and CO cause to

health or environment?VII. Design or adopt a system to control or to treat or to reduce the amount of pollutants

released to the environment in this boiler.

VIII. Discuss or describe how the system you have designed or adopted works.c) Write in not less than a page on how pollution by combustion in transport, utility and industry

can be reduced to conserve the environment for our future generations.

Submission date: By 30 August 2013.