05/04/2011 Tarik Al-Shemmeri 2

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15 There are FIVE forms of ENERGY: 1. MECHANICAL ENERGY 2. ELECTRICAL ENERGY 3. CHEMICAL ENERGY 4. NUCLEAR ENERGY 5. THERMAL ENERGY 05/04/2011 Tarik Al-Shemmeri 15

16 Associated with the ability to perform physical work. MECHANICAL energy can be in either: POTENTIAL form, or KINETIC form. 05/04/2011 Tarik Al-Shemmeri 16

17 POTENTIAL ENERGY As the name implies is contained in a body due to its height above its surroundings, examples such as the gravitational energy of the water behind a dam Potential Energy = mass x g x height Ep = m x g x h 05/04/2011 Tarik Al-Shemmeri 17

18 KINETIC ENERGY Energy due to Motion, Such as the energy of water flowing in a stream. Kinetic Energy = ½ mass x velocity squared Ek = ½ x m x v 2 05/04/2011 Tarik Al-Shemmeri 18

19 This type of energy as the name implies is associated with the electrons of materials. Electrical energy exists in either: Electrostatic energy is produced by the accumulation of charge on the plates of a capacitor. Or Electromagnetic energy is due the Inductive- field energy. 05/04/2011 Tarik Al-Shemmeri 19

20 Associated with the release of thermal energy due to a chemical reaction of certain substances with oxygen. Burning wood, coal or gas is the main source of thermal energy Chemical Energy = Mass of fuel x calorific value x efficiency of combustion 05/04/2011 Tarik Al-Shemmeri 20

21 This energy is stored in the nucleus, and is released as a result of interactions within the atomic nucleus. This reaction form the bases for current nuclear power generation plants. Einstein s energy equation for nuclear fissioning ( i.e. conversion of matter into energy ) : E n = m C 2 Where m is the mass, and C is the speed of light 05/04/2011 Tarik Al-Shemmeri 21

22 Associated with intermolecular vibration resulting in heat and a temperature rise above that of the surroundings. For general heating or cooling : Thermal Energy = mass x specific heat x temperature difference During a change of phase, such as evaporation or condensation, it can be calculated by: Thermal Energy = mass x latent heat 05/04/2011 Tarik Al-Shemmeri 22

23 THE PRINCIPLE OF ENERGY CONSERVATION STATES THAT : ENERGY CAN NOT BE DESTROYED IT CAN HOWEVER, BE TRANSFORMED 05/04/2011 Tarik Al-Shemmeri 23

24 For example consider a power station using coal as a fuel, the following conversions take place: Energy liberated by the combustion of coal, (chemical to thermal); Thermal energy of the combustion gases is used to raise steam (thermal to thermal); High pressure and temperature steam turns the steam turbine (thermal to mechanical). The steam turbine drives the electrical generator (mechanical to electrical) 05/04/2011 Tarik Al-Shemmeri 24

25 Boiler Steam Steam 70 Turbine Torque 45 Electrical Generator Heat 95 Electricity 38 Coal 100 Lighting Heating 05/04/2011 Tarik Al-Shemmeri 25

26 Energy Conversion Matrix From \ To Mechanical Electrical Thermal Chemical Nuclear Mechanical Gear Nutcracker push mower Electric generator friction x x Electrical Electric motor Light bulb Electric fire Electrolysis Particle accelerator Thermal Steam turbine Thermocouple H e a t exchanger x Fusion reactor Chemical jet engine Rocket Battery fuel cell Car engine Boiler Intermediate reaction x Nuclear x x Nuclear reactor x x 05/04/2011 Tarik Al-Shemmeri 26

27 SOLUTION 5 UNIT INPUT OUTPUT Motor car chemical Mechanical Battery chemical electrical Boiler chemical thermal Electric fire electric thermal 05/04/2011 Tarik Al-Shemmeri 27

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29 REACTA NTS FUEL Air Ignition combustion PRODUC TS CO 2 H 2 O N 2 05/04/2011 Tarik Al-Shemmeri 29

30 COMPLETE COMBUSTION EQUATION Step 1 write down the chemical symbol for fuel, say Methane for example, and air as follows : FUEL + AIR CH 4 + X ( O N 2 ) AIR CONSISTS OF OXYGEN AND NITROGEN. 05/04/2011 T. al-shemmeri 30

31 COMPLETE COMBUSTION EQUATION step 2 - write down the chemical equation carbon reacts with available oxygen to produce Carbon Dioxide, Hydrogen reacts with oxygen to produce water vapour Nitrogen, being neutral remains inactive CH 4 + X ( O N 2 ) = a [ CO 2 ] + b [ H 2 O ] + c [ N 2 ] 05/04/2011 T. al-shemmeri 31

32 COMPLETE COMBUSTION OF METHANE Step 3, balance combustion reactants = products CH 4 + X ( O N 2 ) = a [ CO 2 ] + b [ H 2 O ] + c [ N 2 ] CARBON 1 = a or a = 1 HYDROGEN 4 = b x 2 or b =2 OXYGEN X = a + b/2 = 1 +2/2 = 2 NITROGEN X { 3.76 } = c or c = /04/2011 Tarik Al-Shemmeri 32

33 COMPLETE COMBUSTION OF METHANE Step 4 rewrite the BALANCED EQUATION : CH4 + 2 ( O N2 ) = CO2 + 2 [ H2O ] [ N2 ] 05/04/2011 Tarik Al-Shemmeri 33

34 COMPLETE COMBUSTION OF METHANE Step 5 Calculate the air to fuel ratio by mass : 2( x28) A/ F = = 1x12 + 4x /04/2011 T. al-shemmeri 34

35 LEAN-BURN COMBUSTION OF METHANE Methane Air 120% Complete combustion CO 2 H 2 O N 2 05/04/2011 Tarik Al-Shemmeri 35

36 LEAN-BURN COMBUSTION OF METHANE Step 1 write down the chemical symbol for fuel and air as follows : CH ( O N 2 ) WITH 20% excess air X = 1.2 times the stoichiometric ratio which was found to be 2, ie X =2.4 05/04/2011 Tarik Al-Shemmeri 36

37 step 2 - LEAN-BURN COMBUSTION OF METHANE carbon reacts with available oxygen to produce Carbon Dioxide, Hydrogen reacts with oxygen to produce water vapour Nitrogen, being neutral remains inactive Oxygen, some will be left over CH ( O N 2 ) = a [ CO 2 ] + b [ H 2 O ] + c [ N 2 ]+ d [ O 2 ] 05/04/2011 Tarik Al-Shemmeri 37

38 LEAN-BURN COMBUSTION OF METHANE Step 3, balance combustion reactants = products CH ( O N 2 ) = a [ CO 2 ] + b [ H 2 O ] + c [ N 2 ]+ d [ O 2 ] CARBON 1 = a or a = 1 HYDROGEN 4 = b x 2 or b =2 OXYGEN 2. 4 = a + b/2 + d or d = 0.4 NITROGEN 2. 4 { 3.76 } = c or c = /04/2011 Tarik Al-Shemmeri 38

39 LEAN-BURN COMBUSTION OF METHANE Step 4 rewrite the BALANCED EQUATION : CH ( O N 2 ) = CO [ H 2 O ] [ N 2 ] [ O 2 ] 05/04/2011 Tarik Al-Shemmeri 39

40 LEAN-BURN COMBUSTION OF METHANE Step 5 calculate the air to fuel ratio by mass : 2.4( x28) A/ F = = 1x12 + 4x /04/2011 Tarik Al-Shemmeri 40

41 INCOMPLETE COMBUSTION OF METHANE Methane Air 80% Incomplete combustion CO 2 CO H 2 O N 2 05/04/2011 Tarik Al-Shemmeri 41

42 INCOMPLETE COMBUSTION OF METHANE Step 1 write down the chemical symbol for fuel and air as follows : CH ( O N 2 ) SAY THIS COMBUSTION IS SUPPLIED WITH 80% OF REQUIRED AIR, IE RICH COMBUSTION X = 0.8 x 2 = /04/2011 Tarik Al-Shemmeri 42

43 INCOMPLETE COMBUSTION OF METHANE step 2 - carbon reacts with available oxygen to produce carbon Monoxide and Carbon Dioxide, Hydrogen reacts with oxygen to produce water vapour Nitrogen, being neutral remains inactive CH ( O N 2 ) = a [ CO ] +b [ CO 2 ] + c [ H 2 O ] + d [ N 2 ] 05/04/2011 Tarik Al-Shemmeri 43

44 INCOMPLETE COMBUSTION OF METHANE Step 3, balance combustion reactants = products CH ( O N 2 ) = a [ CO ] +b [ CO 2 ] + c [ H 2 O ] + d [ N 2 ] CARBON 1 = a +b or b =1 - a HYDROGEN 4 = c x 2 or c =2 OXYGEN 1.6 = a/2 +b + c/2 NITROGEN 1.6 { 3.76 } = d or d = solve for a and b, a=0.8 and b=0.2 05/04/2011 Tarik Al-Shemmeri 44

45 INCOMPLETE COMBUSTION OF METHANE Step 4 rewrite the BALANCED EQUATION : CH ( O N 2 ) = 0.8 [ CO ] +0.2 [ CO 2 ] + 2 [ H 2 O ] [ N 2 ] 05/04/2011 Tarik Al-Shemmeri 45

46 INCOMPLETE COMBUSTION OF METHANE Step 5 Calculate the air to fuel ratio by mass : 05/04/2011 Tarik Al-Shemmeri 46

47 INCOMPLETE COMBUSTION OF METHANE Step 5 Calculate the air to fuel ratio by mass : A 1.6( x28) / F = = 1x12 + 4x /04/2011 Tarik Al-Shemmeri 47