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### EF

1. 1. EG.EUREM.NETEnergy Fundamentals eg.eurem.net eg.eurem.net
2. 2. Energy Fundamentals What is Work? WORK is done when a force causes an object to move in the direction of the force. For work to be done, two things must occur. First, you must apply a force to an object. Second, the object must move in the same direction as the force you apply. If there is no motion, there is no work. Work can be calculated with this formula: Work = Force X Distance W = FXd standard metric unit of force is the Newton and the standard meteric unit of displacement is the meter, then the standard metric unit of work is a Newton•meter, defined as a Joule and abbreviated with a J. eg.eurem.net
3. 3. Energy Fundamentals What is Work? eg.eurem.net
4. 4. Energy Fundamentals What is Power? is the rate of doing work or the rate of using energy, which are numerically the same. - or Power is defined as the rate at which work is done upon an object. Like all rate quantities, power is a time-based quantity. Power is related to how fast a job is done. - the standard metric unit for power is a Joule / second Power = Work / time P=W/t eg.eurem.net
5. 5. Energy Fundamentals What is Power? eg.eurem.net
6. 6. Energy Fundamentals What is Energy? The capacity or power to do work, such as the capacity to move an object (of a given mass) by the application of force. Energy can exist in a variety of forms, such as electrical, mechanical, chemical, thermal, or nuclear, and can be transformed from one form to another. It is measured by the amount of work done, usually in joules or watts eg.eurem.net
7. 7. Energy Fundamentals What is Energy? eg.eurem.net
8. 8. Energy Fundamentals Mechanical, Kinetic and Potential Energies There are two forms of mechanical energy - potential energy and kinetic energy. Potential energy is the stored energy of position. In this set of problems, we will be most concerned with the stored energy due to the vertical position of an object within Earths gravitational field. Such energy is known as the gravitational potential energy (PEgrav) and is calculated using the equation PEgrav = m•g•h where  m is the mass of the object (with standard units of kilograms),  g is the acceleration of gravity (9.8 m/s/s)  h is the height of the object (with standard units of meters) above some arbitraily defined zero level (such as the ground or the top of a lab table in a physics room). eg.eurem.net 8
9. 9. Energy Fundamentals Kinetic energy is defined as the energy possessed by an object due to its motion. An object must be moving to possess kinetic energy. The amount of kinetic energy (KE) possessed by a moving object is dependent upon mass and speed. The equation for kinetic energy is KE = 0.5 • m • v2 Where  m is the mass of the object (with standard units of kilograms) and  v is the speed of the object (with standard units of m/s). The total mechanical energy possessed by an object is the sum of its kinetic and potential energies eg.eurem.net 9
10. 10. Energy Fundamentals Types of POTENTIAL Energy Stored energy and the energy of position (gravitational).  CHEMICAL ENERGY is the energy stored in the bonds of atoms and molecules. Biomass, petroleum, natural gas, propane and coal are examples.  NUCLEAR ENERGY is the energy stored in the nucleus of an atom – the energy that holds the nucleus together. The nucleus of a uranium atom is an example.  STORED MECHANICAL ENERGY is energy stored in objects by the application of force. Compressed springs and stretched rubber bands are examples.  GRAVITATIONAL ENERGY is the energy of place or position. Water in a reservoir behind a hydropower dam is an example. eg.eurem.net
11. 11. Energy Fundamentals Types of KINETIC Energy Motion: the motion of waves, electrons, atoms, molecules and substances.  RADIANT ENERGY is electromagnetic energy that travels in transverse waves. Solar energy is an example.  THERMAL ENERGY or heat is the internal energy in substances – the vibration or movement of atoms and molecules in substances. Geothermal is an example.  MOTION is the movement of a substance from one placed to another. Wind and hydropower are examples.  SOUND is the movement of energy through substances in longitudinal waves.  ELECTRICAL ENERGY is the movement of electrons. Lightning and electricity are examples. eg.eurem.net
12. 12. Energy Fundamentals Forms of Energy Energy is found in different forms, such as light, heat, sound, and motion. There are many forms of energy, but they can all be put into two categories: kinetic and potential. eg.eurem.net
13. 13. Energy Fundamentals Energy typesKinetic Energy E = 1/2 × m × v2Potential Energy E=m×g×hElectrical Energy E=I×U×tMagnetic Energy E = 1/2 × B × H × VThermal Energy Ei = cv × m × T with Ei = Internal Energy; cv= Specific Thermal ConstantChemical Energy (the binding energy of molecules)Nuclear (Atomic) Energy (E = m × c2)Light Energy (Solar Energy) E = hv eg.eurem.net
14. 14. Energy Fundamentals Important information conservation of energy : The law of conservation of energy says that energy is neither created nor destroyed. When we use energy, it doesn’t disappear. We change it from one form of energy into another. Energy Efficiency Energy efficiency is the amount of useful energy you get from a system. A perfect energy-efficient machine would change all the energy put in it into useful work nonrenewable energy sources. Coal, petroleum, natural gas, propane, and uranium are nonrenewable energy sources. They are used to make electricity, heat our homes, move our cars, and manufacture all kinds of products. These energy sources are called nonrenewable because their supplies are limited. Petroleum, for example, was formed millions of years ago from the remains of ancient sea plants and animals. We can’t make more crude oil deposits in a short time. eg.eurem.net
15. 15. Energy Fundamentals Sources of Energy nonrenewable energy sources. Coal, petroleum, natural gas, propane, and uranium are nonrenewable energy sources. They are used to make electricity, heat our homes, move our cars, and manufacture all kinds of products. These energy sources are called nonrenewable because their supplies are limited. Petroleum, for example, was formed millions of years ago from the remains of ancient sea plants and animals. We can’t make more crude oil deposits in a short time. Renewable energy sources include biomass, geothermal energy, hydropower, solar energy, and wind energy. They are called renewable because they are replenished in a short time. Day after day, the sun shines, the wind blows, and the rivers flow. We use renewable energy sources mainly to make electricity eg.eurem.net
16. 16. Energy Fundamentals eg.eurem.net
17. 17. Energy FundamentalsOrigin of the Concept of Energy The concept of energy was developed in the middle of the 19th century. Scientists and philosophers looked for – the comprehensive reason behind many phenomena – a never changing characteristic in the world which would constitute a hidden common background for constant changes Around 1840 they discovered the characteristic within the overall global system that never changes. They called this characteristic Energy eg.eurem.net
18. 18. Energy Fundamentals The Conservation of Energy Principle Energy can neither be created nor destroyed, but only transformed from one form of energy into another. eg.eurem.net
19. 19. Energy Fundamentals System A system is a region in space that contains an amount of matter and is separated from the environment even if only in an abstract or spiritual sense. This borderline is called system boundary. A system is in a state that can be defined and reproduced if all characteristics have been identified. Systems can be closed: Only heat and work can pass through the system boundary, Or open: Also matter can pass beyond the system boundary. eg.eurem.net
20. 20. Energy Fundamentals HeatHeat: A type of a system’s internal energy, which changes according to temperature differences.Units:Calorie ( The amount of heat needed to warm up 1g of water by 1°K.Joule: SI unit (the mechanical energy used to increase the temperature of 2 kg of water by 1°K). eg.eurem.net
21. 21. Energy Fundamentals Basic Units Power 1 N = 1 kgm/s² Power = Energy, Work 1 J = 1 Ws = 1 Nm Mass * Performance 1 W = 1 J/s = 1 Nm/s Acceleration Pressure 1 Pa = 1 N/m² … 1 bar = 105 Pa Specific Thermal J/(kgK) bzw. J/(m³K) Capacity Specific Weight N/m³ Density kg/m³ Thermal Conductivity W/(mK) Coefficient Thermal Transfer W/(m²K) Coefficient eg.eurem.net
22. 22. Energy Fundamentals Conversion Factors Work kJ kWh kcal kpm kJ 1 0.0002778 0.2388 101.97 kWh 3600 1 860 367000 kcal 4.1868 0.001163 1 427 kpm 0.00981 0.00000272 0.0000037 1 Performance kW Kcal/h kpm/s PS 1 kW 1 860 102 1 1 kcal/h 0.0011628 1 0.119 0.00158 1 kpm/s 0.0098067 8.43 1 0.01333 1 PS 0.7365498 632 75 1 eg.eurem.net
23. 23. Energy Fundamentals ThermodynamicsThermodynamics is the science of the interrelationship between work and heat on the one hand and the internal energy of a system. eg.eurem.net
24. 24. Energy Fundamentals The Main Theorems of Thermodynamics1st Main Theorem of Thermodynamics:The energy of an isolated system remains constant, i.e.energy can neither be created out of nothing, nor can itbe destroyed, it can only be converted from one forminto another.2nd Main Theorem of Thermodynamics:If no energy is introduced into a system nor removedfrom it, in all energy conversions the potential energy ofthe resulting state is lower than that of the initial state. eg.eurem.net
25. 25. Energy Fundamentals First Law of Thermodynamics The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes: The first law makes use of the key concepts of internal energy, heat, and system work. It is used extensively in the discussion of heat engines. The standard unit for all these quantities would be the joule, although they are sometimes expressed in calories or BTU. eg.eurem.net 25
26. 26. Energy Fundamentals It is typical for chemistry texts to write the first law as ΔU=Q+W. It is the same law, of course - the thermodynamic expression of the conservation of energy principle. It is just that W is defined as the work done on the system instead of work done by the system. eg.eurem.net 26
27. 27. Energy Fundamentals Enthalpy Four quantities called "thermodynamic potentials" are useful in the chemical thermodynamics of reactions and non-cyclic processes. They are internal energy, the enthalpy, the Helmholtz free energy and the Gibbs free energy. Enthalpy is defined by H = U + PV where P and V are the pressure and volume, and U is internal energy. Enthalpy is then a measurable state variable, since it is defined in terms of three other precisely definable state variables. It is somewhat parallel to the first law of thermodynamics for a constant pressure system eg.eurem.net 27
28. 28. Energy Fundamentals Internal Energy Internal energy is defined as the energy associated with the random, disordered motion of molecules. - For example, a room temperature glass of water sitting on a table has no apparent energy, either potential or kinetic . But on the microscopic scale it is a seething mass of high speed molecules traveling at hundreds of meters per second. If the water were tossed across the room, this microscopic energy would not necessarily be changed when we superimpose an ordered large scale motion on the water as a whole. U is the most common symbol used for internal energy eg.eurem.net 28
29. 29. Energy Fundamentals Internal energy consists of - thermal energy - chemical binding energy - potential energy of atomic nuclei - interactions with electric and magnetic dipoles eg.eurem.net
30. 30. Energy Fundamentals Gas Laws P*V = Rn*T P – Pressure (bar) V – Volume (m3) T – Absolute temperature (ºK) n – Number of moles R – Gas constant for ideal gases Rn – Specific gas constant eg.eurem.net
31. 31. Energy Fundamentals Gas Laws Compressing results in higher pressure Heat supply -> Volume expansion What happens when a piston gets locked? eg.eurem.net
32. 32. Energy Fundamentals Charles’ Law Boyle’s Law V = k PV = k T P and V T and V Ideal change change Gas Law n, R, T are P, n, R are constant constant PV = nRT P, V, and T change Gas Law n and R are constant Calculations Combined Gas Law PV = k T eg.eurem.net 32
33. 33. Energy Fundamentals Standard Temperature and Pressure (STP) P = pressure V = volume T = temperature (Kelvin) T = 0 oC or 273 K n = number of moles R = gas constant P = 1 atm = 101.3 kPa = 760 mm Hg Solve for constant (R) 1 mol = 22.4 L @ STP PV nT Recall: 1 atm = 101.3 kPa Substitute values: (1 atm) (22.4 L) = R R = 0.0821 atm L (101.3 kPa) = 8.31 kPa L (1 mole)(273 K) mol K ( 1 atm) mol K R = 0.0821 atm L / mol K or R = 8.31 kPa L / mol K eg.eurem.net 33
34. 34. Energy Fundamentals Gas Law #1 – Boyles’ Law (complete TREE MAP) 1 k P  P  “The pressure of a gas is V V inverse related to the k  constant of proportionality volume” PoVo  k Moles and Temperature PV  k are constant PoVo  PV eg.eurem.net 34
35. 35. Energy Fundamentals Gas Law #2 – Charles’ Law “The volume of a gas is Vo To  Vo  kTo directly related to the Vo temperature” k Pressure and Moles are To constant V k T Vo V  To T eg.eurem.net 35
36. 36. Energy Fundamentals Gas Law #3 – Gay-Lussac’s Law Po To  Po  kTo “The pressure of a gas is directly related to the Po temperature” k To Moles and Volume are P constant k T Po P  To T eg.eurem.net 36
37. 37. Energy Fundamentals Gas Law #4 – Avogadro’s Law “The volume of a gas is Vo no  Vo  kno directly related to the # Vo of moles of a gas” k Pressure and no Temperature are V constant k n Vo V  no n eg.eurem.net 37
38. 38. Energy Fundamentals Gas Law #5 – The Combined Gas Law P V  T  P V  kT o o o o o o You basically take Boyle’s PoVo Charles’ and Gay- k Lussac’s Law and To combine them together. PV Moles are constant k T PoVo PV  To T eg.eurem.net 38
39. 39. Energy Fundamentals Example Pure helium gas is admitted into a leak proof cylinder containing a movable piston. The initial volume, pressure, and temperature of the gas are 15 L, 2.0 atm, and 300 K. If the volume is decreased to 12 L and the pressure increased to 3.5 atm, find the final temperature of the gas. PoVo PV To PV  T  To T PoVo (12)(3.5)(300) T  420 K (15)(2) eg.eurem.net 39
40. 40. Energy Fundamentals Gas Law #6 – The IDEAL Gas Law All factors contribute! In the previous examples, the constant, k, represented a specific factor(s) that were constant. That is NOT the case here, so we need a NEW constant. This is called, R, the universal gas constant. PV  nT R  constant of proportionality J R  Universal Gas Constant  8.31 mol  K PV  nRT eg.eurem.net 40
41. 41. Energy Fundamentals Example A helium party balloon, assumed to be a perfect sphere, has a radius of 18.0 cm. At room temperature, (20 C), its internal pressure is 1.05 atm. Find the number of moles of helium in the balloon and the mass of helium needed to inflate the balloon to these values. 4 3 4 Vsphere  r   (0.18)3  0.0244 m3 3 3 T  20  273  293 K P  1.05atm  1.05x105 Pa PV (1.05 x105 )(0.0244) PV  nRT  n  n  1.052 moles RT (8.31)(293) eg.eurem.net 41
42. 42. Energy Fundamentals Efficiency Efficiency η η = Work / Energy < 100% Heat Noise Vibration Machine Losses Energy Work eg.eurem.net
43. 43. Energy Fundamentals Energy Flow, Heat Transfer Heat transfer occurs in three ways, convection, conduction and radiation, tell the system reach to Equilibrium eg.eurem.net
44. 44. Energy Fundamentals Conduction: When you give heat to an object the kinetic energy of the atoms at that point increases and they move more rapidly. Molecules or atoms collide to each other randomly and during this collision they transfer some part of their energy. With the same way, all energy transferred to the end of the object until it reaches thermal balance. As you can see from the picture, atoms at the bottom of the object first gain energy, their kinetic energies increase, they start to move and vibrate rapidly and collide other atoms and transfer heat. Conduction is commonly seen in solids and a little bit in liquids. In conduction, energy transfer is slow with respect to convection and radiation. Metals are good conductors of heat and electricity eg.eurem.net 44
45. 45. Energy Fundamentals Formula to calculate the conductivity gradient for a given system: q = - kA (Δ T/Δ n) Where Δ T/Δ n is the temperature gradient in the direction of area A, and k is the thermal conductivity constant obtained by experimentation in W/m.K. eg.eurem.net 45
46. 46. Energy Fundamentals Convection: n liquids and gases, molecular bonds are weak with respect to solids. When you heat liquids or gases, atoms or molecules which gain energy move upward, since their densities decrease with the increasing temperature. All heated atoms and molecules move upward and cooler ones sink to the bottom. This circulation continues until the system reaches thermal balance. This type of heat transfer does not work in solids because molecular bonds are not weak as in the case of fluids. Heat transfer is quick with respect to conduction eg.eurem.net 46
47. 47. Energy FundamentalsConvection Convection occurs when a solid state body exchanges heat with an adjacent liquid or gas (air). The movement of liquids or gases supports the convection. Newton: Q = h A (TSurface-TEnvironment) eg.eurem.net
48. 48. Energy Fundamentals Radiation: It is the final method of heat transfer. Different from conduction and convection, radiation does not need medium or particles to transfer heat. As it can be understood from the name, it is a type of electromagnetic wave and shows the properties of waves like having speed of light and traveling in a straight line. In addition to, it can travel also in vacuum just like sun lights. Radiation is a good method of transferring heat, in microwave ovens or some warming apparatus radiation is used as a method of heat transfer. eg.eurem.net 48
49. 49. Energy FundamentalsRadiation Thermal radiation does not need a thermal transfer medium. Radiation energy when meeting a surface will:  reflect  absorb  transfer (semi-transparent materials) Stefan Boltzman Law: eg.eurem.net
50. 50. Energy Fundamentals Insulation Losses Energy Flow = Tension / Resistance 350 +20°C Thermal Transfer through a Wall q = D T / R [W/m²] , 300Tension 0°C 40K -20°C 250 200 Q´= A x q [W] Transfer, performance Kelvin Heat Flow 150 Q = Q´ x t [kWh/a] Work 100 50 0 Wall Wall Thermal Resistance R [m²K/W] = S d [m] / l [W/mK] Thermal Transfer towards Air Wall Resistance Thermal Transfer of Air eg.eurem.net
51. 51. Energy Fundamentals Energy Optimisation - Boiler Distribution Losses Boiler Efficiency Quality of Combustion, Exhaust Gas Losses Burner eg.eurem.net
52. 52. Energy FundamentalsYour trainer: Mohamed Mahmoud Mahmoud AliPhone: +20 10 0525 4496Email: Encpc_mm@yahoo.comYour material: http://eg.eurem.net/display/EUREMEG/Training+MaterialsPartners:Supported by: eg.eurem.net 5252