Applied Sciences Education Research Group (ASERG) Faculty of Applied Sciences Universiti Teknologi MARA Introduction to Thermodynamics – Learning the Lingo Thermodynamics Lecture Series

Quotes “Learning is not a spectator sport. Students do not learn much just sitting in classes listening to teachers, memorizing prepackaged assignments, and spitting out answers. They must talk about what they are learning, write reflectively about it, relate it to past experiences, and apply it to their daily lives. They must make what they learn part of themselves.” -Source:"Implementing the Seven Principles: Technology as Lever" by Arthur W. Chickering and Stephen C. Ehrmann

Introduction Objectives: 1.State the meaning of terminologies used in thermodynamics 2.State and identify origins and transformations of the many different forms of energy 3.State and discuss the characteristics and description of changes of and to a system 4.State and discuss the zeroth law of thermo.

CHAPTER 1 Basic Concepts of Thermodynamics – The science of Energy

FIGURE 1–5 Some application areas of thermodynamics. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-1

Steam Power Plant

FIGURE 1–13 System, surroundings, and boundary. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-3

FIGURE 1–14 Mass cannot cross the boundaries of a closed system, but energy can. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-4

Systems Energy cross in and out NO VOLUME CHANGE V initial = V final V =constant A rigid tank W in W out Q in Q out

Systems No mass or dynamic energy transfer An isolated system

FIGURE 1–17 A control volume may involve fixed, moving, real, and imaginary boundaries. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-5

Open system devices Heat Exchanger Throttle

Properties Properties: Temperature Pressure Volume Internal energy Entropy Properties: Temperature Pressure Volume Internal energy Entropy System The system can be either open or closed. The concept of a property still applies.

First Law of Thermodynamics System expands Movable boundary position gone up A change has taken place. System

Classes of properties ExtensiveExtensive –MASS, m –VOLUME, V –ENERGY, E ADDITIVE OVER ADDITIVE OVER THE SYSTEM. ExtensiveExtensive –MASS, m –VOLUME, V –ENERGY, E ADDITIVE OVER ADDITIVE OVER THE SYSTEM. IntensiveIntensive –TEMPERATURE, T –PRESSURE, P –DENSITY –Specific properties NOT ADDITIVE OVER THE SYSTEM. NOT ADDITIVE OVER THE SYSTEM. IntensiveIntensive –TEMPERATURE, T –PRESSURE, P –DENSITY –Specific properties NOT ADDITIVE OVER THE SYSTEM. NOT ADDITIVE OVER THE SYSTEM.

States StateState –A set of properties describing the condition of a system A change in any property, changes the state of that systemA change in any property, changes the state of that system StateState –A set of properties describing the condition of a system A change in any property, changes the state of that systemA change in any property, changes the state of that system

States EquilibriumEquilibrium –A state of balance –Thermal – temperature same at all points of system –Mechanical – pressure same at all points of system at all time –Phase – mass of each phase about the same –Chemical – chemical reaction stop EquilibriumEquilibrium –A state of balance –Thermal – temperature same at all points of system –Mechanical – pressure same at all points of system at all time –Phase – mass of each phase about the same –Chemical – chemical reaction stop

States State postulateState postulate –Must have 2 independent intensive properties to specify a state: Pressure specific internal energyPressure specific internal energy Pressure & specific volumePressure & specific volume Temperature & specific enthalpyTemperature & specific enthalpy State postulateState postulate –Must have 2 independent intensive properties to specify a state: Pressure specific internal energyPressure specific internal energy Pressure & specific volumePressure & specific volume Temperature & specific enthalpyTemperature & specific enthalpy

Processes and cycles

First Law of Thermodynamics System E 1, P 1, T 1, V 1 To E 2, P 2, T 2, V 2 Properties will change indicating change of state Mass out Mass in W in W out Q in Q out

FIGURE 1–25 A process between states 1 and 2 and the process path. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-6

FIGURE 1–28 The P-V diagram of a compression process. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-7

Thermodynamic process State 1 State 2 p V T

Example: Heating water Heat supplied by electricity or combustion. T1T1 T 1 +dTT 1 +2dTT2T2 T1T1 T 1 +dTT 1 +2dTT2T2 ….

System analysis of the slow heating process: Energy in via electricity or gas combustion System Boundary Neglect vapor loss T water T heater Assume no heat losses from sides and bottom.

System analysis for the water under equilibrium processes: Heating via an equilibrium process Energy In T water T heater Reversed process of slow cooling, which is reversible for the water Energy Out T water T heater

Processes & Equilibrium States What is the state of the system along the process path? What is the state of the system along the process path? p V T S1S1 S2S2 Process Path

Thermodynamic process T State 1 State 2 Process 1 p V Process 2

Thermodynamic cycles P1P1 P2P2 State 1 State 2 Process Path I Process Path II

Example: A steam power cycle. Steam Turbine Mechanical Energy to Generator Heat Exchanger Cooling Water Pump Fuel Air Combustion Products System Boundary for Thermodynamic Analysis System Boundary for Thermodynamic Analysis

Types of Energy

DynamicDynamic –Heat, Q –Work, W –Energy of moving mass, E mass Crosses in and out of system’s boundary Crosses in and out of system’s boundary DynamicDynamic –Heat, Q –Work, W –Energy of moving mass, E mass Crosses in and out of system’s boundary Crosses in and out of system’s boundary SystemSystem –Internal, U –Kinetic, KE –Potential, PE Changes occuring within system Changes occuring within system SystemSystem –Internal, U –Kinetic, KE –Potential, PE Changes occuring within system Changes occuring within system

Types of Energy Internal, UInternal, U –Sensible, Relates to temperature changeRelates to temperature change –Latent Relates to phase changeRelates to phase change Internal, UInternal, U –Sensible, Relates to temperature changeRelates to temperature change –Latent Relates to phase changeRelates to phase change

FIGURE 1–32 The various forms of microscopic energies that make up sensible energy. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-8

Types of Energy KineticKinetic –Changes with square of velocity KE = (mv 2 )/2, kJ; ke = v 2 /2, kJ/kgKE = (mv 2 )/2, kJ; ke = v 2 /2, kJ/kg –If velocity doubles, KE = (m(2v) 2 )/2 = (4mv 2 )/2, kJKE = (m(2v) 2 )/2 = (4mv 2 )/2, kJ –If decrease by ½, then KE = (m(v/2) 2 )/2 = (mv 2 )/8, kJKE = (m(v/2) 2 )/2 = (mv 2 )/8, kJ KineticKinetic –Changes with square of velocity KE = (mv 2 )/2, kJ; ke = v 2 /2, kJ/kgKE = (mv 2 )/2, kJ; ke = v 2 /2, kJ/kg –If velocity doubles, KE = (m(2v) 2 )/2 = (4mv 2 )/2, kJKE = (m(2v) 2 )/2 = (4mv 2 )/2, kJ –If decrease by ½, then KE = (m(v/2) 2 )/2 = (mv 2 )/8, kJKE = (m(v/2) 2 )/2 = (mv 2 )/8, kJ

Types of Energy PotentialPotential –Changes with vertical position, PE = mg(y f -y i ) = mgh, kJ; pe = gh, kJ/kgPE = mg(y f -y i ) = mgh, kJ; pe = gh, kJ/kg –If position above reference point doubles, PE = mg(2h), kJ; pe = g2h, kJ/kgPE = mg(2h), kJ; pe = g2h, kJ/kg –If decrease by ½, then PE = mgh/2, kJ; pe = gh/2, kJ/kgPE = mgh/2, kJ; pe = gh/2, kJ/kg PotentialPotential –Changes with vertical position, PE = mg(y f -y i ) = mgh, kJ; pe = gh, kJ/kgPE = mg(y f -y i ) = mgh, kJ; pe = gh, kJ/kg –If position above reference point doubles, PE = mg(2h), kJ; pe = g2h, kJ/kgPE = mg(2h), kJ; pe = g2h, kJ/kg –If decrease by ½, then PE = mgh/2, kJ; pe = gh/2, kJ/kgPE = mgh/2, kJ; pe = gh/2, kJ/kg

APPLICATION OF THE EQUILIBRIUM PRINCIPLE Zeroth Law of Thermodynamics Heat, and Temperature

Temperature & heat...

Heat & temperature Large body at constant temperature T 1 Large body at constant temperature T 1 Large body at constant temperature T 2 <T 1 Large body at constant temperature T 2 <T 1 Our sense of the direction of heat flow - from high to low temperature.

Temperature and heat are related. For metals, high heat flow - diathermal materials. T1T1T1T1 T1T1T1T1 T2T2T2T2 T2T2T2T2 For nonmetals, low heat flow - insulating. T1T1T1T1 T1T1T1T1 T2T2T2T2 T2T2T2T2

Caloric definition of temperature T1T1T1T1 T2T2T2T2 Isolating boundaries

Bring systems into thermal contact and surround with an isolating -- adiabatic -- boundary. Initial configuration of the closed, combined systems with a diathermal wall between the two. T1T1T1T1 T2T2T2T2

Heat is observed to flow from the subsystem at the higher temperature to that with the lower temperature. T1T1T1T1 T2T2T2T2

The final observed state of the total system is that when the temperatures are equal. Heat flow from subsystem 1 to subsystem 2 decreases in time. T 1,final T 2,final

Zeroth Law of Thermodynamics...

Thermal equilibrium T1T1T1T1 T2T2T2T2 T 1,final T 2,final Initial State: Final State:

Demonstration of the Zeroth Law Two subsystems in equilibrium with a third subsystem Adiabatic Diathermal B D A D C

Two systems in thermal equilibrium with a third system are in thermal equilibrium with each other. The Zeroth Law

FIGURE 1–41 The greenhouse effect on earth. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-11

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–45 P versus T plots of the experimental data obtained from a constant-volume gas thermometer using four different gases at different (but low) pressures. 1-12

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–47 Comparison of temperature scales. 1-13

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–51 Absolute, gage, and vacuum pressures. 1-14

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–55 The pressure is the same at all points on a horizontal plane in a given fluid regardless of geometry, provided that the points are interconnected by the same fluid. 1-15

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–57 The basic manometer. 1-16

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–61 Schematic for Example 1–

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–63 The basic barometer. 1-18

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 1–75 Some arrangements that supply a room the same amount of energy as a 300-W electric resistance heater. 1-19

FIGURE 1–39 Ground-level ozone, which is the primary component of smog, forms when HC and NOx react in the presence of sunlight in hot calm days. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-9

FIGURE 1–40 Sulfuric acid and nitric acid are formed when sulfur oxides and nitric oxides react with water vapor and other chemicals high in the atmosphere in the presence of sunlight. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-10

FIGURE 1–7 The definition of the force units. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-2