ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 General Physics Corporation 2003 THERMODYNAMIC UNITS AND PROPERTIES HEAT TRANSFER AND FLUID FLOW ACAD BASIC CURRICULUM

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 Learning Objectives 1.DESCRIBE and DIFFERENTIATE between absolute and relative temperature scales. 2.PERFORM conversions between: A.Absolute and relative temperature scales B.Fahrenheit and Celsius temperature scales C.Rankine and Kelvin temperature scales 3.DESCRIBE and DIFFERENTIATE between absolute and relative pressure scales. 4.PERFORM conversions between absolute, vacuum and relative pressure scales.

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 Learning Objectives 5.DEFINE the following terms: a.Compressible fluidf.Internal Energy b.Stateg.Heat c.Phaseh. Enthalpy d.Specific Volumei. Entropy e.Density 6.EXPLAIN how Pascal’s Law applies to contained fluids. 7.Using Pascal’s Law, A.PREDICT the behavior of the system containing a confined fluid B.CALCULATE any of the values for the application.

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 Learning Objectives 8.STATE the 1st and 2nd Law of Thermodynamics. 9.EXPLAIN the effect of temperature on a confined fluid. 10.Using the Combined Gas Law, DETERMINE the effect of changing temperature, pressure, or volume of a gas.

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Properties  Include pressure, temperature, specific volume, internal energy, ect.  State  The state of a substance can be defined by finding its pressure and temperature. (internal energy or specific volume)  When property changes, “a change of state” has occurred.  Phase  Describe molecular structure of a substance.  Include solids, liquid, vapors, gases, and plasmas.  Change in molecular or atomic spacing → Phase change  During the change of state, a phase change may or may not take place. PROPERTIES OF FLUIDS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 PROPERTIES OF FLUIDS LUBRICATION SYSTEM AIR COOLED OIL COOLER GEAR BOX STATE C 95°F 40 PSIG OIL PUMP STATE A 69°F 35 PSIG STATE B 70°F 45 PSIG C B PRESSURE TEMPERATURE CYCLE NO PHASE CHANGE PROCESS A B PROCESS BC PROCESS C A A Change in state of a substance with no change in phase of the substance Figure 1-1 Typical Oil System

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  PROPERTIES OF FLUIDS Equation 1-1

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Specific Volume Where: lit = liter, dm = deci meter, lbm = pound mass PROPERTIES OF FLUIDS 8 Table 1-1 Typical Units and Conversion Factors for Specific Volume

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  PROPERTIES OF FLUIDS Equation 1-2Equation 1-3Equation 1-4

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Definition  Force per unit of area  Units: pound-force per square inch (psi), Pascals (N/m 2 )  Pressure is dependent upon the area it is spread across.  Where: P =pressure F =force (lb f, N) A =area (in 2, ft 2, cm 2, m 2 ) PRESSURE Equation 1-5

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example 1-1. Block A exerts a force of 500 lbf to a surface area of 200 square inches. Calculate the pressure in psi Block B exerts a force of 500 lbf to a surface area of 100 square inches. Calculate the pressure in psi. PRESSURE 500lb f 20 in 5 in 10 in A 20 in 5 in 10 in B 500 lb f Figure 1-2 Effect of Contact Area for Solid Object 2.5 psi 5 psi

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example 1-3. Convert 5 psi to pounds force per square foot. PRESSURE 720 lb f /ft 2

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Pressure due to a column of liquid  Measured in terms of an equivalent column of liquid: water (H 2 O) or mercury (Hg), feet of water (ft ), inches of mercury (in Hg), millimeters of mercury (mm Hg)  Where: P =pressure absolute pressure scale (psia, Pa)  =density of the fluid (lb m /ft 3, kg/m 3 ) g =gravitational constant (32.17 ft/s 2, 9.81 m/s 2 ) z =height of fluid (in, ft, mm, m) PRESSURE P =  gz Equation 1-6

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example 1-4. Calculate the pressure exerted by the water 10 feet in the tank Calculate the pressure exerted by the water 30 feet in the tank. PRESSURE Density of water  = m ft lb 10 ft 20 ft 30 ft HINT: lb f = lb m x gravitational constant = lb m x ft/s2 Figure 1-4 Pressure Depends on Depth and Fluid Density 4.3 psi 12.9 psi

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example 1-6. Calculate the pressure exerted by seawater 30 feet in the tank. PRESSURE Density of seawater  = m ft lb 30 ft 13.4 psi

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Pressure gauge  Pressure above atmospheric pressure (lb f /in 2. gauge)  Vacuum gauge  Pressure below atmospheric pressure (psiv, in. Hg vac.)  Absolute pressure  Pressure relative to the pressure existing in a perfect vacuum (psia)  Standard atmospheric pressure at sea level  760 mm Hg = in. Hg = 33.9 ft of water = 14.7 psia PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 PRESSURE ATMOSPHERIC PRESSURE (AT SEA LEVEL) psia psia 0 PERFECT VACUUM 0 in Hgvac in Hgvac 0 psiv psiv 10 psig kPa kPa in Hg abs 0 in Hg abs in Hg abs 0 mm Hg abs mm Hg abs mm Hg abs atmosphere atmospheres 0 atmosphere Figure 1-5 Pressure Scale and Vacuum Relationships

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Relationship between P abs, P atm, P gauge, and P vac  Where: P abs = absolute pressure (psia) P atm = atmospheric pressure (psia) P gauge = gauge pressure (psig) P vac = vacuum (psiv) PRESSURE Equation 1-7

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2 PRESSURE Table 1-2 Typical Units and Conversion Factors for Pressure

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example 1-8. A gauge on a steam line drain indicates 20.3 psig. Calculate the absolute pressure in psia Convert 50 psia to psig Convert 40 psig to psia Convert 500 psig to psia Convert 5 psia to psiv Convert 0 psia to psiv Convert 2.5 psiv to psia. PRESSURE 35 psia 35.3 psig 54.7 psia psia 9.7 psiv 14.7 psiv 12.2 psiv

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Compressiblity  Noncompressible fluid: its density remains constant during the flow process. (example: water)  Compressible fluid: its volume changes when pressure is applied. (example: gas) PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Temperature scale  Relative scale Degrees Fahrenheit (  F, American Engineering Sys. of units) Degrees Celsius (  C, SI units) Both scales are based on the boiling and freezing points of water at a standard atmospheric pressure. PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Temperature scale  Absolute scale Rankine scale: one degree change in degrees Rankine (  R) = one degree change in degrees Fahrenheit (  F) Kelvin scale: one degree change in Kelvin (K or  K) = one degree change in degrees Celsius (  C) PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example Convert 0  F into degrees Celsius (  C) Convert 95  F into degrees Celsius (  C) Convert 32  C into degrees Fahrenheit (  F) Convert 58  C into degrees Kelvin (K) Convert 42  F into degrees Rankine (  R) PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Effects of temperature changes on fluid properties  Compressible fluid (gas) in a container Temperature increase → pressure varies in accordance with the combined gas laws  Uncompressible fluid (liquid) in a container Temperature increase → density decreases → liquid expands → pressure increase → failure of the container PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Internal Energy  Several microscopic forms of energy  Due to the rotation, vibration, translation, and interactions among the molecules of the substance  Units British thermal unit (Btu) SI unit (J, joule)  Specific internal energy of a substance Internal energy per unit mass Where: PRESSURE u =specific internal energy (Btu/lb m, J/kg) U =internal energy (Btu, J) m =mass (lb m, kg)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Heat  Thermal energy in transition or  Transfer of energy between substances of different temperatures.  Typical units and conversion factors of heat, energy, and power PRESSURE

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Pascal’s Law  Pressure applied to a confined fluid is transmitted undiminished throughout the confining vessel or system Pressure applied to a confined fluid is transmitted undiminished throughout the confining vessel or system  Fluid force acts equally, at right angles, to every portion of its container surface. PASCAL’S LAW

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example  A 10-pound input force is applied to the 2-inch square surface area of Piston A. What is the pressure developed?  1-23 Calculate the output force of Piston B. If this were a hydraulic jack, how much weight could the jack lift? PASCAL’S LAW

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Ideal gas  Any gas that perfectly obeys the gas laws.  At low pressures, all real gases behave like an ideal gas.  Monatomic gas (He, Ar, ect.) behavior is similar to perfect gases.  Ideal gas law  Where GAS LAWS P =pressure in absolute pressure scale (psia, Pa) V =volume (ft 3, m 3 ) n =number of moles of gas (mol) R =universal gas constant or T =temperature in in absolute temperature scale (  R, K)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Charles’s law  At low pressures, the volume of a gas at constant pressure is directly proportional to the absolute temperature of the gas.  At a constant pressure (P)  Valid only for absolute temperature measurements of low-pressure gases. GAS LAWS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Boyles’ Law  At low pressures, the volume of a gas at constant temperature is inversely proportional to the absolute pressure of the gas.  Valid only for absolute pressure measurements. GAS LAWS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Combined Gas Law  The relationship between changing properties of an ideal gas.  Where:  Assumption; 1) amount of gas (n) will not change 2) universal gas constant (R) will not change GAS LAWS P =pressure in absolute pressure scale (psia, Pa) V =volume (ft 3, m 3 ) T =temperature in in absolute temperature scale (  R, K)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Example A nitrogen bottle that is at 100 psia and 72°F is connnected to a nitrogen purge system but is isolated from the system. The bottle has a relief valve set to relieve at 120 psia. During the day the temperature of the bottle increases to 100°F. Will the relief valve open automatically? 1-25 An air compressor discharges into an air receiver and cycles off when the receiver equals 185 psia. During the compression, heat is added and the temperature in the receiver is 130°F. The compressor auto starts to maintain 165 psia. With no air loads on the receiver, at what temperature should the compressor restarts? GAS LAWS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  First law of thermodynamics  Energy cannot be created or destroyed. One kind of energy can be transformed into another kind of energy, but the sum of energies entering a process must equal the sum of energies stored in or leaving a process FIRST LAW OF THERMODYNAMICS Energy=Energy+Energy In Out Accumulated

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  General energy equation  Where: FIRST LAW OF THERMODYNAMICS PE =potential energy (ft lb f, J) KE =kinetic energy (ft lb f, J) P =pressure (lb f /ft 2, Pa) V =volume (ft 3, m 3 ) U =internal energy (Btu, J) Q =heat transferred to or from the system (Btu, J) W =work done by or to the system (ft lb f, J)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Enthalpy  The energy possessed by a working fluid  Where: FIRST LAW OF THERMODYNAMICS H =enthalpy (Btu, J) U =total internal energy (Btu, J) P=pressure (lb f /ft 2, Pa) V=total volume (ft 3, m 3 ) J=Joule's constant (778 ft lb f /Btu)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Enthalpy  Specific enthalpy:,,  Where: FIRST LAW OF THERMODYNAMICS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Enthalpy  Conversion factors for specific energy FIRST LAW OF THERMODYNAMICS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Second law of thermodynamics  No engine, actual or ideal, when operating in a cycle, can convert all heat supplied to it into work.  Non-flow processes SECOND LAW OF THERMODYNAMICS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Non-flow processes SECOND LAW OF THERMODYNAMICS

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Entropy  A measure of the available energy  A system with high entropy can do less useful work  Where SECOND LAW OF THERMODYNAMICS  S =change in entropy (Btu/°R, J/K)  =symbol for “defined as” Q =heat transferred (Btu, J) T abs =absolute temperature (°R, K)

General Physics Corporation 2003 ABC/ Heat Transfer and Fluid Flow / Chapter 1 / TP / REV.2  Entropy  Specific entropy  Where:  Conversion factors for specific entropy SECOND LAW OF THERMODYNAMICS s=specific entropy (Btu/lb m °R, J/kg K) S=entropy (Btu/°R, J/K) m=mass (lb m, kg)