Chapter 6: Using Entropy
|
|
- Magnus Burke
- 7 years ago
- Views:
Transcription
1 Chapter 6: Using Entropy Photo courtesy of U.S. Military Academy photo archives. Combining the 1 st and the nd Laws of Thermodynamics
2 ENGINEERING CONTEXT Up to this point, our study of the second law has been concerned primarily with what it says about systems undergoing thermodynamic cycles. In this chapter means are introduced for analyzing systems from the second law perspective as they undergo processes that are not necessarily cycles. The property entropy plays a prominent part in these considerations. The objective of the present chapter is to introduce entropy and show its use for thermodynamic analysis. The word energy is so much a part of the language that you were undoubtedly familiar with the term before encountering it in early science courses. This familiarity probably facilitated the study of energy in these courses and in the current course in engineering thermodynamics. In the present chapter you will see that the analysis of systems from a second law perspective is conveniently accomplished in terms of the property entropy. Energy and entropy are both abstract concepts. However, unlike energy, the word entropy is seldom heard in everyday conversation, and you may never have dealt with it quantitatively before. Energy and entropy play important roles in the remaining chapters of this book.
3 Introducing Entropy Corrollary of Second Law is introduced: Clasius Inequality Expands last chapter treatment of Two heat reservoirs to arbitrary number of heat reservoirs from which system receives energy by heat transfer or rejects energy by heat transfer Provides basis for two concepts of second law for analyzing closed and open systems: 1) Entropy as a Property ) Entropy Balance
4 Clasius Inequality For any thermodynamic cycle For any number of reservoirs: δq T b 0 δq Represents heat transfer at local system boundary location, b, at temperature T. Heat transfer may be positive (IN) or negative (OUT) T must be absolute temperature (Kelvin or Rankine) T always positive. Can NOT be negative (Celsius or Farenheit) Indicates integration over all processes and all parts of boundary
5 Clasius Inequality δq T b 0 Inequality has same meaning as with Kelvin-Planck: Equality applies when no INTERNAL IRREVERSIBILITES are present Inequality applies when INTERNAL IRREVERSIBILITES are present
6 Example of Multiple Heat Transfers & Ts Note: δ Q j δ Q 1 δ Q < 0 T j T 1 δ Q 3 Because heat transfer is OUT T 3 T δ Q δq T < 0 We will see later that this is and entropy transfer OUT
7 Reversible Heat Transfers δq j δq 1 T j T 1 δq 3 T 3 T δq Note: T i for reservoir AND at boundary; T must approach zero
8 Developing Clasius Inequality Proof provided in text
9 Alternate Statements of Clasius Inequality δq T b 0 δq + σ generated = T b 0 δq + σ cycle = T b 0 δq = σ T b cycle
10 Alternate Statements of Clasius Inequality δq = σ T b cycle σ σ σ cycle cycle cycle = > < δq + σ generated = T b 0 no irreversibilities present within the system 0 irreversibilities present within the system 0 impossible 0 Unlike mass and energy, which are conserved in every process, entropy in the presence of irreversibilities, is always produced.
11 Defining Entropy Change Quantity is a Property if and only if change in value between two states is independent of process (path) Will now show that the quantity is a Property δq T Reversible Meaning: For a REVERSIBLE process, the integral of the heat transfer divided by the local absolute temperature does NOT depend on the process This integral is therefore a PROPERTY We will give this property the name ENTROPY
12 Defining Entropy Change Quantity is a Property if and only if change in value between two states is independent of process (path) Processes A, B and C are INTERNALLY REVERSIBLE: σ cycle = σ = generated 0 C Cycle A-C: 1 δq δq + = σ T T 1 A C cycle 0 1 B A Cycle B-C: 1 δq δq + = σ T T 1 B C cycle 0
13 Defining Entropy Change Quantity is a Property if and only if change in value between two states is independent of process (path) Subtract: From: 1 δq δq + = σ T T 1 A 1 δq δq + = σ T T 1 B C C cycle cycle 0 0 Yielding: δq δq = T T 1 A 1 B
14 Defining Entropy Change C Since A and B are arbitrary, it follows that the integral is same for ANY Internally Reversible process. B A Thus, the Integral is a Property 1 Property is ENTROPY, S Entropy Change between states 1 & can be calculated for ANY Internally Reversible process as: S δq S = T 1 1 Int Rev
15 Entropy Change 1 C B A Differential basis defining entropy change: ds Entropy, S, is an Extensive property Intensive form is: s = S m δq = T Int Rev Units for Entropy: Extensive (SI): kj/k Extensive (English): BTU/ o R Intensive (SI): kj/kg K Intensive (English): BTU/lb o R
16 Defining Entropy Change Entropy change between states 1 & can be calculated for ANY Internally Reversible process as: B C A S δq S = T 1 1 Int Rev 1 Once calculated, Entropy difference is known Important Note: Entropy change between states 1 & is SAME whether process between 1 & is REVERSIBLE or IRREVERSIBLE. Just can t calculate change for IRREVERSIBLE processes.
17 Recognize that Entropy is still an abstract concept for you Like enthalpy we defined earlier, to gain appreciation for Entropy, need to understand: HOW to use it and WHAT it is used for
18 Retrieving Entropy Data Chapter 3: Means for retrieving property data from Tables, graphs, equations (and software) Emphasis on properties: P, v, T, h Which are required for: 1 st Law (energy conservation) and mass conservation For application of nd Law, entropy values usually needed Thus, we need to understand how to retrieve entropy data
19 Entropy Reference Value? Similarity to Energy with regard to absolute values of Entropy In most cases, absolute values not important- Only difference in Entropy between states is important B C A S =? S y y δq = Sx + T x Int Rev 1 S 1 =? S x is reference value S ref, S ref,1
20 Finding Entropy Data For Water and Refrigerants: Using Tables A- to A-18 and Tables A-E to A-18E
21 Tabulations of Water Properties Liquid Table A5, A5E Superheated Vapor Table A4, A4E T Sat Sat Liquid vapor f g Liquid-Vapor Mixture Table A, A3 (AE, A3E) Saturation Line v s
22 Two Saturated Tables for Each One for Saturated Temperature One for Saturated Pressure Sometimes we know T, sometimes P
23 Saturated Water Table A-, A3, AE, A3E T f g s
24 T Computing Entropy Value Under Dome f s It is not enough to know T, P in order to establish state under dome g S = S + S liquid vapor S Sliq Svap s = = + m m m mliqsf mvapsg s = + m m mvap x = m mliq = 1 x m s = (1 xs ) + xs (x= Quality) f g Need T or P, and one other property ( ) s = s + x s s = s + xis f g f f fg
25 Superheated Vapor Table A-4, A-4E 500 F T f 93 F g s
26 Compressed or Sub-cooled Liquid Table A-5, A-5E T f g Note: v sub-cooled tables are sparse because it is accurate to use incompressible liquid model
27 Text Examples
28 Problem solving using property diagrams is important Two commonly used property diagrams are: Temperature- Entropy (T-s diagram) Enthalpy- Entropy (Mollier diagram)
29 Graphical Entropy Data Temperature-Entropy Diagram Enthalpy-Entropy (Mollier) Diagram
30 Note general features See Figs A-7 & A-7E for water Temperature-Entropy Diagram
31 Figure A-7 Temperature entropy diagram for water (SI units)
32 Figure A-7E Temperature entropy diagram for water (English units).
33 Enthalpy-Entropy (Mollier) Diagram Note general features See Figs A-8 & A-8E for water
34 Figure A-8 Enthalpy entropy diagram for water (SI units)
35 Figure A-8E Enthalpy entropy diagram for water (English units)
36 Examples as per text here
37 Using T ds Equations Although entropy changes can be determined from: S δq S = T 1 1 Int Rev This requires knowledge of how heat transfer and Q vary during a process. In practice, entropy changes calculated from changes in other properties. Let s see how.
38 Using T ds Equations Note that T ds equations are also important with respect to: 1) Deriving other important properties ) Constructing property tables (Chapter 11)
39 Simple Compressible Substance Energy balance in differential form: IN = STORED + OUT Neglecting KE and PE δq = du + δw ( ) ( ) Int Rev Int Rev δ Q = ( ) Int Re v TdS δ W = ( ) Int Re v PdV First TdS Equation: TdS = du + PdV
40 Now consider second TdS equation Recall that, by definition: H = U + PV Form differential: dh = du + d( PV ) = du + PdV + VdP Rearrange: Substitute: du + PdV = dh VdP TdS = du + PdV Second TdS Equation: TdS = dh VdP
41 TdS = du + PdV Per Unit Mass: Tds = du + Pdv Tds = du + Pdv Per Mole: TdS = dh VdP Tds = dh vdp Per Unit Mass: Tds = dh vdp Per Mole:
42 Although internally reversible processes used to derive these equations, they apply generally- do not require reversible processes. Since all terms are properties, applies to irreversible and reversible processes (path-independent) Change in Entropy is independent of details of process
43 Text Example
44 Entropy Determination For Incompressible Substances Incompressible substance model is generally used with liquids and solids only, and assumes constant specific volume. ds ct ( ) dt du P du = + dv = = T T T T Specific heat depends on Temperature only. No difference between c P and c v c= c = c P v T s( T) s1( T1) = c( T) T T Specific heat may be constant: ( ) ( ) 1 dt s T s1 T1 = cln T T 1
45 Entropy Change of an Ideal Gas: TdS equations used to compute entropy change between states of Ideal Gas Tds = du + Pdv Tds = dh vdp For an Ideal Gas: du c ( T ) dt ds ds dh = c ( T ) dt Pv = = v p RT du = + T dh = T p P T v T dv dp c T = c T + R ( ) ( ) v Equation of State
46 Substitute Ideal Gas Relations into TdS equations: du = c ( T ) dt v dh = c ( T ) dt p Pv = RT ds ds du P = + dv T T dh v = dp T T dt ds c T R T = ( ) + s = stv v (, ) dt ds = c ( ) p T R T dv v dp P s = (, ) s T P
47 Can integrate these equations: dt dv ds = cv ( T) + R T v dt dp ds = c ( ) p T R T P T dt v (, ) 1( 1, 1) = v ( ) + ln T v T 1 s T v s T v c T R 1 T dt P ( ) ( ) ( ), 1 1, 1 = P ln T P T 1 s T P s T P c T R 1
48 Where Using Ideal Gas Tables: o Let s define a new variable: ( ) ( ) T Where is an arbitrary reference temperature Thus, in the equation: ( ) T o p s T dt = T c T T T dt P ( ) ( ) ( ), 1 1, 1 = P ln T P T 1 s T P s T P c T R T T T dt dt dt c T = c T c T = s T s T T T T s ( ) ( ) ( ) o( ) o( ) P P P T T T T 1
49 T dt P ( ) ( ) ( ), 1 1, 1 = P ln T P T 1 s T P s T P c T R Becomes: ( ) ( ) o( ) o P ( ) s T, P s1 T1, P1 = s T s T1 Rln P1 Where: 1 ( T) c s T s T dt T 0 0 p ( ) ( 1) = (kj/kg K or BTU/lb o R) T T This integral can be tabulated (Ideal Gas Tables) Tables A-, AE: 1
50 Table A-: Ideal Gas Properties of Air
51 Table A-E: Ideal Gas Properties of Air
52 Using Ideal Gas Tables: Similar approach for per mole basis s( T, P) s( T1, P1) s ( T) s ( T1) Rln P = P1 This integral can be tabulated (Ideal Gas Tables) Tables A-3, A3E: What if we have T and v information, rather than T and P? T dt v (, ) 1( 1, 1) = v ( ) + ln T v T 1 s T v s T v c T R 1
53 Ideal Gases with Constant Specific Heats T dt P (, ) 1( 1, 1) = P ( ) ln T P T 1 s T P s T P c T R T P st (, P) st ( 1, P1) = cp ln Rln T P T dt v (, ) 1( 1, 1) = v ( ) + ln T v T 1 s T v s T v c T R T v st (, v) stv ( 1, 1) = cv ln + Rln T v Use Specific heat data in Tables A-0 and A-1
54 Table A-0: Ideal Gas Specific Heats of Some Common Gases (kj/kg K)
55 Entropy Change for Closed Systems Internally Reversible Processes Entropy transfer ACCOMPANIES heat transfer For Internally Reversible Processes, Entropy change can be calculated from: This links heat transfer and entropy transfer ds δq = T Int Rev Note that for Closed, Internally Reversible system: Entropy INCREASES when heat transfer IN Entropy DECREASES when heat transfer OUT Entropy DOES NOT CHANGE when no heat transfer occurs
56 Entropy Change for Closed Systems Internally Reversible Processes Q & Entropy IN Q & Entropy OUT Q=0 S=0 Process where Q = 0 is: ADIABATIC (Insulated) For process that is ADIABATIC AND REVERSIBLE, The ENTROPY DOES NOT change. A constant Entropy process is called ISENTROPIC Thus, an ADIABATIC AND REVERSIBLE process is an ISENTROPIC process
57 Entropy Change Internally Reversible Processes For internally reversible processes, the area under the process curve represents the process Heat Transfer. ds δq = T Int Rev δ Q = ( ) Int Re v TdS Q Int Rev = TdS 1
58 Entropy Change Internally Reversible Processes 1) Heat transfer is entire area under T-S diagram ) Temperature must be absolute scale (Kelvin or Rankine), >0 δq ds T 3) Not valid for IRREVERSIBLE processes. Then area is NOT equal to heat transfer ds δq T δ Q TdS
59 Entropy Change Internally Reversible Processes Internally reversible processes are idealizations, but are found in all Carnot cycles. Carnot cycles on the T-S diagram. The diagram on the left represents a power cycle, and on the right, a refrigeration/heat pump cycle.
60 Internally reversible processes are idealizations, but are found in all Carnot cycles. Power Cycle Refrigeration Cycle Areas (+ or -) is magnitude of work: cycle η = 1 W = Q IN Q OUT W Q IN = T T C H Note how separation of T H and T C related to more work
61 Example in text
62 Entropy Balance: Closed Systems Rev Irrev, b Cycle consists of process, Irrev, where Internal Irreversibilities are present Followed by process, Rev, which is Internally Reversible 1 Note dotted line 1 δq δq + = σ T T 1 b IntRev cycle Subscript, b, designates evaluation of integral at boundary. Not necessary for second case because temperature is uniform throughout system
63 Entropy Balance: Closed Systems Rev Irrev Cycle consists of process, Irrev, where Internal Irreversibilities are present Followed by process, Rev, which is Internally Reversible 1 1 δq δq + = σ cycle = σ T T 1 b IntRev Where: S 1 δq S = T 1 Int Rev δq + ( S1 S) = σ T 1 b S δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production
64 Entropy Balance: Closed Systems S δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production Total entropy change associated with heat transfer (+ or -) AND entropy generated by IRREVERSIBILITIES (ALWAYS + or 0) Can INCREASE or DECREASE entropy by heat transfer IRREVERSIBILITY will ALWAYS INCREASE entropy ZERO entropy generated for a REVERSIBLE process
65 Entropy Balance: Closed Systems S 1 δq S = + σ T 1 b Entropy Change Entropy Transfer Entropy Production Since σ measures the effect of irreversibilities present within the system during a process, its value depends on the nature of the process, and thus is NOT a property S 1 δq S T 1 b
66 Some Examples Reversible, Adiabatic Process: S δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production 0 Adiabatic 0 Reversible A Reversible, Adiabatic Process: Is an Isentropic Process
67 Some Examples Is an Isentropic Process always a Reversible, Adiabatic Process? S δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production Suppose Entropy generation occurs by Irreversibility, Is there a way to decrease entropy to produce an Isentropic Process?
68 S Some Examples δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production All Reversible and Adiabatic Processes are Isentropic All Isentropic Processes are NOT Reversible and Adiabatic
69 S Some Examples δq S = + σ T ( ) 1 1 b Entropy Change = Entropy + Entropy Transfer Production What happens to Entropy for an Adiabatic, Irreversible Process?
70 Text Example
71 Other common forms of entropy balance: Q 1 For multiple heat transfers T 1 T Q T n Q n S Q j S1 = +σ j Tj (Note: Q could be + or -) S Q Q Q 1 n S1 = σ T1 T Tn Uniform Boundary Temperature, T b S Q S = +σ T 1 b
72 Other common forms of entropy balance: Q 1 Rate basis, multiple heat transfers T 1 T T n ds dt Q j = + σ j Tj Q Q n Q (Note: could be + or -) Differential form: ds δq = + δσ T b Note inexact differential notation for non-properties: Q and σ
73 Evaluating Entropy Production and Transfer Absolute value of entropy production not as useful as relative values: Can use this information to focus attention on components where most irreversibilties are produced
74 Example 6.: Irreversible process of water Example 6.3: Eval Min theoretical compression work Example 6.4: Pinpointing Irrevs
75 Increase in Entropy Principle: Closed Systems Show that the summation of the entropy changes of surroundings AND system must always increase or remain the same System Energy Transfer is Zero Surroundings Mass Transfer is Zero The larger system is an ISOLATED SYSTEM E] = 0 isol
76 System Energy Transfer is Zero Surroundings Mass Transfer is Zero The larger system is an ISOLATED SYSTEM = E] + E] = 0 E] 0 isol system Conservation of energy constrains possible processes: Energy changes in system and surroundings must balance However, not all such processes are possible ( nd Law) surr
77 System Energy Transfer is Zero Surroundings Mass Transfer is Zero Adiabatic 0 δq S] = isol T + σ 1 b isol S] = σ > 0 isol isol ] ] 0 S + S = σ > system surr isol
78 System Energy Transfer is Zero Surroundings Mass Transfer is Zero ] ] 0 S + S = σ > system surr isol Only processes that can occur are when entropy of Isolated System INCREASES. Entropy is Extensive: Entropy need NOT increase for BOTH System AND Surroundings, but SUM must increase. Direction of process and feasibility constrained Spontaneous processes tend to reach equilibrium- increasing S
79 Increase in Entropy Principle: Closed Systems The summation of the entropy changes of surroundings AND system must always increase (or remain the same for ideal) ] ] total S + S = σ system surr σ σ σ total total total = > < 0 ideal 0 actual 0 impossible
80 Examples in Text Example 6.5: Quenching metal bar Statistical Interpretation of Entropy
81 Statistical Interpretation of Entropy
82 Entropy Rate Balance: Control Volumes σ cv Inlets, i T j Q j Exits, e In + Gen = Stored + Out ds dt cv Q j = + ms i i ms e e + σ CV j T j i e Rate of entropy change Rates of entropy transfer Rate of entropy production
83 Entropy Rate Balance: Control Volumes When spatial variations occur, use Integral Form: S () cv t = ρsdv V j Q T j j q = A T b da ms = sρvda i i n i i A i d dt q ρsdv= da+ ( sρvda) ( sρvda) + σ n n gen V A T A i A i e e b
84 At Steady-State Entropy Rate Balance: Control Volumes Mass: Energy: 0 Entropy: i i = me e m Vi Ve = Qcv Wcv + mi hi + + gzi me he + + gze i e Q i i e e j Tj i e j 0 = + ms ms + σ CV
85 Single Inlet, Single Outlet Steady-State Control Volumes Mass: Energy: 0 m = m = m i e ( V ) i Ve Q cv W cv = + ( h h ) + + g z z m m ( ) i e i e Entropy: Q = + m ( s i s e) + j Tj j 0 σ CV 0 1 Qj σ = + ( si se) + m j T j m CV
86 Single Inlet, Single Outlet Steady-State Control Volumes Entropy: ( s s ) e Q i = + m j T j m 1 j σ CV Entropy passing from inlet to exit can: increase, decrease or remain constant. Second term RHS is positive or zero. Entropy/mass can only decrease if NET entropy flow OUT with heat transfer exceeds entropy Generation IN control volume When NO heat transfer (adiabatic): s ( ) CV e σ si = m
87 Single Inlet, Single Outlet Steady-State Control Volumes When NO heat transfer (Adiabatic): s ( ) CV e σ si = m Entropy increases when IRREVERSIBILTY present Entropy constant when REVERSIBLE: ISENTROPIC s e = s i
88
89
90
91 Examples 6.6 Entropy production in a steam turbine 6.7 Evaluating a performance claim 6.8 Entropy production in heat pump components
92 Isentropic Processes Showing isentropic processes is rapid/easy on T-s or h-s diagrams. Vertical lines: However, tabular data may still be used as well.
93 Isentropic Processes State 1 is in superheated region P 1 and T 1 used to get s 1 State is in superheated region Where s = s 1. Use P, T, other Isentropic process: s 3 = s = s 1 Use P 3 or T 3 to get s sat. IF s 3 < s sat, then state 3 is in saturated region. Get quality, x 3, then can get other properties.
94 Saturated Water Table A-, A3, AE, A3E T f g v
95 Superheated Vapor Table A-4, A-4E 500 F T f 93 F g v
96 Isentropic Processes: Ideal Gas o o P s( T, P) s1( T1, P1) = s ( T) s ( T1) Rln P1 s ( T ) s ( T ) Rln P = P1 s = s 1 If we have 3 of: T 1, T, P 1, P, then we can get the fourth Example: T 1 and two pressures, can get T : s T s T P 1exp R ( ) o( ) o 1 = P Use Tables A- and A-3 for AIR and A-E and A3E (English) for other gases
97 Isentropic Processes: Ideal Gas P ( ) ( ) s T s T = R o o exp 1 P1 Define Relative Pressure, P r o s T exp P R = P s T exp R ( ) o 1 1 ( ) r ( ) P T ( T) o s = exp R P P = P P r 1 r1 (for s 1 = s, AIR only) Use Tables A- for Relative Pressure as function of Temperature. Not truly a pressure. Don t confuse with Reduced Pressure (Compressibility Diagram)
98 Isentropic Processes: Ideal Gas v RT P 1 = v P RT 1 1 PG equation of state: v = RT P r ( ) Define Relative Volume, v r v v v v r 1 r1 ( T ) v RT P r1 1 = v1 P T RT1 RT vr ( T) = = f T Pr ( T) = (s 1 =s, AIR only) ( ) Use Tables A- for Relative Volume as function of Temperature. Not truly a volume. Don t confuse with Pseudo-reduced specific volume (Compressibility Diagram)
99
100 Isentropic Processes: Ideal Gas Assume constant specific heats and define ratio of specific heats, k: c p kr = k 1 R = k 1 T P st (, P) st ( 1, P1) = Cp ln Rln T P 1 1 T v st (, v) stv ( 1, 1) = Cv ln + Rln T v c v 1 1 k 1 k 1 T P v = = T1 P1 v ( k 1) k cp = 1 c v T P 0= Cp ln Rln T P 1 1 T v 0= Cv ln + Rln T v P P v = v k
101 Examples: 6.9 Isentropic process in Air 6.10 Air leaking from tank
102 Isentropic Efficiencies Comparing actual (adiabatic) and isentropic devices with - same inlet states - same exit pressure Turbines, compressors, nozzles and pumps Isentropic turbine efficiency: Actual versus Isentropic W Turbine 1 This helicopter gas turbine engine photo is courtesy of the U.S. Military Academy.
103 Isentropic Efficiencies (Adiabatic, Reversible) Turbines 1 st Law: W cv = h h m 1 nd Law: σ cv = s s m 1 0 This helicopter gas turbine engine photo is courtesy of the U.S. Military Academy. Typical: η T W Turbine 1
104 Isentropic Turbine Efficiency p Mollier chart (T-s) s (h 1 h ) Actual expansion s s Isentropic expansion (h 1 h s ) Note: W cv m ( h1 h) η T = = 1 W cv ( h1 h) s m s Accessible states: Q = 0; s > 0
105 Isentropic Turbine Efficiency (T-s) (Mollier chart better) p (h 1 h ) s Actual expansion (h 1 h s ) s s Isentropic expansion Note: W cv m ( h1 h) η T = = 1 W cv ( h1 h) s m s Accessible states: Q = 0; s > 0
106 Compressors and Pumps Reciprocating compressor Rotating compressors Common Form of 1 st Law: W V V = h1 h + g z1 z + m ( ) 1 ( ) [ W < 0 ]
107 Isentropic Compressor Efficiency (Gases) h s s T s p p 1 Actual compression (h h 1 ) Liquid (h s h 1 ) Isentropic compression s 1 T 1 Note: W cv m s ( hs h1) ηc = = 1 W cv ( h h1) m Accessible states: Q = 0; s > 0
108 Isentropic Efficiencies: Compressors (Gases) and Pumps (Liquids) Typical Isentropic Efficiencies of Compressors and Pumps: η c Pumps, assuming incompressible model: (will consider more detail later) η P = v P P ( ) h 1 h 1 s
109 Nozzles and Diffusers Common Form of 1 st Law: 0 V V ( ) 1 = h1 h +
110 Isentropic Nozzle Efficiency V 1 Nozzle V η = nozzle V V s / / Common for: ηnozzle 0.95
111 Examples: 6.11 Eval turbine work using Isentropic efficiency 6.1 Eval Isentropic turbine efficiency 6.13 Eval Isentropic nozzle efficiency 6.14 Eval Isentropic compressor efficiency
112 Special Cases: Evaluate Q & W for NO Internal Irreversibility Internally Reversible, Steady-State Flow One-inlet, One-Outlet: cv Heat Transfer: Q = m Int Rev 0 S.S Q ms s T cv 0 = + ( ) + σ CV Q cv ( s ) = T s m Tds T=T(s)
113 Special Cases (Internally Reversible): Heat Transfer and Work Work Transfer for Reversible or Irreversible: W m cv ( V ) 1 V Q cv = + ( h h ) + + g z z m ( ) 1 1 Internally Reversible, Steady-State Flow One-inlet, One-Outlet: W m cv ( ) ( V ) 1 V ( ) = Tds + h h + + g z z 1 1 Int Rev 1
114 Special Cases: Heat Transfer and Work Tds = dh vdp Thus, W m cv 1 Tds = h h vdp ( ) 1 1 ( V1 V ) Int Rev 1 ( ) = vdp + + g z z 1 KE and PE changes often negligible W m cv Int rev = 1 vdp
115 Note: magnitude of work per mass for gas or liquid is directly related to specific volume of fluid, v W m cv Int rev = 1 vdp Thus, for same pressure rise, magnitude of work per mass for liquid in pump (low v) is much smaller than for gas (larger v) in compressor Derived for Internally Reversible case, but qualitatively true for real, irreversible processes
116 Special Cases: Heat Transfer and Work Internally Reversible, Steady-State Flow: Q cv = m int rev 1 Tds W cv = m int rev 1 vdp (In many cases KE = PE = 0) Internally Reversible, Steady-State, Incompressible fluid: W cv = v P m int rev ( P) 1 Steady State, Reversible, no significant CV work terms (eg nozzles & diffusers): V V1 1 vdp + + g ( z z1) = This equation, used commonly in fluid mechanics, is known as the Bernoulli Equation 0
117 n PV = General: Work in Polytropic Processes constant Internally Reversible cv 1 n W = vdp = ( cons tan t ) m int 1 1 rev dp P 1 n W cv n = ( Pv Pv 1 1) (n 1) m n 1 int rev cv W P = ( Pv 1 1) m P int 1 rev ln (n=1)
118 Work in Polytropic Processes: Ideal Gas For Ideal Gases: n PV = W cv n = ( Pv Pv 1 1) (n 1) m n 1 int rev constant T T Equivalent to: Where: 1 1 k 1 k P = P W cv nr = ( T T 1) (ideal gas, n 1) m n 1 int rev ( n 1) n W nrt P = 1 (ideal gas, n 1) cv 1 m n 1 P1 int rev cv W P = RT ln (ideal gas, n=1) m P int 1 rev
119 Examples: 6.15 Polytropic compression of air
120 END
FUNDAMENTALS OF ENGINEERING THERMODYNAMICS
FUNDAMENTALS OF ENGINEERING THERMODYNAMICS System: Quantity of matter (constant mass) or region in space (constant volume) chosen for study. Closed system: Can exchange energy but not mass; mass is constant
More informationAPPLIED THERMODYNAMICS TUTORIAL 1 REVISION OF ISENTROPIC EFFICIENCY ADVANCED STEAM CYCLES
APPLIED THERMODYNAMICS TUTORIAL 1 REVISION OF ISENTROPIC EFFICIENCY ADVANCED STEAM CYCLES INTRODUCTION This tutorial is designed for students wishing to extend their knowledge of thermodynamics to a more
More informationME 201 Thermodynamics
ME 0 Thermodynamics Second Law Practice Problems. Ideally, which fluid can do more work: air at 600 psia and 600 F or steam at 600 psia and 600 F The maximum work a substance can do is given by its availablity.
More informationThermodynamics - Example Problems Problems and Solutions
Thermodynamics - Example Problems Problems and Solutions 1 Examining a Power Plant Consider a power plant. At point 1 the working gas has a temperature of T = 25 C. The pressure is 1bar and the mass flow
More informationExergy: the quality of energy N. Woudstra
Exergy: the quality of energy N. Woudstra Introduction Characteristic for our society is a massive consumption of goods and energy. Continuation of this way of life in the long term is only possible if
More informationThermochemistry. r2 d:\files\courses\1110-20\99heat&thermorans.doc. Ron Robertson
Thermochemistry r2 d:\files\courses\1110-20\99heat&thermorans.doc Ron Robertson I. What is Energy? A. Energy is a property of matter that allows work to be done B. Potential and Kinetic Potential energy
More informationThe Second Law of Thermodynamics
The Second aw of Thermodynamics The second law of thermodynamics asserts that processes occur in a certain direction and that the energy has quality as well as quantity. The first law places no restriction
More informationGibbs Free Energy and Chemical Potential. NC State University
Chemistry 433 Lecture 14 Gibbs Free Energy and Chemical Potential NC State University The internal energy expressed in terms of its natural variables We can use the combination of the first and second
More informationa) Use the following equation from the lecture notes: = ( 8.314 J K 1 mol 1) ( ) 10 L
hermodynamics: Examples for chapter 4. 1. One mole of nitrogen gas is allowed to expand from 0.5 to 10 L reversible and isothermal process at 300 K. Calculate the change in molar entropy using a the ideal
More informationwhere V is the velocity of the system relative to the environment.
Exergy Exergy is the theoretical limit for the wor potential that can be obtaed from a source or a system at a given state when teractg with a reference (environment) at a constant condition. A system
More informationSupplementary Notes on Entropy and the Second Law of Thermodynamics
ME 4- hermodynamics I Supplementary Notes on Entropy and the Second aw of hermodynamics Reversible Process A reversible process is one which, having taken place, can be reversed without leaving a change
More informationChapter 17. For the most part, we have limited our consideration so COMPRESSIBLE FLOW. Objectives
Chapter 17 COMPRESSIBLE FLOW For the most part, we have limited our consideration so far to flows for which density variations and thus compressibility effects are negligible. In this chapter we lift this
More informationAPPLIED THERMODYNAMICS. TUTORIAL No.3 GAS TURBINE POWER CYCLES. Revise gas expansions in turbines. Study the Joule cycle with friction.
APPLIED HERMODYNAMICS UORIAL No. GAS URBINE POWER CYCLES In this tutorial you will do the following. Revise gas expansions in turbines. Revise the Joule cycle. Study the Joule cycle with friction. Extend
More informationEnergy Conservation: Heat Transfer Design Considerations Using Thermodynamic Principles
Energy Conservation: Heat Transfer Design Considerations Using Thermodynamic Principles M. Minnucci, J. Ni, A. Nikolova, L. Theodore Department of Chemical Engineering Manhattan College Abstract Environmental
More informationChapter 18 Temperature, Heat, and the First Law of Thermodynamics. Problems: 8, 11, 13, 17, 21, 27, 29, 37, 39, 41, 47, 51, 57
Chapter 18 Temperature, Heat, and the First Law of Thermodynamics Problems: 8, 11, 13, 17, 21, 27, 29, 37, 39, 41, 47, 51, 57 Thermodynamics study and application of thermal energy temperature quantity
More informationProblem Set 3 Solutions
Chemistry 360 Dr Jean M Standard Problem Set 3 Solutions 1 (a) One mole of an ideal gas at 98 K is expanded reversibly and isothermally from 10 L to 10 L Determine the amount of work in Joules We start
More informationProblem Set 4 Solutions
Chemistry 360 Dr Jean M Standard Problem Set 4 Solutions 1 Two moles of an ideal gas are compressed isothermally and reversibly at 98 K from 1 atm to 00 atm Calculate q, w, ΔU, and ΔH For an isothermal
More informationEngineering Problem Solving as Model Building
Engineering Problem Solving as Model Building Part 1. How professors think about problem solving. Part 2. Mech2 and Brain-Full Crisis Part 1 How experts think about problem solving When we solve a problem
More informationWhen the fluid velocity is zero, called the hydrostatic condition, the pressure variation is due only to the weight of the fluid.
Fluid Statics When the fluid velocity is zero, called the hydrostatic condition, the pressure variation is due only to the weight of the fluid. Consider a small wedge of fluid at rest of size Δx, Δz, Δs
More informationChapter 2 Classical Thermodynamics: The Second Law
Chapter 2 Classical hermodynamics: he Second Law 2.1 Heat engines and refrigerators 2.2 he second law of thermodynamics 2.3 Carnot cycles and Carnot engines 2.4* he thermodynamic temperature scale 2.5
More informationC H A P T E R T W O. Fundamentals of Steam Power
35 C H A P T E R T W O Fundamentals of Steam Power 2.1 Introduction Much of the electricity used in the United States is produced in steam power plants. Despite efforts to develop alternative energy converters,
More informationUNDERSTANDING REFRIGERANT TABLES
Refrigeration Service Engineers Society 1666 Rand Road Des Plaines, Illinois 60016 UNDERSTANDING REFRIGERANT TABLES INTRODUCTION A Mollier diagram is a graphical representation of the properties of a refrigerant,
More informationThe Second Law of Thermodynamics
Objectives MAE 320 - Chapter 6 The Second Law of Thermodynamics The content and the pictures are from the text book: Çengel, Y. A. and Boles, M. A., Thermodynamics: An Engineering Approach, McGraw-Hill,
More informationThe first law: transformation of energy into heat and work. Chemical reactions can be used to provide heat and for doing work.
The first law: transformation of energy into heat and work Chemical reactions can be used to provide heat and for doing work. Compare fuel value of different compounds. What drives these reactions to proceed
More informationChapter 6 The first law and reversibility
Chapter 6 The first law and reversibility 6.1 The first law for processes in closed systems We have discussed the properties of equilibrium states and the relationship between the thermodynamic parameters
More informationProblem Set 1 3.20 MIT Professor Gerbrand Ceder Fall 2003
LEVEL 1 PROBLEMS Problem Set 1 3.0 MIT Professor Gerbrand Ceder Fall 003 Problem 1.1 The internal energy per kg for a certain gas is given by U = 0. 17 T + C where U is in kj/kg, T is in Kelvin, and C
More informationREFRIGERATION (& HEAT PUMPS)
REFRIGERATION (& HEAT PUMPS) Refrigeration is the 'artificial' extraction of heat from a substance in order to lower its temperature to below that of its surroundings Primarily, heat is extracted from
More informationFundamentals of THERMAL-FLUID SCIENCES
Fundamentals of THERMAL-FLUID SCIENCES THIRD EDITION YUNUS A. CENGEL ROBERT H. TURNER Department of Mechanical JOHN M. CIMBALA Me Graw Hill Higher Education Boston Burr Ridge, IL Dubuque, IA Madison, Wl
More informationQUESTIONS THERMODYNAMICS PRACTICE PROBLEMS FOR NON-TECHNICAL MAJORS. Thermodynamic Properties
QUESTIONS THERMODYNAMICS PRACTICE PROBLEMS FOR NON-TECHNICAL MAJORS Thermodynamic Properties 1. If an object has a weight of 10 lbf on the moon, what would the same object weigh on Jupiter? ft ft -ft g
More informationLesson. 11 Vapour Compression Refrigeration Systems: Performance Aspects And Cycle Modifications. Version 1 ME, IIT Kharagpur 1
Lesson Vapour Compression Refrigeration Systems: Performance Aspects And Cycle Modifications Version ME, IIT Kharagpur The objectives of this lecture are to discuss. Performance aspects of SSS cycle and
More informationAn analysis of a thermal power plant working on a Rankine cycle: A theoretical investigation
An analysis of a thermal power plant working on a Rankine cycle: A theoretical investigation R K Kapooria Department of Mechanical Engineering, BRCM College of Engineering & Technology, Bahal (Haryana)
More informationPhysics 5D - Nov 18, 2013
Physics 5D - Nov 18, 2013 30 Midterm Scores B } Number of Scores 25 20 15 10 5 F D C } A- A A + 0 0-59.9 60-64.9 65-69.9 70-74.9 75-79.9 80-84.9 Percent Range (%) The two problems with the fewest correct
More informationAC 2011-2088: ON THE WORK BY ELECTRICITY IN THE FIRST AND SECOND LAWS OF THERMODYNAMICS
AC 2011-2088: ON THE WORK BY ELECTRICITY IN THE FIRST AND SECOND LAWS OF THERMODYNAMICS Hyun W. Kim, Youngstown State University Hyun W. Kim, Ph.D., P.E. Hyun W. Kim is a professor of mechanical engineering
More informationTheory of turbo machinery / Turbomaskinernas teori. Chapter 4
Theory of turbo machinery / Turbomaskinernas teori Chapter 4 Axial-Flow Turbines: Mean-Line Analyses and Design Power is more certainly retained by wary measures than by daring counsels. (Tacitius, Annals)
More informationES-7A Thermodynamics HW 1: 2-30, 32, 52, 75, 121, 125; 3-18, 24, 29, 88 Spring 2003 Page 1 of 6
Spring 2003 Page 1 of 6 2-30 Steam Tables Given: Property table for H 2 O Find: Complete the table. T ( C) P (kpa) h (kj/kg) x phase description a) 120.23 200 2046.03 0.7 saturated mixture b) 140 361.3
More informationBoiler Calculations. Helsinki University of Technology Department of Mechanical Engineering. Sebastian Teir, Antto Kulla
Helsinki University of Technology Department of Mechanical Engineering Energy Engineering and Environmental Protection Publications Steam Boiler Technology ebook Espoo 2002 Boiler Calculations Sebastian
More informationCHAPTER 7 THE SECOND LAW OF THERMODYNAMICS. Blank
CHAPTER 7 THE SECOND LAW OF THERMODYNAMICS Blank SONNTAG/BORGNAKKE STUDY PROBLEM 7-1 7.1 A car engine and its fuel consumption A car engine produces 136 hp on the output shaft with a thermal efficiency
More informationThe First Law of Thermodynamics
Thermodynamics The First Law of Thermodynamics Thermodynamic Processes (isobaric, isochoric, isothermal, adiabatic) Reversible and Irreversible Processes Heat Engines Refrigerators and Heat Pumps The Carnot
More informationChapter 2 P-H Diagram Refrigeration Cycle Analysis & Refrigerant Flow Diagram
Chapter 2 P-H Diagram Refrigeration Cycle Analysis & Refrigerant Flow Diagram Copy Right By: Thomas T.S. Wan 温 到 祥 著 Sept. 3, 2008 All rights reserved Industrial refrigeration system design starts from
More informationAnswer, Key Homework 6 David McIntyre 1
Answer, Key Homework 6 David McIntyre 1 This print-out should have 0 questions, check that it is complete. Multiple-choice questions may continue on the next column or page: find all choices before making
More informationThermodynamics. Chapter 13 Phase Diagrams. NC State University
Thermodynamics Chapter 13 Phase Diagrams NC State University Pressure (atm) Definition of a phase diagram A phase diagram is a representation of the states of matter, solid, liquid, or gas as a function
More informationWe will try to get familiar with a heat pump, and try to determine its performance coefficient under different circumstances.
C4. Heat Pump I. OBJECTIVE OF THE EXPERIMENT We will try to get familiar with a heat pump, and try to determine its performance coefficient under different circumstances. II. INTRODUCTION II.1. Thermodynamic
More informationHow To Calculate The Performance Of A Refrigerator And Heat Pump
THERMODYNAMICS TUTORIAL 5 HEAT PUMPS AND REFRIGERATION On completion of this tutorial you should be able to do the following. Discuss the merits of different refrigerants. Use thermodynamic tables for
More informationUNIT 2 REFRIGERATION CYCLE
UNIT 2 REFRIGERATION CYCLE Refrigeration Cycle Structure 2. Introduction Objectives 2.2 Vapour Compression Cycle 2.2. Simple Vapour Compression Refrigeration Cycle 2.2.2 Theoretical Vapour Compression
More informationDifferential Relations for Fluid Flow. Acceleration field of a fluid. The differential equation of mass conservation
Differential Relations for Fluid Flow In this approach, we apply our four basic conservation laws to an infinitesimally small control volume. The differential approach provides point by point details of
More informationChapter 10: Refrigeration Cycles
Capter 10: efrigeration Cycles Te vapor compression refrigeration cycle is a common metod for transferring eat from a low temperature to a ig temperature. Te above figure sows te objectives of refrigerators
More informationStirling heat engine Internal combustion engine (Otto cycle) Diesel engine Steam engine (Rankine cycle) Kitchen Refrigerator
Lecture. Real eat Engines and refrigerators (Ch. ) Stirling heat engine Internal combustion engine (Otto cycle) Diesel engine Steam engine (Rankine cycle) Kitchen Refrigerator Carnot Cycle - is not very
More informationSTEAM TURBINE 1 CONTENT. Chapter Description Page. V. Steam Process in Steam Turbine 6. VI. Exhaust Steam Conditions, Extraction and Admission 7
STEAM TURBINE 1 CONTENT Chapter Description Page I Purpose 2 II Steam Turbine Types 2 2.1. Impulse Turbine 2 2.2. Reaction Turbine 2 III Steam Turbine Operating Range 2 3.1. Curtis 2 3.2. Rateau 2 3.3.
More informationTHERMODYNAMICS: COURSE INTRODUCTION
UNIFIED ENGINEERING 2000 Lecture Outlines Ian A. Waitz THERMODYNAMICS: COURSE INTRODUCTION Course Learning Objectives: To be able to use the First Law of Thermodynamics to estimate the potential for thermomechanical
More informationAir Water Vapor Mixtures: Psychrometrics. Leon R. Glicksman c 1996, 2010
Air Water Vapor Mixtures: Psychrometrics Leon R. Glicksman c 1996, 2010 Introduction To establish proper comfort conditions within a building space, the designer must consider the air temperature and the
More informationFEASIBILITY OF A BRAYTON CYCLE AUTOMOTIVE AIR CONDITIONING SYSTEM
FEASIBILITY OF A BRAYTON CYCLE AUTOMOTIVE AIR CONDITIONING SYSTEM L. H. M. Beatrice a, and F. A. S. Fiorelli a a Universidade de São Paulo Escola Politécnica Departamento de Engenharia Mecânica Av. Prof.
More informationTHE KINETIC THEORY OF GASES
Chapter 19: THE KINETIC THEORY OF GASES 1. Evidence that a gas consists mostly of empty space is the fact that: A. the density of a gas becomes much greater when it is liquefied B. gases exert pressure
More informationAvailability. Second Law Analysis of Systems. Reading Problems 10.1 10.4 10.59, 10.65, 10.66, 10.67 10.69, 10.75, 10.81, 10.
Availability Readg Problems 10.1 10.4 10.59, 10.65, 10.66, 10.67 10.69, 10.75, 10.81, 10.88 Second Law Analysis of Systems AVAILABILITY: the theoretical maximum amount of reversible work that can be obtaed
More informationCompressible Fluids. Faith A. Morrison Associate Professor of Chemical Engineering Michigan Technological University November 4, 2004
94 c 2004 Faith A. Morrison, all rights reserved. Compressible Fluids Faith A. Morrison Associate Professor of Chemical Engineering Michigan Technological University November 4, 2004 Chemical engineering
More informationChapter 5 MASS, BERNOULLI AND ENERGY EQUATIONS
Fluid Mechanics: Fundamentals and Applications, 2nd Edition Yunus A. Cengel, John M. Cimbala McGraw-Hill, 2010 Chapter 5 MASS, BERNOULLI AND ENERGY EQUATIONS Lecture slides by Hasan Hacışevki Copyright
More informationOPTIMAL DESIGN AND OPERATION OF HELIUM REFRIGERATION SYSTEMS *
OPTIMAL DESIGN AND OPERATION OF HELIUM REFRIGERATION SYSTEMS * Abstract Helium refrigerators are of keen interest to present and future particle physics programs utilizing superconducting magnet or radio
More informationIsentropic flow. Wikepedia
Isentropic flow Wikepedia In thermodynamics, an isentropic process or isoentropic process (ισον = "equal" (Greek); εντροπία entropy = "disorder"(greek)) is one in which for purposes of engineering analysis
More informationDET: Mechanical Engineering Thermofluids (Higher)
DET: Mechanical Engineering Thermofluids (Higher) 6485 Spring 000 HIGHER STILL DET: Mechanical Engineering Thermofluids Higher Support Materials *+,-./ CONTENTS Section : Thermofluids (Higher) Student
More informationMohan Chandrasekharan #1
International Journal of Students Research in Technology & Management Exergy Analysis of Vapor Compression Refrigeration System Using R12 and R134a as Refrigerants Mohan Chandrasekharan #1 # Department
More informationSheet 5:Chapter 5 5 1C Name four physical quantities that are conserved and two quantities that are not conserved during a process.
Thermo 1 (MEP 261) Thermodynamics An Engineering Approach Yunus A. Cengel & Michael A. Boles 7 th Edition, McGraw-Hill Companies, ISBN-978-0-07-352932-5, 2008 Sheet 5:Chapter 5 5 1C Name four physical
More informationDefine the notations you are using properly. Present your arguments in details. Good luck!
Umeå Universitet, Fysik Vitaly Bychkov Prov i fysik, Thermodynamics, 0-0-4, kl 9.00-5.00 jälpmedel: Students may use any book(s) including the textbook Thermal physics. Minor notes in the books are also
More informationPG Student (Heat Power Engg.), Mechanical Engineering Department Jabalpur Engineering College, India. Jabalpur Engineering College, India.
International Journal of Emerging Trends in Engineering and Development Issue 3, Vol. (January 23) EFFECT OF SUB COOLING AND SUPERHEATING ON VAPOUR COMPRESSION REFRIGERATION SYSTEMS USING 22 ALTERNATIVE
More informationFluid Mechanics Prof. S. K. Som Department of Mechanical Engineering Indian Institute of Technology, Kharagpur
Fluid Mechanics Prof. S. K. Som Department of Mechanical Engineering Indian Institute of Technology, Kharagpur Lecture - 20 Conservation Equations in Fluid Flow Part VIII Good morning. I welcome you all
More informationHEAT UNIT 1.1 KINETIC THEORY OF GASES. 1.1.1 Introduction. 1.1.2 Postulates of Kinetic Theory of Gases
UNIT HEAT. KINETIC THEORY OF GASES.. Introduction Molecules have a diameter of the order of Å and the distance between them in a gas is 0 Å while the interaction distance in solids is very small. R. Clausius
More informationThermodynamics AP Physics B. Multiple Choice Questions
Thermodynamics AP Physics B Name Multiple Choice Questions 1. What is the name of the following statement: When two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium
More informationPERFORMANCE ANALYSIS OF VAPOUR COMPRESSION REFRIGERATION SYSTEM WITH R404A, R407C AND R410A
Int. J. Mech. Eng. & Rob. Res. 213 Jyoti Soni and R C Gupta, 213 Research Paper ISSN 2278 149 www.ijmerr.com Vol. 2, No. 1, January 213 213 IJMERR. All Rights Reserved PERFORMANCE ANALYSIS OF VAPOUR COMPRESSION
More informationChapter 7 Energy and Energy Balances
CBE14, Levicky Chapter 7 Energy and Energy Balances The concept of energy conservation as expressed by an energy balance equation is central to chemical engineering calculations. Similar to mass balances
More informationHigh Speed Aerodynamics Prof. K. P. Sinhamahapatra Department of Aerospace Engineering Indian Institute of Technology, Kharagpur
High Speed Aerodynamics Prof. K. P. Sinhamahapatra Department of Aerospace Engineering Indian Institute of Technology, Kharagpur Module No. # 01 Lecture No. # 06 One-dimensional Gas Dynamics (Contd.) We
More informationChemistry 13: States of Matter
Chemistry 13: States of Matter Name: Period: Date: Chemistry Content Standard: Gases and Their Properties The kinetic molecular theory describes the motion of atoms and molecules and explains the properties
More informationGive all answers in MKS units: energy in Joules, pressure in Pascals, volume in m 3, etc. Only work the number of problems required. Chose wisely.
Chemistry 45/456 0 July, 007 Midterm Examination Professor G. Drobny Universal gas constant=r=8.3j/mole-k=0.08l-atm/mole-k Joule=J= Nt-m=kg-m /s 0J= L-atm. Pa=J/m 3 =N/m. atm=.0x0 5 Pa=.0 bar L=0-3 m 3.
More informationDifferential Balance Equations (DBE)
Differential Balance Equations (DBE) Differential Balance Equations Differential balances, although more complex to solve, can yield a tremendous wealth of information about ChE processes. General balance
More informationCO 2 41.2 MPa (abs) 20 C
comp_02 A CO 2 cartridge is used to propel a small rocket cart. Compressed CO 2, stored at a pressure of 41.2 MPa (abs) and a temperature of 20 C, is expanded through a smoothly contoured converging nozzle
More informationTechnical Thermodynamics
Technical Thermodynamics Chapter 2: Basic ideas and some definitions Prof. Dr.-Ing. habil. Egon Hassel University of Rostock, Germany Faculty of Mechanical Engineering and Ship Building Institute of Technical
More informationAkton Psychrometric Chart Tutorial and Examples
Akton Psychrometric Chart Tutorial and Examples December 1999 Akton Associates Inc. 3600 Clayton Road, Suite D Concord, California 94521 (925) 688-0333 http://www.aktonassoc.com Copyright 1999 Akton Associates
More informationPART 1 THE SECOND LAW OF THERMODYNAMICS
PART 1 THE SECOND LAW OF THERMODYNAMICS PART 1 - THE SECOND LAW OF THERMODYNAMICS 1.A. Background to the Second Law of Thermodynamics [IAW 23-31 (see IAW for detailed VWB&S references); VN Chapters 2,
More informationChapter 1 Classical Thermodynamics: The First Law. 1.2 The first law of thermodynamics. 1.3 Real and ideal gases: a review
Chapter 1 Classical Thermodynamics: The First Law 1.1 Introduction 1.2 The first law of thermodynamics 1.3 Real and ideal gases: a review 1.4 First law for cycles 1.5 Reversible processes 1.6 Work 1.7
More informationTopic 3b: Kinetic Theory
Topic 3b: Kinetic Theory What is temperature? We have developed some statistical language to simplify describing measurements on physical systems. When we measure the temperature of a system, what underlying
More informationDOE FUNDAMENTALS HANDBOOK THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW Volume 1 of 3
DOE-HDBK-1012/1-92 JUNE 1992 DOE FUNDAMENTALS HANDBOOK THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW Volume 1 of 3 U.S. Department of Energy Washington, D.C. 20585 FSC-6910 Distribution Statement A. Approved
More informationAME 50531: Intermediate Thermodynamics Homework Solutions
AME 50531: Intermediate Thermodynamics Homework Solutions Fall 2010 1 Homework 1 Solutions 1.1 Problem 1: CPIG air enters and isentropic nozzle at 1.30 atm and 25 C with a velocity of 2.5 m/s. The nozzle
More informationThis chapter deals with three equations commonly used in fluid mechanics:
MASS, BERNOULLI, AND ENERGY EQUATIONS CHAPTER 5 This chapter deals with three equations commonly used in fluid mechanics: the mass, Bernoulli, and energy equations. The mass equation is an expression of
More informationIntroduction to the Ideal Gas Law
Course PHYSICS260 Assignment 5 Consider ten grams of nitrogen gas at an initial pressure of 6.0 atm and at room temperature. It undergoes an isobaric expansion resulting in a quadrupling of its volume.
More informationAN INTRODUCTION TO THE CONCEPT OF EXERGY AND ENERGY QUALITY. Truls Gundersen
AN INRODUION O HE ONEP OF EXERGY AND ENERGY QUALIY by ruls Gundersen Department of Energy and Process Engineering Norwegian University of Science and echnology rondheim, Norway Version 4, March 211 ruls
More informationThe First Law of Thermodynamics
The First aw of Thermodynamics Q and W are process (path)-dependent. (Q W) = E int is independent of the process. E int = E int,f E int,i = Q W (first law) Q: + heat into the system; heat lost from the
More informationDevelopment of a model for the simulation of Organic Rankine Cycles based on group contribution techniques
ASME Turbo Expo Vancouver, June 6 10 2011 Development of a model for the simulation of Organic Rankine ycles based on group contribution techniques Enrico Saverio Barbieri Engineering Department University
More informationTHE IDEAL GAS LAW AND KINETIC THEORY
Chapter 14 he Ideal Gas Law and Kinetic heory Chapter 14 HE IDEAL GAS LAW AND KINEIC HEORY REIEW Kinetic molecular theory involves the study of matter, particularly gases, as very small particles in constant
More informationThe final numerical answer given is correct but the math shown does not give that answer.
Note added to Homework set 7: The solution to Problem 16 has an error in it. The specific heat of water is listed as c 1 J/g K but should be c 4.186 J/g K The final numerical answer given is correct but
More informationWarm medium, T H T T H T L. s Cold medium, T L
Refrigeration Cycle Heat flows in direction of decreasing temperature, i.e., from ig-temperature to low temperature regions. Te transfer of eat from a low-temperature to ig-temperature requires a refrigerator
More informationHeat and Work. First Law of Thermodynamics 9.1. Heat is a form of energy. Calorimetry. Work. First Law of Thermodynamics.
Heat and First Law of Thermodynamics 9. Heat Heat and Thermodynamic rocesses Thermodynamics is the science of heat and work Heat is a form of energy Calorimetry Mechanical equivalent of heat Mechanical
More informationC H A P T E R O N E FUNDAMENTALS OF ENERGY CONVERSION
1 C H A P T E R O N E FUNDAMENTALS OF ENERGY CONVERSION 1.1 Introduction Energy conversion engineering (or heat-power engineering, as it was called prior to the Second World War), has been one of the central
More informationStandard Free Energies of Formation at 298 K. Average Bond Dissociation Energies at 298 K
1 Thermodynamics There always seems to be at least one free response question that involves thermodynamics. These types of question also show up in the multiple choice questions. G, S, and H. Know what
More informationPhys222 W11 Quiz 1: Chapters 19-21 Keys. Name:
Name:. In order for two objects to have the same temperature, they must a. be in thermal equilibrium.
More informationThermodynamics. Thermodynamics 1
Thermodynamics 1 Thermodynamics Some Important Topics First Law of Thermodynamics Internal Energy U ( or E) Enthalpy H Second Law of Thermodynamics Entropy S Third law of Thermodynamics Absolute Entropy
More informationdu u U 0 U dy y b 0 b
BASIC CONCEPTS/DEFINITIONS OF FLUID MECHANICS (by Marios M. Fyrillas) 1. Density (πυκνότητα) Symbol: 3 Units of measure: kg / m Equation: m ( m mass, V volume) V. Pressure (πίεση) Alternative definition:
More information1 CHAPTER 7 THE FIRST AND SECOND LAWS OF THERMODYNAMICS
1 CHAPER 7 HE FIRS AND SECOND LAWS OF HERMODYNAMICS 7.1 he First Law of hermodynamics, and Internal Energy he First Law of thermodynamics is: he increase of the internal energy of a system is equal to
More information) and mass of each particle is m. We make an extremely small
Umeå Universitet, Fysik Vitaly Bychkov Prov i fysik, Thermodynamics, --6, kl 9.-5. Hjälpmedel: Students may use any book including the textbook Thermal physics. Present your solutions in details: it will
More informationDiesel Cycle Analysis
Engineering Software P.O. Box 1180, Germantown, MD 20875 Phone: (301) 540-3605 FAX: (301) 540-3605 E-Mail: info@engineering-4e.com Web Site: http://www.engineering-4e.com Diesel Cycle Analysis Diesel Cycle
More informationSIMULATION OF THERMODYNAMIC ANALYSIS OF CASCADE REFRIGERATION SYSTEM WITH ALTERNATIVE REFRIGERANTS
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6340 (Print) ISSN 0976 6359
More informationOptimal operation of simple refrigeration cycles Part I: Degrees of freedom and optimality of sub-cooling
Computers and Chemical Engineering 31 (2007) 712 721 Optimal operation of simple refrigeration cycles Part I: Degrees of freedom and optimality of sub-cooling Jørgen Bauck Jensen, Sigurd Skogestad Department
More informationCHAPTER 14 THE CLAUSIUS-CLAPEYRON EQUATION
CHAPTER 4 THE CAUIU-CAPEYRON EQUATION Before starting this chapter, it would probably be a good idea to re-read ections 9. and 9.3 of Chapter 9. The Clausius-Clapeyron equation relates the latent heat
More informationChapter 6 Thermodynamics: The First Law
Key Concepts 6.1 Systems Chapter 6 Thermodynamics: The First Law Systems, States, and Energy (Sections 6.1 6.8) thermodynamics, statistical thermodynamics, system, surroundings, open system, closed system,
More information