Thermodynamics I
MECHANICAL ENGINEERING THERMODYNAMICS
THERMODYNAMIC SYSTEMS WORKFLOW EQUATION
SYSTEM MATTER ENERGY Steady Flow (WSF) -V (P1 - P2)
Closed NO YES Non-Flow (WNF) P (V2 – V1)
Open YES YES UNIT FOR FLOWRATE
Isolated NO NO Mass Flow Rate (𝑚̇) Kg/s
THERMODYNAMIC PROPERTIES Volumetric Flow Rate (𝑄) ̇ Ft3/s
Force, F (Mass)(g) → mg Molecular Flow Rate (𝑛̇ ) Mol/s
𝑚
Density, 𝜌 Mass/Volume → 𝑣 SPECIFIC HEAT RELATION
𝑣 1
Specific Volume, 𝑣 Volume/Mass → 𝑚 or R = Cp-Cv
𝜌
Specific Weight , 𝛾 Density(g) → 𝜌𝑔 k = Cp/Cv
Specific Gravity, SG Substance/Reference @ Constant Pressure 𝑘𝑅 ∆ℎ
REFERENCE Cp 𝐶𝑝 = =
𝛾𝑆𝑈𝐵𝑆𝑇𝐴𝑁𝐶𝐸 𝜌𝑆𝑈𝐵𝑆𝑇𝐴𝑁𝐶𝐸 𝑘 − 1 𝑚∆𝑇
Liquid : Water = @ Constant Volume 𝑅 ∆𝑈
𝛾𝑅𝐸𝐹𝐸𝑅𝐸𝑁𝐶𝐸 𝜌𝑅𝐸𝐹𝐸𝑅𝐸𝑁𝐶𝐸 𝐶𝑝 = =
Gas : Air Cv 𝑘 − 1 𝑚∆𝑇
Internal Energy, U (mass)(volume) IDEAL GAS FORMULA
Enthalpy, h (U+PV) PV = mRT Pressure and Temperature must be absolute
Entropy, s ∆𝑄
∆𝑆 = [ ]𝑟𝑒𝑣𝑒𝑟𝑠𝑖𝑏𝑙𝑒 GAS CONSTANT , R
𝑇
Pressure, P Pabs = Patm+Pgauge 𝑅̅
Any Gas
Pvac = Patm - Pabs 𝑀𝑊
(Force/Area) → F/A
Mass of Gas 𝑚 = 𝑛(𝑀𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑊𝑒𝑖𝑔ℎ𝑡)
Specific Heat, Q mCpΔT or mCvΔT
IDEAL GAS LAW
𝑉1 𝑉2
Charle’s Law Constant Pressure, P = C =
𝑇1 𝑇2
Boyle’s Law Constant Temperature, T = C 𝑃1 𝑉1 = 𝑃2 𝑉2
𝑃1 𝑃2
Gay Lussac’s Law Constant Volume, V = C =
𝑇1 𝑇2
𝑚1 𝑅1
Avogadro’s Constant Pressure and Temp =
𝑚2 𝑅2
𝑃1 𝑉1 𝑃2 𝑉2
Combined Gas Law - =
𝑇1 𝑇2
Daltons Law of Partial -
𝑃𝑇 = 𝑃1 + 𝑃2 … … … + 𝑃𝑛
Pressure
THERMODYNAMIC LAW
Zeroth Law, Thermal Equilibrium A
TA
If A=B and B=C, therefore A=C
B TC C
TB
1ST Law, Conservation of Energy
Energy cannot be created nor destroyed 1 SYSTEM 2
Q W
𝑃𝐸1 + 𝐾𝐸1 + ℎ1 + 𝑄 = 𝑊 + 𝑃𝐸2 + 𝐾𝐸2 + ℎ2
2ND Law of Thermodynamics
Natural processes moves toward greater disorder, or
entropy, or over time. Heat moves from Hot to Cold.
: High Temperature to Low Temperature
3rd Law of Thermodynamics CARNOT CYCLE FOR HEAT ENGINE
The entropy of a system approaches a constant value as the Efficiency, e
Temperature approaches absolute zero
𝑊𝑁𝐸𝑇 𝑇𝐻 − 𝑇𝐿 Qin QR
𝜂= =
MECHANICAL ENGINEERING THERMODYNAMICS
THERMODYNAMIC SYSTEMS WORKFLOW EQUATION
SYSTEM MATTER ENERGY Steady Flow (WSF) -V (P1 - P2)
Closed NO YES Non-Flow (WNF) P (V2 – V1)
Open YES YES UNIT FOR FLOWRATE
Isolated NO NO Mass Flow Rate (𝑚̇) Kg/s
THERMODYNAMIC PROPERTIES Volumetric Flow Rate (𝑄) ̇ Ft3/s
Force, F (Mass)(g) → mg Molecular Flow Rate (𝑛̇ ) Mol/s
𝑚
Density, 𝜌 Mass/Volume → 𝑣 SPECIFIC HEAT RELATION
𝑣 1
Specific Volume, 𝑣 Volume/Mass → 𝑚 or R = Cp-Cv
𝜌
Specific Weight , 𝛾 Density(g) → 𝜌𝑔 k = Cp/Cv
Specific Gravity, SG Substance/Reference @ Constant Pressure 𝑘𝑅 ∆ℎ
REFERENCE Cp 𝐶𝑝 = =
𝛾𝑆𝑈𝐵𝑆𝑇𝐴𝑁𝐶𝐸 𝜌𝑆𝑈𝐵𝑆𝑇𝐴𝑁𝐶𝐸 𝑘 − 1 𝑚∆𝑇
Liquid : Water = @ Constant Volume 𝑅 ∆𝑈
𝛾𝑅𝐸𝐹𝐸𝑅𝐸𝑁𝐶𝐸 𝜌𝑅𝐸𝐹𝐸𝑅𝐸𝑁𝐶𝐸 𝐶𝑝 = =
Gas : Air Cv 𝑘 − 1 𝑚∆𝑇
Internal Energy, U (mass)(volume) IDEAL GAS FORMULA
Enthalpy, h (U+PV) PV = mRT Pressure and Temperature must be absolute
Entropy, s ∆𝑄
∆𝑆 = [ ]𝑟𝑒𝑣𝑒𝑟𝑠𝑖𝑏𝑙𝑒 GAS CONSTANT , R
𝑇
Pressure, P Pabs = Patm+Pgauge 𝑅̅
Any Gas
Pvac = Patm - Pabs 𝑀𝑊
(Force/Area) → F/A
Mass of Gas 𝑚 = 𝑛(𝑀𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑊𝑒𝑖𝑔ℎ𝑡)
Specific Heat, Q mCpΔT or mCvΔT
IDEAL GAS LAW
𝑉1 𝑉2
Charle’s Law Constant Pressure, P = C =
𝑇1 𝑇2
Boyle’s Law Constant Temperature, T = C 𝑃1 𝑉1 = 𝑃2 𝑉2
𝑃1 𝑃2
Gay Lussac’s Law Constant Volume, V = C =
𝑇1 𝑇2
𝑚1 𝑅1
Avogadro’s Constant Pressure and Temp =
𝑚2 𝑅2
𝑃1 𝑉1 𝑃2 𝑉2
Combined Gas Law - =
𝑇1 𝑇2
Daltons Law of Partial -
𝑃𝑇 = 𝑃1 + 𝑃2 … … … + 𝑃𝑛
Pressure
THERMODYNAMIC LAW
Zeroth Law, Thermal Equilibrium A
TA
If A=B and B=C, therefore A=C
B TC C
TB
1ST Law, Conservation of Energy
Energy cannot be created nor destroyed 1 SYSTEM 2
Q W
𝑃𝐸1 + 𝐾𝐸1 + ℎ1 + 𝑄 = 𝑊 + 𝑃𝐸2 + 𝐾𝐸2 + ℎ2
2ND Law of Thermodynamics
Natural processes moves toward greater disorder, or
entropy, or over time. Heat moves from Hot to Cold.
: High Temperature to Low Temperature
3rd Law of Thermodynamics CARNOT CYCLE FOR HEAT ENGINE
The entropy of a system approaches a constant value as the Efficiency, e
Temperature approaches absolute zero
𝑊𝑁𝐸𝑇 𝑇𝐻 − 𝑇𝐿 Qin QR
𝜂= =
