open system

1. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com
First law of thermodynamics
Open System
‫أو‬ ‫لداخل‬ ‫إما‬ ‫متحركة‬ ‫طاقة‬
‫معين‬ ‫بمعدل‬ ‫النظام‬ ‫لخارج‬
‫الطاقة‬ ‫حفظ‬ ‫قانون‬
‫الكتلة‬ ‫حفظ‬ ‫قانون‬

2. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com

3. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com
Energy (E)
Heat (Q)
𝐻2 − 𝐻1
𝐻𝑔 − 𝐻𝑓
= 𝐻𝑓𝑔
C*m*ΔT
Cv*m*ΔT
Cp*m*ΔT
ሶ
𝑚 * H.V
Work (W)
T * 𝜔
1
2
𝑘(x2
2
− 𝑥1
2
)
ሶ
𝑊 = 𝑉 ∗ 𝐼
Internal
Energy (U)
Kinetic Energy
(KE)
1
2
𝑚𝑉2
Potential
Energy (PE)
M*g*z
Moving Flow
Work
P*V
▪Polytropic process
▪Isentropic process
▪Isothermal process
▪Isobaric process
▪Isochoric process
Conservation of Energy Principle

4. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com
Conservation of Mass Principle
State
1
State
2
m1
m2
𝒎𝟏 + 𝛴𝒎𝒊𝒏= 𝒎𝟐 + 𝛴𝒎𝒐𝒖𝒕
𝛴𝒎𝒊𝒏 − 𝛴𝒎𝒐𝒖𝒕= 𝒎𝟐 − 𝒎𝟏

5. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com
Energy (E)
Heat (Q)
𝐻2 − 𝐻1
𝐻𝑔 − 𝐻𝑓
= 𝐻𝑓𝑔
C*m*ΔT
Cv*m*ΔT
Cp*m*ΔT
ሶ
𝑚 * H.V
Work (W)
T * 𝜔
1
2
𝑘(x2
2
− 𝑥1
2
)
ሶ
𝑊 = 𝑉 ∗ 𝐼
Internal
Energy (U)
Kinetic Energy
(KE)
1
2
𝑚𝑉2
Potential
Energy (PE)
M*g*z
Moving Flow
Work
P*V
▪Polytropic process
▪Isentropic process
▪Isothermal process
▪Isobaric process
▪Isochoric process
Conservation of Energy Principle
𝒉: Specific enthalpy of fluid (kJ/kg).
V: Velocity of fluid (m/s)
z: Elevation of fluid (m)
𝒎: Mass of the fluid (kg)

6. Ahmed Medhat - Thermodynamics 1 - ahmedhatfa@hotmail.com
For different working substance used:
(1) Pure substances
(2) Ideal gases
Equation of state
𝑷𝟐 𝑽𝟐 =𝒎𝑹 𝑻𝟐
h= CpT
𝑷𝟏 𝑽𝟏 =𝒎𝑹 𝑻𝟏