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STEAM TABLE Nur Istianah,ST.,MT.,M.Eng
THP UB 2017
STEAM
• Water in gas phase
• Contain higher energy (heat)
• Has wide uses in food industry:
Preheating
Boiling
Sterilisation
Pasutisation
Cleaning
etc
Energy
Sources
Coal, oil, gas
Nuclear
Combustion (Boiler)
HEAT
Potential Energy
Mechanical energy (Turbin)
Electricity (Generator)
Light Calor
(Termal) Rotor
(mechanic) Saved energy
(Transformator)
Fire Tube boiler
Water Tube boiler
STEAM TABLE
• The steam tables are tabulated values for the properties of saturated and superheated steam.
• Specific volume is the volume in cubic feet occupied by 1 lb of water or steam under the conditions given.
• Enthalpy is the heat content of a unit mass of steam or water at the indicated temperature and pressure.
Boiling point
Boiling point
Saturated Vs Superheated steam
Sat. Liquid
Sat. Vapor
Super heated
Saturated steam
Superheated steam
STEAM TABLE
Example: At what vacuum would water boil at 80◦F?
Answer: 0.50683 psia
HEAT
• Heat is a kind of energy that is related to the temperature or phase change. It involved in thermodynamic transformations
• Sensible heat is defined as the energy transferred between two bodies at different temperatures
• Latent heat is the energy associated withphase transitions
ENDOTERM
System Energy
(steam)
Environment
Q>0
Steam in endothermic process
Steam (sat.vapor)
Steam (sat.liquid)
Susu (30°C)
Susu (60°C)
Sensible heat: mCp(T2-T1)
Latent heat: mhfg
Ilustasi pasterisasi susu dengan HE
Sensibel and latent heat
∆H = H2 – H1 = Q = m 𝐶𝑝𝑑𝑇 = 𝑚𝐶𝑝
𝑇2− 𝑇1 = 𝑄𝑇2
𝑇1
Q= mhf atau Q = mhv
Energy Balance
Total energy entering the system
Total energy leaving the system
Change in the total energy of system =
The first law of thermodynamic states that energy can be neither created nor destroyed.
Conservation Law
E in = Eout + Acc
For steady state process:
E in = Eout
Steam in energy balance
Q= 𝑚𝐶𝑝 𝑇2− 𝑇1 = ms(hg – hf)
For T2 > T1
Laten heat
Laten heat
-40
-20
0
20
40
60
80
100
120
140
Tem
pe
ratu
r
Entalpi
Heat of Fusion (+)
Heat of Vaporization (+)
Heat of Solidification (-)
Heat of Condensation (-)
Heat term
• Units of heat: joule (J), Calorie (Cal), or British thermal unit (Btu)
• 1 Calorie: amount of heat needed to raise the temperature of 1 gram of water by 1 C0 (from 14.50C to 15.50C)
• 1 Btu: amount of heat needed to raise the temperature of 1 lb of water by 1 F0 (from 630F to 640F)
• 1 cal = 10-3 kcal = 3.969 x 10-3 Btu = 4.186 J
Example
– 150 kg of apple was heated at 30oC until the temperature raise up to 50oC. Calculate the heat transfered if the apple has composistion; water 84,4%, Protein 0,2%, carbohydrate 14,5%, fat 0,6%, dan Ash 0,3% ?
– How much steam (saturated at 105oC) need for that process ?
– Defined: m = 150 kg
T1 = 0oC
T2 = 20oC
Xw = 0,844, Xp = 0,002,
Xh = 0,145, Xf = 0,006, Xa = 0,003
– Q = ?
– Solusi: ∆H = Q = m CpdT𝑇2
𝑇1
• For unknown Cp, Cp can be calculated from Siebel Eq.
•
• ∆H = Q = m CpdT𝑇2
𝑇1
= 150 kg x 3,76 kJ/kg.oC x (20-0) oC
= 11280 kJ
Cp = 1,424Xh +1,549Xp + 1,675Xf + 0,837Xa + 4,187Xw = 1,424 (0,145) +1,549 (0,002) + 1,675 (0,006) + 0,837 (0,003) + 4,187 (0,844) = 3,76 kJ/kg.K
Steam Table
Q= 𝑚𝐶𝑝 𝑇2− 𝑇1 = ms(hg – hf)
ms = Q/ (hg – hf)
ms = Q/hfg
ms = 11280 kJ
2243.54 kJ/kg
ms = 5.03 kg
THANKS FOR YOUR ATTENTION
The best person is one give something useful always
28/04/2017 Nur Istianah-KP1-neraca energi-2015
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