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Ch.8-Balances on Non-Reactive Processes and Energy Balances
n/a
48
Chemical Engineering
Undergraduate 2
04/06/2011

Additional Chemical Engineering Flashcards

 


 

Cards

Term

Changes in P

Temp Constant

(gas)

Definition

delta U hat = 0

delta H hat = 0

Term

Changes in P

Temp Constant

(liquid/solid)

Definition

delta U hat= 0

delta H hat = V(hat)*delta P

Term

Changes in Temp

P is constant

(gas)

Definition

delta U hat = integral from T1 to T2 of Cv dT

delta H hat = integral from T1 to T2 of Cp dT

 

Term

Changes in T

P is constant

(solid/liquid)

Definition

delta U hat = integral from T1 to T2 of Cv dT

delta H hat = integra from T1 to T2 of Cp dT

Term

Changes in T and P

(gas)

Definition

delta U hat= integral from T1 to T2 of CvdT

delta H dat = integral of T1 to T2 CpdT

Term

Change in T and P

(solid/liquid)

Definition

delta U hat = integral from T1 to T2 of CvdT

delta H hat = integra from T1 to T2 of CpdT + V(hat)*deltaP

Term

Phase Change at constant T and P

vaporization/condensation

 

Definition

delta U hat = (delta heat of vaporization)- R*T

delta H hat = dela heat of vaporization

Term

Phase Change at Constant T and P

(melting and freezing)

Definition
delta U hat = delta H hat = delta Heat of fusion (Hm)
Term
Cp or Heat Capacity at Constant Pressure
Definition

Cp = a +bt+ct^2+dt^3 or a+bt+ct^-2

Cp = Cv for liquids and solids

Cp = Cv + R for ideal gases

Term

m(dot) = (A*u1)/V(hat)1

where A = cross-sectional area - (D^2*pi)/4

Definition

therefore,

 

(D1^2*u1)/V(hat)1 = (D2^2*u2)/V(hat)2

Term
delta U hat
Definition
= delta H hat- deltaP*V(hat)
Term
Closed System Energy Balance
Definition
Q+W = delta U +deltaKE+deltaPE
Term
Open System
Definition
Q(dot)+ Ws(dot) = m(dot)*deltaH(hat)+m(dot)*deltaKE + m(dot)*deltaPE
Term
Turbines
Definition
-high pressure to shaft work
Term
Bernoulli Equation
Definition
(gc*deltaP)/density + deltau^2/2 + g*deltaz = 0 units in m^2/s^2
Term
Density of Water at 4 degrees C
Definition

pH20 = 1.000 g/cm^3

= 1000 kg/m^3

= 1 kg/L

= 62.43 lbm/ft^3

Term
gc
Definition
= (1 kg*m/s^2)/1N = (32.174 lbm*ft/s^2)/1 lbf
Term
gravity
Definition

 = 9.8066 m/s^2

= 32.174 ft/s^2

Term
Value of U
Definition
-for ideal gases, delta U is zero when delta T is zero
Term
Sign of Q and W
Definition

-Q is positive when added to the system

-W is positive when done on the system

Term
First Law of Thermodynamics
Definition

"law of conservation of energy"

total energy of the universe is constant, energy is neither created or destroyed

Term
Work(dot)
Definition
W(dot) = Ws(dot)+netWfl(dot)=Ws(dot)-delta(PVdot)
Term
Energy Equation with H
Definition
Q+W = deltaH + deltaEk + deltaEp (all dotted)
Term
Enthalpy 'H' and Internal Energy 'U' Expression
Definition
H = U + PV
Term
delta H
Definition
delta H = sigma(n(dot)*h(hat))out - sigma(n(dot)*h(hat))in
Term
Compressors
Definition
shaft work to high enthalpy(pressure)
Term
Pumps
Definition
Shaft work to high enthalpy (pressure)
Term
Nozzles
Definition
high enthalpy (pressure) to kinetic energy
Term
Diffusers
Definition
kinetic energy to high enthalpy (pressure)
Term
Kopps Rule
Definition
Cp for a molecular compound
(solid or liquid at or near 20 oC) is
the sum of contributions for each
element in the compound. (table in back of book for reference)
Term
Q at constant pressure
Definition

Q = deltaH

 

Term
Q at constant volume
Definition
Q = deltaU
Term
State Functions vs. Path Functions
Definition

state = u(hat) and h(hat)

path = Q and W (depend on path chosen)

Term
Function of H(hat)
Definition

H(hat) is a function of temperature, but not pressure for ideal gases

H(hat) is function of both temp and pressure for real gases and liquids

Term
State
Definition

A state is defined by all three of these:

 

Temperature

Pressure

Phase

Term
Reference of Steam Tables
Definition
Liquid water at the triple point, 0.01 degrees C and 0.00603 atm
Term
Cpmix(T)
Definition
Cpmix(T)= sigma(yi*Cpi(T)f)
Term
Estimation of Latent Heat of Vaporization???
Definition
Term
Absolute Humidity
Definition
ha = kg H20/kg DA
Term
Relative Humidity
Definition
hr = partial of H20/vp of H20 *100
Term
Dew Point
Definition
Temp at which humid air becomes saturated if cooled at constant pressure
Term
Humid Volume (m^3/kg DA)
Definition
the volume occupied by 1 kg DA plus the water vapor that it contains
Term
Specific Enthalpy of Saturated Air
Definition

H(hat) (kJ/kg DA)

Enthalpy of one kg of dry air plus the water it contains at saturation

Term
Heat of Solution
Definition

deltaHsoln = Hmix - (total enthalpies of pure solvent and solute)

at same temp and pressure

Term
Adiabatic Mixing
Definition
-occurs when heat is not exchanged with the surroundings
Term
Flash Calculations from Lecture 19 pg.20***
Definition
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