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Pharma Engineering > Energy and Mass Balance > Flashcards

Energy and Mass Balance Flashcards

1
Q

what is a System? (learn how to draw it)

A

a system is made out of an equiment, the system border and its surrounding

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2
Q

Which kind of system do we have?

A

Open, closed and isolated system

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3
Q

open system is? (give an example)

A

can exchnage mass and energy with environment

system boundary is open

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4
Q

closed system is? (give example)

A

exchnage of energy, but not mass with enviroment

system boundary is closed

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5
Q

isolated system is? (give example)

A

neither exchange of mass or energy with enviroment

system boundary is closed

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6
Q

what is a state variables?

A

set of variables used to describe the mathematical “state” of a dynamical system

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7
Q

which state variables do we have

A

mechanical systems and the thermodynamics

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8
Q

what are typical state variables in mechanical systems?

A

position coordinates and velocities of mechnical parts

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9
Q

the state variables in a mechanical system are used for?

A

to determine the futre state of the objects in the system

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10
Q

how is the state variable in thermodynamics?

A

they are independent variable of a state function like internal energy, enthalpy and entropy

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11
Q

give some examples of state varaibales in thermodynamics

A

temperature, pressure and volume

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12
Q

what are heat and work?

A

are not state functions, but process functions

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13
Q

How can you group the state variables?

A

extensive property and intensive property

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14
Q

what are extensive property?

A

physical quantity whose value is proportional to the size of the system, which means the voulme of the system is dependent o th esize of the system (same mass)

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15
Q

give example of extensive property

A

amount of substance, engery, enthaly, entropy, mass, vloume, internal engery

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16
Q

what are intensive property?

A

phsical quantity whose value does not depend on the amount of substnace for which it is measured, which means it does not depends on the size of the system

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17
Q

give example of intensive property

A

temperature, pressure, concentration, density, viscosity and surface tension

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18
Q

what is the ratio of two extensive properties of the same onject or system?

A

the ratio is an intensive property

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19
Q

give examples of the ratio

A

mass/vloume=densiry

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20
Q

how can one obtained the specific property (intensive property?

A

divinding an extensive property of a system by its mass (specific volume in m^3/ kg)

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21
Q

a molar property is obtained by?

A

expressing an extensive property of a system on a molar mas, (specific molar volume in m^3/ mol)

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22
Q

what are colligative properties?

A

are properties of solution that depned on ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the nature of the chenical species present

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23
Q

examples of colligative properties

A

Relative lowering of vapor pressure
elevation of boiling point
depression of freezing point
Osmotic pressure

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24
Q

How is a process defined?

A

defined by change in a system

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25
Q

what is a thermodynamic process?

A

it is a system from an initial to a final state of thermodynamics equilibrium

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26
Q

what defined the process?

A

the initial and final states

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27
Q

what is a flow process?

A

it is a steady state of flows into and out of a vessel with definit wall properties

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28
Q

what does the quantities of primary concern describe?

draw the process

A

the states of the inflow and the outflow materials, and on the side, the transfers for eat, work, and kinetic and potential engergies for the vessel

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29
Q

what is the law of conservation of mass

A

that for any isolated system, the mass of the sytsem must reman constant over time

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30
Q

what does the law implies?

A

the mass can neither be created nor destroyed, but may be reaaranged in space

31
Q

give an example of conservation of mass

A

in a chemical reation: input mass= output mass

32
Q

what happend without the chemical reactions?

A

the mass and composition stays the same

33
Q

what is the case in an open system?

A

the mass inside the system at the initial state plus all mass that has entered the system during the process is equal to the mass inside the system at the final state plus all mass that leaved the system during the process

34
Q

what is the law of conservation of energy?

A

the total engery of an isolated sytem remains constant

35
Q

what does the law of conservation of engery means?

A

engery can neither be created nor destroyed, it can only be transformed or transferred from one form to another

36
Q

what happend in an open system with the energy?

A

the engery inside the system at the initial state plus all energy that has entered the system during the process is equal to the energy inside the system at the final state plus all energy that leaved the system during the process

37
Q

what is the equation of state?

A

a thermodynamic equation relating state varibales which describe the state of matter under a given ste of pyhsical condition such as pressure, volume

38
Q

what is a flow?

A

A flow is an amount G per time interval

39
Q

How can a actual flow be defined?

A

a flow at a certain time point is dG/dt = G(prime)
[unit of G/s]
change of the flow rate over time

40
Q

A continous flow is defined by

A

dG(prime)/t=0=G(double prime)=0

no change of the flow rate

41
Q

in case of a continuous flow the equation is

A

Do you know it?

42
Q

write down the equation od the mass balance in continuous flow

A

do you know it?

43
Q

what is accumulation? (know the equation)

A

Change of the quantity of material or mass of a material over tim i the system can be defined as

44
Q

what is a stationary system?

A

is a system with a constant system state over time

45
Q

how is the system in CM

give exceptions

A

is a stationary system

  • start up of the system
  • shut down of the system
  • distrubances
46
Q

where do we have the stationary system?

A

in the controlled state and not steady state, small distrubnaces are tolerated

47
Q

Energy balance in a closed system

A

ecange of energy between the system and its surrounding

48
Q

why do we have th heat transfer?

A

due to tempertaure difference

49
Q

unit of heat (Q)

A

joule

50
Q

unit of rate of heat transfer

A

J/s or W

51
Q

what is the heat capacity of an object?

A

i an amount of energy divided by a temperature chnage, which has the dimension (L2 M T(-2) K(-1)

52
Q

what is the SI unit of heat capacity?

A

J/K= kg m(2) s(-2) K(-1)

53
Q

what is the specific heat capacity of a substance?

A

is th heat capacity of a sample of the sunstnace divided by the mass of the sample (J/K kg)

54
Q

the specific heat varia with

A

temperature, and diferent from each state of matter

55
Q

example of the specific heat capacity

A

liquid water has the highest specific heats amoung common substance, but that of ice is low

56
Q

describe the energy balance in aclosed system?

A

ineraction between closed system and enviroment
not related to temperature difference
Work W in J

57
Q

equation of Work?

A 
W= -Fds
W(1-2)= -integral Fds=-F(s2-s1)
58
Q

what happend with the heat whyn a cylinder filled with gas and piston (know the equation)

A

system: as inside the cylinder

by applying heat, the cyliner will move

59
Q

how do one describe work due to gravitatiola forces? (know the equation)

A

do you know it?

chnage in potential engery

60
Q

work due to change in velocity (know the equation)

A

if an object is moving with a velocity u (1), then work to chnage velocity u(2) is
,leading to chnage in kinetic energy

61
Q

work due to shaft rotation

A

Movement along circumference is s

know the equation

62
Q

work due frictionla forces

A

W=-Ef, wokr done is overcome friction (J)

63
Q

what is now the total change in energy in a closed system? (know the eqaution balance

A

heat added to the system - work done by the system

64
Q

What does sensible heating means?

A

a process where we have the chnage in temperature

65
Q

What is the opposite of sensible heating process?

A

latent heating, where there is no change in temperature, only phase change

66
Q

give example of letent heating

A

more than one phase in equilibrium of a thermodynamic system
e.g water and heat: when reaching the boiling point of the water, the temperature will not change, but the water will evaporate, same in condensation, sublimation or re-sublimation

67
Q

what happend with the temp at sensible heating at constant pressure?

A

T(1)–> T(2), change in enthalpy

68
Q

write down the equation of the change in enthalpy

A

Do you know it

69
Q

How is the energy balance in an open system

A

Transfer of mass in addition to energy, which means the energy is associated to mass

70
Q

What is the equation of the energy balance in an open system

A

Do you know it?

71
Q

which energy can one see in a fluid elements (write down the equation)

A

internal, kinetic and potential engergy

72
Q

What is the engery balance in a steady state?

A

E(in)= E(out) ( no accumulation)

73
Q

Know the equation on slide 40

A

hope you know it

74
Q

What are the equation for energy balance if there is no chnage in kintic and potential energy

A

hope you know it

Pharma Engineering (8 decks)

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