chapter 3

properties of pure substances

what is pure substance???

A substances that has fixed chemical composition throughout is called a pure substances.

PHASE OF A PURE SUBSTANCES


PHASE-CHANGE PROCESSES OF PURE SUBSTANCES

compressed liquid = water exist in the liquid phase
saturated liquid = a liquid that is about to vaporize
saturated vapor = a vapour that is about to condense
superheated vapor = a vapour is not about to condense



PPROPERTY DIAGRAMS FOR PHASE-CHANGE PROCESSES

1) THE T-V DIAGRAM

To read and to know the values in the diagram,we must refer to table A-5 which is at the back of thermodynamics book.At the liquid-vapour saturation region,the first point of the straight is called vf-the specific volume of the liquid.at the last point of the straight is called vg-the specific volume of the vapour.All the superheated vapour states are located to the right of the saturated vapour line is called the superheated vapour region.to read the value of the superheated vapour region must to refer at A-6 table.

2)THE P-V DIAGRAM

3)THE P-T DIAGRAM

4)THE P-V-T SURFACES


ENTHALPHY-A COMBINATION PROPERTY

h=u+pv (KJ/KG)
H=U+PV (KJ)

SATURATED LIQUID AND SATURATED VAPOR STATES

Vf - specific volume of saturated liquid
Vg - specific volume of saturated vapor
Vfg - differences between Vg and Vf.

SATURATED LIQUID-VAPOR MIXTURE.

X - mvapor/mtotal
V - mv
Mtotal = Mliquid + Mvapour = Mf + Mg

COMPRESSED LIQUID

h = h + v (p2-p1)

The ideal-gas equation of state

Any equation that relates pressure,temperature,and specific volume of a substances is called an equation state.

P = R (T/V)

PV = RT

R= Ru/M

Chapter 2 thermodynamic

Alright guys time for next lesson. In the previous chapter we already know about the law of thermodynamic and also most of the introduction of what is about thermodynamic. Now we move to chapter 2 which is Energy, Energy Transfer, and General Energy Analysis

CHAPTER 2

Introduction

       In this chapter we will learn about the energy. All type of energy that are involve in general energy system analysis. Plus we will study about heat and work which also involved in the energy analysis. The first law of thermodynamics: energy can be neither created nor destroyed during a process; it can only change forms. Energy can transfer between a system and surroundings

                                                              Form of energy around us
                                                             Source: www.phibetaiota.net

Forms of Energy

Total E = sum of all energies
Macroscopic
-energy possesses as a whole with respect to an outside reference frame
- gravity, magnetism, electricity, and surface tension
- organized as a result of motion of all in one direction
Microscopic
- related to structure of a system
- degree of activity
- Independent of outside reference frame
- Internal Energy = sum of microscopic energies

Energy can exist in numerous forms:

•Internal energy: May be viewed as the sum of the kinetic and potential energies of the molecules.

•Sensible heat: The kinetic energy of the molecules.

•Latent heat: The internal energy associated with the phase of a system.

•Chemical (bond) energy: The internal energy associated with the atomic bonds in a molecule.

•Nuclear energy:  The internal energy associated with the bonds within the nucleus of the atom itself.

But in this chapter we will focus on internal energy

Kinetic and potential energies: two forms of mechanical energy. these two energy are existed in the total energy system(sometimes it doesn't).

                                                             kinetic and potential energy
                                                        source: bvg8science.wikispaces.com

Kinetic Energy

- Possessed by a system as a result of its motion relative to some reference frame

Potential Energy

      Since heat and work are path dependent functions, they have inexact differentials designated by the symbol d.  The differentials of heat and work are expressed as dQ and dW.  The integral of the differentials of heat and work over the process path gives the amount of heat or work transfer that occurred at the system boundary during a process.

how to write Q and W in test or exam or quiz

                                                  The correct way of
                                                 expressing Q and W

Heat and Work

-a quantity that is transferred to or from a system during an interaction is not a property

- the amount of such a quantity cannot be determined only by the state of a system


- thus, heat (Q) and work (W) are energy transfer mechanisms 



Similarities
1. recognized at the boundaries of a system as they cross the boundaries, they are boundary phenomena
2. Systems possess energy, but not heat or work
3. Both are associated with a process, i.e. there is no 'state heat or work' as their meaning does not change - unlike 'properties' which change with state
4. They are path functions (i.e., mag depends on the path of the process and the end states)

*Adiabatic process

-no heat transferred, Q = 0
- well insulated system = assume negligible heat transfer
- system/surrounding are same temp.

Summary

  

  The sum of all forms of energy of a system is called total energy, which is considered to consist of internal, kinetic, and potential energies. Internal energy represents the molecular energy of a system and may exist in sensible, latent, chemical, and nuclear forms.

Chapter 1 Introduction

1st Law of Thermodynamic

• Heat is one type of energy ,and it can change each other with work and energy.
• Energy can't be destroy but can change form----conservation of energy.
• Here is a video of example of conservation energy.

The importance of dimension and unit

• In engeering course we should know about the dimension and SI unit.
• Here is a list  of dimension and it's unit.http://www.ebyte.it/library/educards/siunits/TablesOfSiUnitsAndPrefixes.html

Systems and control volume

• Systems-the quantity of matter or region in space chosen for study
• System boundary- system boundary can separate in to two ,that is Open and Closed.

Closed system=one in which heat and work crosses the system when undergoing a process without any mass transfer.

Open system=one in which heat and work crosses the system when undergoing a process with  mass transfer.

Properties of a system

• In the properties of system is any measurable  characteristic of a system.
• Separate in to two type ,Extensive properties and Intensive properties.
• Extensive properties =mass dependent (volume)
• Intensive properties = mass independent ,eg(temperature, density)
• Extensive properties can change to Intensive properties by divide by Mass.

Zeroth law of Thermodynamic

• If two body are thermal equilibrium with a third body,they also in thermal equilibrium with each other.

International Temperature scale

Pressure

• That is the pressure unit table.
• 
  

Time to take a rest

Thx all from group 1. Thank you.