CHAPTER 1a: BASIC CONCEPTS OF THERMODYNAMICS
Thermodynamics and Energy Dimensions and Units Systems and Properties State, Processes and Cycles Temperature Pressure and Measuring Devices Problem Solving Technique
At the end of the lesson, you should be able to:
Identify application of thermodynamics
Define & differentiate between closed system and control volume (open system)
Differentiate between intensive and extensive properties
What Is Thermodynamics?
Therme (heat) Dynamis (Power)
It is a science of energy.
Early description: Convert heat into power. Current Definition: The study of ...view middle of the document...
Others: viscosity, thermal conductivity, thermal expansion coefficient and etc
independent of the size/ extent (or mass) dependent on the size/ extent (related to mass) T, P, age, colour
m, V, total E
Specific properties E.g. specific volume
extensive properties per unit mass
V m 10
DENSITY & SPECIFIC GRAVITY
Density (kg/m3) depends on T & P
Specific gravity or relative density (ratio of the density of
a substance to the density of some standard substance at a specified temperature e.g. water)
s H 2O
Specific weight – is the weight of a unit volume of a
STATE & EQUILIBRIUM
A set of properties that describe the condition of a system at certain time At a given state, all the properties of a system have fixed values. If the value of one property changes, the state will change to a different one. If the state changes, the system is said to have undergone a process
STATE & EQUILIBRIUM
A state of balance. In an equilibrium state, there are no
unbalanced potentials (or driving forces) within the system.
Thermal equilibrium: If the temperature is the same throughout the entire system. Mechanical equilibrium: If there is no
change in pressure at any point of the system with time. Phase equilibrium: If a system involves two phases and when the mass of each phase reaches an equilibrium level and stays there. Chemical equilibrium: If the chemical composition of a system does not change with time, that is, no chemical reactions occur.
A closed system reaching thermal equilibrium.
PROCESSES & CYCLES
PROCESS A transformation from one state to another
If a system exhibits the same values of...