EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsINTRODUCTION AND BASIC CONCEPTS

Thermodynamics and Energy Importance of Dimensions and Units System and Control Volume Properties of A System State and Equilibrium Processes and Cycles Temperature and Zeroth Law of Thermodynamics Pressure The manometer The barometer and Atmospheric Pressure

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.1 Thermodynamics & Energy Thermodynamics can be define as the science of energy. Conservation of energy - it state that during an interaction, energy can change from one form to another but the total amount of energy remains constant. Energy cannot be created or destroyed.

A rock falling off a cliff

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsA person has a greater energy input (food) than energy output (exercise) will gain weight (store energy in the form of fat) The change in energy content of a body or any other system is equal to the difference between the energy input and the energy output. Energy balance is expressed Ein Eout =E

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsApplication Areas of Thermodynamics

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.2 Importance of Dimensions and UnitsThe seven fundamental dimensions and their units in SI

DimensionUnitLengthMeter (m)MassKilogram (kg)TimeSecond (s)TemperatureKelvin (K)Electric currentAmpere (A)Amount of lightCandela (cd)Amount of matterMole (mol)

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsThey are standard for all units and the student is encouraged to memorize them because of their widespread use.Some SI and English units

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.3 Systems and Control Volumes Surrounding the mass or region outside the system Boundary the real or imaginary surface that separates the system from its surrounding Close system (control mass) consists of a fix amount of mass, and no mass can cross its boundary Isolated system a special case, even energy is not allowed to cross boundary

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsAn open system or a control volume, is a properly selected region in space. It usually enclose a device that involves mass flow such as a compressor or turbine. Flow through these devices is best studied by selecting the region within the device as the control volume. Both mass and energy can cross the boundary of a control volume.

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.4 Properties of A System Property any characteristic of a system, e.g. pressure, P temperature, T volume, V and mass m Intensive properties those that are independent of the mass of a system, such as temperature, pressure and density Extensive properties - those whose values depend on the size _or extent_ of the system such as total mass, total momentum and total volume

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.5 State and Equilibrium State set of properties that completely describe the condition, at the given state all the properties of the system have fix values, if the value of even one property changes, the state will change to different one Equilibrium implies a state of balance, e.g. thermal equilibrium, the temperature is the same throughout the entire system, the system involves no temperature differential.

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.6 Processes and Cycles Process any change that a system under goes from one equilibrium state to another Path the series of states through which a system passes during a process Quasi-equilibrium process as a sufficiently slow process that allows the system to adjust itself internally so the properties in one part of the system do not change any faster than those at other parts

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics Thermodynamics cycle when a system starts at an initial state and undergoes a sequence of changing states and then returns to its initial state Chapter 1: End of first part

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.7 Temperature and The Zeroth Law of Thermodynamics Temperature as a measure of hotness or coldness Zeroth Law of Thermodynamics if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsTemperature Scales Kelvin scale is related to the Celsius scale byT(K) = T (oC) + 273.15 Rankine scale is related to the Fahrenheit byT(R) = T (oF) + 459.67 The temperature scales in 2 units systemT(R) = 1.8T(K)T (oF) =1.8T (oC) +32

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.8 Pressure Pressure a normal force exerted by a fluid per unit area, it has the unit of newtons per square meter (N/m2), which is called a pascal (Pa)

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1 bar = 105 Pa = 0.1 MPa = 100 kPa1 atm = 101,325 Pa = 101.325 kPa = 1.01325 bars

Pgage = Pabs PatmPvac = Patm - Pabs

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.9 The ManometerManometer commonly used to measure small and moderates pressure differences

P2 = Patm + gh

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsDetermine the absolute pressure, P Determine the absolute pressure, P1

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics1.10 The Barometer and Atmospheric Pressure

Atmospheric Pressure is measured by a device called a barometer and is referred to as the barometric pressure

EPT 201 THERMODYNAMICS Chapter 1: Introduction to ThermodynamicsEffect of piston weight on pressure in a cylinderDetermine the absolute pressure, P Chapter 1: End of second part

EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics