Thermodynamics 1 Lecture 1-Engineering

THERMODYNAMICS I

LEARNING OUTCOMES• explain work and heat transfer• apply First Law of Thermodynamics to

engineering systems• analyze non-flow processes• analyze flow processes• apply Second Law of Thermodynamics to

engineering systems• analyze basic properties of steam • analyze air standard cycles in reciprocating

internal combustion engines

COURSE CONTENTS

1.Fundamental ConceptsUnits and dimensions, key definitions of thermodynamic terms, Types of thermodynamic systems, System properties, Forms of energy and their transformations.

 2.First Law of Thermodynamics

Definition of the First law of thermodynamics, Internal energy, Reversibility and Irreversibility, Energy balance of systems, Estimation of heat and work interactions. 

COURSE CONTENTS…

3.Non-flow ProcessesProperties of perfect gases, Standard non-flow processes, Estimation of heat and work interactions of such processes 

4.Flow ProcessesConcept of flow work, Concept of control volume, Energy equation, Steady Flow Energy Equation (SFEE), Application of SFEE to standard flow processes and devices, Estimation of heat and work interactions of such processes.

COURSE CONTENTS…

5.Second Law of ThermodynamicsDefinition of Second law of thermodynamics, Concept of Heat Engine and Heat Pump, Heat engine Efficiency, Coefficient of Performance of Heat Pump, Second law statements, Basic Carnot Cycle, Carnot Cycle Efficiency and COP, Concept of entropy, Change of entropy, Estimation of the change of entropy of standard processes.

 6.Properties of Steam

Properties of steam and use of steam tablesBoiler, condenser, turbine, compressor, expansion valveCarnot Steam Cycle, cycle efficiency, work ratio, specific steam consumption, isentropic efficiency

COURSE CONTENTS…

7.Air Standard Cycles – Reciprocating Internal Combustion EnginesOtto, Diesel and Dual Cycle

Air Standard efficiency and Mean effective pressure

References

1. Yunus A. Cengel & Michael A. Boles, Thermodynamics, An Engineering Approach, Tata McGraw- Hill

2. T.P. Eastop, A. McConkey; Applied Thermodynamics for Engineering Technologists – SI Units, Longman publishers.

3. G.F.C. Rogers, Y.R. Mathew; ELBS, Engineering Thermodynamics - Work and Heat Transfer, Longman publishers

4. R.S. Khurmi & J.K.Gupta, A Text book of Thermal Engineering, S Chand & Company LTD, New Delhi.

Definition of thermodynamics

• The science concerned with the relations between heat and mechanical energy or work, and the conversion of one into the other

• The branch of physical science concerned with the interrelationship and inter-conversion of different forms of energy and the behaviour of macroscopic systems in terms of certain basic quantities, such as pressure, temperature, etc

Fundamental Concepts

• Units and dimensions

• key definitions of thermodynamic terms, Types of thermodynamic systems

• System properties

• Forms of energy and their transformations.

Units

Units..

Units…

• Thermodynamics– The branch of science that deals with the study

of different forms of energy and the quantitative relationships between them.

• System– Quantity of matter or a region of space which is

under consideration in the analysis of a problem.

• Surroundings: – Anything outside the thermodynamic system is

called the surroundings. The system is separated from the surroundings by the boundary. The boundary may be either fixed or moving.

• Closed system: – There is no mass transfer across the system

boundary. Energy transfer may be there.

• Open system– There may be both matter and energy transfer

across the boundary of the system.

• Isolated system– There is neither matter nor energy transfer

across the boundary of the system.

• State of the system and state variable:– The state of a system means the conditions of the

system. It is described in terms of certain observable properties which are called the state variables, for example, temperature (t), pressure (p), and volume (v).

• State function: – A physical quantity is a state function in the

change in its value during the process depends only upon the initial state and final state of the system and does not depend on the path by which the change has been brought about.

• Macroscopic system and its properties:– If as system contains a large number of chemical

species such as atoms, ions, and molecules, it is called macroscopic system.

– Extensive properties: These properties depend upon the quantity of matter contained in the system. Examples are; mass, volume, heat capacity, internal energy, enthalpy, entropy

– Intensive properties: These properties depend only upon the amount of the substance present in the system, for example, temperature, refractive index, density, surface tension, specific heat, freezing point, and boiling point.

• Types of thermodynamic processes: – We say that a thermodynamic process has

occurred when the system changes from one state (initial) to another state (final).

• Isothermal process:– When the temperature of a system remains

constant during a process, we call it isothermal. Heat may flow in or out of the system during an isothermal process.

• Adiabatic process: – No heat can flow from the system to the

surroundings or vice versa.

• Isochoric process: – It is a process during which the volume of the

system is kept constant.

• Isobaric process:– It is a process during which the pressure of the

system is kept constant.

• Reversible processes: – A process which is carried out infinitesimally

slowly so that all changes occurring in the direct process can be exactly reversed and the system remains almost in a state of equilibrium with the surroundings at every stage of the process

• The word system is very commonly used in thermodynamics;

• Certain quantity of matter or the space which is under thermodynamic study or analysis is called as system.

• engine of the vehicle, in this case engine is called as the system,refrigerator, air-conditioner, washing machine, heat exchange, etc.

Types of Thermodynamic Systems

• There are three mains types of system– open system– closed system and – isolated system

All these have been described below

Open system

• The system in which the transfer of mass as well as energy can take place across its boundary is called as an open system. Our previous example of engine is an open system. In this case we provide fuel to engine and it produces power which is given out, thus there is exchange of mass as well as energy. The engine also emits heat which is exchanged with the surroundings. The other example of open system is boiling water in an open vessel, where transfer of heat as well as mass in the form of steam takes place between the vessel and surrounding.

Closed system• The system in which the transfer of energy takes place

across its boundary with the surrounding, but no transfer of mass takes place is called as closed system. The closed system is fixed mass system. The fluid like air or gas being compressed in the piston and cylinder arrangement is an example of the closed system. In this case the mass of the gas remains constant but it can get heated or cooled. Another example is the water being heated in the closed vessel, where water will get heated but its mass will remain same.

Isolated system

• The system in which neither the transfer of mass nor that of energy takes place across its boundary with the surroundings is called as isolated system. For example if the piston and cylinder arrangement in which the fluid like air or gas is being compressed or expanded is insulated it becomes isolated system. Here there will neither transfer of mass nor that of energy. Similarly hot water, coffee or tea kept in the thermos flask is closed system. However, if we pour this fluid in a cup, it becomes an open system.

System Properties

• Macroscopic characteristics of a system to which a numerical value can be assigned at a given time without knowledge of the history of the system, e.g., mass, volume, pressure

Type of system properties

• Extensive – the property value for the system is the sum of the values of the parts into which the system is divided (depends on the system size) e.g., mass, volume, energy

• Intensive – the property is independent of system size (value may vary throughout the system), e.g., pressure, temperature

What is Energy Transformation?

• The conservation of energy principle states that energy can neither be destroyed nor created. Instead, energy just transforms from one form into another.

• So what exactly is energy transformation? Well, as you might guess, energy transformation is defined as the process of changing energy from one form to another.

Energy Transformation

• There are so many different kinds of energy that can transform from one form to another. There is energy from chemical reactions called chemical energy, energy from thermal processes called heat energy, and energy from charged particles called electrical energy. The process of fission, which is splitting atoms, and fusion, which is combining atom gives us another type of energy called nuclear energy. And finally, the energy of motion, kinetic energy, and the energy associated with position, potential energy, are collectively called mechanical energy.

Extensive and Intensive property

Energy Form

Gravitational or potential energy

Kinetic Energy

Flow Energy

Flow energy…

Internal Energy

Enthalpy

Energy Transfer

Heat Transfer

Heat Transfer

Work Transfer

Work Transfer…

Example

key definitions of thermodynamic terms

Thermodynamic systems

Thermodynamic systems…

Non flow system

Non Flow system

Steady flow system

Steady flow system

Examples

Examples..