Mechanical Engineering  >  Mechanical Engineering SSC JE (Technical)  >  Second Law of Thermodynamics

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

Document Description: Second Law of Thermodynamics for Mechanical Engineering 2022 is part of Mechanical Engineering SSC JE (Technical) preparation. The notes and questions for Second Law of Thermodynamics have been prepared according to the Mechanical Engineering exam syllabus. Information about Second Law of Thermodynamics covers topics like and Second Law of Thermodynamics Example, for Mechanical Engineering 2022 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for Second Law of Thermodynamics.

Introduction of Second Law of Thermodynamics in English is available as part of our Mechanical Engineering SSC JE (Technical) for Mechanical Engineering & Second Law of Thermodynamics in Hindi for Mechanical Engineering SSC JE (Technical) course. Download more important topics related with notes, lectures and mock test series for Mechanical Engineering Exam by signing up for free. Mechanical Engineering: Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering
1 Crore+ students have signed up on EduRev. Have you?

SECOND LAW OF THERMODYNAMICS

  • Work is said to be high grade energy and heat is low grade energy. The complete conversion of low grade energy into high grade energy in a cycle is impossible while the complete conversion of high grade energy into low grade energy is possible.
  •  A heat engine works on a thermodynamic cycle in which there is net heat transfer to the system and a net work transfer from the system.

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering
Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

  • Boiler, turbine, condenser and pump, all four together constitute a heat engine.

Thermal Efficiency
Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

Wnet = Qnet (First law of thermodynamics)

  •  A thermal energy reservoir (TER) is defined as a large body of infinite heat capacity which is capable of absorbing or rejecting an unlimited quantity of heat without any appreciable changes in its thermodynamic properties.

PMM2 

  •   It is a device which produces work while exchanging heat with single reservoir in a cycle.

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

Q2 = 0 , Wnet = Q1 , hth = 1
Such a heat engine is called as PMM2.

  • Second Law of Thermodynamics:
    • Kelvin Plank Statement: It is impossible for a heat engine to produce net work in a complete cycle if it exchange heat only with a single reservoir.
    • PMM2 is impossible according to Kelvin-Plank statement.
    • Clausis statement: it is impossible to transfer heat from lower temperature to higher temperature without any external input.
    • Heat always flow from a body at higher temperature to a body at lower temperature but it can not flow in reverse direction on its own. Some work must be done to achieve this.
  •  Refrigeration plant and heat pump constitute of
    •  Evaporator
    •  Compressor 
    •  Condenser
    •  Expander

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

(Figure: Schematic diagram of Refrigeration plant and heat pump.)

Coefficient Of Performance(COP) = Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering
(COP) ref =
Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering
(COP) H.P = 
Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

(COP) H.P = (COP) ref  + 1

  • The basic cycle in refigerator and heat pump is same. But the main purpose of refrigerator is to maintain temperature which is less than that of surrounding while in heat pump, the main purpose is to maintain temperature which is more that of surrounding.
  • PMM–3 : Continual motion of a movable device in complete absence of friction is known as PMM-3.

Carnot Cycle:

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

  • It is a reversible cycle.
  • It is an ideal cycle.

Carnot Theorem: It states that all heat engines operating between a given constant temperature source and given constant temperature sink, none has higher efficiency than a reversible engine.

  • The efficiency of all reversible heat engines operating between the same temperature levels is the same.
  • Third law of thermodynamics : It is impossible by using any procedure, no matter how idealised the procedure is. to reduce any system to absolute zero of temperature in a finite no. of operations.
  • The effect of decreasing T2 to increase thermal efficiency of Carnot cycle is more than the effect of increasing T1 by same amount.
  • First law of thermodynamics gave origin to internal energy and second law leads to entropy.
The document Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering is a part of the Mechanical Engineering Course Mechanical Engineering SSC JE (Technical).
All you need of Mechanical Engineering at this link: Mechanical Engineering

Related Searches

Previous Year Questions with Solutions

,

practice quizzes

,

Semester Notes

,

Sample Paper

,

Important questions

,

past year papers

,

Viva Questions

,

Summary

,

MCQs

,

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

,

Exam

,

ppt

,

study material

,

shortcuts and tricks

,

mock tests for examination

,

Extra Questions

,

pdf

,

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

,

Free

,

Second Law of Thermodynamics Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

,

Objective type Questions

,

video lectures

;