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    Showing posts with label Quiz. Show all posts
    Showing posts with label Quiz. Show all posts

    Friday, February 14, 2020

    Difference between 'Thermodynamics' and 'Heat Transfer'

    Thermodynamics and Heat Transfer both are part of thermal engineering and each one has its own meaning and importance. Both deal with heat and energy then, one might ask, what is the real difference between the two subjects? i.e. Thermodynamics and Heat Transfer

    "Thermodynamics" deals with the amount of energy in the form of heat or work during a process and only considers the end states in equilibrium. It will not give information about how long it will take to reach to the final state in equilibrium. While

    "Heat Transfer" deals with the rate of energy transfer thus, it gives an idea of how long a heat transfer will occur? Heat transfer deals with time and nonequilibrium phenomena. Heat can only transfer when there is a temperature gradient that exists in a body and which is an indication of nonequilibrium phenomena.

    In short, Thermodynamics gives "Why"  a process will occur and Heat Transfer will tell, "How" a process will occur when there is a concern about the transfer of heat.

    To support all these arguments, Thermodynamics uses the following laws,

    • Zeroth Law of Thermodynamics (defines temperature)
    • The first law of Thermodynamics (defines internal energy)
    • Second Law of Thermodynamics (defines entropy)
    • Third Law of Thermodynamics (limits the lowest temperature attainable)

    While Heat Transfer uses,

    • Fourier's Law (Heat conduction)
    • Newtons Law of Cooling (Heat convection)
    • Planck's Law (Thermal Radiation)
    • Stephan Boltzman's Law (Thermal Radiation)
    • Wein's Law (Thermal Radiation)
    • Kirchoff's Law (Thermal Radiation)
    • Lambert's Law (Thermal Radiation)
    Learn more about such important questions to be asked in Mechanical Engineering Interview

    Wednesday, January 16, 2019

    Best books on Objective Questions in Mechanical Engineering

    In today's competitive world, one has to come out of the crowd and has to prove by SCORE in various competitive exams like State Public Service Commission (Like GPSC - Gujarat Public Service Commission in Gujarat), Graduate Aptitude Test in Engineering (GATE), Indian Engineering Services (IES) or any State, Centre level exams.

    Monday, October 16, 2017

    What would happen if compressor is removed from the refrigerator?

    Simply, the refrigerator would STOP! but why?

    To answer this question, one needs to know the Second law of thermodynamics (Clausius Statement) which states "It is impossible to construct a heat pump which continuously takes away the heat from low-temperature region to high-temperature region without taking any external work". 

    Here, the heat pump is our refrigerator which keeps on throwing heat from low-temperature environment to room temperature. As per the above statement, external work is must to run the refrigerator. That external work is represented by "Compressor".

    Wednesday, June 28, 2017

    Why overall efficiency of thermal power plant is very low?

    Are you wondering why the overall efficiency of the thermal power plant is very low? Reason?

    The major part of the electricity that the world is producing nowadays comes from Thermal Power Plant (which works on the Rankine Cycle or Modified Rankine Cycle).

    The principal parts of the Thermal Power Plants are

    Sunday, October 30, 2016

    Online Mechanical Quiz-GPSC Assistant Professor 2015-16

    This online quiz consists of some selected multiple-choice questions from the GPSC Entrance exam for Assistant professor Mechanical Engineering (the Year 2015-16).

    Appear for the quiz and get your score instantly.

    Saturday, February 22, 2014

    Why compression ratio of petrol engine is kept low compared to diesel engine?

    What is the need of high compression ratio? 

    Today every machine is expected to give higher efficiency. When we talk about the petrol engine and diesel engine whose thermal efficiency is directly related to the 'compression ratio'. That means if we want to achieve higher thermal performance in terms of efficiency, we should provide a high compression ratio for both the engine.