Thermodynamics Basics for Competitive Exams 2021

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Thermodynamics: Laws Of Thermodynamics And Heat Transfer Processes (Environmental Science)

Image Thermodynamics

Laws of Thermodynamics

  • First Law:

Stated by Mayer and Helmholtz

Energy can neither be created nor destroyed by any physical or chemical change. It may change from one form to another.


  • Second Law:

According to Kelvin, it is impossible to take heat from a cold reservoir and convert it into work without at the same time transferring heat from a hot to cold reservoir.

  • Third Law:

It is not possible to reduce the temperature of any system to absolute zero by any method involving finite number of operations, however, the ideal method may be.

Heat Transfer Processes

  • Planck՚s Law

Every object emits over the entire electromagnetic spectrum.

  • Stefan-Boltzmann Law

Total energy emitted by a black body is directly proportional to fourth power of its temperature.

  • Wien՚s Displacement Law

The product of peak wavelength and temperature of a blackbody radiator is constant.

Mass and Energy Transfer Across Various Interfaces

Image Mass and Energy Transfer Across Various Interfaces

Material Balance

  • Also known as Mass balance.
  • Used to find the accumulation of a contaminant/pollutant/substance in a particular region.
  • Those particular region are also called as control volume.
Image Material Balance

Mass Balance Equation

Accumulation rate = Input rate – Output rate + Reaction rate

  • For Steady-State conservation Systems

Input rate = Output rate



#Fundamentals of Environmental science

#Laws of thermodynamics


#Mass and energy transfer across interfaces

#Material balance

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