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Saturday, 31 March 2012

Important concepts in Thermal Engineering for GATE 2019 Mechanical

The present post (Part-1) contains the important basic concepts in Thermal Engineering in Mechanical Engineering. Note down each concept which might help in GATE 2019 Mechanical.

  • The pressure of the gas in terms of its mean kinetic energy per unit volume E is equal to 2E/3 and Kinetic Energy is always proportional to temperature.
  • The superheated vapor acts as perfect gas and obeys all gas laws
  • Absolute zero pressure will occur when there is no molecular momentum
  • No liquid can exists at absolute zero pressure and absolute pressure can be attained at 0 Kelvin
  • The behavior of gas can be fully determined by four gas laws
  • For air ratio of specific heats is 1.4

  • Mono-atomic gas has the highest ratio of specific heat = 1.66
  • As per Joule’s law, internal energy is a function of temperature.
  • The same volume of all gases would represent their molecular weights
  • Gases have two value of specific heat. One is at constant pressure and one is at constant volume
  • The molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature.
  • Work done in free expansion process is always zero
  • Work done for a rigid container having gas is zero
  • Heat and work are not properties of the system
  • The absolute value of internal energy cannot be found but only change in internal energy can be found
  • On weight, basis air contains 23 parts of oxygen
  • Heat and work are path functions

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