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Convection vs Conduction vs Radiation for Rad Techs

Convection vs Conduction vs Radiation for Rad Techs: will be an intro to heat, heat measurements and comparison of the heat transfer mechanisms. As a Radiologic Technologist or Radiographer the concepts of heat and heat transfer are important as the heat in an x-ray tube will often limit the x-ray technique parameters at a given time (i.e. the kVp and mA). Chapters 00:00 Introduction 01:00 Heat -Kinetic Energy 01:38 Calories-Heat Measurement 02:55 Heat Transfer 03:10 Conduction Heat Transfer 04:20 Convection Heat Transfer 04:58 Radiation Heat Transfer 05:52 Summary Heat Transfer Heat is the kinetic energy of the molecules in the environment. If you remember kinetic energy is the energy of objects in motion and potential energy is stored energy. Hot environments are due faster random motion of the molecules, ie higher kinetic energy. Cold environments are from slower motion of the molecules, ie lower kinetic energy. Heat is quantitatively measured by calories which is the amount of heat that is required to heat 1 gram of water by 1 degree C. Methods of heat transfer in order of efficiency are: Conduction Convection Radiation Conduction requires direct contact and is most efficient in transferring the energy. An example of conduction is heat transfer from the rotor to cooling oil in an X-ray tube. Convection requires movement of the gas or liquid for heat transfer and is less efficient that conduction but more efficient than radiation. Convection ovens are an example of heat transfer assisted by movement of the molecules. Radiation is actually heat transfer via electromagnetic radiation (visible light and x-rays are also electromagnetic radiation). Radiation does not require any physical contact of matter. Examples of radiative heat transfer include the sun, the fire in the thumbnail of this video and the x-ray target where electrons are impinging upon the heavy metal.