====== Notes on Thermodynamics Real-life Applications ======

efficiency steam combustion electric

Re: Earth wind & fire, \\
Until ..., fire was believed to be a fluid form of matter.

==== Transfer of heat ====

Examples:

Ice cube in coffee cup - heat flows naturally from hot to cold.

Air conditioner and Refrigerator - evaporator, compressor, condenser, refrigerant, fan. Heat flows in opposite of natural direction and this requires external energy in the form of electricity.

Transfer of heat, three methods:
  * Convection
  * Conduction
  * Radiation

== Conduction ==
molecule to molecule

Conduction works well in solids particularly metals. Liquids and non-metallic solids very in their ability to conduct heat but gas is always a poor conductor of heat.

The characteristics that make metal a good conductor of heat also make it a good conductor of electricity.

== Convection== 
moving hot molecules among cold molecules, in a fluid, gas or liquid. 

Hot air is less dense than cold air.

Hot air rising from the land on a sunny day - natural convection.

Oven - forced convection.

Fridge - forced convection in the opposite direction.

Heart - natural convection. a pump circulates blood which moves excessive heat out to the skin where it moves to sweat which is evaporated.


== Radiation ==
While Convection and conduction involve thermal energy,

Radiation involves electromagnetic energy.

The electromagnetic spectrum includes:
  * visible light, 
  * infrared light, 
  * ultraviolet light, 
  * x-rays, 
  * gamma rays, 
  * radio waves, 
  * microwaves for TV and radar.

Any glowing object is an example of radiation: The sun, a fire, a light bulb. 

We can see the radiation of visible light. \\
We can feel as heat the radiation of infrared and ultraviolet light.


==== Laws ====

there is no definitive phrasing; instead, there are various versions, all of which say the same thing.