Air Conditioning and HVAC Basics: A Simple Explanation. This explanation of air conditioning and HVAC basics will expand a little bit on the air hvac design basics pdf cooling process.
The first topic to discuss about air conditioning and HVAC basics will be the laws of thermodynamics that describe how heat moves. Heat energy will move from a place of high intensity towards a place of lower intensity. Kind of like water flowing down-hill, heat energy will naturally and automatically move from a hot place to a cooler place.
You don’t have to do anything to make it happen. Sensible heat is measured in degrees C, F, or K. Latent heat measures the quantity of heat energy in a substance.
Latent heat is measured in British Thermal Units, or btu. When latent heat energy is added to a substance, or when a substance absorbs latent heat, the substance will feel “warmer”. When latent heat energy is removed from a substance, or when a substance releases latent heat, the substance will feel “cooler”. It takes 1 btu of latent heat to raise or lower the temperature of 1 lb of water 1 degree F.
So if 1 lb of water is at 45 degrees F, and warms to 50 degrees F, it will have absorbed 5 btu of latent heat. And if that 1 lb of water is warmed to 212 degrees F, it will have absorbed 162 more btu of latent heat. And now we’re at 212 degrees F, the boiling point of water, and something significant will happen that is an extremely important aspect of air conditioning and HVAC basics. By the time the 1 lb of water has totally evaporated, it will have absorbed 970 btu, which is almost 1,000 times more heat energy than it absorbed warming from 211 to 212 degrees.
970 btu is the latent heat of evaporation of water, or, the amount of heat energy required to evaporate 1 lb of water. And when the water vapor, or steam, is cooled back down, it will release that 970 btu of latent heat as it condenses from steam to water. So you can see that it is an essential topic when discussing air conditioning and HVAC basics.