## THERMODYNAMICS CONSIDERATION ON HVAC DESIGN TUTORIALS

Thermodynamics has to do with the thermal characteristics of matter and with the natural affinity of the universe to go from a higher to a lower energy state. Thermodynamics deals with the ability of matter to accept changes in energy level (relates to specific heat as a property and to enthalpy as a scale of measurement of energy level).

For this reminder paragraph, remember:

The energy acceptance capacity of a substance is called specific heat with English units of Btu per pound per degree Fahrenheit. Water with a specific heat of 1.0 Btu/(lb F) is one of the best heat accepting media.

The energy acceptance capacity in a change of phase is called the latent heat of vaporization from liquid to gas (i.e., water to steam) and latent heat of fusion from liquid to solid (i.e., water to ice).
Again, water with a latent heat of vaporization of approximately 1000 Btu/lb and a latent heat of fusion of 144 Btu/lb is very good at involving large quantities of energy at constant temperature in
the phase change.

Thermodynamics can be used to examine the refrigeration cycles with mathematical tools and techniques to analyze performance of equipment and systems.

The first law of thermodynamics says that ‘‘energy is conserved.’’ For matter as for money, we can account for energy inputs, outputs, and storage. Combining thermodynamics with fluid mechanics allows us to calculate energy flows piggybacked onto fluid flows with accuracy and confidence.

The second law of thermodynamics says that energy left to itself always goes from high to low, from fast to slow, from warm to cold. To make things go uphill, to go otherwise, we must expend energy. There is no such thing as a perpetual-motion machine.
Psychrometrics is a specialty of thermodynamics involving the physics of moist air, a mixture of air and water vapor.