HVAC - R

HVAC - heating, ventilating, and air conditioning; also heating, ventilation, and air conditioning, is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a sub-discipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR.

HVAC is important in the design of medium to large industrial and office buildings such as skyscrapers and in marine environments such as aquariums, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.
 

Heating

Heating is the process of generating heat energy and its application to systems which requires heat to operate efficiently. Applications include keeping the buildings warm, heating of automobiles & homes, heating various circuit network systems, and mechanical systems. 

Air Conditioning

Perhaps ironically, every heating ventilation engineer will likely, at one point or another, be charged with removing heat from structures. The simple name for this is air conditioning. Many of the most efficient and effective air conditioning systems cool entire buildings with a minimum of electricity; Heating ventilation engineers are hard at work trying to make the refrigeration cycle, which is responsible for the cooling effect provided by air conditioners, more efficient.

Efficiency

A good heating ventilation engineer is always looking for ways to make HVAC systems work better and use less energy. By studying the principles of thermodynamics and their applications to new systems, engineers hope to create new heating and air conditioning devices that are less expensive and more environmentally friendly.

Ventilation

Without proper ventilation, we would – to be blunt – suffocate. Without the proper ventilation a heating ventilation engineer provides, skyscrapers and other tall buildings wouldn’t be very comfortable places to work. But that’s not all – these engineers must also make sure the air quality throughout buildings is uniform and safe. A talented heating ventilation engineer might also work on ventilation and air quality systems in vehicles, like submarines, airplanes and spacecraft. Ventilation is of vital importance in controlling the quality of air in sensitive environments such as hospitals, and bio-technical laboratories. 

Refrigeration

The process of keeping an item below room temperature by storing the item in a system or substance designed to cool or freeze. The most common form of refrigeration is provided by systems (i.e. refrigerators) that use a refrigerant chemical to remove heat from items stored inside the system.
Mechanical refrigeration, often referred to simply as refrigeration, is a process by which heat is removed from a location using a man-made heat-exchange system. The system of refrigeration can be cyclic, non-cyclic, thermoelectric or magnetic depending on the application for which refrigeration is needed.

Want to visualize? Here are some examples!