AIR CONDITIONING AND HEATING
Air conditioning refers to the cooling, heating and dehumidification of indoor air for thermal comfort. In a broader sense, the term can refer to any form of that modifies the condition of air. An air conditioner (often referred to as AC or air con.) is an appliance, system, or mechanism designed to regulate the air temperature and humidity within an area (used for cooling as well as heating depending on the air properties at a given time), typically using a refrigeration cycle but sometimes using evaporation, most commonly for comfort cooling in buildings and motor-cars. The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier. There are many different types of air conditioning systems of all shapes and sizes, however they all work in a similar way utilizing refrigerant gas which is the chemical medium used within an air conditioning system to facilitate the cooling process. How it works! Simply explained there are a number of stages commonly referred to as the refrigeration cycle. Please follow the diagram below for reference.
- The refrigerant in liquid form flows into the internal unit (the fan coil).
- The internal unit draws warm air from the room into the unit where the air circulates around the fan coil.
- Refrigerant runs through the fan coil making it very cold. The refrigerant absorbs the heat from the air drawn over the fan coil leaving the air cool. This air is then blown back into the room cooling the room down.
- As the refrigerant absorbs the heat from the room it increases its temperature and turns into a vapour. The vapour flows back toward the outdoor unit where it passes through the compressor squeezing it into a high pressure, high temperature vapour.
- The high pressure, high temperature vapour flows through another coil, this time in the condensor. The heat dissipates into the outdoor air changing the vapour into a high pressure, high temperature liquid.
- The liquid runs through an expansion valve, and in the process it becomes a cold, low-pressure liquid and the cycle begins again.
Most modern air conditioning units are also heat pumps, which means they are able to reverse the refrigeration cycle and heat as well as cool. For more information on heat pumps, please see the section titled ‘Heat Pumps ‘.