Air Conditioning:

Just lowering or enhancing the temperature does not provide soothe generally to the machines or its components & living beings in particular. In case of the machine components, with temperature, humidity (moisture content in the air) also ought to be controlled & for the comfort of human beings along with these two significant parameters, air motion & cleanliness also play a major role. Therefore air conditioning is a wide aspect which looks into the concurrent control all mechanical parameters which are necessary for the comfort of human beings or animals or for the correct performance of some industrial or scientific procedure. The exact meaning of air conditioning may be given as the procedure of simultaneous control of, humidity, temperature, cleanliness and air motion. In some of applications, even the control of air pressure falls within the purview of air conditioning. This is to be noted down that refrigeration which is control of temperature is the most significant aspect of air conditioning.

To understand the above definition in a superior way, consider one instance. In the summer, the temperature of particular place is approximate 10 ^oC higher than in another where temperature differs in the range of 32 ^oC to 35 ^oC. We feel uncomfortable in both of the places. Weather in first place is hot & dry (means moisture content in the air is low) while in another place this is (mild) hot but humid (means moisture content in the air is very high). If in the summer, we go to a hill-station, we feel comfortable there. Temperature there remains approximate 25 ^oC and relative humidity of the air is also in the relaxing range, say approximate 65%. In one place, temperature is so high & humidity is low, whereas in another, temperature is low but humidity is high. In one place if there fall a rain, we feel more comfy compare to another place even with rain, the relative comfort is less. In first place temperature falls down & humidity also increases towards the comfortable value. In another, temperature falls down but humidity until remains on the higher side. Therefore, for comfort, both temperature & humidity ought to be in the specified range. It is true for human beings and scientific processes both. In spite of  from the above two, from intuition one may also say that cleanliness or purity of the air is an necessary item for the comfort and it has been established that the air motion is also needed for the comfort condition.

Based upon the requirement, air conditioning is divided into the winter air conditioning and the summer air conditioning. In the summer air conditioning, in spite of cooling the space, in most cases, additional moisture from the space is eliminate, while in the winter air conditioning, space is heated and as in the cold places, generally the humidity remains low, moisture is added up to the space to be conditioned. The summer air conditioning therefore uses a dehumidifier & a refrigeration system. The winter air conditioning utilizes a heat pump (refrigeration system operated in the reverse direction) & a humidifier. Based upon the comfort of the human beings & the control of environment for the industrial products & processes, air conditioning may also be classified in comfort air conditioning & industrial air conditioning. Comfort air conditioning deals with the air conditioning of residential buildings, cars, buses, offices spaces, airplanes, trains etc. Industrial air conditioning includes air conditioning of the, textile plants, printing plants, computer rooms, photographic products etc.

This has been mentioned above that the refrigeration & air conditioning are associated. Even while a space ought to be heated, this can be done so by changing the direction of flow of the refrigerant in the refrigeration system, that means ,the refrigeration system may be utilized as a heat pump (how it is possible will be described later). Though, some section of the people, treat refrigeration typically the procedure which deals with the cooling of the space. They treat heating operation connected with the heat pump. The relationship among air conditioning & refrigeration fields may be understood from the given figure

Relationship between the Refrigeration & Air Conditioning