Course Name: Air-conditioning: Introduction Prof. A. D. Kale Vishwakarma Institute of Information Technology, Pune

1) Definition 2) Classification 3) Applications Unit IV: Psychrometry Basics Air Conditioning : 1) Definition 2) Classification 3) Applications

The air conditioning is that branch of science, which consists simultaneous control of temperature, humidity, air cleanliness & air motion to meet the requirements of conditioned space.

Temperature of Air : It may be noted that a human being feels comfortable. When air is at 210c with 56 % relative humidity. Greater the temperature difference, faster is the heat flow. Humidity of air : means the increasing or decreasing of moisture content of air. RH changes w.r.t Temperature. Cool air has less capacity to hold moisture compared to warm air. At less RH heat dissipated through evaporation is more.

Motion of air : The motion or circulation of air is another important factor which should be controlled in order to keep constant temperature throughout the conditioned space. Air motion affects the heat rejection of body. (0.13 to 0.25 m/sec for Human Comfort) Forced air convection accelerates the rate of evaporation. If there are no air currents air surrounding the body gets saturated. Purity of air It is an important factor for comfort of a human body . It has been noticed that people do not feel comfortable when breathing contaminated air, even if it is within acceptable temperature & humidity ranges. If IAQ is not monitored it could lead to sickness and loss of efficiency.

Classification of AC Air conditioning are broadly classified as According to purpose a) Comfort air conditioning system b) Industrial air conditioning system According to season of year a) Winter air conditioning system b) Summer air conditioning system c) Year round air conditioning system According to arrangements of equipment a) Unitary air conditioning system b) Central air conditioning system

Applications of Refrigeration and Air-conditioning Comfort Air Conditioning : Applications relate to Human Comfort. Process Air Conditioning : To maintain conditions which will help in carrying out the process effectively and satisfactorily. Examples are: Textile Air Conditioning : Humidity control is imp. Printing and Paper Manufacturing : Temp and Humidity Control Electronics and Computer Rooms : Air Cleanliness ,Lower Temp and Humidity Control Pharmaceuticals : IAQ, Positive Static Pressure in Space Hospitals and Operation Theaters : IAQ and Contamination of Air

Central Air- conditioning System

Equipment used in air conditioning system Circulation fan :- The main function of this fan is to move air to and from the room. Air conditioning unit:- It is a unit which consists of cooling & dehumidifying processes for summer air conditioning or heating & humidification processes for winter air conditioning. Supply Duct:- It directs the conditioned air form circulating fan to space to be air conditioned at proper point . Supply Outlets:- These are grills , which distribute the conditioned air evenly in room. Return Outlets:- These are the opening in a room surface which allow room air to enter the return duct. Filters:- The main function of filter is to remove dust & other harmful bacteria from air.

Assignment No 1 Q.1) Explain how does a complete HVAC system work to meet the heating, ventilating and air conditioning requirements of a large complex ? Q.2) Describe three major ways of classifying air conditioning system ? Q.3) Briefly describe the working of window air conditioner and split air conditioner by drawing schematic diagram.