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علم سیستمهای تهویه مطبوع

علم سیستمهای تهویه مطبوع. تهیه کننده: محسن اشکذری. Himech.wordpress.com. What is 'Air Conditioning'?. Air Conditioning is the simultaneous control of Temperature, Humidity, Motion & Purity of the atmosphere in confined Space. What are the Requirements of comfort Air Conditioning?

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علم سیستمهای تهویه مطبوع

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  1. علم سیستمهای تهویه مطبوع تهیه کننده: محسن اشکذری Himech.wordpress.com

  2. What is 'Air Conditioning'? • Air Conditioning is the simultaneous control of Temperature, Humidity, Motion & Purity of the atmosphere in confined Space. What are the Requirements of comfort Air Conditioning? • Supply of Oxygen & removal of Carbon-di-oxide. • Removal Of heat dissipated by the occupants. • Removal of moisture dissipated by the occupants. • To provide sufficient air movement & air distribution in the confined space. • To maintain the purity of air by removing odor & dust

  3. What is Air Conditioning load? • Any heat generated with in the space to be air-conditioned forms a load on the air conditioning system. Examples: Occupants, Lights, Fans, Photocopier, Stabilizers, Computers, TV's etc.., Heat also enters the enclosed space from outside through walls, glass windows, roof, open doors, etc.

  4. What are the types of Air Conditioning? • Summer Air Conditioning - To reduce the heat & moisture Content of the air by cooling De-humidification. • Winter Air Conditioning - To increase the heat & moisture content of air by heating Humidification. • Year Round Air Conditioning - To control temperature & moisture content of the air throughout the year as per the climatic changes.

  5. What are the types of Air Conditioning systems? • Unitary air Conditioning Systems • Window Air Conditioner • Split Air Conditioner • Central Air Conditioning Systems • Package Unit • Central Plants

  6. What do you mean by Ton of Refrigeration (TR)? Ton of refrigeration is the amount of heat removed to convert 1000Kgs of water at ' zero' degrees Celsius into Ice in 24 hrs. In other words. Ton of refrigeration is the capacity to remove 3000 Kilo Calories (12,000 Btu) of heat per hour from the conditioned space. • What is BTU? The British Thermal Unit (BTU) is defined as the amount of heat required to raise or lower one pound of water to one degree Fahrenheit. • What is Kilo Calorie? It is the amount of heat required to raise the temperature of 1000 grams of water by 1 degree C.

  7. What is Comfort Air-Conditioning? 1. Temperature : 24 + 2 Degree Celsius DBT. 2. RH : 50 + 10% RH.

  8. What do you mean by Dry Bulb Temperature (DBT), Wet Bulb Temperature (WBT), and Relative Humidity (RH)? 1. Dry Bulb Temperature: The temperature of air measured by ordinary thermometer is known as Dry Bulb Temperature. 2. Wet Bulb Temperature: The temperature measured by the thermometer when its bulb is covered with Wet Cloth & exposed to airflow is known as Wet Bulb When the difference between DBT and WBT is Zero, the air becomes fully saturated (100 % RH). 3. Relative Humidity : The relative humidity is defined as the ratio of actual mass of water vapor in a given volume to the mass of water vapor if the air is saturated at the same temperature. RH = Mass of the water vapor actually present in a volume of air at T degree C. Mass of the water vapor required to saturate the same volume of air at T degree C .

  9. What are the basic components in an Air Conditioner? 1. Compressor - It is heart of the air conditioning system. Its function is to suck the refrigerant vapor from the evaporator, and to raise its temperature & pressure by compression to a point such that it can be condensed with the available atmospheric air. 2.Condenser - The function of condenser is to provide a heat transfer surface through which heat passes from hot refrigerant vapor to the atmospheric air. In condenser high temperature vapor is converted in to high temperature liquid by removal of latent heat .3.Strainer - Strainer is normally fitted in between a condenser & Capillary tube to remove moisture & foreign particles from the refrigerant. The moisture & foreign particles if allowed to enter may choke the capillary tube thereby restricting the flow of refrigerant resulting in less cooling / no cooling. 4.Capillary Tube - It is a tube with a very small orifice and its function is to meter the proper amount of refrigerant to the evaporator and reduce the temperature & pressure of liquid refrigerant entering the evaporator. Hence, this low temperature liquid will vaporize in the evaporator and take out sufficient amount of heat from room air 5.Evaporator - Its operation is similar to that of condenser. Here Liquid refrigerant is converted to low temperature vapor by taking the heat from the room air. It is at the evaporator cooling is produced and room is conditioned

  10. What is Refrigerant? • Refrigerant is a substance that absorbs heat through expansion or vaporization and loses the same through condensation in a refrigeration system. In what way refrigerant helps in achieving cooling in a confined space? • Refrigerant flowing through the closed cycle absorbs heat from the space to be cooled & rejects heat to the outside surrounding by continuously changing its phase from liquid to vapor & Vice-versa. Does the use of R-22 affect the ozone layer? • Ozone layer is normally affected by the presence of chlorine molecules (two atoms) Since R-22 has only one atom of chlorine, the effect of refrigerant on ozone is very less.

  11. What is CFM? • The Volume flow rate of air (Volume of air handled) is measured by Cubic Feet Per Minute (CFM) What is EER? Energy Efficiency Ratio =Cooling Capacity (BTU/Hr.) /Power consumption (Watts/Hr.)

  12. What are the functions of various components used in an air conditioner? • Thermostat - Its function is to controls the room temperature as per the settings by cutting in & off the compressor. Rotary switch - It is through the rotary switch the desired mode of operation is selected (i.e.) Off, Fan, Super quiet, Normal, High cool etc. Running Capacitor - The Function of running capacitor is to store the current & thereby maintain constant supply of current to the compressor. Starting Capacitor - The function of starting capacitor is to increase the starting torque of the compressor. Starting relay - The function of starting relay is to disconnect the starting capacitor from the circuit as soon as the compressor reaches the rated speed. Fan Blower - The function of starting relay is to disconnect the starting capacitor from the circuit as soon as the compressor reaches the rated speed. Condenser Fan Blade - It sucks the atmospheric air through sides of the outer cabinet and the same is made to pass through the condenser to take the heat from the refrigerant flowing through it. Fan Motor - It rotates the condenser fan blade and blower for handling the air at condenser and evaporator side. In case of split air conditioner two fan motors are used. (One at the condensing unit and the other at the evaporator unit) Oscillation Motor - This helps to circulate the cold air uniformly into the roomwith the help of the oscillation louvers.

  13. What are types of compressors normally used?. . Reciprocating Compressor . Rotary Compressor. Centrifugal compressor What types of compressor is normally used in Window / Split Air Conditioner?. . Reciprocating Compressor . Rotary Compressor

  14. مقایسه بین کمپرسورهای پیستونی و روتاری

  15. What is the need for having fins in condenser and evaporator?Fins are provided to increase the heat transfer area and thereby to improve the efficiency of the unit. What is the advantage of having grooved copper tubes? The advantage of grooved copper tubes over ordinary tubes is that it increases the resistance to the flow of refrigerant and thereby increasing the heat transfer rate.

  16. Where split air conditioners can be installed? 1. It can be installed where window AC's cannot be installed. 2. It can be installed in places where the aesthetics is the first priority. 3. It can be installed in places where the noise level is to be minimum.

  17. Explain how an Air Conditioner works? When the compressor is started it sucks the refrigerant vapor at low temperature and low pressure from the evaporator through the suction line. After compressing, it discharges the refrigerant at high temperature and high pressure in vapor state to condenser through the discharge line. Here the vapor is condensed at high pressure by lowering down the temperature of refrigerant with the help of atmospheric air, which was circulated by condenser fan. This liquid flows towards capillary tube through the liquid line & strainer. When the liquid passes through the capillary tube, its pressure and temperature are lowered and enters into the evaporator. Here this liquid refrigerant gets vaporized by absorbing the heat from the room air, which is being sucked by the blower through the evaporator coil. Hence the room air gets cooled and the same is discharged to the room. The compressor sucks the vaporized refrigerant at low temperature and low pressure. This cycle is repeated till the compressor works.

  18. mohsenshkezari@yahoo.comTEL: 09151575745 THE END

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