Air Conditioning Systems-sanjib

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AIR-CONDITIONING SYSTEM

SUBMITTED BY:SANJIB KUMAR MANDAL

ROLL NO: 97/ELM/104011



INTRODUCTION TO AIR

CONDITIONING SYSTEMS

(a) Air conditioning is the removal of heat fromindoor air for thermal comfort.

(b) Air conditioning means conditioning of airfor maintaining specific conditions of temperature, relative humidity and low dust

levels inside an enclosed space.(c) An air conditioner is an appliance, system or

machine designed to change the airtemperature and humidity within an area(Used for cooling as well as heating

depending on the air properties at a giventime) typically using a refrigeration cyclebut sometimes using evaporation,commonly for comfort cooling in buildingsand motor vehicles.



PURPOSE OF AIR CONDITIONING

• To control the temperature

• To control the humidity

•

To filtering the air to minimize dust• To provide moisture free dry air

• To remove air-borne bacteria



METHODS OF REFRIGERATION

• CHANGE OF PHASE

• EXPANSION OF A LIQUID

•

STEADY FLOW OF EXPANSION OF A PERFECTGAS

• EMPTYING PROCESS

•

ELECTRICAL PROCESSES



CYCLES USED FOR AIR CONDITIONING

• Vapor compression cycle

• Carnot refrigeration cycle



REFRIGERANT AND ITS PROPERTIES

• WHAT IS A REFRIGERANT ?

• BASIS OF SELECTION OF A REFRIGERANT

It depends upon three factors:(A)Thermodynamics

(B)Chemical

(C)Physical



COMPARISION OF FREEZING

TEMPERATURE OF DIFFERENT

REFRIGERANT

Refrigerants must operate above its freezing point temperature,making a low freezing point desirable. Freezing temperature of

different refrigerants are given below-• Ammonia -107˚F (-77.22 ˚C)

• Carbon dioxide -69.9˚F (-56.61 ˚C)

• Refrigerant 11 -168˚F (-111.11 ˚C)

• Refrigerant 22 -256˚F (-160 ˚C)

• Refrigerant 113 -31˚F (-35 ˚C)

• Water 32˚F (0˚C)



COMMONLY USED AIR

CONDITIONING SYSTEM

• (1) ROOM AIR CONDITIONER(RAC)

• (2) SPLIT AIR CONDITIONER(SAC)

•

(3) PACKAGE AIR CONDITIONER• (4) CENTRAL AIR CONDITIONING PLANTS



ROOM AIR CONDITIONER



HOW TO AVOID PROBLEM OF

INEFFICIENT FUNCTION OF RAC

• 1. Measure the air velocity per minute of the

supply grill air by using Anemometer and take

5 readings. Average air velocity = ((i) + (ii) +

(iii) + (iv) + (v))/5 (Say 959 ft. /min.)

• 2. Measure the Area of the supply Grill (say

0.5 sq. ft.)

• 3. Calculate the Air volume coming out of the

supply grill (say 480 cfm)



CONTINUED… • 4. Read the wet bulbs and Dry bulb

temperature of the supply air wet bulb 52.7°F

(11.5°C) Dry bulb 55.4°F(13°C)

• 5. Corresponding to the said wet bulb and dry

bulb temperature/ read the specific volume

of the supply air in the cubic feet per pound

from the enclosed psychometric chart. 13.1

cft/lb. (If chart is not available, 13.5 cft/lb may

be taken for practical purpose)

• 6. Calculate the Mass of the supply air by

dividing 3 by 5.(480/13.1)= 37 lbs/minute.



CONTINUED… • 7. Read the Wet bulb temperature of the

Return air 66.2°F (19°C)WB.• 8. Calculate the total heat of the Return air

and supply air corresponding to wet bulb

temperature of Return air and supply air fromthe enclosed Table.

Return air 30.9 BTU/lb Say 31 BTU/lb.

Supply air 21.9 BTU/lb and 22 BTU/lb.Drop in the total heat

= 30.9 – 21.9 = 9 BTU/lb.



CONTINUED… • 9. Capacity is equal to:

Mass of the supply air x Drop in total heat=37 x 9 BTU / min.= 333 x 60 BTU / lb.

=(333 x 60)/12000 = 1.6 Refrigeration Tons.

But to be sure regarding the capacity under any

situation,care to be taken whether the

difference in wet bulb temperature of the

supply air and return air is not less than 12°Fand also the air volume of the supply air is not

less than 400-500 cfm. for 1.5 Ton and 300-

350 cfm for 1 Ton machine.



CENTRAL AIR CONDITIONING

PLANT



DEVICE USED IN CENTRAL AC PLANT

AND ITS FUNCTIONING

• 1. evaporator

• 2. compressor

•

3. condenser• 4. receiver

• 5. expansion device



THE VAPOR COMPRESSION CYCLE

Evaporator

Compressor

CondenserReceiver

ExpansionDevice



CHILLED WATER SYSTEM• Water chillers are used with duct or water

piping system.

• The water chiller contains a compressor, a

condenser, a thermal expansion valve and a

refrigerant evaporating coil.• Instead of cooling air as in vapor compression

system, the water chilled by the evaporation

coil.• The chilled water is then pumped into piping

system.



FAN-COIL UNIT/AIR HANDLER

•It consists of :

• (1) the housing

• (2) the fan

• (3) the coils

• (4) face and bypass dampers

• (5) mixing box

• (6) fitters

• (7) spray humidifiers.



REFRIGERATION BY ABSORPTION



ROUTINE MAINTENANCE • Unnecessary heat development in rotating

parts• Undue vibration and noise

• Checking of voltages and currents

• Oil level check• Leakage of refrigerant vapor

• Air Filter Changing

• Cleaning of water-cooled condensers

• Maintenance and servicing of water cooling-

towers



CONTINUED…

• Checking of water hardness

• Room Air-Conditioners

•

Water-cooled Packaged Units• Pump down of refrigerant system

• Cleaning of the Compressor

• Electrical system



HOW WE WILL DETERMINE

REQUIRED CAPACITY IN TONS?

• A general office measuring 30 ft. x 20 ft. x 12

ft. height is to be Air Conditioned. There are

floors above the office and the West wall is

made of brick. What will be the requiredcapacity in tons ?



CONTINUED… • i) Area of the office = 30 x 20 = 600 sq. ft.

• ii) Required capacity = 600 x 72 = 43200BTU/Hr = 3.6 Tons

• For 12 ft. height, if will be 3.6 / 9 x 12= 4.8 Tons

• iv) Add 10% Safety factor = 4.8 + 0.48= 5.28Tons

• So either 3 numbers 2 Tons capacity or 4

numbers 1.5 Tons capacity room AirConditioners should be recommended.



ENERGY CONSERVATION IN THE

AREA OF REFRIGERATION

AND AIR CONDITIONG

• Energy conservation is now a tonic of the day

throughout the world and its bits are more feltin India and West Bengal in particular.

• The efficiency of an air conditioning and

refrigeration plant is expressed as the ratio of the refrigeration effect produced to the power

consumed (BTU per watt hour or kcal/Wh)



CONTINUED…

• This ratio, known as the ‘Energy Efficiency

Ratio’ (EER) is useful in comparing various

compressors as well as the performance of a

particular compressor at different operating

conditions.

• In a developing country like India 10 to 15% of

the total electricity produced, is used for

refrigeration and air-conditioning.



CONTINUED…

• A few method for consideration of Electrical

energy in the area of refrigeration and air-

conditioning area summarized below:

• Domestic Refrigeration and Air-conditioning

• Ice Bank Principle

• Heat Recovery System

•

Use of Centrifugal Compressor• Better Design of cooling tower



THANK YOU

Air Conditioning Systems-sanjib

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