BCD UNIT V UNIT-VProfP f S S JAHAGIRDARBE (CIVIL), ME(ENV.),PhD(persuing)NK Orchid college of Engg and Tech , Solapur Engg. Tech.
Process of treating the air so as tocontrol simultaneously itstemperature, humidity, purityand distribution to meet therequirements of controlled space.
1) Comfort and health of occupants p2) Needs of certain industrial processes3) Efficient working of commercial premises/offices p /
Comfort air conditioning : - Aim atgiving max human comfort tooccupants/users of conditionedspaceIndustrial air conditioning : - Thecoditioning creates, controls andmaintains such an environmentinside the conditioned space, that itwould suit b t t th needs of ld it best to the d findustry.
)1) Summer air conditioning g In summer outside temp is more and hence cooling of air is required Consists ofi) Air cleaningii) ) Air coolingiii) Dehumidificationiv) Air distribution/circulation
2) Winter air conditioning In winter outside temperature is low hence h i of air i needed f h heating f i is d d for comfort. Cycle of operations consists ofi) ) Air cleaningii) Air heatinggiii) Humidificationiv) Air di t ib ti / i l ti Ai distribution/circulation
1) Temperature control Effective temp = 200C to 230C in summer Effective Temp = 180C to 220C in winter For Indian conditions 250C with 60% relative humidity to 300C with 45 % relative h idit with air velocity not l ti humidity, ith i l it t exceeding 10 m/min
During summer dehumidificationis done so that relative humidity yis 40 to 50%During winter h humidification is dfdone so that relative humidity is50 to 60 %
High velocity of conditionedair may y cause g greatertemperature differencebetween outside and inside inside.Velocity = 6 to 9 m/sec isdesirable
Air should be free fromodour, toxic gases, bacteriaand other micro-organisms
1. Filtration2. Heating (in winter)3. Cooling (in summer)4. Humidification5. Dehumidification6.6 Air circulation or distribution
Should be capable of removing dust, ash,smoke,smoke bacteria etcShould be capable of holding moderateamount of d f dust without affecting the h ff hefficiencyShould offer low resistance to flow of airWorkable under sufficient range ofvelocities.Should ff dSh ld afford easy cleaning manually or l i llmechanically
Heating is necessary in winter soas to compensate heat loss fromroom.Pre heating of incoming air may bedone by passing over air furnacesor coils through which hot water iscirculated.
Cooling of incoming air isnecessary in summer. yPrinciple of mechanicalrefrigeration is used. f d
Humidification or addition ofwater is necessary in winterwhen air because of low temphas less humidity.Incoming air is passed throughpans of water or wet cloth strips
In this process certain amount ofwater is extracted from air.This is done in summer whereincoming air is cooled cooled.Adsorbents can be used toadsorb excess moisture from air