Air-Conditioning Systems

Purpose of an air-conditioning system is to control indoor air parameters within required thermal comfort and indoor air quality. To achieve required indoor air parameters, the system: heat, cool, humidify, dehumidify and filter outdoor air.

HVAC Subsystems

See Figure on the next page:

O

End Use

Consumes capacity to condition space air or air stream supplying space. Air-conditioning systems = air handling systems + ducts + air distribution devices

How to select an air-conditioning system?

• Performance requirements (loads, process)

• Capacity requirements (building types, loads)

• Spatial requirements (building types)

• First costs (location, size of HVAC, investment)

• Operating costs

• Reliability

• Flexibility

• Maintainability

Air-Conditioning Systems

R. nm INC, PRODUCTION

Classification in terms of system:

O

Classification in terms of air supplied

O

Classification in terms of load carried:

O

=Q3W1_

подпись: =q3w1_

-Q — W

Qfw

Air-water

подпись: -q -w
qfw
air-water

Q w t!

All-air

Production

Q — Q.-W

^ Q w

*

Ti

RҐi

All-water

Q — Q.-W

^Qw

Ti

N

Refrigerant

Convert primary energy for heating/cooling. Energy sources:

• Coal

• Natural gas

• Fuel oil

• Biomass

Produce steam and electricity.

Heating production equipment:

O

Air-Conditioning Systems

A packed fire-tube boiler, (iCourtesy of Federal Corp., Oklahoma City, OK)

Cooling production equipment:

O

Vapor compressor:

• Refrigerant

• Compressor

• Drive (usually electric motor)

Air-Conditioning Systems

Components in a Vapor-Compression Refrigeration Cycle

Waiei-wetEd

Air-Conditioning Systems

Centrifugal chiller cutaway drawing (iCourtesy United Technology Cairier)

Heat rejection:

• Disposes of heat from cooling process

• Cooling tower, evaporative condenser, air-cooled condenser

• “Sink” for waste heat: ambient dry bulb, ambient wet bulb, ground, surface water

• Trades offs between cost and COP

Air-Conditioning Systems

Forced-draft cooling tower (Courtesy Marley Co.)

CLC

CIR<

CLOSEO CIRCUIT

/

CLOSED-CIRCUIT HEAT EXCHANGE COIL

\\

////// / / / / /

HEATED AND HUMIDIFIED AIR OUT

DRIFT ELIMINATORS 4

Air-Conditioning Systems

COLD WATER

Factory-Assembled Counterflow Forced — Draft Tower

 

HEAT AND HUMIDIFIED AIR OUT

 

DHIFT

ELIMINATORS

 

Air-Conditioning Systems

EXTERNAL

WATER

 

HOT

-WATER

 

Air-Conditioning Systems

COLD

WATER

 

AIR IN

 

PUMP

 

Indirect-Contact Evaporative Cooling Tower

 

Air-Conditioning Systems

Distribution

Air-Conditioning SystemsMoves capacity from production to use. Water and steam distribution:

O

Air distribution: O

Centrifugal fan (iCourtesy of the Train Company, LaCrosse, WT)

Packed equipment Air-handling unit: O

Posted in Fundamentals of Heating. Ventilating, and Air-Conditioning


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