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Ventilation

2 Ventilation and Air-conditioning

Systems

Vladimír Zmrhal (room no. 814)

http://users.fs.cvut.cz/~zmrhavla/index.htmDptDpt. . OfOf

EnvironmentalEnvironmental

EngineeringEngineering

2

�Ventilation systems

Natural ventilation

� is the flow of outdoor air caused by wind and air density

differences

Mechanical (forced) ventilation

� is driven by mechanical work - fan

Hybrid ventilation

� combination of natural and mechanical ventilation

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� natural ventilation by louvers (permanent)

� shaft ventilation (permanent)

� interupted natural ventilation (time limited)

� infiltration (time limited)

Natural ventilation

heat source

depends on

external (ambient)

climatic conditions

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Mechanical ventilation

Air exchange in the room:

� exhaust-only ventilation system

� supply-only ventilation system

� supply and exhaust ventilation system

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5

Exhaust-only ventilation systems

Mechanical ventilation

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Mechanical ventilation

Local exhaust ventilation systems

� unitary exhaust

� central exhaust

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7

Supply-only ventilation system

Mechanical ventilation

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Supply and exhaust ventilation system

Mechanical ventilation

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9

Supply and exhaust ventilation system

� recirculation without exhaust

Mechanical ventilation

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Supply and exhaust ventilation system

� recirculation with exhaust

Mechanical ventilation

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11

Supply and exhaust ventilation system

� with heat recovery, recirculation, heating, cooling (drying),

humidifying, double filtration

Mechanical ventilation

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Pressure condition of the space:

�underpressure

Vs< V

exusually 15 - 30 Pa

400 Pa for work with radioactive materials

� overpressure

Vs> V

exe.g. clean rooms, operating room, …

min. 10 -15 Pa

� balanced

Vs= V

ex

Mechanical ventilation

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13

Local air supply

For local conditioning of air temperature or cleanlines

� air curtain

� air shower

� personalized ventilation

Mechanical ventilation

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Air curtain

a) door curtain with upward supply

b) two side curtain

Local air supply

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Air shower

� people protection in hot industrial work places with radiation

(steel foundry,…)

� higher air convection

Local air supply

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Personalized ventilation

� outdoor air supply directly to the breathing zone

Local air supply

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Hybrid ventilation

Solar chimney

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Heat Transfer

- convective

- radiant

Air-conditioning

Medium

- air

- water

- air + water

- refrigerant

Purpose

- comfort

- technology

- biology

- safety

Number of zones

- one - zone

- multizone

→→→→ single-duct, dual-duct

→→→→ cooled ceilings, fan coil units

→→→→ induction units (chilled beams)

→→→→ split, multisplit, VRV

Air-conditioning

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Air-conditioning

Single-duct air system with constant air flow

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Air-conditioning

Single-duct air system – VAV (variable air volume)

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Air-conditioning

Dual-duct air system

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Air-conditioning

Fan-coil unit system

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Air-conditioning

Induction unit, Chilled beams system

VP

P

VOb

Ob=I

OhOb, ChOb

Oh, Ch

Prim

VP

P

VOb

Ob=I

OhOb, ChOb

Oh, Ch

Prim

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Air-conditioning

Cooled ceiling system

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Air-conditioning

Refrigerant systems

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Split Multi-split VRV

Air-conditioning

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Thank you for your

attention