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Cooling and

dehumidification The dehumidification can be achieved by thefollowing methods :

1-Using electric heater.2-Using heating coil.3-Using gas reheatmethod.

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Gas Reheat FeatureHow It Works

 The hot gas reheat feature (St. St. HeatExchanger), is designed to control humidity at aspecific level in the conditioned space. This isusually required when the outside temperature

is cool and humid; it controls humidity withoutexpending additional energy to reheat thecooled air. With conventional systems, thecooled and dehumidified air would require the

use of a heater to bring the temperature to thedesired level. Hot as reheat s stems rec cles

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AirConditioni

ng

Lecture

3

dry-bulbtem erature

humi

dity

ratio

  w  e   t

 -   b  u   l   b

    t  e  m

  p  e  r  a   t  u  r  e 70 %

50 %

30 %

28 ⁰C

26 ⁰C

22 ⁰C

Comfort

Zone

Sometimes thecustomer requiresa certain relativehumidity &temperature (ex:

26oC &50%RH) andto achieve this aheater or heatingcoil must be used.

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Conditioned

Space SE R

Supply Duct

OHeating CoilCooling Coil

FanDamper

 configuration

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ADP

dry-bulbtemperature

   w  e   t  -    b   u    l    b

 

   t  e   m   p  e

  r  a   t   u

  r  e

SR

ADP

(A/C)

spa

celoa

d

line

(A/C)load

line

Normal cooling

O

M

Cooling with dehumidification

dry-bulbtemperature

   w  e   t

  -    b   u    l    b

 

   t  e   m   p  e

  r  a   t   u

  r  e

S

R

Heating

process

By hot gas

reheat.

spaceload

line

(A/C)

loadline

O

M26 ⁰C

70 %50 %

50 %

26 ⁰C

26 ⁰C 70 % 26 ⁰C