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Operation And Troubleshooting Air Cooled, Water Cooled And Chilled Water System

8th -11th of December 2013By: Muhd Nasir Bin Mhd Yusuf

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Mollier

• Evaporation• Compression• Condensation• Expansion

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Mollier

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Mollier

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Compression• Adiabatic – Insulate compressor• Isentropic – Parallel with Entropy• Isothermal – Compressor Same temperature

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Subcooling• Subcooling– Range -15°C ~ -9.4°C (5°F ~ 15°F)– >-9.4°C over-charged or mismatched component installed– <-15°C undercharged or mismatched component installed– <-15°C will reduce efficiency metering device– Solution;• Check evaluate system components, locate & repair

leaks.• Charge in refrigerant to correct subcooling.

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Superheating• Superheating– Range -6.7°C ~ -1.1°C (20°F ~ 30°F)– <-6.7°C liquid enter into compressor– > -1.1°C compressor too hot (burn)– Charging Refrigerant – Correct Subcooling &

Superheat

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Superheat – Capillary tube

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Superheat – TXV

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Superheat

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Cooling Coils

• Off Coil- 4 ~10°C• Air Velocity- 500 ~ 550 ft/min• Design – 350 ~ 450 CFM / TR

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Troubleshooting Using PH Chart

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• P2 ↑– Cooling Capacity = ṁ ↓ x RE ↓– Power Input = ṁ ↑ x HC ↑– COP = RE ↓ = ↓

HC ↑

Mollier

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• P2 ↓– Cooling Capacity = ṁ x RE ↑– Power Input = ṁ x HC ↓– COP = RE ↑ = ↑

HC ↓

Mollier

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• P1 ↑– Cooling Capacity = ṁ ↑ x RE ↑– Power Input = ṁ ↑ x HC ↓ = ↑ (little bit)– COP = RE ↑ = ↑

HC ↓

Mollier

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• P1 ↓– Cooling Capacity = ṁ ↓ x RE ↓– Power Input = ṁ ↓ x HC ↑ = ↓– COP = RE ↓ = ↓

HC ↑

Mollier

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Troubleshooting by Temperature Checking

• Return Air Temperature – Indicave of Room Temperature

• Causes for high temperature• Supply Air Temperature – Indicative of coil

performance• Supply Air Temperature and room humidity

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Troubleshooting of Air Cooled System

• How ambient air temperature affects system performance

• Effects of high entering air temperature• Non-performance due to high condensing

pressure• Servicing of condenser coil• Effects of fouling on the cooling coils• Servicing of the cooling coils

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Troubleshooting of Air Cooled System

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Case StudyCase No.

P2 (psig)

P1 (psig)

Possible Problems

1 310134°F

7343°F

•Check condenser•Air temperature @ condenser•Condition on condenser coil

2 270123°F

53285°F

•Indoor Site•Evaporator problem

3 220108°F

20-5°F

•Refrigerant leak

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Operation & Troubleshooting of Cooling Tower

• Types of Cooling Towers• Working principles of Cooling Towers• Performance of Cooling Tower: Range,

Approach• Troubleshooting of cooling towers

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Cooling Tower

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Cooling Tower

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Water Pump

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Case StudyCase No. Ambient

Twb°F

T1°F

T2°F

P1psig

P2psig

Possible Problem

1

2

3

4

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