Chillers

Overview:

Chiller is equipment commonly used in HVAC or industrial applications to cool liquids to low temperatures. There can be multiple chillers in a chilled water plant. Chillers are the main part of the cooling plant that provides chilled water to the cooling system in the facility. chilled water plant mainly consists of Chillers, piping, pumps and control.

 water cooled chiller

 

image source (http://www.tecogen.com/products-chillers-ton-water-cooled.htm)

Chiller types:

Chillers are classified into two main categories:

I- Evaporative chillers.

II- Absorption.

I- Evaporative chiller: Evaporative chillers are classified according to:

Condenser cooling:

1- Water cooled evaporative chiller.

2- Air cooled evaporative chiller.

Condenser location:

1- Package chiller.

2- Remote condenser chiller.

Compressor type:

1- Positive Displacement (Reciprocating).

2- Centrifugal (Rotary Screw and Scroll).

 

II- Absorption chillers: absorption chiller may be classified to:

1- Air-Cooled Absorption Single Effect.

2- Water-Cooled Absorption Single Effect.

3- Absorption Double Effect, Indirect-Fired.

4- Absorption Double Effect, Direct-Fired.

 

Chiller selection:

When selecting chiller types and numbers, The following factors shall considered:

1- Chiller price.

2- Chiller plant requirements include pumps, cooling towers, control and piping.

2- Installation cost.

3- Energy cost at full and partial loads.

4- Water cost for water cooled chillers.

5- Maintenance cost.

6- Insurance and taxes.

7- Noise and Vibration.

8- Unit size and weight.

9- Applicable codes and standards.

 

Location of central plant:

Location of central plant shall be determined during the early stages of the project. Once type of chilled is selected, mechanical engineer shall coordinate with the other disciplines in the project to locate the chiller plan.

When indoor chiller selected, some design consideration shall be considered for Refrigerant machine room

See also:

Refrigerant machine room

chiller efficiency comparison

chiller efficiency comparison

Minimum Ventilation for indoor chillers:

1- Emergency ventilation:

For system refrigerant charges less than or equal to 7000 kg (15 400 lb) :

Q = 70 × G0.5 (Q = 100 × G0.5)

For system refrigerant charges greater than 7000 kg (15 400 lb):

Q = 16 × G2/3 (Q = 20 × G2/3)

where

Q = airflow, L/s (ft3/min)

G = mass of refrigerant, in kg (lb), in the largest chiller that is located or partly located in the mechanical room

 

2- Minimum ventilation:

2.54 L/s for every m² or

0.5 cfm per ft² of machinery room area;

 

For natural ventilation

Free opening area, m² = 0.138 √(G) or

Free opening area, ft² = √(G)

where

G = mass of refrigerant, in kg (lb), in the largest chiller that is located or partly located in the mechanical room

©2013, Eng. M.S. Alwarawreh

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