Chillers

In a pharmaceutical facility maintaining the environmental condition is very important irrespective of the weather situation of the surrounding environment. Every processing area demand certain temperature and relative humidity to be maintained throughout. This necessitate industrial chillers for processing of air apart from hot water. Also, some of the process requires chiller for achieving required process parameter. Typically, water or a water/glycol mix are used as a medium to cool. The chilled water absorbs heat from what is being cooled and then goes through the chiller where the heat is removed from the fluid and transferred to the ambient air. It is extensively use in HVAC system in pharmaceutical facility.

The Process:

Industrial water or glycol chiller systems contain two main circuits: a refrigeration circuit and a fluid circuit (water or water glycol mix). The refrigeration circuit is made up of four components: the compressor, the condenser, the expansion valve and the evaporator. It uses a specified refrigerant which takes the heat from the fluid (water or water glycol mix).?The Fluid circuit consisting of pumps and sometimes with a reservoir takes the heat from other process ( eg. HVAC) and enters the chiller at an elevated temperature and gets out of chiller at a desired temperature.

Types of Chillers:

1. Based on Compression: Based on refrigeration cycle as described below
2. Based on Absorption: Selective absorption media like Lithium bromide/ dehumidification bed is used to absorb the evaporated water and cool the water.
3. Vacuum based using high pressure Steam convergent- divergent nozzles are used to create high vacuum and take away hot evaporate water along to cool the water.

The refrigeration cycle based on compression and expansion are most commonly used in the industry and the description as below.

The Refrigeration Cycle Step by Step – Chiller Diagram based on Compression

Compressor

The refrigeration cycle begins with the compressor. The compressor takes low-pressure low-temperature refrigerant in gas form and compresses it into a high-pressure high-temperature gas.

Condenser

This gas then flows through coils in the condenser. While in the condenser, air or water will flow over the coils and remove heat from the refrigerant. As the refrigerant loses heat it will begin to condense until all of the gas has condensed into a liquid.

Expansion Valve

After leaving the condenser, the liquid goes through the expansion valve. The expansion valve restricts the flow of refrigerant. When the high-pressure liquid goes through the expansion valve it enters the evaporator.

Evaporator

The evaporator is where the refrigerant starts evaporating back into a gas. When the refrigerant evaporates it gets very cold and absorbs a lot of heat. It is in the evaporator that the process fluid will interact with the cold refrigerant.?Heat from the fluid and transferred to the refrigerant. The refrigerant will then enter the compressor and the cycle begins again.

The difference is that the water-cooled chillers or rather the cooling towers use a humid air stream (ambient air stream + water spray) while the air-cooled chillers use ambient air.

Normally water-cooled chillers are?cheaper and more efficient, with the disadvantage of?high-water consumption.

However, air cooled chillers too provide certain benefits and those are as below.

·???????No cooling towers

·???????Better environmental stability-no water wastage

·???????Low maintenance costs

·???????Chemical costs avoided

·???????Water costs avoided, especially in cities

·???????No water problems to deal with in case of disaster

Safe refrigerants

These are the non-toxic, non-flammable refrigerants such as R11, R12, R13, R14, R21, R22, R113, R114, methyl chloride, carbon dioxide, water etc.

Toxic and moderately flammable are Dichloroethylene methyl format, ethyl chloride, sulphur dioxide, ammonia etc. come under this category.

?Highly flammable refrigerants are butane, isobutene, propane, ethane, methane, ethylene etc.

?DESIRABLE PROPERTIES OF REFRIGERANTS

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Economic Criteria: Apart from the desired technical properties one must evaluate the economic criteria taking in to account the cost of the refrigerant, the availability and supply levels of the refrigerant, cost of storage and handling.

?COMMON REFRIGERANTS: The refrigerants which are available commercially in the market are numerous. Some of them which are in common use are mentioned below:

The chemical arrangement of the refrigerants decides in which group it should be considered. As per the various manufacturers’ guidelines, there are four main refrigerant types:

1.?????CFCs – Chlorofluorocarbons

2.?????HCFCs – Hydro chlorofluorocarbons

3.?????HFCs – Hydro fluorocarbons

4.?????Natural Refrigerants

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CFCs – Chlorofluorocarbons

These are the refrigerants which contain chlorine, fluorine, and carbon. These are hazardous for the layer of ozone and unfriendly for the environment.

R11, R12, R13, R113, R114, R500, R502, R503 are the top refrigerants covered under the group.

2) HCFCs – Hydro chlorofluorocarbons

HCFCs were referred to as the substitute of CFCs. It contains hydrogen, chlorine, fluorine, and carbon. The impact on environment of this group is relatively very low comparing to CFCs.

HCFCs are non-toxic, cheap, and competent. They can also deplete the ozone slowly, but continuously.

R22, R123, R124, R401A, R401B, R402A, R403B, R408A, R409A, R414B, R416A are the refrigerants which are covered under the group of HCFCs.

3) HFCs – Hydro fluorocarbons

These refrigerants do not include any particles of chlorine. So, they are not at all harmful to the environment and do not deplete the ozone layer. This is better than HCFCs.

It includes hydrogen, fluorine, and carbon.

R23, R134a, R404A, R407C, R410A, R417A, R422A, R422B, R422D, R507, R508B are included in the HFC group.

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4) Natural Refrigerants

As the name suggests, natural refrigerants are completely natural. They do not harm the nature, environment, or the ozone layer.

Moreover, they are quite inexpensive as compared to other refrigerants. Air, HC, ammonia, CO2, H2O, etc. are the examples of natural refrigerants. They have zero ozone depletion potential and negligible effects on global warming.

Useful tips for Energy savings:

1. Use efficient motors & compressors. Select type( Screw/Centrifugal/Reciprocating) based on the efficiency.
2. Use proper insulation: the temperature from the generation and farther end of supply line should be with 1 degree C Plus.
3. Use Non scale forming and low tds water slightly alkaline about pH 8 -8.5.
4. Proper filter system in the return to ensure clean water to chiller. Auto tube cleaning mechanism may aid to efficiency.
5. Maintain good inlet cooling media temperature, and quality
6. Use IIOT to monitor and manage chiller