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Desiccant Dehumidifier
(Desiccant Dehumidification)


1. Principles of Technology
The Air Dehumidifiers system, generally, can be classified into two different types namely, Desiccant Dehumidification and Mechanical Refrigeration.  Both of these systems have both advantageous and disadvantageous based on the different types of usages. Selecting any one system or use both of the systems together to remove the moisture form the air, will depend on the type of usage for dehumidification system.  As for the Mechanical Refrigeration system are more effective and economical than desiccant at high temperatures and moisture levels. (Typically, moisture is usually higher than 45% RH, but in some cases may be lower than 40% RH). For example, in order to maintain an outlet condition of 40% RH, it would be necessary to bring the coil temperature down to -10º c, which results in the formation of ice on the coil and a reduction in moisture removal capacity. Efforts to prevent this (defrost cycles) or other methods can be very cumbersome and expensive. Desiccant dehumidification system, on the other hands, is more effective and economical than refrigeration systems at lower temperatures and lower moisture levels.  (Typically, moisture is below 45% RH to 1% RH.) Thus, in many applications, a DX or Direct Expansion cooling coil is mounted directly at the dehumidifier inlet. This design allows for removal of moisture prior to entering the dehumidifier where the moisture is reduced even further.

Desiccant Dehumidifier

It is operated by allowing moist air from the manufacturing process (Process Air) to flow through the desiccant wheel coating which serves to absorb the moisture of the air. Then, the wheel is rotated to transfer the moisture stored to hot air t and low humidity (Heated Air) to discharge the moisture from dehumidifier. Production of the hot air used to draw moisture out of the air humidity. You can use the waste heat from the production process or the sun.

Desiccant is commonly used,namely Silica Gel, Activated Alumina, Natural and Synthetic Zeolite, Lithium Chloride, Titanium Silicate andSynthetic Polymers

Equipment and Components of Desiccant Dehumidifier

The Desiccant Dehumidifiers main component is wheel assembly, which contains a desiccant such as silica gel. The wheels rotor assembly will be driven by a motor in order to remove the moisture from the air flowing through the manufacturing process. An example of using a desiccant dehumidifier in the industry is made up of two types namely,
• Rotary desiccant dehumidifier, which combined with a heater to heat up the air for heating the air that is used to reactivate the capacity of the desiccant. This type is ideal for applications with storage space and a small-sanitized room

• Rotary desiccant dehumidifier with heat recovery.


2. Technological Application

Desiccant Dehumidifiers by using Silica Gel, and Activated Alumina can be applied in the various manufacturing process which required to control of air humidity levels between 10-50% and 5-30 oC temperature. It had been applied in industries including
• Electrics Industry (clean room and electronic assembly)
• Food Industry (fruit juice, cooking flour, candy and cookies)
• Pharmaceutical Industry (capsules and powder)
• Warehouse (food pallets. printing, steel, plywood, and explosives)
• Air Conditioning System.

In general, temperature and humidity control for each industrial sector can show as below

Process

Controlled

Controlled

Temperature

Humidity

(°F)

(%RH)

Electronic and Electrical Par Manufacture

Clean Room

22

45

Impiements and Machines

22

30-40

Food Production

Grain Storage

<27

<60

Sugar Storage

25-27

40-50

Bakery Premises

21-26

40-70

Confectionery Manufacture

18-20

40-50

Packaging Room

18-20

40-50

Pharmaceuticals Production

Manufacturing Power

24-27

15-35

Storage and Packaging

Tablet Compressing and

20-26

35-45

Cooling

Medicine Preparation

26-28

35-45

Biological Manufacture

26-28

30-40

Workshops

Precision Mechanics

20-22

50-55

Control and Calibration

24

45-50

Telecommunication Centre

18-20

40-60


Energy Saving

Energy saving with installation of Desiccant Dehumidifiers, it will depend on the application of each situation. Therefore, selecting of dehumidifier system shall require cost saving comparison incurred with Desiccant Dehumidifiers and other system. In addition, It must also take into account the area of installation, temperature and humidity requirements and other alternatives of Desiccant Dehumidifiers. At present, Desiccant Dehumidifier has developed into high performance by using Liquid Desiccant instead of the old system. It is operated by working in conjunction with heat pumps to reduce energy consumption with regenerator before bring the desiccant to be reused.

Operating Principle of Liquid Desiccant Dehumidifier

It utilized LiCl solution to remove moisture from the air and use a heat pump draws heat from the air to draw the moisture from the desiccant.




Replacement of the old technology.

It controls humidity levels below 40% RH by replacing the desiccant wheel and use Electric Heater or Steam Heater to increase the air temperature to remove moisture out of the desiccant.



Target Groups comprises of designers

Entrepreneurs who has a dehumidifier system in use such as educational institutions and general public

Impact on the Environment

There is no environmental impact because the use of desiccant are not toxic and harmful to the environment. Also, the technology is designed to help reduce energy consumption and reduce emissions of greenhouse gases.