Desiccant dehumidifiers How do they differ from refrigeration models?

Déshumidificateurs à dessiccation En quoi diffèrent-ils des modèles à réfrigération ?

When it comes to dehumidifiers, it's important to mention that there are several types on the market, including refrigerant and desiccant, which present significant differences that we consider important to know about in order to determine which is best suited to your needs.

What is a desiccant dehumidifier?

To begin with, let's try to give a clear and simple definition of this piece of equipment, namely the desiccant dehumidifier. A desiccant dehumidifier is a device that regulates the humidity present in the air, using a chemical substance capable of effectively absorbing moisture: silica, which is the substance most commonly used in desiccant dehumidification devices, although other options such as lithium chloride are also used to a lesser extent.

Silica gel is a solid, adsorbent and transparent substance, capable of absorbing large quantities of moisture without undergoing chemical or physical alterations. It is also highly porous, with numerous capillaries in which moisture is absorbed, then condensed and contained in liquid form.

You are probably already familiar with this material, as it is frequently used in a variety of products liable to be damaged by moisture, such as medicine bottles, foodstuffs, footwear, electronic equipment and so on. It often comes in packaging form, in small textured bags or as tiny transparent grains. Silica gel (as it is also known) is not harmful to health, although it can present certain levels of toxicity if combined with cobalt chloride. Fortunately, such a combination is not used for commercial applications, nor for the operation of dehumidification equipment, which is why its use for moisture absorption is totally safe. What's more, it's one of the longest-lasting desiccant materials, so it rarely needs replacing.

How do desiccant dehumidifiers work?

The dehumidification process of desiccant equipment is controlled by an internal impeller made of a desiccant material such as silica gel. This wheel or rotor is also made up of several layers and channels through which the air absorbed by the system from the environment passes.

When the unit is switched on, the wheel begins to rotate, making the process of absorbing moisture from the air constant and uniform; it's important to note that two air flows pass through the rotor when it's operating: the air flow coming from the environment to be dehumidified, and the hot air flow needed to reactivate the desiccant material (this reactivation consists of transferring the liquid absorbed by the wheel to the hot air flow, in order to precipitate it in a filling tank).

It should be added, without going into the physics, that the pressure difference between the surface of the desiccant and the ambient air causes the wheel to emit or absorb moisture.

What is a refrigerant dehumidifier?

Refrigerant dehumidifiers are also very useful. The most notable difference is that refrigerant models are also considered compressor units. By means of a fan, refrigeration systems draw in air, filter it and direct it to an evaporator, which is at a very low temperature thanks to the built-in refrigerant gas.

As the humidity present in the environment passes through the evaporator, the water reaches its dew point, then condenses and separates from the evaporator. The water extracted from the environment can be stored in a reservoir built into the unit, or discharged via a drain. To complete the cycle, the air passes through a condensation system, where it is reheated to its initial temperature before being returned to the outside.

So... What are the differences?

With what's been said so far, it's likely that some of the differences between desiccant and refrigerant units may be intuitive, however, there are other idiosyncrasies you need to be aware of, which we'll mention below:

Because they do not incorporate a compressor, and due to the reduced mechanics used in the construction of desiccant models, they are generally quieter than refrigerant models.
As mentioned in the previous point, the absence of a compressor makes desiccant models smaller and lighter than their counterparts.

Desiccant units are extremely useful in cold rooms such as warehouses, ships or basements, as they have no compression system.

Desiccant systems, although more economical, consume more electricity than their counterparts.

It's true that desiccant dehumidifiers are generally more expensive to operate, but they are more efficient in terms of dehumidification, which is why they are more in demand than refrigeration equipment.

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