HUMIDITY CONTROL
A guide to energy- efficient solutions
By John Barker of Humidity Solutions. E
nergy efficiency is a key consideration in the decision-making process of any financial investment – no more so than in
recent months.
As specialists in humidity control, Humidity Solutions is frequently asked for advice about low-energy systems and, by identifying a few key application criteria, we can make a sound recommendation. Firstly, we would look at whether the application requires a humidifier, dehumidifier or
both.Secondly, does the application requires cooling? If so, an adiabatic humidifier can assist in providing low-energy cooling. Thirdly, what is the duty required?
Humidification
Humidity can be added to the air by either boiling the water to generate steam, spraying/ atomising water or by evaporation. Steam humidifiers will unavoidably use a lot
of energy in the isothermal process of changing the physical state of the water from a liquid to a gas (steam). However, as a system this process may provide the most energy-efficient way of adding humidity. Low-energy humidifiers are generally adiabatic systems which include ultrasonic, high-pressure spray and evaporative humidifiers. Because no heat energy is required the power source is only to power oscillators
28 March 2023 •
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in the case of the ultrasonics or small pumps in the case of the evaporative or spray system. Consequently, these use approximately 10% of the energy to run the humidifiers compared with steam generation. In addition, these cold water humidifiers provide cooling to the air which can reduce the load on traditional air conditioning. Two energy savings in one system results in potentially lower running costs for the temperature/humidity control after adding the humidifier.
The system design also needs to be considered to determine which method of cold water humidification is best suited. Large direct air systems are generally spray systems, small laboratories or test chambers are often suited to the ultrasonics while data centres and manufacturing process control frequently favour evaporative systems. Despite using a lot of energy themselves, steam humidifiers may in some cases be the low-energy option for the system. The reason for this is that adiabatic humidifiers, while using a small amount of energy themselves, do cool the air. This can be a great advantage in environments where excess heat is a by-product of the process, or in warmer climates. However, if the building or process requires heating, then this cooling effect is not welcome and requires additional heat energy
to be added to the air. This heat energy equates to the amount of energy difference between a similarly sized adiabatic system versus a steam humidifier – so no system energy saving. Retrofit systems or new designs may require
a larger heating coil to be added to provide this extra heat, larger burners and bigger heat pumps, all of which come at a capital and running cost. Taking the energy source into account and the cost per kW is also part of the calculation. It takes the same amount of energy to convert water to steam whatever the technology. However, where energy can be saved is in the way that the system prevents condensation, which when produced is essentially throwing energy down the drain.
So we can also make the steam humidifiers as efficient as possible – the normal steam humidifier has a drain cycle to remove dissolved solids from the steam cylinder to extend the maintenance period. However, by adding a reverse osmosis plant we can remove the minerals before entering the boiling process – the drain cycle is no longer needed so can be turned off which stops hot, heated water from going to the drain and making this system 20% more energy efficient than a standard set up. For additional energy saving the solution
from Humidity Solutions is Neptronic X-stream Technology, which is a high-efficiency insulated
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