Feature atmosphere or in a duct . Steam offers intrinsically hygienic humidification so is ideal for use in sensitive applications such as healthcare environments .
However , both electrode and resistive steam humidifiers are electrically powered so a major disadvantage to the end-user is their high energy consumption . This also has implications for those end-users looking to minimise their
CO 2 emissions .
COLD WATER Cold water humidifiers present a low energy and low maintenance alternative to steam humidification in certain applications . An evaporative humidifier can deliver highcapacity humidification to an air handling unit ( AHU ) while running on just 0.5kW of energy .
The energy used to evaporate the cold water is taken from the air rather than electricity or gas . This process provides adiabatic cooling to the air as well as humidification , which can be an added advantage of cold water systems . Up to 12 o C of cooling can be achieved .
For many comfort applications additional pre-heating is needed to raise the temperature of the air back to the desired level . However , using gas pre-heating or heat exchangers , cold water humidification is still 75 % cheaper in energy costs than using electric steam humidifiers .
The two main types of cold water humidifiers are spray and evaporative . A spray humidifier consists of a series of nozzles that produce fine droplets of water that rapidly evaporate in the air stream . They can be located either inside a duct or mounted directly in a room . Humidity control is good at ± 4 % RH , and outputs can be very large with a single system delivering over 1 000l per hour , while running on only 3.2kW of electricity .
Evaporative humidifiers are located inside a duct or AHU and consist of a continually moistened evaporative matrix through which the air flows . As the air passes through the wet matrix it picks up the moisture and is cooled . As there is no aerosol with these systems they can be located inside a short section without any risk of the humidity wetting out on to a nearby bend .
Hygiene in cold water humidifiers is assured through the use of drain and flush cycles . With the humidifier design preventing water from remaining inside the system , bacterial growth is controlled . Silver ion dosing can also be used in cold water humidifiers on the incoming water supply . Silver has a powerful antibacterial action that has a residual effect throughout the humidifier , further restricting bacterial growth .
Installation of cold water humidifiers is straight forward , especially as there is no requirement for three-phase power or gas supply . Maintenance is much less onerous than steam
Remy Geiling / Unsplash © RACA Journal | Eamonn Ryan
humidifiers as the minerals in the water are either removed by water treatment plant or simply flushed to drain , in the case of the evaporative humidifier .
This double saving of reduced energy cost and low maintenance combined with the additional benefit of adiabatic cooling makes cold water humidifiers a very attractive alternative to traditional steam humidification .
THE SPECIFICATION OF HUMIDIFICATION Ensuring you specify the correct humidification system largely depends on being able to extract the right information from the end-user on how the system will be employed . However , it can be difficult to build-up enough experience to know the
SCE logo .
Factories making textiles require humidity control .
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