Excessive air humidity can cause undesirable effects, such as feeling unwell, sicknesses, material losses and increased hazard of workplace accidents. They can all be counteracted by reducing the amount of water in the air.
Air drying can be applied in several areas, the most important ones being:
- providing appropriate climate comfort,
- technological processes in various industries,
- protection against corrosion,
- protection against steam condensation,
- protection against icing,
- protection against fungal and bacterial growth,
- improving repair and construction works,
- avoiding product agglomeration.
Climate comfort
Apart from heating, cooling and humidifying, air drying can be used to keep the proper air parameters indoors, where people live or technological processes are performed. The state of the surroundings, where the air has the parameters to provide well-being to people is called thermal comfort. As a part of the overall climate comfort, thermal comfort can be provided, among others, by keeping the air at an appropriate temperature and humidity levels. Air drying is advisable when the humidity in an air-conditioned room exceeds the thermal comfort level.
Technological processes
The technological processes in numerous industries require that the air is at a specific humidity level, which is often a lot lower than the ambient humidity. Dry air is mostly used to remove water from manufactured products. Some products can only be manufactured in a low humidity atmosphere, as water could cause unwanted chemical reactions.
Removing precipitation from the air also stops bacteria, viruses and mould from developing. Due to this effect, drying can be applied in some manufacturing processes. Air drying is mainly used in pharmaceutical, food-processing, construction, electronic and wood-processing industries, as well as numerous others.
Protection against corrosion
Corrosion largely depends on air humidity. Exposing steel to air with a relative humidity of approx. 60% causes corrosion spots to show up. The air with the humidity level between 60 and 100% will considerably accelerate corrosion. Keeping air humidity at 45-50% protects ferrous metals against corrosion. The relationship between relative humidity and corrosion is shown on the Vernon’s graph.
Protection against steam condensation
Water condensation takes place where the surface is cooer than the dew point of the surrounding air.
Steam condensation is a widespread problem in water pumping stations and waterworks. The temperature of devices, tanks, pipes and other installations is near the ground water temperature of 5 to 12°C.
When both ambient temperature and humidity rise, water can begin to condense on such elements. It also condense on the walls of ice rinks, that are cooled by ice.
Water condensation may cause damage and other hazards. Dried air helps lower the dew point. This stops water from condensing in undesirable places.
Protection against icing
Humid air makes the ice “grow” in freezers, refrigerators and in loading areas. Air drying protects such places from icing and speeds up the process of carrying the warmth from the product (freezing). This lowers the cost and improves safety.
Protection against fungal and bacterial growth
High air humidity accelerates the growth of mould, that may be contained in various materials and may stay there for years, not causing any damage or loss. However, air humidity as high as 70% dramatically accelerates their growth, contributing to various material and health issues. The most prevalent problems are wall damages, mould growth and rotting of stored grains, fodders and food products.
Air humidity also speeds up bacterial growth, which might lead to various illnesses and contaminations. Mould and bacteria may also cause unpleasant odours. Air drying helps eliminate the issues of mould and bacteria.
Construction
Water is widely used in construction, mainly as a substrate for mortar, concrete, adhesives and paints. That is why excessive water contents have to be removed from both new and renovated buildings. This ensures proper insulation, resistance and durability of paint layers. Additionally, it serves as a protection against fungal and bacterial growth Water can be removed from the inside of the building using several methods, but one of the best ones is air drying, which makes the walls “give up” excessive water.
Agglomeration
Many loose products (especially powdered ones) have hygroscopic properties. Due to the humidity, the material becomes lumpy and agglomerated, which has a direct bearing on their quality and manufacturing cost. Storing damp products may also cause several complications. Lowering the air humidity helps protect against such issues.Others
Air drying is also useful in other situations. One of them is using condensation dryers in places where clothes dry. Portable condensation dryers can also be used in buildings affected by floods, where they allow for quickly drying damp walls, regardless of the weather.
Air drying is also crucial in air-conditioned buildings with high humidity, such as pools, showers, labs, etc. This helps limit the operation cost, mostly due to the recuperation of heat and part of water.
High water contents may also change the physical and chemical properties of materials. Paper stored in humid places loses its rigidity and becomes deformed. Some binding materials and plastics lose their properties when exposed to dampness.
Humidity-sensitive products, such as some medicines, can only be stored in low-humidity environments.
