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Effective prevention of condensation water in refrigeration and air-conditioning systems

They ensure a pleasant room temperature, refrigerate foodstuffs and support the production of pharmaceutical products, comestible goods or chemicals. Refrigeration and air-conditioning systems are an important component of commercial, retail and industrial companies. However, using them also comes at a price, because, depending on the scale of the system, the costs of energy use can make up an entire 40 to 80 % of the total costs. For this reason, the topic of energy efficiency – and thus also technical insulation – is particularly important.

Optimal technical insulation minimises energy losses, reduces greenhouse gas emissions and, with refrigeration and air-conditioning systems in particular, fulfils an additional purpose: the prevention of condensation water. Condensation water results when the temperature of a material lies below that of its environment and thus an atmosphere saturated with moisture occurs on the material. Pipework in the refrigeration technology, the cold water zone and the air-conditioning technology transport media that have a temperature much lower than that of the environment. This temperature differential causes moisture condensation on the external surfaces of the pipes.

                       
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The results include frozen condensation water, drips, moisture penetration, corrosion and mould. A lack of insulation or incorrect insulation can therefore cause considerable damage. An increase in energy consumption, operational disruptions or even the total failure of the system lead to increasing and incalculable operating costs, not to mention the need to replace all of the insulation. To prevent this, it is crucial to both select the right insulation as well as correctly calculate the insulation thickness. Anyone who ensures diligent planning, installation and quality at this stage will prevent costly system disruptions or even failures and thus keep operating costs stable in the long term – or even permanently reduce them.


Selecting the right insulation product

However, there are a few things to consider when selecting the optimal insulation. Both its technical properties as well as the correct insulation thickness play an important role. To insulate refrigeration and air-conditioning systems, closed cell insulation products such as Kaiflex offer a clear advantage over open cell materials.

                       
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For example, the insulation product must be resistant to moisture in order to prevent condensation and for it not to become saturated. The barrier effect against the penetration (diffusion) of water vapour is measured by the water vapour transmission factor μ. The greater the resistance – or better said, the higher the µ value – the higher the level of protection. This is where Kaiflex insulation products score with a very good value of up to μ 10,000. As closed cell insulation products, they already come with an integrated “vapour barrier”. In flexible, fine-celled elastomeric foams, this is as thick as the insulation itself. A reliable vapour barrier is thus integrated over the entire insulation thickness and pipework is permanently protected. Open cell structures, that to a large extent consist of air and are not permanently hydrophobic, soak up water like a sponge and consequently lose their insulating properties.

Open cell materials to some extent have a significantly lower μ-value of <10 or even 1, making them susceptible to water vapour migration and giving them a water vapour diffusion “resistance” that only matches that of the air. They therefore always require an external vapour barrier such as a film, which makes them more complicated to install and less reliable in terms of their impermeability.

                       
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The super-fine structure of Kaiflex insulation products is formed of individual cells that are self-contained units. Scratches on the surface of the insulation therefore do not cause any damage to the adjacent unit and the moisture resistance is thus retained despite the damage. In comparison, any damage to water vapour barriers on open cell insulation products allows the moisture to penetrate the insulation product unhindered, and this becomes entirely saturated over time, with all the associated consequences for the insulation effect and installation.

However, not only are Kaiflex products impressive because of their resistance to moisture, they also have low thermal conductivity. The low temperature of the transport medium remains constant over the entire distance so there are no temperature losses.


Correctly calculating the insulation thickness

In addition to selecting a suitable insulation material, it is also necessary to calculate the insulation thickness in order to prevent the accumulation of condensation water. If the insulation thickness is insufficient or has been calculated incorrectly, the coldness of the pipe can penetrate through the insulation to its surface – or the moisture in the outside air to the pipe – and condensation forms. Achieving a correct calculation requires knowing the ambient temperature, the humidity of the room, the medium and the temperature of the medium. It is important that the dew point lies within the insulation.

 

Incorrect calculations can be caused by e.g. incorrect information about the prerequisites listed above. If the room is not ventilated and the air does not circulate – which is generally not recommended in the area around refrigeration pipes – other parameters must also be included in the calculation. The VDI 2055 series of guidelines is very helpful in this regard. It supports the design process by providing calculation notes for planning insulating materials and gives advice on how to guarantee the promised properties of insulation products and insulation systems.

 

 

 

 

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