Páratartalom - az alábecsült mérési paraméter
Regisztráljon most a „A levegő páratartalma a helyiségekben” című négyrészes szakértői sorozatért, és a szakvéleményeket ingyenesen letöltheti e-mail-en keresztűl.
1. Jó beltéri klíma: Mennyire fontos a beltéri levegő páratartalma?
2. EN 16798 és társai: A páratartalom az európai szabályozásban
(angol tartalom)
3. A levegő páratartalma a helyiségekben: változóban az új referencia érték?
(angol tartalom)
4. A levegő páratartalma helyiségekben, termodinamika és entalpia
(angol tartalom)
(Olvasási minta a 4 részes sorozat 1. cikkéből)
A beltéri klíma akkor komfortos, ha az emberek a páratartalmat és a hőmérsékletet kellemesnek érzékelik. A modern házakban ezt a lakóterek szellőztetése, a nagy épületekben pedig a szellőzőrendszerek, az úgynevezett HVAC-rendszerek biztosítják. Sajnos, légkondicionálásnál gyakran túl kevés figyelmet fordítunk a páratartalomra és annak a beltéri klímára gyakorolt hatására - amely gyakran súlyos következményekkel jár.
A kereskedelemben és az iparban más a helyzet. A termékminőség vagy a gyártási folyamatok döntően a beltéri levegő páratartalmától függenek, így a beszállított levegőt érzékelőkkel vagy páratartalom-mérő eszközökkel folyamatosan ellenőrizni kell. Ugyanez vonatkozik a nedvességre érzékeny áruk tárolására, illetve a múzeumokban, levéltárakban vagy akár a régi autók garázsában található értéktárgyakra és műtárgyakra is.
A megfelelő rendszertechnológia és páratartalom-szabályozás hiánya száraz beltéri levegőt eredményez. Ez különösen igaz a téli fagyos hidegben. Ilyenkor a radiátorok vagy a padlófűtési rendszerek felmelegítik a belső hőmérsékletet. Ha ilyenkor nem mérjük a relatív páratartalmat, és a helyiség levegője nincs párosítva a szükséges mértékben, akkor a helyiség levegőjének relatív páratartalma jóval a 40 százalékos érték alá csökken. Ez negatív hatással van a nyálkahártyára, és fokozott fertőzésveszélyt jelent. Ezenkívül a nedvességre érzékeny berendezési tárgyak, például a fabútorok vagy a parketta szenvedni fognak - sőt, akár meg is repedhetnek. Valami más is előfordulhat – különösen a nedves helyiségekben, például a fürdőszobákban, vagy a főzés, illetve a növények és akváriumok miatt -, ha túl sok a nedvesség a helyiségben.
Szeretné elolvasni a teljes szakértői tudást? Akkor regisztráljon itt a 4 részes sorozatra.
(reading sample article 2 of the 4-part series)
There are a number of international regulations for HVAC systems in residential and non-residential areas. From the point of view of the building, the most important is the EN 16798 series of standards. Their main focus is always on the air quality in rooms and air hygiene. In the meantime, energy-efficient operation has also become increasingly important. The requirements of regulations, standards or directives concern testing and measuring procedures for the handover, execution and operation, hygiene, hygiene inspections or maintenance and service of the systems.
But what is the actual significance of indoor humidity in international standards and legislation and what is the current situation? Let us look at an example: Since 1 January 2018, new minimum heat recovery figures have been applicable in Europe for non-residential ventilation systems. For closed loop systems this is 68 percent, for rotary and plate heat exchangers 73 percent. This is stipulated by the Ecodesign Directive, or more precisely its implementation by EU Regulation 1253/2014 “Ecodesign requirements for ventilation units”.
The European industry associations Eurovent and EVIA are currently working on incorporating moisture recovery into the EU Regulation along with efficiency-enhancing measures for non-residential ventilation systems for heat and moisture recovery. This means the associated energy for dehumidification (cooling) as well as all the humidification and frost protection required. It therefore seems to be of importance. But apart from this example, what else is in the pipeline, and what is the current status of European standards and regulations with regard to indoor humidity today?
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(reading sample article 3 of the 4-part series)
If condensation is non-desirable when cooling with an air conditioner or an HVAC system, it is important to keep indoor air above the dewpoint. This will save energy. But does it also make sense and is the constant measurement of temperature and relative humidity in rooms a suitable reference variable?
Depending on the location, season and application, the supply air for rooms, production or storage facilities needs to be humidified or dehumidified in different ways. For example, the ideal value for people is a near as possible constant 40 percent relative humidity in indoor air. This is different in the case of the indispensable antibiotic penicillin. This is most reliably produced at a relative humidity of 60 percent. The same applies to the moisture value in rotary printing in the paper industry.
Technical humidification is carried out isothermally with steam or adiabatically by evaporation, misting and atomisation of water. Dehumidification is achieved by means of adsorption and condensation processes. This almost always requires additional energy input, usually electrical, but occasionally with gas. However, air humidity in rooms is actually rarely the significant reference variable when planning a ventilation or air conditioning system. But would it perhaps be better to work with the operator to determine what the requirements will be and how the air humidity in rooms can be ensured on this basis before designing air conditioning and ventilation systems? It may even make sense to recover humidity. And, if relative humidity is taken into account with foresight and continuously measured, can energy, money and above all CO2 emissions be saved to a significant extent if the air humidity in rooms is introduced as a reference variable for air conditioning and ventilation technology? The report provides answers about the real significance of moisture in the air we consume.
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(reading sample article 4 of the 4-part series)
What is “moist” air, when or why does it become “dry”, how much heat energy does it contain, and what does all this have to do with specific enthalpy? An insight into the correlations between moisture, dryness, thermal energy and enthalpy is provided by physics, more precisely by the laws of thermodynamics. Anyone who has grasped this not entirely simple subject knows, for example, about possible ways of playing with the dewpoint of water in evaporative coolers, can explain the concept of wet bulb temperature without a second thought, and has an impressive grasp of isentropic changes of state – not to mention, being able to sleepwalk through the h-x diagram with complete accuracy, even without an explanatory video as back-up.
These days, however, the design of air conditioning units, HVAC systems or recooling systems is very often carried out by computer programs. The danger of this: Expert knowledge gained by planners or plant engineers about thermodynamic behaviour is increasingly being forgotten. And sometimes there is simply not enough time in day-to-day business to give any thought to an energy-efficient alternative.
However, maybe by thinking about air conditioning technology or recooling units in more depth, one or two kW of mechanically generated cooling energy might be saved or a refrigeration system might even become superfluous? This is especially true when it comes to cooling temperature limit ranges. That is, providing that the possibilities of adiabatic cooling, but also new ones for moisture recovery are properly understood. This is where thermodynamic knowledge helps to deal “correctly” with humid air.
Do you want to read the full technical article? Then register here for the 4-part series.