Air is a mixture, not a single number
Sizing any sistema de recuperación de calor starts with the state of the air. Four properties define it:
- Dry-bulb temperature (DB): the ordinary thermometer reading.
- Wet-bulb temperature (WB): thermometer with a wet wick; tracks the cooling effect of evaporation.
- Humidity ratio (W): mass of water vapour per mass of dry air, kg/kg.
- Relative humidity (RH): how close the air is to saturation at its temperature.
- Enthalpy (h): total energy per kg of dry air, sensible plus latent, in kJ/kg.
The psychrometric chart
A psychrometric chart plots these properties on one diagram. A point fixes DB, WB, W, RH and h at once. Engineers use it to read what happens when air is heated, cooled, humidified or dehumidified – exactly the processes a recovery core performs.
A practical approximation for moist-air enthalpy is:
h ≈ 1.006 x T + W x (2501 + 1.86 x T) (kJ/kg dry air, T in degC)
Why recovery engineers must know this
Heat recovery moves entalpía, not just temperature. A Rueda sensible shifts the dry-bulb part; an enthalpy wheel shifts both. Reading the exhaust and supply states on the chart tells you how much energy is actually available and whether you need latent recovery at all.
Frequently asked questions
DB vs WB – what is the difference? DB is the real air temperature; WB reflects both temperature and moisture and is the lowest temperature the air can reach by evaporative cooling.
Does low RH mean dry air in winter? Cold outdoor air can have low RH but very little absolute moisture (low W); it still needs humidification indoors for comfort.
Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team – WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.
Preguntas frecuentes
What does a psychrometric chart tell an engineer?
It plots dry-bulb temperature against humidity ratio at a given pressure, showing enthalpy, wet-bulb, relative humidity and dew point so you can read every state of moist air.
Why is humidity ratio more useful than relative humidity for recovery calculations?
Relative humidity depends on temperature, while humidity ratio is the actual mass of water per mass of dry air; energy and moisture balances use humidity ratio directly.
Preguntas frecuentes
What does a psychrometric chart tell an engineer?
It plots dry-bulb temperature against humidity ratio at a given pressure, showing enthalpy, wet-bulb, relative humidity and dew point so you can read every state of moist air.
Why is humidity ratio more useful than relative humidity for recovery calculations?
Relative humidity depends on temperature, while humidity ratio is the actual mass of water per mass of dry air; energy and moisture balances use humidity ratio directly.
Especifique el intercambiador adecuado
Nuestros ingenieros dimensionan el núcleo según su caudal, temperatura y presupuesto de caída de presión, y seleccionan recuperación por placa, rotativa o caloduc según la aplicación. Lea la guía del intercambiador , o contáctenos para una especificación.
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