Air Heating Systems - Using air to heat buildings - temperature rise diagram.

Air - Humidifying with Steam - SI units - Using steam to humidify air.

Air - Humidifying by Adding Steam or Water - Air can be humidified by adding water or steam.

Air - Heating, Cooling, Mixing, Humidifying or Dehumidifying Processes - Basic air changing state processes - heating, cooling, mixing, humidifying and dehumidifying by adding steam or water - psychometric diagrams and the Mollier charts.

Air Conditioning - Air Conditioning systems - heating, cooling and dehumidification of indoor air for thermal comfort.

The Sensible Heat Ratio can be expressed as

Using (3b) the total sensible and latent heat removed from the air can be calculated as H t = (1.202 kg/m 3) ( 1 m 3/s) (( 77 kJ/kg dry air) - (28 kJ/kg dry air))ДЇrom the psychrometric chart we estimate the water enthalpy in the hot air to be 19 Btu /lb dry air, and the enthalpy in the cold air to be 13.5 Btu /lb dry air. Using (3) the total sensible and latent heat removed from the air can be calculated as = 1.08 q dt + 0.68 q dw gr (4) Example - Cooling or Heating Air, Total HeatДЇrom the Mollier diagram we estimate the water enthalpy in the hot air to be 77 kJ/kg dry air, and the enthalpy in the cold air to be 28 kJ/kg dry air. estimate enthalpy with the Mollier diagramДh = enthalpy difference (btu/lb dry air).Total heat due to both temperature and moisture can be expressed in SI units as: Latent Heat Load and Required Air Volume Chart (pdf).Latent heat load - humidifying and dehumidifying - and required air volume to keep temperature constant at various temperature differences between entering air and room air are indicated in the chart below: = 12.2 (Btu/hr) Latent Heat Load and Required Air Volume Chart H l = 0.68 (1 cfm) (( 45 grains water/lb dry air) - ( 27 grains water/lb dry air)) Using (2b) the latent heat removed from the air can be calculated as The relative humidity of the air is 70% at the start and 100% at the end of the cooling process.ДЇrom the psychrometric chart we estimate the water content in the hot air to be 45 grains water/lb dry air, and the water content in the cold air to be 27 grains water/lb dry air. Using (2) the latent heat removed from the air can be calculated as The relative humidity of the air is 70% at the start and 100% at the end of the cooling process.ДЇrom the Mollier diagram we estimate the water content in the hot air to be 0.0187 kg water/kg dry air, and the water content in the cold air to be 0.0075 kg water/kg dry air. Latent evaporation heat for water can be calculated asДw gr = humidity ratio difference (grains water/lb dry air)Дw lb = humidity ratio difference (lb water/lb dry air)ДЄn air flow of 1 m 3/s is cooled from 30 to 10 oC. estimate humidity with the Mollier diagram.H we = latent heat evaporization water ( 2454 kJ/kg - in air at atmospheric pressure and 20 oC)Дw kg = humidity ratio difference (kg water/kg dry air) Latent heat due to the moisture in air can be calculated in SI-units as: Sensible Heat Load and Required Air Volume Chart (pdf).

Sensible heat load and required air volume to keep the temperature constant at various temperature differences between make up air and room air: = 21.6 (Btu/hr) Sensible Heat Load and Required Air Volume Chart Using (1b) the sensible heat added to the air can be calculated as Using (1) the sensible heat added to the air can be calculated as Q = air volume flow (cfm, cubic feet per minute)Дt = temperature difference ( oF) Example - Heating Air, Sensible HeatДЄn air flow of 1 m 3/s is heated from 0 to 20 oC. The sensible heat in a heating or cooling process of air (heating or cooling capacity)В can be calculated in SI-units asД¬ p = specific heat of air (1.006 kJ/kg oC)

Radiator calculation tool