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# Moist Air - the Mollier Diagram

Air is a mixture of mostly oxygen, nitrogen and water vapor. The Mollier diagram is a graphic representation of the relationship between air temperature, moisture content and enthalpy, and is a basic design tool for building engineers and designers.

The Mollier diagram is a variant of the psychrometric chart .

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### Example - How to use the Mollier Chart

The state of air with dry bulb temperature 21 oC and relative humidity 50% is indicated in the Moliier chart below:

From the Mollier chart the enthalpy of the moist air is approximately 40 kJ/kg . The wet bulb temperature is approximately 14.5 oC . The specific humidity is approximately 0.0076 kg/kg .

Alternatively - if the dry bulb temperature is 19 oC and the wet bulb temperature is 12 oC - the state of the air can be visualized in the Mollier chart like:

From the chart we can see that the enthalpy of the air is approximately 33 kJ/kg and the specific humidity is approximately 0.0056 kg/kg .

## Related Topics

### • Air Psychrometrics

Moist and humid air calculations. Psychrometric charts and Mollier diagrams. Air-condition systems temperatures, absolute and relative humidities and moisture content in air.

## Related Documents

### Air - Drying Force

The drying force of air depends on the air moisture holding capacity and the water surface to air evaporation capacity.

### 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 - Humidifying by Adding Steam or Water

Air can be humidified by adding water or steam.

### Air - Humidifying with Steam, SI units

Using steam to humidify air.

### Air - Humidity Measurement from Dry and Wet Bulb Temperature

Relative humidity in moist air can estimated by measuring the dry and wet bulb temperature.

### Air - Psychrometric Chart for Standard Atmospheric Conditions - Imperial Units

Psychrometric chart for air at barometric pressure 29.921 inches of Mercury and temperature ranging 20oF to 120oF.

### Cooling and Heating Equations

Latent and sensible cooling and heating equations - imperial units.

### Dehumidifiers

Classification of dehumidifiers.

### Evaporation from a Water Surface

Evaporation of water from a water surface - like a swimming pool or an open tank - depends on water temperature, air temperature, air humidity and air velocity above the water surface - online calculator.

### Heat Recovery Efficiency

Classification of heat recovery efficiencies - temperature efficiency, moisture efficiency and enthalpy efficiency - online heat exchanger efficiency calculator.

### Mixing of Humid Air

The change in state wwhen mixing moist air - enthalpy, heat, temperature and specific humidity.

### Moist Air - Cooling and Dehumidifying

Cooling and dehumidifying processes of moist and humid air - sensible and latent cooling.

### Moist Air - Psychrometric Terms

Dry and wet bulb temperature, specific volume, relative humidity,  enthalpy and more.

### Moist Air - Transforming the Mollier Diagram to a Psychrometric Chart - or vice versa

The relationship between the psycrometric chart and the Mollier diagram.

### Relative Humidity in Production and Process Environments

Recommended relative humidity in production and process environments - like libraries, breweries, storages and more.

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