Air Psychrometrics
The study of moist and humid air - psychrometric charts, Mollier diagrams, air-condition temperatures and absolute and relative humidity and moisture content
Absolute Humidity of Air
Humidity - or moist - is the water vapor present in air where commonly used terms are Absolute, Specific and Relative Humidity
Air - Altitude, Density and Specific Volume
Density and the specific volume of air vary with elevation above sea level
Air - Composition and Molecular Weight
Dry air is a mechanical mixture of nitrogen, oxygen, argon and several other gases in minor amounts
Air - Density at varying pressure and constant temperatures
Figures and tables showing changes in air density at pressure varying from 1 to 10 000 bara (14.5 - 145000 psi) and constant, selected temperatures. Figures are given in different scales.
Air - Density, Specific Weight and Thermal Expansion Coefficient at Varying Temperature and Constant Pressures
Online calculator, figures and tables showing density, specific weight and thermal expansion coefficient of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units
Air - Diffusion Coefficients of Gases in Excess of Air
Diffusion coefficients, D12, for gases in large excess of air at temperature varying from 0 - 400 °C
Air - Dynamic and Kinematic Viscosity
Online calculator, figures and tables showing dynamic (absolute) and kinematic viscosity of air at temperatures ranging from -100 to 1600°C (-150 to 2900°F) at pressure ranging from 1 to 10 000 bara (14.5 - 145000 psia) - SI and Imperial Units
Air - Maximum Moisture Carrying Capacity
Maximum water content in humid air depends on temperature
Air - Molecular Weight and Composition
Dry air is a mixture of gases where the average molecular weight (or molar mass) can be calculated by adding the weight of each component
Air - Prandtl Number
Figures and table showing changes in Prandtl number for air with changes in temperature and pressure
Air - Properties at Gas-Liquid Equilibrium Conditions
Figures and tables showing how the properties of air changes along the boiling and condensation curves (temperature and pressure between triple point and critical point conditions). An air phase diagram are also given.
Air - Specific Heat at Constant Pressure and Varying Temperature
Online calculator, figures and tables showing how specific heat (Cp and Cv) of dry air vary with temperature at different pressures, SI and imperial units
Air - Specific Heat at Constant Temperature and Varying Pressure
Figures and table showing isobaric (Cp) and isochoric (Cv) specific heat of air at constant temperature and varying pressure ranging 0.01 to 10000 bara
Air - Thermal Conductivity
Online calculator, figures and tables showing air thermal conductivity at varying temperature and pressure, SI and imperial units.
Air - Thermal Diffusivity
Figures and tables showing dry air thermal diffusivity at varying temperarure and pressure, SI and Imperial units
Air - Thermophysical Properties
Thermal properties of air - density, viscosity, critical temperature and pressure, triple point, enthalpi and entropi, thermal conductivity and diffusicity, and more
Air Humidity measured by Dry and Wet Bulb Temperature
Estimate moist air relative humidity by measuring dry and wet bulb temperature
Air Humidity Ratio
The ratio between the mass of water vapor present in moist air - to the mass of dry air
Air- Moisture Holding Capacity vs. Temperature
Moisture holding capacity of air increases with temperature
Ammonia - Density at Varying Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of ammonia at temperatures ranging -50 to 425 °C (-50 to 800 °F) at atmospheric and higher pressure - Imperial and SI Units
Changing the State of Air by Heating, Cooling, Mixing, Humidifying or Dehumidifying Processes
Basic air condition processes - heating, cooling, mixing, humidifying and dehumidifying by adding steam or water - psychometric diagrams and the Mollier charts
Compressed Air Water Content
Saturation pressure and maximum water content in compressed air
Cooling and Dehumidifying Moist Air
Cooling and dehumidifying processes of moist and humid air - sensible and latent cooling
Cooling Tower Efficiency
Maximum cooling tower efficiency is limited by the wet-bulb temperature of the cooling air
Dehumidifiers
Classification of dehumidifiers
Density of Moist Humid Air
Density of dry air and water vapor - moist or humid air
Dry Air and Water Vapor - Density and Specific Volume - Imperial Units
Density and specific volume of dry air and water vapor at temperatures ranging 225 to 900 degF (107 to 482 degC)
Dry Air Properties
Dry air properties at temperatures ranging 175 - 1900 K - specific heat, ratio of specific heats, dynamic viscosity, thermal conductivity, Prandtl number, density and kinematic viscosity
Dry Bulb, Wet Bulb and Dew Point Temperatures
Dry Bulb, Wet Bulb and Dew Point temperatures are important to determine the state of humid air
Drying Force of Air
The drying force of air can be expressed with moisture holding capacity of air and the evaporation capacity from water surface to air
Enthalpy of Moist Air
The enthalpy of humid air consists of sensible and latent heat
Evaporation from 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
Evaporative Cooling
An evaporative cooling tutorial
Great Sensible Heat Factor - GSHF
Great Sensible Heat Factor is the ratio between sensible and total heat in a cooling coil
Heat Recovery Efficiency
Classification of heat recovery efficiency - temperature efficiency, moisture efficiency and enthalpy efficiency - online heat exchanger efficiency calculator
Heating Humid Air
Enthalpy change and temperature rise when heating humid air without adding moisture
Human Heat Gain
Heat gain from persons in air conditioned spaces - in btu/hr
Humid Air and the Ideal Gas Law
Pressure, temperature and volume for an ideal or perfect gas like air with water vapor - or moist air
Humidifying Air by Adding Steam or Water
Air can be humidified by adding water or steam
Humidifying Air with Steam - Imperial Units
Amount of vapor (lb/h in 100 cfm) in humid air
Humidifying Air with Steam - SI units
Use steam to humidify air
Humidity and Heat Index
Humidity and the apparent temperature
Ideal Gas Law
The relations between volume, pressure, temperature and quantity of a gas, including definition of density of a gas
Indoor Comfort Temperature versus Outdoor Temperature
Recommended indoor comfort temperature vs outdoor temperature
Indoor Relative Humidity versus Outdoor Temperature and Relative Humidity
Indoor relative humidity versus outdoor temperature and relative humidity
Latent Heat Flow
Latent heat is the heat, when supplied to or removed from air, results in a change in moisture content - the temperature of the air is not changed
Metabolic Heat Gain from Persons
Human metabolic heat gain in air conditioned rooms
Mixing Humid Air
The state of mixed moist air - enthalpy, heat, temperature and specific humidity
Moist Air - Degree of Saturation
Humidity ratio of moist air to humidity ratio of saturated moist air
Moist Air - Density vs. Pressure
Density of moist air versus pressure ranging 75 - 1000 mm Hg
Moist Air and Daltons Law of Partial Pressure
Pressure in a mixture of dry air and water vapor - humid or moist air - can be estimated by using Daltons Law of Partial Pressures
Moist Air Properties
Psychrometric table with humid air properties
Mole Fraction of Water Vapor in Moist Air
Mole fraction of water vapor is the ratio of water molecules - to air and water molecules
Mollier Diagram
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
Non-ideal gas - Van der Waal's Equation and Constants
Listing of van der Waals constants for more than 200 gases, used to correct for non-ideal behavior of gases caused by intermolecular forces and the volume occupied by the gas particles
Outdoor Temperature and Relative Humidity - US Winter and Summer Conditions
Outdoor summer and winter design temperature and relative humidity in US states and cities
Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury
A psychrometric chart in English units - temperature ranging 20oF to 120oF
Psychrometric Chart for High Temperatures at Sea Level
Psychrometric Chart in I-P Units at high temperature at sea level and barometric pressure 29.921 Inches of HG
Psychrometric Chart for Low Temperatures at Sea Level
Psychrometric chart in I-P Units at low temperature at sea level and barometric pressure 29.921 Inches of HG
Psychrometric Chart for Normal Temperatures at 5000 Feet Altitude
Psychrometric chart in I-P Units at 5000 feet and barometric pressure 24.896 Inches of HG
Psychrometric Chart for Normal Temperatures at 7500 Feet Altitude
Psychrometric chart in I-P Units at 7500 feet and barometric pressure 22.653 Inches of HG
Psychrometric Online Calculator
Calculate moist air properties in SI and Imperial units with this online calculator
Psychrometric Table - 29.92 Inches of Mercury
Dry and wet bulb temperature, pressure and weight saturated water vapor and air saturated with water vapor
Psychrometric Terms
Dry and Wet Bulb Temperature, Specific Volume, Relative Humidity, Enthalpy and more ..
Relationship between Specific and Relative Humidity of Air
Calculating specific humidity of moist air - knowing relative humidity, water vapor and air density
Relative Humidity in Air
The relative humidity in air can be expressed by partial vapor and air pressure - density of the vapor and air - or by the actual mass of the vapor and air
Relative Humidity in Production and Process Environments
Recommended relative humidity in production and process environments - like libraries, breweries, storages and more
Removing Heat with Air
Estimating heat removed with air using wet bulb temperature
Room Sensible Heat Factor - RSHF
Room Sensible Heat Factor - RSHF - is defined as sensible heat load divided by total heat load in a room
Sensible Heat Flow
Sensible heat is dry heat causing change in temperature but not in moisture content
Sensible Heat Ratio - SHR
Sensible Heat Ratio - SHR - is defined as the sensible heat or cooling load divided by the total heat or cooling load
Specific Volume of Moist Air
Specific volume is defined as the total volume of humid air per mass unit of dry air
Transforming a Mollier Diagram to a Psychrometric Chart - or vice versa
The relation between Psycrometric charts and Mollier diagrams
Universal and Individual Gas Constants
The Universal and Individual Gas Constants in fluid mechanics and thermodynamics. Individual gas constant is given for the most common gases.
Vapor Pressure in Moist Air
Vapor pressures vs. dry and wet bulb temperature in moist air
Water - Saturation Pressure
Online calculator, figures and tables showing water saturation (vapor) pressure at temperatures ranging from 0 to 370 °C and from 32 to 700°F - in Imperial and SI Units
Water Vapor and Saturation Pressure in Humid Air
The saturation pressure of water vapor in moist air varies with temperature
Water Vapor in Air
Weight of water vapor in air
Wet Bulb Globe Temperature (WBGT)
The wet bulb globe temperature can be used to measure general heat-stress index