Air Psychrometrics

Absolute Humidity of Air

Humidity - or moist - is the water vapor present in air. Commonly used terms are Absolute, Specific and Relative Humidity

Air - Altitude, Density and Specific Volume

The density and the specific volume of air varies with the elevation above sea level

Air - Specific Heat at Constant Temperature and Various Pressures

Specific Heat of air at constant temperature 20^oC and pressure ranging 0.01 to 100 atm

Air Composition

Dry air is a mechanical mixture of nitrogen, oxygen, carbon dioxide and more

Air Humidifying with Steam - Imperial Units

Amount of vapor (lb/h in 100 cfm) in humid air

Air Properties

Temperature, density, specific heat, thermal conductivity, expansion coefficient, kinematic viscosity and Prandtl's number for temperatures ranging -150 - 400 ^oC

An Introduction to Psychrometry

An introduction to air psychrometrics

Changing Air Condition 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

Comparing Mollier Diagrams and the Psychrometric Charts

Transforming between psycrometric charts and Mollier diagrams

Cooling Tower Efficiency

The maximum cooling tower efficiency is limited by the wet-bulb temperature of the cooling air

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Cooling and Dehumidifying Air

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

Daltons Law of Partial Pressures in Moist Air

Pressure in a mixture of dry air and water vapor - humid or moist air - can be estimated by using Daltons Law of Partial Pressures

Dehumidfication in Psychrometric Charts

A dehumidification tutorial with psychrometric charts

Dehumidifiers

Classification of dehumidifiers

Densities and Specific Volumes of Dry Air and Water Vapor

Densities and specific volumes of dry air and water vapor at temperatures ranging 225 to 900 degF (107 to 482 degC)

Density of Dry Air, Water Vapor and Moist Humid Air

Calculate the density of dry air, water vapor or the mixture of air and water vapor - moist or humid air

Density of Moist Air

Density of moist air - pressure ranging 75 - 1000 mm Hg

Dry Bulb, Wet Bulb and Dew Point Temperature

Dry Bulb, Wet Bulb and Dew Point temperatures are commonly used to determine the state of humid moist air

Drying Force of Air

The Drying Force of air may be expressed as the moisture holding capacity of the air and the evaporation capacity from a water surface to the air

Enthalpy of Moist and Humid Air

The enthalpy of moist and humid air consist of sensible heat and latent heat - enthalpy is used to calculate cooling and heating processes

Evaporation from Water Surfaces

The amount of evaporated water from a water surfaces - like swimming pools or an open tanks - depends on the temperature in the water and in the air, and the humidity and velocity of the air above the surface - online calculator

Evaporative Cooling

An evaporative cooling tutorial

Great Sensible Heat Factor - GSHF

The Great Sensible Heat Factor is the ratio between the sensible and total heat for a cooling coil

Heat Humidity Factor

Moisture - temperature and heat humidity factor

Heat Removed by Air

Heat removed with air - dry and wet bulb temperature

Heating Humid Air

Calculating enthalpy change and temperature rise when heating moist and humid air without adding moisture

Humid Air and the Ideal Gas Law

The Ideal Gas Law relating pressure, temperature, and volume of an ideal or perfect gas used for 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 - SI units

The amount of vapor - kg per cubic meter - in humid air

Humidity Ratio of Air

Humidity ratio (GPP) is the ratio between actual mass of water vapor present in moist air - to the mass of dry air

Ideal Gas Law

In perfect or ideal gas the change in density is directly related to the change of temperature and pressure as expressed by the Ideal Gas Law

Latent Heat Flow

Latent heat is the heat, when supplied to or removed from air, results in a change of moisture content - the temperature of the air is not changed

Maximum Moisture Content in Air

Moisture limit in air varies with temperature

Measuring Air Humidity

Measuring relative air humidity with dry and wet bulb temperatures

Mixing Humid Air

Calculating enthalpy, heat, temperature and specific humidity in mixing humid air

Moist Air Properties

A psychrometric table with moist humid air properties

Moist Air and Degree of Saturation

The ratio of humidity ratio of moist air to humidity ratio of saturated moist air - the Degree of Saturation

Mole Fraction of Water Vapor in Moist Air

Mole fraction of water vapor expresses the ratio of water molecules - to air and water molecules

Molecular Mass of Air

Dry air is a mixture of gases where the molecular weight can be calculated by adding the weight of each component

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

Outdoor Temperature and Relative Humidity - US Winter and Summer Conditions

Outdoor design temperature and relative humidity in US states and cities - summer and winter

Outdoor to Indoor Temperature Rise and Relative Humidity

The relationship between outdoor and indoor temperature rise - and the effect on the relative humidity

People and Heat Gain

Heat Gain from Occupants in Air Conditioned Spaces - in btu/hr

Persons and Metabolic Heat Gain

Metabolic heat gain from occupants in air conditioned spaces at different degrees of activities - in Watts

Pressure and Maximum Content of Water in Saturated Air

Air pressure and maximum content of water in saturated air

Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury

A psychrometric chart in English units - temperature ranging from 20^oF to 120^oF

Psychrometric Chart at 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 at 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 at Normal Temperatures at 5000 Feet

Psychrometric chart in I-P Units at 5000 feet and barometric pressure 24.896 Inches of HG

Psychrometric Chart at Normal Temperatures at 7500 Feet Altitude

Psychrometric chart in I-P Units at 7500 feet and barometric pressure 22.653 Inches of HG

Psychrometric Chart at Normal Temperatures at Sea Level

Sea Level Psychrometric Chart - Ledger Size - Both US and SI units

Psychrometric Chart in SI Units for Download

A downloadable psychrometric chart at normal temperatures in SI Units

Psychrometric Chart with an Extended Range

An psychrometric chart with extended range.

Psychrometric Charts - An Introduction

Air conditions can be characterized by using the psychrometric chart. Properties on the chart include dry-bulb and wet-bulb temperatures, relative humidity, humidity ratio, specific volume, dewpoint temperature and enthalpy

Psychrometric Online Calculator

Calculate moist air properties in both 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 Bulb and Wet Bulb Temperature, Specific Volume, Relative Humidity,  Enthalpy and more ..

Recommended Indoor Temperature versus Outdoor Temperature

Recommended indoor effective temperatures at various outdoor dry-bulb temperatures

Recommended Indoor Temperature versus Outdoor Temperature

Recommended indoor effective temperatures at various outdoor dry-bulb temperatures

Recommended Relative Humidity in Production and Process Environments

Recommended Relative Humidity - RH - in production and process environments like libraries, breweries, storages and more

Relative Humidity of Air

The relative humidity of 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

Room Sensible Heat Factor - RSHF

The Room Sensible Heat Factor - RSHF - is defined as the sensible heat load in the room divided by the total heat load in room

Sensible Heat Flow

Sensible heat is dry heat causing change in temperature but not in the 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 Heat of Dry Air

Specific heat of dry air varies with temperature

Specific Volume of Moist Air

Specific volume is defined as the total volume of humid air per mass unit of dry air

Temperature and Moisture Holding Capacity of Air

The moisture holding capacity of air varies with temperature

The relationship between Specific and Relative Humidity of Air

Calculating specific humidity of moist air knowing relative humidity, water vapor and air density

Vapor Pressure in Moist Air

Vapor pressures in moist air from dry and wet bulb temperatures

Water Flow Hose - Pressure Loss

Pressure loss due to friction

Water Saturation Pressure

Water saturation pressure at temperatures ranging 0 - 100 ^oC and 32 - 700 ^oF - Imperial and SI Units

Water Vapor - Weight in Air

Weight of water vapor in air

Water Vapor and Saturation Pressure in Humid Air

The saturation pressure of water vapor in moist air varies with temperature