Psychrometer
Any instrument capable of measuring the psychrometric state of air is called a psychrometer. As mentioned before, in order to measure the psychrometric state of air, it is required to…
Wet-Bulb Thermometer
In practice, it is not convenient to measure the wet-bulb temperature using an adiabatic saturator. In stead, a thermometer with a wetted wick is used to measure the wet bulb…
Psychrometric chart
A Psychrometric chart graphically represents the thermodynamic properties of moist air. Standard psychrometric charts are bounded by the dry-bulb temperature line (abscissa) and the vapour pressure or humidity ratio (ordinate).…
Humid specific heat
From the equation for enthalpy of moist air, the humid specific heat of moist air can be written as: where cpm = humid specific heat, kJ/kg.K cp = specific heat of dry…
Enthalpy
Enthalpy is the measure of heat energy in the air due to sensible heat or latent heat. Sensible heat is the heat (energy) in the air due to the temperature…
Important psychrometric properties
Dry bulb temperature (DBT) is the temperature of the moist air as measured by a standard thermometer or other temperature measuring instruments. Saturated vapour pressure (psat) is the saturated partial pressure of…
Methods for estimating properties of moist air
In order to perform air conditioning calculations, it is essential first to estimate various properties of air. It is difficult to estimate the exact property values of moist air as…
Amagat’s & Dalton’s Law
Amagat’s Law The volume of an ideal gas mixture (V) is equal to the sum of the component volumes (Vj’s) of each individual component in the gas mixture at the…
MASS AND MOLE FRACTION
If we want to deal with the problems of gas mixture, two laws should always be taken into consideration. One is the conservation of mass. And the other is the…
Coil Load Calculation Example
Determine the minimum cooling coil load and required chilled water flow for a system serving an office space with a sensible cooling load of 30,800 Btu/h and a latent load…
