Air-conditioning Processes (Module 3)

A comprehensive set of vocabulary flashcards covering the various psychrometric processes, governing equations, and thermodynamic principles used in air conditioning and ventilation systems.

Air-conditioning Process

A change in the thermodynamic state-point of air caused by adding or removing heat, performing work, adding or removing mass (water vapor), or mixing fluids at dissimilar states.

Sensible Cooling

The process of reducing the dry bulb temperature of air without changing the quantity of water it contains, represented as a horizontal line moving left on a psychrometric chart.

Sensible Heating

The process of increasing the dry bulb temperature of air without changing the moisture content, represented by horizontal lines parallel to the abscissa on a psychrometric chart.

Air dew point temperature ($T_{\text{dewpoint}}$)

The temperature at which air is $100\%$ saturated and water vapor begins to condense out of the air.

Humidification

The process of introducing moisture into the airstream to increase humidity, commonly used in winter for dry air or in summer as part of evaporative cooling.

Heating and Humidifying

A process that simultaneously increases both the dry-bulb temperature and the humidity ratio, appearing as a line sloping upward and to the right on a psychrometric chart.

Latent cooling

Also known as dehumidification, this is the process of cooling air below its dew point temperature to condense and remove moisture.

Cooling and Dehumidifying

A process used in hot, humid climates where air is cooled below its dew point, represented on a psychrometric chart as a line sloping downward and to the left.

Bypass factor ($b$)

The ratio of the amount of air which does not contact the coil ($m_{ab}$) to the total amount of supply air ($m_a$), calculated as $b = \frac{t_2 - t_d}{t_1 - t_d}$ where $t_d$ is the apparatus dew point.

Chemical Dehydration

Another term for Heating and Dehumidification, where air is passed over a desiccant or sorption material to remove water vapor, thereby increasing air temperature via the heat of condensation.

Absorption

The mechanism of desiccant dehumidification that occurs when physical or chemical changes take place in the material.

Adsorption

The mechanism of desiccant dehumidification that occurs when there are no physical or chemical changes in the sorption material.

Evaporative Cooling

An adiabatic process where the sensible heat of air vaporizes water; the dry bulb temperature drops while the wet-bulb temperature remains constant.

Steady Flow Mixing Process

The mixing of two air streams with different properties and flow rates, resulting in a mixture whose state-point lies on the line connecting the two incoming streams on a psychrometric chart.