Mine Ventilation and Psychrometry Definitions

Flashcards testing vocabulary and key psychrometric definitions from the mine ventilation lecture transcripts.

Dry-bulb temperature

A measure of the sensible internal energy measured by a conventional thermometer.

Wet-bulb temperature

A temperature measurement indicated by a thermometer whose bulb is covered by a wetted wick and exposed to an air flow of $3\,m/s$, which together with the dry-bulb temperature measures the evaporative capacity of the air.

Dew-Point temperature

The temperature at which a sample of air must be cooled for condensation to just begin, at which temperature the air sample is saturated.

Partial Pressure

The pressure (measured in $kPa$) that a quantity of water vapour in a container of air would exert on the walls of that container if it were present alone at constant temperature.

Total Pressure

The sum of all partial pressures of dry air and water vapor ($P_a + P_v$).

Vapour Pressure

The partial pressure exerted by the water vapour present in a sample of air, measured in $kPa$.

Saturated Vapour Pressure (SVP)

The partial pressure exerted by water vapour when the air sample is saturated.

Absolute Humidity

The mass of water vapour present per unit volume of air ($m/V$).

Effective Temperature

The temperature of motionless saturated ambient air that would produce the same sensation as the ambient air being considered; note that effective temperature is subjective.

Metabolic rate

The rate at which energy is generated by various chemical processes in the body to do work and sustain life, associated with heat production and oxygen consumption.

Heat Tolerance Screening (HTS)

A procedure whose objective is to identify gross heat intolerance (not to be confused with heat tolerance testing), applying to all employees routinely exposed to $T_{wb} > 27.5^\circ\text{C}$.

Natural Acclimitization

The development of heat tolerance over a period of $12$ consecutive underground shifts, with no restriction applicable to the job or work category.

Deterministic effects

Radiation effects for which a threshold of radiation dose exists, and the severity of the effect increases with radiation dose above this level (e.g., cataract formation, fibrosis of lung tissue).

Mass flow of Dry Air

The measure of the mass of dry air present in a mixture of air, ignoring the mass of the water vapour present, which remains constant as air flows from one part of the mine to another.

Sigma Heat

The total heat enthalpy of air at the atmospheric wet-bulb temperature (in $kJ/kg$) less the enthalpy of the water vapour ($h_w$) in the liquid phase at wet-bulb temperature.

Enthalpy (Total Heat)

The sum of all sensible heat, latent heat, and superheat of a sample of air calculated above an arbitrary datum of $0^\circ\text{C}$, with units in $kJ/kg$.

Gauge pressure

Represents the amount by which the actual pressure differs from atmospheric pressure.

Standard Air

Air having a true density of $1,2\,kg/m^3$.

Free Air

Air having a true density of $1,0\,kg/m^3$.

Normal Temp & Pressure

Conditions specified by a temperature of $T = 0^\circ\text{C}$ and a pressure of $P = 1011,325\,kPa$.