Search results
Results From The WOW.Com Content Network
Hygrometer. Dry / Wet-bulb temperature. v. t. e. Psychrometrics (or psychrometry, from Greek ψυχρόν (psuchron) 'cold' and μέτρον (metron) 'means of measurement'; [ 1][ 2] also called hygrometry) is the field of engineering concerned with the physical and thermodynamic properties of gas - vapor mixtures .
The psychrometric constant relates the partial pressure of water in air to the air temperature. This lets one interpolate actual vapor pressure from paired dry and wet thermometer bulb temperature readings. [1] γ = {\displaystyle \gamma =} psychrometric constant [kPa °C −1 ], P = atmospheric pressure [kPa], λ v = {\displaystyle \lambda _ {v}=}
The dew point of a given body of air is the temperature to which it must be cooled to become saturated with water vapor. This temperature depends on the pressure and water content of the air. When the air is cooled below the dew point, its moisture capacity is reduced and airborne water vapor will condense to form liquid water known as dew. [ 1]
The heat index ( HI) is an index that combines air temperature and relative humidity, in shaded areas, to posit a human-perceived equivalent temperature, as how hot it would feel if the humidity were some other value in the shade. For example, when the temperature is 32 °C (90 °F) with 70% relative humidity, the heat index is 41 °C (106 °F ...
Use a psychrometric chart to calculate wet bulb temperature, and then add 5–7 °F as described above. Use a rule of thumb which estimates that the wet bulb temperature is approximately equal to the ambient temperature, minus one third of the difference between the ambient temperature and the dew point. As before, add 5–7 °F as described above.
An enthalpy–entropy chart, also known as the H–S chart or Mollier diagram, plots the total heat against entropy, [1] describing the enthalpy of a thermodynamic system. [2] A typical chart covers a pressure range of 0.01–1000 bar, and temperatures up to 800 degrees Celsius. [3] It shows enthalpy in terms of internal energy , pressure and ...
Thermal comfort is the condition of mind that expresses subjective satisfaction with the thermal environment. [ 1] The human body can be viewed as a heat engine where food is the input energy. The human body will release excess heat into the environment, so the body can continue to operate. The heat transfer is proportional to temperature ...
Psychrometric chart - PMV method.pdf. English: This psychrometric chart represents the acceptable combination of air temperature and humidity values, according to the PMV/PPD method in the ASHRAE 55-2010 Standard. The comfort zone in blue represents the 90% of acceptability, which means the conditions between -0.5 and +0.5 PMV, or PPD < 10%.