24 °C
14 °C
7 °C
32 °C to 37 °C
Fresh air
The major concepts include humidity, temperature, specific enthalpy, and the relationships between these properties in moist air.
h_fg,0 = 2501 kJ/kg
The psychrometric chart can be used to obtain properties of air.
The General Gas Law can be applied to the dry air and water vapor separately.
1. Gibbs-Dalton Law holds. 2. Enthalpy of dry air and water is zero at 0ºC. 3. All water vapor is vaporized at 0ºC.
h = h0 + ω(hv + cp,da(t - t0) + cp,v(t - t0))
The equation for relative humidity includes the mole fractions of water vapor in both moist air and saturated moist air, as well as the conditions of temperature and pressure.
The relationship can be expressed through equations that involve the specific enthalpy and humidity ratio of moist air.
A relative humidity of 100% indicates that the air is fully saturated with water vapor.
Use the formula ϕ = (p_v / p_vs) * 100, where p_vs is the saturation vapor pressure at 20ºC, which is 2.337 kPa. Thus, ϕ = (1.5 kPa / 2.337 kPa) * 100 = 64%.
A graphical representation showing the relationship between dry bulb temperature (T db), wet bulb temperature (T wb), dew point temperature (T dp), humidity ratio (ω), relative humidity (ϕ), specific enthalpy (h), and specific volume (v), valid only for one constant pressure.
T1 = T2 = T3 = T4 = T5.
Wet bulb temperature is the temperature measured by a thermometer that has a wet wick. It can be used to determine relative humidity.
Measured wet bulb temperature can be converted to relative humidity using specific formulas that relate wet bulb temperature, dry bulb temperature, and humidity ratio.
Relative humidity (φ) is calculated as the ratio of the partial pressure of water vapor (p) to the saturated pressure of water vapor (p_sat) at the same temperature, expressed as φ = (p / p_sat) * 100%.
In moist air, the total mole fraction is the sum of the mole fractions of water vapor and dry air, expressed as x_v + x_a = 1.
25.5 °C.
Yes, a psychrometric chart can be used to obtain the properties of moist air.
T dp = 8.5 °C
cp,da is the specific heat capacity of dry air, and cp,v is the specific heat capacity of water vapor.
The mass of a gas mixture can be calculated by summing the masses of the individual gases in the mixture.
h = 45 kJ/kg
0.0102 kg.
R_a is approximately 287 J/kgK.
The temperature (T) is 9.2 ºC.
Nitrogen, oxygen, argon, carbon dioxide, minor gases, water vapor, dust, fog, and microbes.
The total enthalpy is calculated using the specific enthalpy of dry air and water vapor, along with the humidity ratio.
The chart is valid for one constant pressure, and specific conditions like T wb, φ, T dp, h, and v can also be constant.
Dalton's law states that total pressure equals dry air pressure plus water vapor pressure.
8.314 kJ/kmolK
c_pda = 1.005 kJ/kg·K
The latent heat of vaporization for water at 0°C is 2501 kJ/kg.
The total pressure of a gas mixture can be calculated by adding the partial pressures of each component gas.
Properties such as dry bulb temperature, wet bulb temperature, relative humidity, humidity ratio, and specific enthalpy can be determined using a psychrometric chart.
The relationship involves calculations using psychrometric principles, where Tdb, Twb, and Tdp are interconnected through specific equations.
T db = 28 °C
T wb = 16 °C
Dry bulb temperature is greater than wet bulb temperature, which is greater than dew point temperature.
Relative humidity is the ratio of the current amount of water vapor in the air to the maximum amount of water vapor the air can hold at a specific temperature, expressed as a percentage.
It is useful for visualizing air-water vapor processes at constant pressure.
Dry bulb temperature is the air temperature, denoted as T_db (°C).
Relative humidity is represented by the symbol φ.
ω = 0.009 kg/kg
The Gibbs-Dalton law is related to the conservation of mass in gas mixtures, stating that the total mass of the mixture is equal to the sum of the masses of the individual gases.
99.692 kPa.
You can calculate the energy required for heating, cooling, humidification, and dehumidification of air.
Given the indoor design conditions and cooling load, you can determine the required supply air conditions and flow rate, or vice versa.
c_pv = 1.88 kJ/kg·K
A psychrometric chart is a graphical representation of the physical and thermal properties of moist air, used to analyze air conditioning processes.
Condensation occurs.
The humidity ratio (ω) is 0.007215 kg/kg dry air.
Relative humidity is defined as the ratio of the mole fraction of water vapor in a given moist air sample to the mole fraction of water vapor in a saturated moist air sample at the same temperature and pressure.
The humidity ratio is used to determine the contribution of water vapor to the total enthalpy of moist air.
The ω-coordinate is rotated so that the line of t = 0ºC becomes parallel with the w-ordinate.
Dry air and water vapor.
Humidity ratio is based on 1 kg of dry air because the total mass of moist air varies with the addition or removal of water vapor, while the mass of dry air remains constant.
The pressure exerted by each constituent of a gas mixture is independent of the presence of the others.
Air is modeled as dry air plus water vapor.
h = h_da + h_v + c_pda * t + c_pv * t
The specific heat of dry air is 1.005 kJ/kg·K and for water vapor, it is 1.88 kJ/kg·K.
h0 is the specific enthalpy of dry air at a reference state.
A Wetted Wick Thermometer is used to measure wet bulb temperature, which is essential for calculating humidity and other properties of moist air.
T wb = 15 °C
T db = 20 °C
R_a is the gas constant for dry air and R_v is for water vapor, measured in J/kgK.
φ = 40%
The factors include dry bulb temperature, pressure, humidity ratio, specific enthalpy, relative humidity, dew point temperature, and wet bulb temperature.
The T-v diagram represents the relationship between temperature (T) and specific volume (v) of a substance during constant-pressure phase-change processes.
29 kg/kmol
ω represents the humidity ratio, which is the mass of water vapor per kilogram of dry air.
ω = 0.0065 kg/kg
A psychrometric chart is a graphical representation of the physical and thermal properties of moist air, showing the relationships between temperature, humidity, and other air properties.
ω = pda + pv + fg h c c t h
c_pda = 1.005 kJ/kg·K
ω = 0.02156 kg/kg dry air
φ = 60%
Relative humidity is the ratio of the current amount of moisture in the air to the maximum amount of moisture the air can hold at a given temperature, expressed as a percentage.
The dry-bulb temperature is higher than the dew point temperature.
The science of studying the thermodynamic properties of moist air and applying these properties to analyze air conditioning processes.
The moisture content is 0.02156 kg/kg of dry air.
The specific enthalpy can be calculated using the specific heat values and latent heat, but the exact value is not provided in the text.
Humidity ratio (ω) is the mass ratio of water vapor to dry air, expressed in kg/kg dry air.
Normal pressure at sea level is 101.325 kPa.
Given any two parameters, you can find the other parameters using the chart.
hv represents the specific enthalpy of vapor.
The formula for calculating the humidity ratio is ω = a * (vp / (p - vp)).
1.633 kPa.
101.325 kPa.
p = 1 atm
p = 1 atm
You can determine the condition of moist air by using the table of properties of water.
Moist air is a mixture of dry air and water vapor.
The three principal phases of matter are solid, liquid, and gas.
No, the amount of water vapor in the air will affect enthalpy, making this formula not applicable.
1: Compressed liquid, 2: Saturated liquid, 3: Saturated liquid-vapor mixture, 4: Saturated vapor, 5: Superheated vapor.
The dew point temperature (T dp) can be calculated using the formula involving the saturation vapor pressure and the actual vapor pressure. For this case, it can be found from property tables.
Constant-pressure phase-change processes are thermodynamic processes where a substance changes phase (e.g., from liquid to gas) while maintaining a constant pressure.
P1 > P2 = P3 = P4 > P5.
The mole fraction of water vapor in moist air is represented as x_v.
υ1 < υ2 < υ3 < υ4 < υ5.
Dalton's law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each individual gas in the mixture.
The key properties of moist air include dry bulb temperature, wet bulb temperature, dew point temperature, humidity ratio, and relative humidity.
1.005 kJ/kgK
ω = 0.007 kg/kg
T dp = 12 °C
RT = p * v / M
The partial pressure of water vapor must be less than or equal to the saturated pressure of water vapor at a given temperature.
The whole chart is set at an angle so that the ω-coordinate is vertical.
You can find the dew point temperature using the psychrometric chart.
c_pv = 1.88 kJ/kg·K
The wet bulb temperature indicates the cooling effect of evaporation and is crucial for understanding humidity and its effects on comfort and air conditioning.
T db = 23 °C
p = 1 atm
φ = 27%
T dp = 7.5 °C
Relative humidity is represented as curved lines on a psychrometric chart, indicating the percentage of moisture in the air relative to the maximum it can hold at a given temperature.
Calculations by equations may be complicated due to the interdependencies of various properties and the need for precise measurements.
h_fg,0 = 2501 kJ/kg
R_v is approximately 462 J/kgK.
Two different chart formats exist: one represented by ASHRAE and CIBSE chart, and the other used by most non-English-speaking European countries.
h = 42 kJ/kg
ω = (R_a * T) / (R_v * P_v) - (R_a * T) / (R_v * P_a)
The straight lines on a psychrometric chart represent constant enthalpy, showing the energy content of the moist air as temperature and humidity change.
h = 85.29 kJ/kg dry air
h = c_p * T
T wb = 14.5 °C
h = 41 kJ/kg
You can access an online psychrometric chart at http://www.flycarpet.net/en/PsyOnline.
