Question

On a warm summer day in Oslo, the temperature is 21 degree C and the relative humidity is 70%. What is the absolute humidity? What is the humid volume of the air? What is the specific enthalpy of the air, taking H_2O (L, 0 degree C, 1 atm) as a reference state? What is the wet bulb temperature? What is the dew point temperature?

Answer 1

Step-by-step explanation:

According to the psychrometric chart at dry bulb temperature of
`21^(o)C` and RH 70%, the absolute humidity = 0.011 kg/kg dry air

Formula to calculate humid volume is as follows.

`\\u_(H) m^(3)/kg` dry air =
`(22.41)/(273)TK ((1)/(28.97) + (1)/(18.02)H)`

=
`(2.83 * 10^(-3) + 4.56 * 10^(-3) H) T K`

=
`(2.83 * 10^(-3) + 4.56 * 10^(-3) * 0.011) * 294`

= 0.847
`m^(3)/kg` dry air

Hence, humid volume of air is 0.847
`m^(3)/kg` dry air.

Specific enthalpy of dry air = specific heat capacity of dry air × dry bulb temperature

=
`1.006 kJ/kg ^(o)C * 21^(o)C`

= 21.126 kJ/kg dry air

Hence, the specific enthalpy of the air is 21.126 kJ/kg dry air.

As per the psychrometric chart at given conditions wet bulb temperature = 17.5
`^(o)C`

As per the psychrometric chart at given conditions dew point temperature = 15.5
`^(o)C`