Ask Question
24 February, 01:54

2.73 A fan within an insulated duct delivers moist air at the duct exit at 358C, 50% relative humidity, and a volumetric flow rate of 0.4 m3 / s. At steady state, the power input to the fan is 1.7 kW. The pressure in the duct is nearly 1 atm throughout. Using the psychrometric chart, determine the temperature, in 8C, and relative humidity at the duct inlet.

+3
Answers (1)
  1. 24 February, 05:44
    0
    Temperature at 8C = 32 °C * 8 = 256

    Relative humidity is = 60% * 8 of 256°C accordingly.

    Explanation:

    Considering the volumetric flow rate = 0.4 m³/s

    Moist air delivered (Temperature T1 = 358 C)

    With Relative humidity at duct outlet = 50%

    Power input at steady rate = 1.7 KW

    Pressure in the duct = 1 atmosphere

    Temperature at 8C = ?

    Relative humidity at the duct inlet = ?

    Recalling that the value for specific enthalpy and specific volume is

    Specific Enthalpy = h1 = 81 kj/kilogram of dry air

    and Specific Volume = v1 = 0.9 m³/kg

    Now, recalling the formula for mass flow rate,

    We have, m = Volumetric flow rate / Specific volume

    Therefore, 0.4 m³/s : 0.9 m³/kg

    = 0.44 kilogram / second

    Recalling the enthalpy at inlet,

    we have, h2 = h1 - p/m

    Where h1 = Specific enthalpy

    p = power input at steady rate

    m = calculated mass flow rate

    Now, if we substitute the values into the equation,

    we have h2 = 81 kj/kilogram of dry air - 1.7 KW / 0.44 kilogram / second

    h2 = 77.175 kj / kilogram of dry air.

    Therefore, the properties of air at constant absolute humidity and specific enthalpy is 77.175 kj/kg.

    Temperature at 8C = 32 °C * 8 = 256

    Relative humidity is = 60% * 8 of 256°C accordingly.
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “2.73 A fan within an insulated duct delivers moist air at the duct exit at 358C, 50% relative humidity, and a volumetric flow rate of 0.4 ...” in 📘 Engineering if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers