HOMEWORK 4

1. For air having a dry bulb temperature of 28 C and a relative humidity of 60% find the following (remember units are half of the answer):

T_dp = _______________ dew point temp
T_wb = ______________ wet bulb temp
w = _______________ humidity ratio
h = _______________ specific enthalpy
n = _______________ specific volume

2. If the atmospheric pressure is 101.32 kPa, what is the vapor pressure and partial pressure of air at the conditions?
   
3. Shelled corn at 21 C and at moisture content of 18.5% wet basis is stored outdoors in a metal grain. If the steel bin wall temperature is lowered to 4 C will condensation occur? Explain why.
   
4. Calculate the average molecular weight of dry air. Base your calculation on the composition of a standard atmosphere.
   
5. If 100 kg/h of air at 28 C and 60% relative humidity is cooled to 18 C, what is the rate of condensate removal? (Hint: Sketch problem and use m_air to represent mass flow of air and m_c to represent mass flow of condensate).
   
6. How much grain at 12% moisture (wb) must be mixed with corn at 18.5% moisture (wb) to give a mixture moisture content of 14%.

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