1. A fan connected to a grain dryer will move 12,500 cfm of air. The dryer system has a heater that will heat ambient air to 104° F. Ambient conditions are 60°F, 20% RH, and Patm = 14.7 psia. Determine the following: 1. Volume flow rate (Q) of heated air 2. Q of moist air leaving the dryer (Assume 92% RH) (cfm) 3. Quantity of sensible heat added to the ambient air (Btu/hr) 4. Relative humidity of heated air (entering the dryer). 5. Cost of heating air using a natural gas burner @ $7.50/MCF. Note that an MCF is 1,000 ft³. Assume a heating value for natural gas of 1050 Btu/ft³. Assume 35% efficiency when heating with natural gas. 2. Rework Problem 1 for ambient conditions of 50°F, 55% RH, and Patm = 13.5 psia.

2. A vertical Cylinder with a heavy piston contains air at 300 K. The initial pressure is 3.35*10^5 Pa, and the initial volume is 0.300 m^3. Take the molar mass air as 28.9 g/mol and assume Cv = 5R/2, R = 8.314 J/mol K 
a) Find the specific heat of air at constant volume in units of J/kg C 
b) Calculate the mass of the air in the cylinder
 c)Suppose the piston is held fixed. Find the energy input required to raise the temperature of the air to 691K.

4. An ideal gas is contained in a vessel of volume 12 L (12 liters) at a temperature of 20 °C and a pressure of 9 atm. a) How many moles of gas are in the vessel? b) How many molecules of gas are in the vessel?

1. Two moles of helium gas are placed in a cylindrical container with a piston. The gas is at room temperature 27 °C and under a pressure of 3.3.105 Pa. When the pressure from the outside is decreased, while keeping the temperature the same as the room temperature, the volume of the gas doubles. Use that the gas constant R = 8.31 J/(mol K). Think: What kind of process is this? Isobaric, isothermal, adiabatic, isochoric or non-quasi-static? (a) Find the work the external agent does on the gas in the process. W = ext. agent (b) Find the heat exchanged by the gas and indicate whether the gas takes in or gives up heat. Assume ideal gas behavior. Q= ✓J Q is realeased by gas Q is absorbed by the gas