In a local restaurant, a soda dispenser was located is the cash register. The water reservoir for this dispenser is likely located in the back of the restaurant, around 15 meters from the outlet of the dispenser near the cash register. The diameter of the tubing from the back of the restaurant to the dispenser is 1 cm. Assume that the tubing is a very smooth plastic and that you can ignore frictional contributions.
A. What pressure do you need at the reservoir to deliver the soda to a glass at a reasonable rate? Assume that you will need to fill an average size glass (350 mL) in 25 seconds. State all assumptions and justify all estimates. Assume that the soda has the same viscosity and density of water at normal conditions. [Pa] Approx. answer: 850 Pa
B. Based on your answer in part A is this a large pressure?
C. If you have 15 m of tubing with diameter D or 7.5 m of tubing with diameter 0.5D, which tubing would you use to minimize pumping costs?
problem 2A pitcher throws a standard baseball with a diameter of 2.9 inches and a mass of 0.3 lbm toward home plate. A scout measures the speed of the fastball as 100 mph on the radar gun. The distance is 60 ft from home plate to the pitcher's mound. Neglect any effects due to spin on the ball or the stiching of the ball. What is the speed of the ball when it leaves the pitcher's hand? Assume a drag coefficient of 0.5. [mi/hr] Approx. answer 120 mi/hr
problem 3Pulverized coal with a density of approximately 1000 kg/m3 is to be burned in a packed bed reactor. The coal particles can be assumed to be spherical in shape. The mean particle diameter is 50 microns and the gas (mostly air) moving through the reactor has a viscosity of10-4 Pa*s. Assume that e3/(1-e) = 0.09. (This is a good assumption if you are not given the porosity.)
A. Estimate the minimum fluidization velocity. [m/s] Approx. answer: 1.5(10-4)m/s
B. Estimate the entrainment velocity. Hint: The entrainment velocity for a sphere is equal to its settling velocity. [m/s] Approx. answer: 0.01 m/s