Let's say that you want to build an air-powered vehicle by attaching a high-pressure air tank to your little wagon, as s

[answerhappygod]

Let S Say That You Want To Build An Air Powered Vehicle By Attaching A High Pressure Air Tank To Your Little Wagon As S 1 (114.57 KiB) Viewed 22 times

Let's say that you want to build an air-powered vehicle by attaching a high-pressure air tank to your little wagon, as shown in the figure below. This is not quite as outlandish as it sounds like because efforts have been made since the 1920s to make a commercial car based on compressed air propulsion. The Wikipedia article is a good starting point if you are interested. You can also a quick Google search to find more ideas for compressed cars that never really seem to be able to break into the market. Below are two links. https://sites.google.com/site/rijdenopp ... en/history https://en.wikipedia.org/wiki/Compressed_air_car Complexities of making a commercially available car apart, let's try to look at some of the thermodynamics involved in this kind of propulsion. b The air from the bottle is exhausted through a nozzle in order to produce a high-velocity flow that provides the thrust required and causes your wagon to accelerate. In this case, let's assumed some details based on what is reasonable. The air cylinder has a volume of 20 liters and is initially charged to a pressure of 2400 psia. The air in the tank always stays at ambient temperature, assumed to be 20°C. The air passes through a pressure regulator when leaving the tank prior to entering the nozzle. This pressure regulator reduces the pressure of air from the tank pressure at that instant to 20 psia at the nozzle inlet. The propulsion system stops working when the cylinder pressure reaches 20 psia. The nozzle has an isentropic efficiency of 0.92. The nozzle exit pressure is assumed to be atmospheric pressure (14.7 psia) and the outlet diameter of the nozzle is 0.2 inches. Isentropic efficiency of a nozzle
vac,out = nis,noz (Actual outlet velocity)2 (Ideal outlet velocity)2 víd,out Answer the following questions (using mostly EES and Excel) a. Determine the velocity of air and the mass flow rate of air leaving the nozzle. You can assume that the nozzle inlet diameter is large enough that the nozzle inlet velocity of air is negligible. b. Explain in short why the mass flow rate and velocity of air stays constant during the process even though the tank pressure is changing. c. Determine the time tstop that the propulsion system will operate before the tank pressure reaches the nozzle inlet pressure. d. List the phenomena that will cause entropy generation in this process. e. Calculate the entropy change Inside the cylinder during the time when propulsion was running ii. In the atmosphere due to the mass of air leaving through the nozzle