We have a school project to design a bicycle pump. It's maximum operating pressure is 10 bar (1 MPa)
The pump is designed so that there is a section at the bottom that will always have air in it, i.e. the pump will never be completely empty. So there is the main canister where, when you pull up the piston, the air collects, and then there is this section, B. We have been told that as the air pressure in the tire increases, this pressure causes less air to be pumped into the tyre, and the air pressure in the second section B increases because of this and also because the air in the main canister is being exerted in to this canister as well on it's way out.
We need to calculate and generate a graph showing mass vs pressure at varying pressures.
Questions:
1. How do we calculate mass flow rate? What variables would I need? What I'm looking for is a qualitative explanation of how to approach this.
2. How do we calculate the pressure in B at tire pressure = 0 MPa? 0.1 MPa? Etc? I'm thinking we minus the tire pressure from maximum operating pressure to find a new operating pressure and re-run the calculations with this new operating pressure, but I could be wrong.
We were using air density and volume to calculate the mass, and then using the mass, the molar mass, R,T and V to calculate pressure, but we keep missing something and getting the wrong values.
Variables we have (that I am absolutely sure about):
Volume of main canister = 49.25468 cm^3
R = 8.314 cm^3)MPA/K*mol
T = 298 K
Air density = 0.001184 g/cm^3
Molar Mass of air = 28.97 g
Assumptions:
Take air pressure = atmospheric pressure
The pump is designed so that there is a section at the bottom that will always have air in it, i.e. the pump will never be completely empty. So there is the main canister where, when you pull up the piston, the air collects, and then there is this section, B. We have been told that as the air pressure in the tire increases, this pressure causes less air to be pumped into the tyre, and the air pressure in the second section B increases because of this and also because the air in the main canister is being exerted in to this canister as well on it's way out.
We need to calculate and generate a graph showing mass vs pressure at varying pressures.
Questions:
1. How do we calculate mass flow rate? What variables would I need? What I'm looking for is a qualitative explanation of how to approach this.
2. How do we calculate the pressure in B at tire pressure = 0 MPa? 0.1 MPa? Etc? I'm thinking we minus the tire pressure from maximum operating pressure to find a new operating pressure and re-run the calculations with this new operating pressure, but I could be wrong.
We were using air density and volume to calculate the mass, and then using the mass, the molar mass, R,T and V to calculate pressure, but we keep missing something and getting the wrong values.
Variables we have (that I am absolutely sure about):
Volume of main canister = 49.25468 cm^3
R = 8.314 cm^3)MPA/K*mol
T = 298 K
Air density = 0.001184 g/cm^3
Molar Mass of air = 28.97 g
Assumptions:
Take air pressure = atmospheric pressure