Motor RPM needed to create low pressure

[deleted-379502]

Hi!
I'm trying to create a small fuel vaporizer for my science project. If I need to vaporize 1-5 mL petrol from a very small container (Half the volume of a Coffee Mug) using low pressure, would a 12V 3500 RPM DC motor be enough? Also, I think I will attach a fan to it that either resembles one from a jet engine or one from a vacuum cleaner. Which one is better?
Thanks in Advance!

[norman40]

Hi Mayank0809,

After some online searching I found a few references to “fuel vaporizers”. Most of these describe do-it-yourself devices intended to be installed in fuel intake systems of automotive engines. These devices appear to heat or bubble air through the fuel to vaporize it.

I suppose that you might be able to evaporate small amounts of gasoline by blowing air over the liquid’s surface. And your motor with an attached fan might do the job.

You might consider posting more information about your project, the design of your fuel vaporizer and what you want to accomplish with the vaporizer. With more details one of the contributors to this forum may be able to provide a more helpful response.

I hope this helps. Please ask again if you have more questions.

A. Norman

[deleted-379502]

Hi Norman!
I intend to reduce PM and HC emissions from internal combustion engines using this device. But instead of using heat or turbulence to vaporize petrol, I will depressurize it in a closed container. I have made a model before, but I am trying to create a smaller one so it fits better with an engine and gets better vaporization. In my older model, I simply attached a vacuum cleaner motor to a tiffin-sized container with a hole on the top. The motor depressurized the container and pulled up fumes. But since the motor requires a lot of power and makes a lot of noise, I am trying to downscale it.

[norman40]

Hi Mayank0809,

The experiment you’ve described seems dangerous for a high school science project. In addition to the obvious fire hazard, gasoline is toxic. Work with flammable and toxic chemicals should be done in a laboratory with appropriate safety equipment and with proper procedures in place to avoid injuries. If you do not have access to appropriate safety equipment and you do not have an experienced person to supervise your work I urge you to discontinue this project.

That said, the minimum amount of work required from your motor to reduce the pressure in your container is the product of the container volume and the change in pressure. For a constant pressure change, less work is needed from the motor with a smaller container volume. If you reduce the container volume by a factor or two, the motor has to do half as much work. So if you know the volumes of the container in your original model, and in your downsized model you can estimate the reduction in work required for the downsized motor. The torque specification for the motor is an indication of the amount of work it can do.

I hope this helps. Please ask again if you have more questions.

A. Norman

[deleted-379502]

I've measured the evaporation rate of the model to be about 0.5 mL/s. But the rate is too low as a car may need a rate of about 5-6 mL/s. I'm thinking about increasing the surface area of the base as a solution. Would that work? Do you have any more solutions?

[norman40]

Hi Mayank0809,

Increasing the surface area of the liquid that is exposed to the atmosphere will increase the evaporation rate. For example, you could place the liquid in a container of larger diameter to increase the exposed surface area. Rotary evaporators (and spinning disk evaporators) use a moving surface to form a liquid film to facilitate evaporation. You might want to take a look at rotary evaporators and spinning disk evaporators to see if you could incorporate either mechanism in your design.

Also, you might consider heating the liquid to increase the evaporation rate.

I hope this helps. Please ask again if you have more questions.

A. Norman