Measuring Airflow With A Silicon Pressure Sensor

[@ramanr8552]

Awesome concept it very helpfull to do our prototype could help us to develop further

[@ahmedtbd]

This is pretty cool, I'm actually working on a similar project right now and this video is really helpful. I just have a question, since you are using a venturi tube, wouldn't you need some upstream and downstream piping to allow the airflow profile to develop?

[@senorjp21]

Engineers use venturi tubes with standard profiles, or orifice plates for flow measurement. This sinusoidal profile is my own idea and probably not ideal. To choose the right strategy for measuring flow you need to consider several things including necessary accuracy, nominal flow rate, max/min flow rate... I was testing if the cheap mems pressure sensors might work for me, and it does work to some extent.

[@NanoActuator]

Results?

[@guneetsharma7814]

great project sir i want to ask can we measure air velocity through it using a pitot tube and whats its maximum??

[@senorjp21]

There are many different pressure sensors with different sensing ranges. I'm sure you could find a sensor to fit your application. This MCP5010 has a 10psi range.

[@galihsetyawan4679]

can you share the wikipedia article link?

[@senorjp21]

I think the equation I show was from en.wikipedia.org/wiki/Venturi_effect

[@vaughan.gittel]

awesome man :)

[@legerjean9085]

bonjour, with you continued your gasification project for heat production? I have a project similar to yours and I would like to submit a plan if you are available

[@senorjp21]

Yes I continue. I had a design I liked that was a positive pressure design (air blows in) and this will always be more dangerous than a negative pressure design (air sucked out) so I'm working on a practical negative pressure design. It's harder to test.

[@legerjean9085]

@@senorjp21 what is the way for send you somedocs and pictures .

[@joewhite4564]

Hi Jesse. Very nice. How are you determining the minimax airflow that you require for your system? Do you have baseline calculations, or is it just trial and error?

[@senorjp21]

I am winging it! In gasification the fuel is in excess supply, so the generation of gaseous fuel is determined by the amount of gasification air that is supplied. Then, I am trying to add a balanced amount of combustion air to burn the gaseous fuel. This project stalled because I am also trying to test "spark ignition" and the spark is causing interference in my electronics somewhere... I need to shield things.

[@Thrive-Off-Grid]

You would be better off simply automating a grate and hopper agitator system. Very cool project though, but it is not needed. You need to correct those flow problems at their source vs trying to over come them with brute force. You can then add a mixer control at the engine to self mix air fuel. I have a tutorial on DOW for this and you obviously could build that. This is still very cool what you are doing here and it could certainly be used for more advanced monitoring.

[@senorjp21]

Thanks, Thrive. I'm interested in thermal power instead of fueling an engine. This is for an integrated updraft gasifier and coupled burner, so for me air-fuel mix needs to be controlled at this point.

[@Thrive-Off-Grid]

@@senorjp21 Oh I got ya. Nice!! I build pellet stoves too. Yeah I can see that working well then

[@Thrive-Off-Grid]

@@senorjp21 Could use an Oxygen sensor? That was my plan anyways. Im something similar but with a gravity down draft stove. Later iterations will use steam reforming for H production.

[@senorjp21]

Engines suck in a known quantity of air and fuel each cycle - like a positive displacement pump. In this way your gasifier is also doing volumetric air supply - the resistance provided by the fuel doesn't matter because the engine keeps the airflow constant (at constant RPM.) For a forced air approach, controlling pressure isn't going to be accurate as the composition of the fuel column changes. Just experiments at this point... Cheers

[@Thrive-Off-Grid]

@@senorjp21 Yeah thats what Im saying. If you had an 02 sensor just after your secondary combustion, you can then meter your primary combustion air accordingly. Thats if there is fuel there to burn. so adding a temp probe here in conjunction may also benefit. Secondary input may also be controlled this way or a combination of what you are doing plus reading a sensor. As for engine running it does not quite work that way, if the gasifier system becomes restricted then it will pull more in through the air intake mixer, leaning out the mixture then the engine will stall and vice versa. On my systems all flows are automated and controlled plus I use an 02 sensor driven system to automatically adjust air fuel mixtures. On my pellet stoves they are down draft and share much of the same tech as the engine systems. I plan develop further and doing much the same as you are with forced air. This is so I can expand the char bed in the stoves for the steam reforming systems. Additionally I will be experimenting with enriched Oxygen eliminating the NOx input to allow for higher flows of the steam input. So this stove will essentially run partly on water.

[@heshamtanbour3363]

Hello, I was wondering what the "PASCALS_PER_BIT" equal to 10.4 was in your code? and why is the Offset = 1023? Thanks

[@senorjp21]

The arduino's 10 bit a2d converter returns values from 0-1023. The MPX5010 has a dynamic range of 10kPa (10,000 Pa.) The sensor reads 10,000 Pa / 1024 a2d values - this is pascals_per_bit

[@heshamtanbour3363]

@@senorjp21 ok thanks. and what about the offset?

[@senorjp21]

@@heshamtanbour3363 when the pressure difference is zero a small voltage is measured. The sketch reads the voltage on the sensor before the fans are powered to determine a zero offset. The offset is subtracted from the sensor reading.

[@heshamtanbour3363]

@@senorjp21 okay thank you for your help. I am using the same sensor you are and was wondering if you used the voltage amplifier for the setpoint knob or for the output voltage coming from the sensors? I also have a few other questions, what is the best email or contact to reach you at? Thanks

[@luisfabianurregosanchez4744]

Hello, where could I get the venturi CAD file? Do you have any link for look that ?

[@senorjp21]

This specific part can be found here: www.thingiverse.com/thing:3559981 But, if you want to measure air flow in a more proven way use an orifice www.dwyer-inst.com/ApplicationGuides/?ID=44

[@luisfabianurregosanchez4744]

@@senorjp21 thanks men ¡ 👍

[@TheShovon123]

Hi! I am from Bangladesh and trying to build a working ventilator in our country. I was thinking about using one of these pressure sensors to measure my output airflow. Any idea how that can be done? Please get back to me asap as the situation here is worsening by the minute.

[@senorjp21]

Hi, Shovon. Many different pressure sensors are available. This particular sensor might work and might not work depending on the specific implementation of flow measurement. The MPX5010 is a differential pressure sensor, so it can be used to measure airflow indirectly by using an orifice. As air flows through an orifice or constriction, a pressure differential is created and a formula can be used to calculate air flow from pressure differential. This specific sensor would probably require calibration to provide accurate measurements.

[@TheShovon123]

@@senorjp21 I am using a MPXV5050DP but cannot make sense of the data getting out from it. I am not sure I have connected the sensor correctly. It'd be great if you could let me know more about it.

[@senorjp21]

@@TheShovon123 Like the 5010, the 5050 has analog outputs. You will need to connect the output of the pressure sensor to something that can measure voltage, for example, an analog-to-digital input on a microcontroller. The 5050 has a dynamic range of 0-7 psi. A high peak inspiratory pressure PIP for a medical ventilator is 80 cm H20 - around 1 PSI. You will lose some sensitivity because you will only use a small fraction of the sensor's dynamic range. The 5010 has a 0-1 psi dynamic range.

[@TheShovon123]

@@senorjp21 Yup!! I finally got the value. :D

[@putrabagusramadhan6256]

Can you share schematic for this project sir.?

[@senorjp21]

Hi, Putra. I took this apart a while ago, but the wiring is pretty simple. The MPX5010 sensor takes 5V and ground and outputs an analog voltage, which is connected directly to one of the Arduino A2D pins. PWM outputs on the arduino (with ~) is connected directly to the ULN2003 which acts as a low-side switch.

[@ryandillane4320]

Could you upload the code , it’s not in the description

[@senorjp21]

You can get it here: github.com/jesseparker/constant_flow_airsupply

[@syauqisabili3776]

How about water flow? is it possible?

[@senorjp21]

I don't think MPX5010 is intended for liquids. Surely my printed parts are not water tight. The general approach of calculating flow from measured pressure differential across a restriction works pretty well with water and most free flowing fluids.

[@syauqisabili3776]

@@senorjp21 thanks for ur information. any recommendation for DP transmitter sensor to calculate water flow rate? Or anything flow rate measurement, but without hall effect method.

[@LuizCarlos-py7zl]

Looks promising... I saw this before your video. Looks like the same principle: kzbin.info/www/bejne/oae1fGOieJaIgc0. Also They did another venturi between the flame and the chips. Another thing to add, to ignite the gas why you don't use the ignier for furnaces, the glow 2000 and it's DC not EMS to deal with.

[@senorjp21]

I'll look into the furnace igniter. I have been playing with an arc-type barbecue igniter, but it is emf noisy and causes problems with my control circuitry.