CNG pump compressor DIY home refueling

[P-hack]

Originally Posted by rmay635703

I am wondering if any of the ANG tanks are dual pressure compatible? ...
If so I could stick to a relatively low pressure unit for home use (500psi) but have the tank capable of withstanding a quick fill from a local CNG fill station.

How about a pressure reducing cng fill valve?

[vlad]

I checked gas stations for CNG prices around here in BC and...... CNG gas equivalent price is 5-10% lower than gas price.

I am adding CNG to my diesel truck not for power gains and smoking tires but for economy/ecology reasons. This is why I must get gas from my home gas line. If I can't use my home gas all this conversion makes no sense....

This is why at this moment I am working only on "pumping" part of this diesel/CNG project.

[vlad]

Originally Posted by P-hack

How about a pressure reducing cng fill valve?

I would never try this. It is like connecting propane tank to cng station. Something goes wrong you end up with BOOOOOM just like some guys in well known video on YouTube.

[cRiPpLe_rOoStEr]

Originally Posted by vlad

I am adding CNG to my diesel truck not for power gains and smoking tires but for economy/ecology reasons. This is why I must get gas from my home gas line. If I can't use my home gas all this conversion makes no sense....

Altough CNG has to rely either on a spark plug or a secondary fuel to provide compression-ignition, it actually ends up even improving the combustion of regular Diesel fuel since it ends up increasing the flame propagation inside the combustion chambers.

[vlad]

Originally Posted by cRiPpLe_rOoStEr

Altough CNG has to rely either on a spark plug or a secondary fuel to provide compression-ignition, it actually ends up even improving the combustion of regular Diesel fuel since it ends up increasing the flame propagation inside the combustion chambers.

It makes sense because you gain extra power without adding extra air. Also your exhaust is much cleaner.

If you add more diesel fuel you will gain extra power but you also "gain" much more smoke.

Just to remind others how diesel engine works: high pressure pump is the device that controls amount of diesel injected. The main parameter is used by pump is engine RPM. Pump is always hunting to keep right engine RPM.

When CNG is delivered into combustion chamber regular amount of diesel is injected. Because CNG gives extra power (stock 5.9 Cummings can get extra 100HP) your engine RPM will start climbing. As soon as this happens high pressure pump will start to cut down amount of diesel fuel injected until engine RPM is lower than we set it up with our gas pedal. This will happen very quick just few engine revolutions. This is actually normal pump operation cycle.

[P-hack]

Originally Posted by vlad

I would never try this. It is like connecting propane tank to cng station. Something goes wrong you end up with BOOOOOM just like some guys in well known video on YouTube.

Um, not sure why you are fear mongering at this particular point... the pressure is dropped later on in a CNG vehicle anyway, this way you can use a lower pressure (cost) ANG tank, presumably with safety bypass on the fill valve or something so you can do a "quick fill" when you need one, given the limited energy density...

[P-hack]

little more on adsorption:
Adsorbed Natural Gas (ANG) vs. LNG and CNG - scopeWe - a Virtual Engineer


"The amount of adsorbed and delivered natural gas strongly depends on the type of adsorbent solids used. There are two important numbers: 213 v/v is the maximum theoretical capacity of activated carbon, and 120 v/v that is the capacity of usual adsorbents. Reaching to the maximum theoretical capacity from the low normal capacity of adsorbents has been the activating energy to expand ANG industry. It is notable that 150 v/v is known to be economical capacity for industrial adsorbents. "

[vlad]

Originally Posted by P-hack

Um, not sure why you are fear mongering at this particular point... the pressure is dropped later on in a CNG vehicle anyway, this way you can use a lower pressure (cost) ANG tank, presumably with safety bypass on the fill valve or something so you can do a "quick fill" when you need one, given the limited energy density...

In theory this is all possible. But the main problem is right here:

Tank manufacture will go one way ANG which is low pressure or the other empty tank high pressure.

Just think for a moment. If you have high pressure tank like 3000 Psi why would you fill it 500 Psi? Just because your home compressor can't pump more? Do you think one of the tank builders will ever think about you......?????

The other way.... Do you think any tank builder will take potential responsibility to let you connect 500 Psi rated tank to 3000 Psi pump.....????? They will never get approval for set up like this. And why would they do this? Remember all this systems must be idiot-proof before the even can think about certification.

We need a company that will think outside of the box. But reality is telling me that right now nobody will do this for us. This is why I started this DIY project. I don't want to wait 20-30 years.... I want to fill up my truck using my home gas line and pay 40 cents a liter when diesel costs 1 dollar and 40 cents......

[CFECO]

I would think all tanks would have a overpressure relief valve, so you could not get 3k in a 300 tank any way.

[P-hack]

My response was to ryland about his desire to be able to fill ANG tanks from cng stations in a pinch. and compared to a diy multi-stage electrical ng pump, a regulator/safety valve is a lot simpler. Which means you can get the vehicle running on ANG before you get the homebrew compressor working even.