LNG heavy vehicle refueling issues
Thread Content
A single-fuel LNG heavy tractor with an LNG cryogenic liquid semi-trailer attached at the rear. There is no turbocharger on the semi-trailer. I now want to fill the tractor’s LNG fuel tank using the LNG in the attached semi-trailer. I was thinking of using the natural pressure difference between the two liquid levels to achieve this, but how can I fill the LNG fuel tank when only a small amount of liquid remains in the semi-trailer? How can this be achieved? Some experts in this field, please give me some advice. . Thank you
If the residual liquid is below the outlet, it won’t be able to flow out no matter what. If the residual liquid is above the outlet, then there is still a level difference; in other words, the pressure isn’t sufficient for it to flow out, so one must find a way to increase the pressure. The solutions are increasing pressure, reducing the level difference, or using a pump – those are the only options.
Since there is no turbocharger on LNG cryogenic liquid semi-trailers, self-pressurization becomes a problem. You’re thinking of using the natural pressure difference due to the liquid level between the two, but when only a small amount of liquid remains in the semi-trailer, it becomes difficult to determine the liquid level; moreover, transferring the liquid while on the road is very dangerous, so caution is needed
Thank you for the answers from both of you; my thoughts are similar to theirs. Similar vehicles are already in use, and I think there should be a pump on the vehicle. I need to go and conduct some research soon.
If it’s residual liquid, cavitation caused by pumping could be a problem; I think LNG tankers should be equipped with a pressure-boosting device, just like liquid nitrogen tankers. If it’s residual liquid, the pressure inside the tank vehicle is likely to be high as well. I’m not sure if it would work to connect gas directly to the vehicle for combustion; anyway, your vehicle uses LNG anyway, haha.
Personally, I think this residual liquid cannot be utilized; the filling of LNG into the tractor’s LNG fuel tanks is considered only in the case of a fully loaded vehicle.