Quote:
Originally Posted by instarx
Second, CO2 is a major greenhouse gas. So as well as using more fuel to drive the same distance you would be adding even more greenhouse gases to the environment from the dry ice.
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Nitrogen could be used instead.
Carrying around this much inert gas in any form is likely to be a problem.
Let's get a rough idea of how much volume one would need. Assume a 2.0 L engine. If the car's average RPM is 2000, and there is one intake cycle every other rotation (4 stroke engine), then the motor will suck in 2000 L per minute. Assume the maximum perturbation is replacing 10% of that with the inert gas, which would be 200 L per minute. A scuba tank (80 cu ft at 3000 psi) is equivalent to (2265 L at 3000 (PSI)/14.7 (PSI/ATM) = 204 atm) so at 1 atm that would be 2265*204 L = 462060 L. At 200 L per minute this method could run for 2310 minutes, or 38.5 hours. In other words, it is within the realm of engineering feasibility to inject this much inert gas under more or less normal driving conditions.
Does it make sense to do so? That depends on how much energy it takes to load that scuba tank with nitrogen, and how much energy is wasted carrying around the extra weight. One also has to consider the lowered intake temperature which would result from expanding the compressed gas, although by routing the nitrogen line alongside the exhaust manifold it is probably possible to compensate pretty well for that effect.