Thanks Anthony N, but I’m not looking to alter the tastes of my favorite beers by attempting this.
Brewer here…you probably won’t change the taste significantly by adding a little corn sugar - we’re talking about a very small amount and it would pretty much all be fermented into alcohol.
But as a practical matter, you don’t have much chance of success. Calculating the right amount of suagr (and then measuring it) would be next to impossible, so you’d probably end up with too much or too little carbonation. You also have a good chance of introducing contaminants and getting some weird strain of something growing in there. And you’d have to leave it at room temperature (assuming this is an ale, not a lager) for a few days, which come to think of it might create some flavor changes.
You’d also need a way to seal the bottle back up like a bottle capper, and it would need to be more than a cheap reusable cap.
As you go on to say, it probably wouldn’t all be fermented into alcohol. Add enough corn sugar to even attempt to cause yeast eat it up and cause enough carbonation, and you’re going to affect the taste of that beer enough where it might not be a favorite beer any more.
No, you can go from fridge temps and back to room temperature multiple times and there won’t be any flavor change. It’s light that’s a concern.
Press fit bottle caps are darn cheap, even cheaper than twist-offs, which is I’m guessing what you meant by reusable. Of course the capper is going to run a few bucks.
Oxigen is more soluble in water than CO2 and will displace it. Your best bet is to add CO2 under pressure (forced carbonation). I figure this should not be difficult to do. Build a cap with two valves so that one goes about half way down the bottle. Open both and inject CO2 via this one so that air is displaced through the other one. Close the other one and then fill with CO2 up to the required pressure (32 PSI?). Then close the filling valve.
Air is the enemy of carbonation and you want to get rid of air. Also, low temperatures, about 4 C, work best. Heat
Chemist and homebrewer chiming in:
Dr. Russell mentioned in the OP is right: pumping air into the bottle does not force more CO2 into the liquid. Only pumping in extra CO2 will do it. Also, for practical purposes, you can’t make water fizzy with just any gas. CO2 is much more soluble in water than air or nitrogen, or else someone would be selling cheaper “aironated water” instead of carbonated water. You may get the PSSSST! when opening the container, but there’s no fizz in the liquid. See the Fizz Keepers discussion at: http://www.stevespanglerscience.com/experiment/00000103
Re: sugar and yeast: After carefully “priming” with sugar and recapping, you’ll have to wait days for the yeast to rouse from dormancy, eat the sugar, “pee” the alcohol and “burp/fart” the CO2 to get the carbonation you’re looking for. Plus you’ll probably have to keep it near room temp, and it may be infected from unsanitary conditions when you had the bottle open. Flat beer from underpriming, or exploding bottles from overpriming or an infection, are more likely than getting it just right.
Building caps and buying CO2 is probably more than I’m willing to go through, but thanks for posting the idea; It sounds pretty interesting.
It’s not supposed to. It’s supposed to work by pumping air in the headspace of the bottle at higher than atmospheric pressure and prevent CO2 from escaping the beverage.
Last night I sent for a few cheaper devices that get good reviews and are supposed to perform well. When I get them I’ll perform an experiment. First I’ll store an unopened beer in the fridge. I’ll empty another half way and cork it. A third bottle will also be emptied half way and this one will get the device. I’ll wait 48 hrs and pour equal amounts into three glasses and test for visual differences and mouthfeel and taste. I’ll post the results in this thread.
Yah, and I thought that would work - however, on thinking it over, it seems that merely keeping compressed air over the drink doesn’t help, because CO[sub]2[/sub] will still migrate from higher to lower concentration, i.e. out of the liquid. But by all means, conduct the experimental trial. 
Ideally, you’d also have someone helping you with the experiment, to blind it. For instance, assistant puts labels A, B, and C on three glasses, and chooses and records which one to pour into each, based on the roll of a die. You leave the room. Assistant enters the room, pours all three glasses according to the random selection, and leaves. You re-enter the room, and try all three glasses and give your opinion. This way, you’re not influenced by your knowledge (or your assistant’s knowledge) of which one is which. Ideally, you’d also repeat the experiment several times, but I’m not sure how much beer you’re willing to drink for the sake of science.
Yeah, I thought of this too. I’ll have my wife assist me in the tasting. Oh, I’m willing to drink plenty of brew for science’s sake. 
I’m also going to experiment with squeezing a half full plastic bottle of cola and a half full but un-squeezed bottle and pouring them at the same rate after a few days and compare fizz and taste. If high pressure won’t help preserve carbonation, then it would seem that low pressure shouldn’t make the soda lose carbonation any faster either.
While that’s true for ideal gases, it isn’t so true for CO[sub]2[/sub]. The formation of Carbonic acid, H[sub]2[/sub]CO[sub]3[/sub], is favored at higher pressures; see post #8 for refs. That means that compressing with air actually will force a slightly higher fraction of carbonate into the liquid phase.
As I said in earlier threads, it doesn’t appear to be a big effect, but it is there.
There are machines made specifically for carbonating water in the home. You can use them to make your own soda. They claim to make soda more cheaply than buying it in the store, but I am not sure I believe it.
Like I said in Post #5, just buy a carbonator cap ($19), some hose ($5), an CO2 bottle (20# for about $60 used), and 20# of CO2 ($20). Still cheaper than those phony devices that waste CO2, don’t let it dissolve, and have proprietary canisters. I’m thinking of adding paint can shaker to my setup if I find one cheap enough.
I used to work with machines used in the manufacture and carbonation of beverages and any oxigen in the water would seem to expel the CO2 creating lots of problems.
The water would be first de-aerated with vacuum. All traces of air, had to be removed. Then the syrup was added with great care that no air could creep back in and finally the beverage was carbonated. Any air left in the water meant the carbonation was expelled explosively at the filling machine where pressure was removed. You would end up with almost empty bottles as the carbonation foamed out of the bottle. The key to successful carbonation is low temperature and no dissolved air.