How long should it take my refrigerator to recover from adding new food to it? I recently bought a new refrigerator, and just to make sure it's working right, I bought two standalone fridge thermometers to put in it, one for the freezer &amp; one for the fridge portion. (We replaced our last fridge because it wouldn't cool lower than 45°F, even though its digital readout said the temperature was 34°F.)

The new fridge was down to 34°F this morning (according to the standalone thermometer) and about 30% full when I returned from a big shopping trip, and added a large amount of already-cool food to it, now it's about 80% full. But it's been over 6 hours since I added all that (already cool from the grocery store) food, and the fridge is still measuring above 47°F!

From the advice I read, above 41°F is in the food safety danger zone, and 2 hours is the maximum time food should be allowed to be in the danger zone. But my new fridge apparently can't get the food back in the safety zone within 2 hours; is that normal? How long should I expect it to take my refrigerator to recover from adding a bunch of already-cold food to it?
Your fridge's recovery time will depend on the manufacturer and quality of appliance, how full your fridge is before adding new items to it, the density of those items, and the temperature, density, and volume of the new items.

If your fridge is normally pretty empty it's a good practice to put empty bottles in it (or better, bottles filled with water or other liquid — or, better yet, a bunch of beer :o). 

Every time you open your fridge or freezer all the cold air falls out, so the less air there is to fall out the faster it will recover and the less energy it will use.

If your fridge is filled with items with a high thermal mass (such as potatoes, not that I'm suggesting you store potatoes in the fridge), then it will have an easier job recovering. 

Never put hot foods directly into your fridge. If you make soup for another day, e.g., chill it in ice water first (obviously in a heat-proof container first) and then refrigerate it. If you put hot foods directly into the fridge it will warm up everything else in the fridge and cause the other foods to spoil faster. If you don't have ice then cold water from the tap will cool your items. If it's food that won't spoil quickly (such as a pot of beans with no meat) then letting it get to room temperature on your counter, covered, is fine. 

In the case of soup or broth, putting it into smaller containers first will let you cool it more quickly and easily. 

Also, make sure that the air vents for your fridge are not blocked. If you block them the fridge will not be able to chill itself very well.