Thermodynamics related question here: If I buy a carton of eggs from the store and then drive home, how much does the temperature change for the eggs before I get them in my refrigerator?
Known Specifications:
• 1 carton is 12 eggs in the standard 6 X 2 config carton
• The eggs are size ‘extra large‘
• Eggs chilled at the store at 45 degrees (approx)
• The eggs are the last thing I put in my shopping cart, so as soon the eggs leave the store refrigerator they’re on their way home
• It takes 15 minutes to get them in the house in my own refrigerator
Impossible to determine without a whole lot of additional information:
R value of the egg carton
mass of the egg
ambient temperature
heat capacity of the egg
airspeed velocity of an unladen swallow
The easiest thing to do is to determine this empirically. Get a hold of an IR thermometer, measure the egg temperature as you leave the store, and again when you get home. Remember, the core temperature is likely to be less than the exterior temperature.
My guess is unless you live near me, the eggs only warm up a few degrees.
Incidentally, if you’re worried about this from a food-safety point of view, don’t be. In a lot of countries (the UK included), eggs aren’t even refrigerated in the store.
I think an egg in its carton is going to have a heat transfer coefficient somewhere around 10 or so W/(m^2 K), a surface area somewhere around 3e-3 m^2, a volume of around 5e-5 m^3, and a heat capacity of 4e6 J/(m^3 K). So I get 7,000 seconds for a relaxation time. This means only three Fahrenheit degrees during your drive. If I did that right…
