Wednesday, June 10, 2009

Heat transfer: meatballs and ice

I have a heat transfer question. It's a mother/daughter argument ready to happen and I need backup.

My mom is transporting 10 pounds of frozen Swedish meatballs (in 4 bags) from Minneapolis to Bismarck by car tomorrow. That's a six-hour trip. The objective is to keep them frozen. She's purchased a small cooler. The cooler is exactly the right size for the meatballs, with no space left over for ice. The question we face is whether the meatballs will fare better if she fills the single cooler with meatballs and no ice, or if she buys a second cooler and fills the two coolers half with meatballs and half with bags of ice.

I'm thinking the heat transfer coefficient of the meatballs is lower than that of ice (i.e. that meatballs thaw more slowly than ice cubes melt, given equal surface area in identical environmental temp), and further that the meatballs have less surface area that the ice cubes and therefore she'd be better off filling one cooler with frozen meatballs. I KNOW she's not going to believe that such a thing could possibly be true.

I could well be wrong about the comparative heat transfer coefficients of meatballs/ice (opinions, please), but if I'm right about that, then I'm right about the cooler conclusion, am I not?

I guess there's one other factor to consider. The meatballs, being bigger than the ice cubes leave greater air space between/amongst them than a bag of small ice cubes would, and that would result in faster heat transfer/thawing. That favors the two-cooler plan.

9 comments:

Scooter said...

This is way beyond me but don't meatballs have more surface area as opposed to ice cubes (at least the smooth ones)? Assuming a ping pong ball and golf ball have the same diameter, wouldn't a golf ball have more surface area than the ping pong ball?

Stephanie said...

One meatball is larger than one ice cube so yes more surface area. But a bag of ice cubes has more ice cubes than a bag of meatballs, so more surface area per bag or per volume.

Scooter said...

I was going for the rough/smooth argument and assuming the same size but yeah, you're right of course.

Stephanie said...

Was hoping a mechanical engineer amongst our readership would weigh in. T-45 min.

Anonymous said...

Meatballs alone.

Stephanie said...

Thank you.

Stephanie said...

Was a little hard to explain how I could be sure that "Anonymous" was Michael. But once I convinced her of that, she was up for the one cooler plan. (Never mind that my senior labs in college were heat transfer projects.)

Anonymous said...

Uh, wasn't me. Probably Leviticus guy. I was thinking ice...

Stephanie said...

Funny.

Had a lovely time with our mothers.