Keeping Food Cold on a Long Summer Trip: Solving the Ice Melt Problem

In summary, the conversation discusses the logistics of keeping food cold during a long summer trip. The cooler has specific dimensions and insulation, and the bags of ice have a certain average density. The main concern is keeping the food cold despite the melting ice, with the only given information being the thermal conductivity. Two questions are posed about how long it will take for the ice to melt in different scenarios, and the conversation ends with a mention of needing to find another variable in order to calculate the time.
  • #1
icetea07
2
0

Homework Statement



You are going on a long trip in the summer with a dessert that must stay cold.
You have a cooler with the interior dimensions measuring 13 in x 8.5in x 11 in. The cooler has 1.75 in of polyurethane foam insulation. The dish is in a water tight container so food getting wet from melting ice is not a problem. The dish is a surprise so no one will open the cooler. The only concern is keeping the food on ice. You buy bags of ice with the average density of the bag at only 55% (due to air pockets). While the ice bags may be very cold in the freezer in which they were stored, by the time you get them out to your cooler, they have begun to melt. The average temperature in your vehicle is 80°F. The space occupied by the dish is relatively small and the dish itself has little overall effect on the problem.

1. How long will it take for the ice to completely melt if the cooler is completely filled with ice?
2. How long will it take for the ice to completely melt assuming you put a couple 8 lb bags of ice in the cooler?

(The themal conductivity we have to look up. I found it to be .03)

Homework Equations



Q=(KA(T-T0))/X

The Attempt at a Solution



Q=(.03(694 in.)(48°F))/1.75in Q=571.063

I believe I am supposed to also find H (i think that is what it is) and then divide them to get my time but i am not sure, and if so I have yet been able to figure out how to do so. Still working on that. Any help is appreciated.
 
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  • #2
icetea07 said:
(The themal conductivity we have to look up. I found it to be .03)
In what units?
Q=(.03(694 in.)(48°F))/1.75in Q=571.063
Q is usually used for a quantity of heat. What you are calculating is a rate of flow of heat (in what units)?
I believe I am supposed to also find H (i think that is what it is) and then divide them to get my time but i am not sure, and if so I have yet been able to figure out how to do so. Still working on that. Any help is appreciated.
Depending on what 'H' means, and which way you divide, yes.
 

What is the best way to keep food cold on a long summer trip?

The best way to keep food cold on a long summer trip is to use a combination of ice and a cooler. Start by filling the cooler with ice and placing the food on top. Make sure to use large blocks of ice instead of smaller cubes, as they will melt more slowly. You can also add a layer of insulation, such as towels or newspaper, on top of the food to help keep it cold.

How often should I replace the ice in my cooler?

This will depend on a few factors, such as the outside temperature and how often you open the cooler. As a general rule, it is recommended to replace the ice every 24 hours to ensure that the food stays at a safe temperature. If you notice that the ice has melted significantly, it is best to replace it sooner.

Can I use dry ice to keep my food cold?

Yes, dry ice can be a great option for keeping food cold on a long summer trip. It is much colder than regular ice and will last longer, but it must be handled with caution. Make sure to wear gloves when handling dry ice and do not place it directly on top of your food as it can freeze and damage it.

What can I do if I don't have access to a cooler?

If you do not have a cooler, you can still keep food cold by using a thermal bag or insulated lunch box. These are designed to keep food at a safe temperature for a few hours. Alternatively, you can also use a cooler bag and ice packs. Just make sure to keep the bag out of direct sunlight and try to limit the amount of time the food is outside of the cooler.

How can I prevent water from leaking out of the cooler?

To prevent water from leaking out of the cooler, make sure to drain it regularly. As the ice melts, the water will build up and can cause the cooler to leak. You can also place a tray or dish inside the cooler to catch any excess water. Additionally, make sure to keep the cooler level and avoid tipping it over to prevent water from spilling out.

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