I just spent a week camping, around a whole lot of other people who were camping. There was a lot of discussion about coolers. What is the best way to keep coolers cold, while adding the least amount of ice? Two subjects dominated:
1) Block versus cube - It was observed that if you buy 10 pounds of ice cubes, they won't last as long as a 10 pound block of ice. This, it was said, showed that block ice kept your cooler cold for a longer period of time.
On this point, I think I know the answer. I think that cubes are better. It seems to me that the cooler is a closed box. Heat flows in, and melts ice. For each calorie of heat that flows in, a certain amount of ice melts, until it is all melted, and then it starts raising the temperature of the water. Of course, ice only melts at the surface, so the block cannot melt as fast. However, the heat still comes in at the same rate, which means the only way the ice can melt slower is if some of the energy coming in goes into heating water instead of melting ice. The block lasts longer precisely because the it isn't as good at cooling. In other words, you cooler might stay cold longer, but it won't stay as cold. This might be ok if all you are doing is trying to keep the beer at a reasonable serving temperature, but for preserving meat in the cooler, you probably want the temperature as low as possible.
2) Drain frequently, or do not drain frequently?
On this point, I am not certain. As the ice melts, you now have water and ice in the cooler. Is it better to drain off the water? On the one hand, it seems to me that the water is sitting at 32 degrees. If all the ice does melt, if there is a large quantity of 32 degree water available, it will take a lot of heat to raise the temperature of the water by one degree, meaning with water present, the food should stay reasonably cold for a longer time. On the other hand, the transfer of heat into the cooler interior is via conduction. Water being a better heat conductor, the presence of water will bring more heat into the cooler.
3) Covering - how much is the minimum?
Obviously, coolers in the sun warm up faster than coolers that are protected from the sun. However, how much does it take to provide some sort of protection. Would a heavy white cloth thrown over the cooler make any difference at all? My argument for it would be that the sunlight strikes the uncovered plastic of the cooler, heating the plastic. That heat then gets transferred to the interior of the cooler. If there were a cloth, the cloth would absorb the heat of the sun, and it would only then transfer to the cooler plastic via conduction, an inefficient process. On the other hand, it just seems like a cloth is just like increasing the width of the cooler walls a little bit. It's hardly noticeable. However, some people swore that a simple white cloth was adequate to greatly improve cooling life. Is this possible?
Are there any other interesting, but not universally understood, cooler phenomena that could help improve food safety on long camping trips?
1) Block versus cube - It was observed that if you buy 10 pounds of ice cubes, they won't last as long as a 10 pound block of ice. This, it was said, showed that block ice kept your cooler cold for a longer period of time.
On this point, I think I know the answer. I think that cubes are better. It seems to me that the cooler is a closed box. Heat flows in, and melts ice. For each calorie of heat that flows in, a certain amount of ice melts, until it is all melted, and then it starts raising the temperature of the water. Of course, ice only melts at the surface, so the block cannot melt as fast. However, the heat still comes in at the same rate, which means the only way the ice can melt slower is if some of the energy coming in goes into heating water instead of melting ice. The block lasts longer precisely because the it isn't as good at cooling. In other words, you cooler might stay cold longer, but it won't stay as cold. This might be ok if all you are doing is trying to keep the beer at a reasonable serving temperature, but for preserving meat in the cooler, you probably want the temperature as low as possible.
2) Drain frequently, or do not drain frequently?
On this point, I am not certain. As the ice melts, you now have water and ice in the cooler. Is it better to drain off the water? On the one hand, it seems to me that the water is sitting at 32 degrees. If all the ice does melt, if there is a large quantity of 32 degree water available, it will take a lot of heat to raise the temperature of the water by one degree, meaning with water present, the food should stay reasonably cold for a longer time. On the other hand, the transfer of heat into the cooler interior is via conduction. Water being a better heat conductor, the presence of water will bring more heat into the cooler.
3) Covering - how much is the minimum?
Obviously, coolers in the sun warm up faster than coolers that are protected from the sun. However, how much does it take to provide some sort of protection. Would a heavy white cloth thrown over the cooler make any difference at all? My argument for it would be that the sunlight strikes the uncovered plastic of the cooler, heating the plastic. That heat then gets transferred to the interior of the cooler. If there were a cloth, the cloth would absorb the heat of the sun, and it would only then transfer to the cooler plastic via conduction, an inefficient process. On the other hand, it just seems like a cloth is just like increasing the width of the cooler walls a little bit. It's hardly noticeable. However, some people swore that a simple white cloth was adequate to greatly improve cooling life. Is this possible?
Are there any other interesting, but not universally understood, cooler phenomena that could help improve food safety on long camping trips?
via International Skeptics Forum http://ift.tt/1MiF0OW
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