THE IDIOT AND THE $130 COOLER. I LIKE MY COFFEE HOT, BUT NOT TOO HOT!

Introduction

In my original experiment, THE IDIOT AND THE $130 COOLER. AN EXPERIMENT IN HEAT TRANSFER. we saw the difference in heat transfer between the Yeti Rambler 1 Gallon Cooler and the Coleman 1 Gallon Cooler using a controlled amount of ice and water.

While the  Long Distance Rider (LDR) can exist for extended periods of time solely on water, beef jerky, and the carefully chosen non-melting protein bar, there are times when a hot cup of coffee, tea, or even soup, would be a welcome addition to the LDR's diet. 

I decided to perform a second experiment, to test the relative performance of the Yeti and Coleman Coolers on hot beverages. But, it was not immediately clear, what the best temperature to start would be. So, I made myself a cup of coffee, and did a little research. 

175F was way too hot.

147F was stll a little too warm for my tastes.

134F was just about right!

It turns out, that someone else had already done some real research, with a study of 300 coffee drinkers: Calculating the optimum temperature for serving hot beverages.

I was actually pretty close. The study found that a range of 140F (+/- 15F) was ideal, with a mean of 136F. Temperatures of 160F or above can cause scald burns. So, I decided to start my experiment at 155F. 

Materials

Taylor Digital Probe Thermometer, Item #9848BEFDA, Operating Range (-40F - 450F).

Yeti Rambler 1 Gallon Jug, Item # YRAMOGJ.

Coleman 1 Gallon Cooler, Item # 3000000731.

Hot Water

Methods

On August 31, 2017, the author plans to fill the Yeti and Coleman Coolers each wth 128oz (1 US gallon) of hot water to attain a temperature of 155F. The coolers will be placed on a kitchen counter away from any external heat source. The room temperature is controlled by digital thermostat to an ambient temperature of 70F. The coolers will remain sealed between temperature readings and opened only for the minimum amount of time needed to take a temperature reading. The author plans to run the experiment for 12 hours.

Technique

On the evening of August 31, 2017, each cooler was carefully inspected and noted to be in good, usable condition, with a properly fitting lid.

Coleman Cooler Start Temperature, 155.2F

Yeti Cooler Start Temperature, 154.9F.

The temperature in both coolers was noted at 155F (rounded).

At the first temperature reading, the lid on the Coleman Cooler was significantly warmer than the lid on the Yeti Cooler. You may recall from our firt experiment, that the lids had significant design differences:

Yeti vs. Coleman Lids

A temperature reading was taken of the lids surfaces, using the Taylor thermometer:

Coleman Cooler Lid, 98.4F.

Yeti Cooler Lid, 77.1F

Multple temperature readings were then taken for a 12 hour perod, and rounded to the nearest whole degree. 

Results

On September 1, 2017 the Yeti and Coleman Coolers were opened 12 hours after the start of the experiment. At the end of the 12 hour period, the temperature in the Yeti Cooler remained at 130F, while the temperature in the Coleman Cooler had dropped to 94F.

Using the data from the 2008 Burns study referenced earlier in this post (140F +/- 15F) for the optimum serving temperature of coffee the lower heat transfer properties of the Yeti Cooler become more significant than durng our previous ice water experiment. The Yeti Cooler is capable of keeping a hot beverage at optimum temperatures for 12 or more hours, while the Coleman Cooler is only capable of maintaining these optimum temperatures for 4 hours. 

Future Reasearch

• Half Gallon Coolers from Yeti, Coleman, or other manufacturers. 
• Smaller cup or tumbler style coolers with various lids, since not everyone wants to carry around a gallon of coffee or soup. 
• Changing the external temperature of the environment the cooler is placed in to simulate cold riding conditions, such as running the experiment with the coolers in a refrigerator. 
• A combination study using two or more coolers to start off with ice and hot coffee, and eventually a combined result of iced coffee.