Test Equipment: a microwave oven, a bike with two water bottle holders mounted at the same angle, left and right behind the seat, a ThermoHAWK Pro632 Remote Infrared Pyrometer, (or heat gun sensor.)
One bottle was heated to 206 degrees Fahrenheit in a microwave oven, stopping just as liquid began to boil. The second bottle was left unheated with water straight out of the faucet at 53 degrees Fahrenheit.
Both bottles were placed in holders on the bike. The outdoor temperature at my house was 17 degrees Fahrenheit. I decided to agitate (shake) both bottles every fifteen minutes to simulate the motion of drinking.
15 minutes: the heated bottle had cooled to 140 degrees, the unheated bottle, to 43 degrees.
45 Minutes: the heated bottle had cooled to 97 degrees, the unheated bottle to 31 degrees. Ice was beginning to form on the nipple of the unheated bottle. Sharp agitation freed the nipple from icing.
One Hour 15 minutes: the heated bottle is still perceptibly warm and reads 73 degrees. The unheated bottle has equilibrated at the freezing point and continues to form ice on the nipple, now difficult to dislodge.
One Hour 45 Minutes: the heated bottle reads 53 degrees. The unheated bottle is now completely unusable. The nipple is frozen solid. There is visible slush in the bottle when shaken.
Two Hours: The heated bottle reads 49 degrees. The unheated water bottle continues to freeze more solidly.
In the real world, I would expect to be near a store stop by now. Experiment ended.
Conclusions: The microwave heated bottle remained far above the freezing point for the duration of the test while the unheated bottle froze and became unusable. While the "Mpemba Effect" may be a real phenomenon that predicts hot water will freeze before cold water in certain circumstances, my test did not show this to be the case when applied to a real world cyclist's water bottle.
Dr. Larry Preble is LBC’s resident Mad (Dog) Scientist and a graduate of both Vanderbilt University and Logan College of Chiropractic. He has headed research projects in computer science, psychology and biomechanics. After moving to Louisville, he wrote for both PCM and Rainbow Magazines for several years and continues in the practice of chiropractic in the Louisville area. Larry is an enthusiastic LBC Mad Dog cyclist and is often spotted riding either his Bacchetta recumbent or Trek upright bicycle.
Mad Dog Scientist’s Corner:
By Laurence D. Preble, D.C.
Duc Do’s kycyclist.org e-mail list server is a source of fun, controversy, and (sometimes) fascinating information. Cycling topics range from the mundane to the sublime. Here is a great example:
011/26/2008: I Wrote: One good measure against (water bottle) freeze-up is to heat the bottles in a microwave at each store stop along the way. The water may be uncomfortably warm at ride start, but "just right" a little later on. It buys some time before freezing.
11/26/2008: Lucy Linet referenced an article on the Mpemba effect in response to my suggestion to heat a (microwave safe) water bottle in the microwave to extend the time before the bottle freezes. The Mpemba article suggests that hot water may freeze before cold water under certain circumstances.
11/26/2008: Joe Ward wrote: Hey Larry, google "Mpemba." You will find that "The fact that hot water freezes faster than cold has been known for many centuries. The earliest reference to this phenomenon dates back to Aristotle in 300 B.C."
Mad Dog Scientist Report #1
12/21/2008: Today, Perry Finley, Peter Kemmerle and I rode out of Thurman-Hutchins Park for a delightful ride in sub-freezing temperatures. Long before we got back to the park, I noted that my water and Gatorade both had turned to slush. As I returned to the park, I thought, "Hey, it looks like a good day to do a controlled test of the Mpemba effect on cyclists’ water bottles!"
So here I am. Here is the experiment and the result.
Hypothesis: "Mpemba" effect suggests that an initially heated water bottle will freeze before an unheated water bottle.
Materials: 600 grams of water in each of two identical LDPE plastic water bottles. These are ordinary bottles obtained from Bluegrass Bicycle.