Direct observation of the Mpemba effect with water: Probe the mysterious heat transfer

Abstract

The Mpemba effect is one of the most perplexing puzzles in nature. Although it has been discussed extensively, direct observation of the Mpemba effect is extremely challenging and rare. Herein, we report the first systematic study of the Mpemba effect with water and clearly point out the conditions required for the observation of the Mpemba effect. The results demonstrate that hot water usually has a faster cooling rate than cold water. The initial temperature, temperature difference, shape of the container, and water volume influence the heat exchange and the cooling process. Owing to the influential factors of heat exchange, the Mpemba effect can only be observed under specific conditions. This work helps to clarify doubts and confusion about the Mpemba effect and can offer alternative strategies for energy storage and transfer materials.

Exploring the Mpemba effect: a universal ice pressing enables porous ceramics

“…The Mpemba effect is utilized to achieve fast freezing. 36,38 To evaluate this, water with different initial temperatures is introduced into a container, and its temperature changes are observed as it freezes entirely in a liquid nitrogen bath. According to the results of in situ temperature mappings (Movie S1, ESI †) and temperature curves (Fig.…”

Perspectives on a Few Puzzles in Phase Transformations: When Should the Farthest Reach the Earliest?

“…We have provided a general discussion on phase transition, covering passive as well as active matter systems. − ,,,,− Our primary focus has been on the Mpemba effect, , which is rapidly becoming a topic of much interest. ,− After a brief introduction to and discussion on the original observation of faster freezing of hotter water, we switched to more recent interest in the generalized Mpemba effect. We have discussed in this context the roles of spatial correlation in the initial configurations and glasslike metastability in the pathway to the final equilibrium.…”

“…Though a clear understanding is not obtained yet for water, similar questions have recently been asked in a rather general context, ,− including in colloidal, granular, and active matter systems. In the case of water, there are discussions of associating the effect with the cooling rate, evaporation, and related consequences .…”

Predicting the Mpemba Effect Using Machine Learning

“…The Mpemba Effect has been observed in a number of systems. In addition to water, [14,15], it has been predicted in magnetoresistance alloys [16], numerically predicted in colloids [17], predicted analytically and numerically in gasses [18,19], predicted in particles bounded by anharmonic potentials [20], observed in computational simulations and experiments in gas hydrates [21], and in computational simulations of carbon nanotube resonators [22]. It has been demonstrated to have application for faster heating with precooling [23], that the effect happens for temperatures dependent on the maximum work that can be extracted from the system [24], and that the Mpemba Effect can lead to quantum heat engines with greater power output and stability [25].…”