Cooling jug physics

TL;DR

This paper models the physics of a pot-in-pot cooler, predicting its equilibrium temperature and cooling dynamics by balancing evaporation and heat exchange, with theoretical results validated by experiments.

Contribution

It introduces a simplified physical model of the cooling jug that accurately predicts temperature and cooling rate, including effects of vapor diffusion and heat conduction.

Findings

Theoretical equilibrium temperature matches psychrometric tables.

Cooling rate predictions align with experimental data.

Factors like capillary effects influence cooling performance.

Abstract

We discuss the physics of the pot-in-pot cooler. By balancing temperature decrease due to evaporation and temperature increase due to heat exchange, we find the equilibrium temperature of the pot. In this simplified model, the cooling jug acts as a psychrometer, and the theoretical prediction of our model is in a good agreement with psychrometric tables. Next, we study dynamics of the jug cooling. The cooling rate is limited by water vapour diffusion through air, heat conduction through air, and heat conduction through the body of the jug. The derived rate of temperature decrease is in general agreement with the result of our experiment. In the end, we discuss some additional factors, such as capillary effects in the raw clay, water viscosity in the capillaries, and impact of complex shape of the jug.