The cooling or warming of objects warmer or colder than their environment to the ambient temperature does not take the same amount of time. The physical law describing the speed of this phenomenon is now called Newton's Law of Cooling in science. Isaac Newton was the first scientist to describe a nonlinear relationship between the change in temperature of a cooling object and the change in time in an article published anonymously in Latin in 1701 – without a calculation formula.
István Árpád, an assistant professor at the Department of Mechanical Engineering at the Faculty of Engineering (MK) of the University of Debrecen (UD), and two of his colleagues recently examined the literature and the heat transfer textbooks’ descriptions of this process as well as the formula used today for calculations, which was developed as a result of the work of numerous scientists over the past three centuries.
“The interpretation of the cooling and heating of objects was not easy. It took a long time, because scientists dealing with heat and thermodynamics had to recognize the difference between the concepts of heat and temperature, as well as the difference between convection and heat radiation processes. Further difficulties in creating the mathematical model were caused by the reconciliation of the different experimental results into one formula, due to the differences in shape, size and material of the objects participating in the practical experiments, as well as the differences in environmental conditions. In fact, this article is the most recent step and result of this long research process,” said István Árpád to hirek.unideb.hu.
The researchers divided the presentation of their findings into three chapters. In the first one of these, they described a new approach and a new form of the Newtonian Law of Cooling, which is simpler and easier to interpret than those used so far. In the second part, they supplemented and corrected the scientific descriptions in the literature and chemical engineering textbooks explaining cooling and heating. In the third chapter, they presented a heat storage design example, which illustrates that the energy efficiency of larger heat stores is better than that of smaller ones.
The results obtained at the University of Debrecen can be linked to many practical applications, for example, in the mechanical engineering industry, when designing the heat transfer of batteries or calculating the thermal management of buildings, and when installing different kinds of heat storage equipment. The same knowledge can also be applied in the food industry as well as in metallurgy and the chemical engineering industries.
As an acknowledgement of their excellent theoretical scientific article, the researchers were awarded the University of Debrecen Publication Award by Count István Tisza Foundation for the University of Debrecen and the University of Debrecen.
This contribution was published in the prestigious technical journal International Journal of Heat and Mass Transfer, and can be accessed in full by clicking here.
Press Center – OCs
