Role of the volume-specific surface area in heat transfer objects: A critical thinking-based investigation of Newton's law of cooling

•Volume-specific surface area is crucial for heat transfer.•New expression for Newton's law of cooling offered.•Importance of volume-specific surface area in thermal and technical design.•Energy efficiency improves with larger heat stores. In this research, the process whereby objects are cooled (or heated) is reconsidered by studying Newton's law of cooling. The findings of the study highlight the important relationship between the volume-specific surface area of objects and the dynamics of heat content change; that is, the rate at which the temperature of an object decreases is shown to additionally depend on the size of the volume-specific surface area of the object. If the surface area in contact with the environment is small compared to the volume of the object, then the effect of the environment (e.g., heat exchange, heat loss) on the object will also be small. Consequently, when attempting to enhance the energy efficiency in heat storage design, apart from increasing the thickness of the thermal insulating layer, the specific heat loss of an object could be lowered by reducing the volume-specific surface area as an additional option. This hypothesis was based on observations, and the observed phenomenon has been confirmed by a computational example following the renewed interpretation of Newton's law of cooling, which has become more understandable by applying critical thinking. Newton's law of cooling has been newly expressed for use in engineering design, practice, and education. The interpretation of this law presented in this study can be used to reduce specific heat loss and intensify heat transfer. The article draws attention to the importance of the volume-specific surface area, which is an important variable in many engineering fields other than the case presented here. The method described here can be viewed as an additional alternative to the traditional education methods considered in heat transfer textbooks.