Economies of scale: The physics basis

Abstract

Why is size so important? Why are "economies of scale" a universal feature of all flow systems, animate, inanimate, and human made? The empirical evidence is clear: the bigger are more efficient carriers (per unit) than the smaller. This natural tendency is observed across the board, from animal design to technology, logistics, and economics. In this paper, we rely on physics (thermodynamics) to determine the relation between the efficiency and size. Here, the objective is to predict a natural phenomenon, which is universal. It is not to model a particular type of device. The objective is to demonstrate based on physics that the efficiencies of diverse power plants should increase with size. The analysis is performed in two ways. First is the tradeoff between the "external" irreversibilities due to the temperature differences that exist above and below the temperature range occupied by the circuit executed by the working fluid. Second is the allocation of the fluid flow irreversibility between the hot and cold portions of the fluid flow circuit. The implications of this report in economics and design science (scaling up, scaling down) and the necessity of multi-scale design with hierarchy are discussed. Published by AIP Publishing.

Entrance-length dendritic plate heat exchangers

“…This is the universal physics phenomenon of economies of scale [43,44], and it is more pronounced in the behavior of _ W P with respect to the sizeṼ. This trend is oriented against the behavior of the cost of material, which increases withṼ.…”

The constructal size of a heat exchanger

“…It is the problem of determining the size, and the effect that the size has on performance. We show how and why larger heat exchangers perform better, and as a consequence, we unveil the physics basis for the phenomenon of economies of scale 13 in heat exchangers. A fundamental step is most clear when presented in the simplest setting.…”

Current trends in constructal law and evolutionary design

“…How technology evolution follows naturally the constructal law of evolutionary design is being demonstrated in many directions, not just aircraft evolution. The evolution of science itself (thermodynamics, economies of scale, heat transfer) was treated in Bejan, Bejan, Almerbati, and Lorente, and Bejan . The evolution of thermal design (condensers, cooling of electronics, miniaturization) was presented in Bejan and Errera, Bejan, and Bejan, Lee, Lorente, and Kim .…”