Design and bio-inspired optimization of direct contact membrane distillation for desalination based on constructal law

At the present study, a one-dimensional model for the flat sheet direct contact membrane distillation (DCMD) for desalination purposes is proposed. Flows and membrane properties have been estimated by appropriate temperature-dependent correlations. Results show that the numerical model is in a very good agreement with experimental data at various feed temperatures, flow rates and concentrations. A constructal design is investigated for DCMD to assess how constructal law can improve the DCMD performance. With the same thermal efficiency of 93.5%, constructal design improves the water mass flux by 37.5% in comparison with the conventional DCMD design. Also, an evolutionary-based optimization algorithm is employed to increase the efficiency of the constructal and conventional design. The Pareto frontier of the constructal and conventional design is compared with each other and the correlations between design variables are investigated. Overall, the present study demonstrates how constructal law can increase the performance of energy systems with a simple modification.

Study on the Performance of a Y-Shaped Liquid Cooling Heat Sink Based on Constructal Law for Electronic Chip Cooling

The power of one rack in a data center can be greater than 3 kW, which is released within a relatively small area. However, most of the heat in a data center is released from the electronic chips. Thus, the energy consumption of the air-conditioning system in a data center will be significantly decreased if the heat released by the electronic chips can be reduced directly. Although liquid cooling heat sinks (LCHS) have been demonstrated as an effective way to resolve this problem, the application of LCHS is limited by the uneven cooling distribution on the surface of the electronic chips and the liquid leakage of the LCHS. The constructal law optimizes the design of the pipeline by introducing the freedom of deformation in the fluid geometry to obtain the optimal global performance. In this study, a novel Y-shaped liquid cooling heat sink (YLCHS) was proposed based on the constructal law, in which the cooling water enters the center of the heat sink through the inlet pipe and diffuses into the periphery through the internal Y-shaped microchannels. A numerical simulation was carried out to determine the cooling effect of the YLCHS. Compared to those of the conventional S-shaped liquid cooling heat sink (CSLCHS), the peak surface temperature and the average surface temperature of the electronic chip with YLCHS were decreased by 15.2 °C and 6.3 °C, respectively. Furthermore, the pressure loss of the electronic chip with YLCHS was also reduced by 63.0%.

Systèmes vivants : Lois locales et globales, invariance d'échelle

To survive that is 'to eat and not to be eaten', to live on [9, 11]. Any living system [10], to survive and live on [9], whatever is its spatial [28] and temporal [23, 29, 35] level of organization, owns 7 invariant qualitative characteristics (degrees of freedom) [19]. Any alive system is formed by embedding and juxtapositions [17] of pre-existing systems [22]. How are the local quantitative laws, of their spatial-temporal structuring and functioning, associated with these qualitative characteristics independently from the dimensional scales? How are they independent/dependent from the new global level of organization and the local situations of emergence? How do the local actors become mutually integrated into their global whole? And reversely (systemic constructal law [4]), why and how is the global whole reciprocally integrating the local parceners [18, 20]? At every level of organization, the evolution of the living systems obeys 5 organizing principles of emergence [33] and the space (the volume of the adult system VA) and the duration (time of generation tg) are linked through a power law (generalized Kepler's 3rd law like VA2 = C.tg3), a law of growth (figure 3) and exchange (figure 4). As all the sub-systems which live in it, the whole Universe is living in an ecoexotope that it can share with other Universes.

Corona virus, tariffs, trade wars and supply chain evolutionary design

PurposeUsing the constructal law of physics this study aims to provide guidance to future scholarship on global supply chain management. Further, through two case studies the authors are developing, the authors report interview findings with two senior VPs from two multi-national corporations being disrupted by COVID-19. This study suggests how this and recent events will impact on the design of future global supply chains.Design/methodology/approachThe authors apply the constructal law to explain the recent disruptions to the global supply chain orthodoxy. Two interviews are presented from case studies the authors are developing in the USA and UK – one a multi-national automobile parts supplier and the other is a earth-moving equipment manufacture. Specifically, this is an exploratory pathway work trying to make sense of the COVID-19 pandemic and its impact on supply chain scholarship.FindingsAdopting the approach of Bejan, the authors believe that what is happening today with COVID-19 and other trade disruptions such as Brexit and the USA imposing tariffs is creating new obstacles that will redirect the future flow of supply chains.Research limitations/implicationsIt is clear that the COVID-19 response introduced a bullwhip effect in the manufacturing sector on a scale never-before seen. For scholars, the authors would suggest there are four pathway topics going forward. These topics include: the future state of global sourcing, the unique nature of a combined “demand” and “supply shortage” bullwhip effect, the resurrection of lean and local production systems and the development of risk-recovery contingency strategies to deal with pandemics.Practical implicationsSupply chain managers tend to be iterative and focused on making small and subtle changes to their current system and way of thinking, very often seeking to optimize cost or negotiate better contracts with suppliers. In the current environment, however, such activities have proved to be of little consequence compared to the massive forces of economic disruption of the past three years. Organizations that have more tightly compressed supply chains are enjoying a significant benefit during the COVID-19 crisis and are no longer being held hostage to governments of another country.Social implicationsAn implicit assumption in the press is that COVID-19 caught everyone by surprise, and that executives foolishly ignored the risks of outsourcing to China and are now paying the price. However, noted scholars and epidemiologists have been warning of the threats of pandemics since the severe acute respiratory syndrome (SARS) virus. The pundits would further posit that in their pursuit of low-cost production, global corporations made naive assumptions that nothing could disrupt them. Both the firms the authors have interviewed had to close plants to protect their workforce. It was indicated in the cases the authors are developing that it is going to take manufacturers on average one month to recover from 4–6 days of disruption. These companies employ many thousands of people, and direct and ancillary workers are now temporarily laid off and face an uncertain future as/when they will recover back to normal production.Originality/valueUsing the constructal law of physics, the authors seek to provide guidance to future scholarship on global supply chain management. Further, through two case studies, the authors provide the first insight from two senior VPs from two leading multi-national corporations in their respective sectors being disrupted by COVID-19. This study is the first indication to how this and recent disruptive events will impact on the design of future global supply chains. Unlike the generic work, which has recently appeared in HBR and Forbes, it is grounded in real operational insight.

Social Affinity Flow Theory

This article presents a new theoretical construct, Social Affinity Flow Theory (SAFT), which both describes and predicts fl ow phenomena across a diversity of human social systems and is founded upon constructal law. Constructal law and its associated s-curves describe many phenomena, both in nature and in human societies. Extrapolated from the work of Bejan and Zane and integrating social science research, it provides a foundational explanation of social rifts prevalent in many societies today as well as constructive efforts of social change, whether secular or religiously based. A primary example of constructive change explained by SAFT is the community-building work of the Bahá’í Faith, as reflected in both its teachings and its training institute process.