Tuesday, January 1, 2019

Thermal engineering challenges for the 21st century

Despite the lots of global engineering challenges that have been identified for the 21st century, this article focuses on those challenges that are primarily germane to thermal engineering. Some specific challenges that include energy conservation and efficiency of mechanical equipment, energy conservation/ thermal management in buildings, development of sustainable energy generation, and advancement of thermal management technologies from Nano- to macro-scale. Thermal engineers will also be required to attain a better understanding of fundamental phenomena governing complex and integrated mechanical and energy systems as well as broaden the perspectives to include an ever-widening range of length and time scales.
In the 20th century engineering recorded some of its grandest accomplishments. During the period of (between.1900 and 2000) the world saw for the first time a number of innovations (inventions) that we generally take for granted today. These innovations include automobiles, airplanes, phones, refrigeration, radio and television, rockets, spacecraft, computers, lasers, the internet, and fiber optics. Many others have been compiled in the National. Academy of Engineering (NAE's) lists of the 20 greatest engineering achievements of the 20th century ways the engineering accomplishments during the century. In the early part of the century, engineers divided complex systems into their most fundamental elements for the purpose of study. As the century progressed scientific understanding enabled the enormous developments of many new technologies.
The topic considered in the article is very broad, and the technical challenges identified are great. It is not possible to include a detailed account of the tasks. Instead numerous references are cited in the paper in which an interested. Reader can find in depth discussion of the specific thermal engineering challenges that are identified.
As it has already been noted, in the past millennia engineering has recorded some grand accomplishments and has driven advance of civilization. In early 2008) the National Academy of Engineering established an international group of leading technological thinkers and solicited its members and the public at large to identify "the grand challenges for engineering in the 21st century". After receiving the input from a large number of individuals, the Academy announced the 14 most important challenges for thermal sciences for next few decades. During the past few decades engineers have addressed thermal management issues ranging in scales from micro to macro. Examples of such devices and/ or systems include computer chips, rack-box-board modules, computers and data centers. Enormously great progress has been made.by engineers during the past few decades in cooling of electronic components. The thermal issues are associated with the spreading of heat by conduction, thermal interface resistances (I. e., between chip and substrate and external heat removal from the heat sink) and heat removal. Other probably more familiar devices and/ or equipment worth mentioning are microchannel, micro-heat exchangers and large heat exchangers used in power plants and chemical processing industry.
It is recognized that the challenges thermal engineers will be facing during this century depend greatly on the particular country, on available energy resources, economy, location on the earth and other circumstances as well as the primary energy use by individuals, commercial, residential, industrial and agricultural sectors. For example, in 2010 in the USA, up to 39% of primary energy was estimated to be.
Other topics need continued research attention some specific challenges on a fundamental scientific level relevant to nanotechnology, information technology are identified below. For example, nanotechnology is considered to be the next industrial revolution and is poised to impact our lives through consumer products, communication, health care, transportation to name just a few aspects. It is generally recognized that interfacial phenomena, size and dimension effects, multi-physics, computational methods and model validation remain important scientific issues. Some specific challenges are identified below.
- Fundamental research in thermal sciences (Heat transfer, mass transfer and fluid mechanics) in microscale remains a challenge for the next few decades and includes such phenomena as phase change in microscale channels and devices, measurement techniques, and numerical simulation and modelling.
- Nanoscale heat and mass transport at different interfaces (i. e., solid-fluid, metal-nonmetal and others) is an important scientific and engineering challenge remaining to the explored.
- Heat transfer in small scale, Nano/ microscale thermal radiation, experimental heat transfer on micro- and nanoscale are some additional.
- There is a need for development of predictive Multiphysics tools with quantified uncertainties that can address micro- and Nano-scale transport in thermal sciences.
- Nano-to- macro integration (i. e., coupling across spatial and temporal scales) remains a challenge to thermal engineers. Theoretical, computational and experimental approaches across scales and disciplines should be embraced during the next few decades.