detedarc zebadiah fabrienne
Karlyn Hemmerling
Thermal Engineering and Gas Dynamics Definition
Thermal engineering is concerned with heat transfer and energy conversion processes, whereas gas dynamics is concerned with the behaviour of gases in motion, particularly with regard to propulsion and fluid flow.
Contribution to Energy Conversion and Fluid Behaviour
Thermal engineering and gas dynamics are critical in designing energy conversion systems and understanding fluid behaviour in a variety of applications.
Understanding Fluid Flow and Its Impact on the Environment
Gas dynamics provides insights into fluid behaviour, assisting in the design of efficient pipelines, pumps, and turbines while taking environmental impact into account.
Renewable Energy Technology Innovations
Thermal engineering concepts are critical in the development and advancement of renewable energy technologies such as solar thermal systems and geothermal power plants.
JSME has decided that a new conference series, Pacific Rim Thermal Engineering Conference (PRTEC), will be launched collaborating with the Korean Society of Mechanical Engineers (KSME) and the American Society of Thermal and Fluids Engineers (ASTFE). The key themes of PRTEC 2016 are "Fundamental", "Interdisciplinary" and "Diversity" with a vision for the future of Thermal Engineering.
The PRTEC 2016 provides an international forum for the exchange of new ideas and direction related to the future thermal engineering and the presentation of the latest work in this field. We strongly encourage attendance and extended abstract submission not only from the Pacific-rim countries but also from all over the world.
This unique 16-hour online course presents satellite thermal control for small satellites as an organized engineering discipline. Students will learn how to design SmallSat thermal control systems based on best practices developed by the satellite industry.
Thermal tools are needed to design a thermal management system for a CubeSat, and commercially available tools are complex and typically require a deep knowledge of thermal physics. The tools are also expensive, making them unaffordable for small companies or universities. A freeware simplified thermal tool is shared during class, which can be used by CubeSat designers without thermal training. The defining feature of this tool is simplicity of use even for users without a thermal background. Transient and steady-state analysis are available.
Students will finish this course with an understanding of the problems and methods encountered in SmallSat thermal design and the effect of spacecraft size and mission goals on thermal control systems. Many of the points that have made thermal control a confusing subject are clearly explained.
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It is known that the study of the processes of heat generation and propagation, as well as its transformation into other types of energy, led to the discovery of fundamental physical laws. We should remember, first of all, the laws of thermal radiation, the discovery of which just over a century ago radically changed physics as a science and became the basis of incredible technical advances. The revolution in theoretical physics has greatly accelerated research in heat transfer and various applications, especially in thermal engineering. Textbooks usually distinguish three ways of heat transfer: conduction, convection, and thermal radiation. However, attempts to solve real problems show that we are usually dealing with combined heat transfer, when different modes of heat transfer interact with each other.
In my opinion, thermal radiation is closer to fundamental science and appears to be a more global phenomenon than other modes of heat transfer. It is not even the fact that life on our planet exists because of thermal radiation from the Sun, and this radiation extends 150 million kilometers to reach the Earth. Contrary to popular belief, thermal radiation turns out to be important at any temperature and at any distance, and its spectrum includes the microwave range used in remote sensing of the ocean surface. This explains why we focus on radiative and combined heat transfer, and the variety of problems involved is so great.
The classical theory of radiative transfer in such media is based on the integrodifferential equation, which was independently derived early last century by Orest Khvolson and Subrahmanyan Chandrasekhar in connection with the study of radiative transfer in stellar photospheres (Chandrasekhar 1960; Rosenberg 1977). A modern systematic account of the theory of radiative heat transfer can be found in textbooks by Howell et al. (2021) and Modest and Mazumder (2021), and an engineering approach to modeling radiative and combined heat transfer in disperse systems is discussed in Dombrovsky and Baillis (2010).
The radiative transfer equation in a scattering medium does not take into account the wave nature of electromagnetic radiation, which appears most strongly when the radiation is scattered by particles whose size is of the same order of magnitude as the wavelength of the radiation. However, the wave properties of the medium are taken into account in the coefficients of the equation. In the simplest case of homogeneous spherical particles and with independent scattering (Mishchenko 2018), these properties can be calculated using the rigorous Mie theory. The general solution obtained by Gustav Mie in 1908 and useful approximate theoretical models are described in detail in a well-known monograph (Bohren and Huffman, 1998). At present, similar solutions have also been obtained for optically inhomogeneous particles of complex shape.
Of course, the radiative transfer equation is not always applicable. In some cases, one has to consider alternative physical models up to a very complex numerical solution of the wave equation for the electromagnetic field in an inhomogeneous medium. Also the situation deserves special attention when the so-called near-field radiative transfer takes place and the theory of fluctuational electrodynamics, developed by Sergei Rytov around the beginning of the 1950s, can be used (Song et al., 2015).
It should be said that the numerical solution of the classical radiative transfer equation is by no means a simple task, and in some cases one has to use very complicated algorithms to obtain reliable results (Coelho 2014). Fortunately, in heat transfer problems, as a rule, only such angular-integral characteristics of the radiation field as the radiation flux and its divergence are of interest. This allows (at least at the first stage of the solution) to use simple assumptions for the angular dependence of the radiation intensity and the resulting differential approximations. In addition, in the common case of multiple scattering, the transport approximation for single scattering can be used. As a result, the simple calculation of the differential model can be combined with the usual ray-tracing procedure for the transport radiative transfer equation with a known source function (Dombrovsky and Baillis 2010; Dombrovsky 2019). The limited scope of this article does not allow us to go into detail about the theory and individual methods in radiative transfer. Therefore, below we will only name the main research topics and recommend key publications for each of them on which further work can be based.
We have briefly discussed various approaches to calculating radiation heat transfer. However, the mathematical formulation of the complete heat transfer problem usually involves a transient energy equation with various heat sources and sinks: due to thermal conduction, first-order phase transitions, and convective heat transfer. The integral radiative flux divergence is only one of the terms of the energy equation. Moreover, when convection is taken into account, at least the continuity equation and the equation of motion (usually nonlinear) appear in the equations to be solved. Of course, any detailed analysis of convective heat transfer, especially in turbulent flow, is beyond the scope of the research topics considered. Fortunately, it is possible to use commercial CFD codes for problems with an important role of convection and focus on the radiative heat source. There are also many problems where convection affects the boundary condition only and it is sufficient to analyze coupled radiation and conduction.
The length of this article does not allow us to review the content and objectives of all research topics. Therefore, we will limit ourselves to a few key areas of research, including both traditional and cutting-edge ones.
The importance of calculating thermal radiation in combustion systems is obvious and undeniable. The theoretical foundations of this research and some engineering problems have been addressed in a monograph by Raymond Viskanta (2005). Spectral models and the interaction of thermal radiation and turbulence in combustion systems are discussed in more detail in (Modest and Haworth 2021).
It is known that the role of emission, absorption, and scattering of thermal radiation by particles is particularly important in coal or coal dust combustion (Im and Ahluwalia 1993; Krishnamoorthy and Wolf 2015; Wu et al., 2017; Wang L. et al., 2021). In connection with coal combustion, it is worth recalling the concomitant particle pollution in the atmosphere that affects the propagation of solar radiation and infrared radiation from the Earth in the atmosphere. Solving this problem is important for predicting and preventing unwanted climate change.
The problem associated with solid-propellant rocket engines should also be recalled. The fact is that the combustion products of these solid propellants contain micron-sized alumina particles, which determine both the radiative heat transfer in the rocket engine and the visible and infrared emission of the exhaust jet, which is important for missile detection and identification. Information on this topic can be found in monographs (Dombrovsky 1996; Dombrovsky and Baillis 2010) as well as in (Duval et al., 2004; Ponti et al., 2021; Hao et al., 2022). The effect of micron-sized alumina particles in combustion products of solid propellants on radiation of rocket plumes was studied in (Surzhikov 2004; Shuai et al., 2005; Binauld et al., 2019).
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