Solar transparent insulation materials: a review
TL;DR: In this article, the authors present a status report on solar transparent insulation materials (TIM), which covers a survey of the literature, various physical and other properties of TIM devices, their classifications, applications, fabrication procedures, availability and cost trends.
Abstract: This paper presents a status report on solar transparent insulation materials (TIM). It covers a survey of the literature, various physical and other properties of TIM devices, their classifications, applications, fabrication procedures, availability and cost trends. The global resurgence of research is clarified. Subsequently, the development of TIM cover systems (often referred to as advanced glazing) from such products as polymer sheets, capillaries and cellular profiles, is discussed. Their design and performance characteristics are investigated; results corresponding to experimental measurements, as well as computational models, are presented. An explicit comparative study of absorber parallel and absorber perpendicular configurations of TIM cover systems is presented. The TIM covers with black end cover plates, and cellular walls of high emissivity, as well as those with selective cover plates and cellular walls fully transparent to IR radiations, have relatively lower heat loss coefficients.
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TL;DR: In this article, a review of the knowledge of aerogel insulation in general and for building applications in particular is given, where the possibility of high transmittances in the solar spectrum is of high interest for the construction sector.
819 citations
TL;DR: Aerogel is a kind of synthetic porous material, in which the liquid component of the gel is replaced with a gas as mentioned in this paper, and it is considered as one of the most promising thermal insulating materials for building applications.
Abstract: Aerogel is a kind of synthetic porous material, in which the liquid component of the gel is replaced with a gas. Aerogel has specific acoustic properties and remarkably lower thermal conductivity (≈0.013 W/m K) than the other commercial insulating materials. It also has superior physical and chemical characteristics like the translucent structure. Therefore, it is considered as one of the most promising thermal insulating materials for building applications. Besides its applications in residential and industrial buildings, aerogel has a great deal of application areas such as spacecrafts, skyscrapers, automobiles, electronic devices, clothing etc. Although current cost of aerogel still remains higher compared to the conventional insulation materials, intensive efforts are made to reduce its manufacturing cost and hence enable it to become widespread all over the world. In this study, a comprehensive review on aerogel and its utilization in buildings are presented. Thermal insulation materials based on aerogel are illustrated with various applications. Economic analysis and future potential of aerogel are also considered in the study.
538 citations
TL;DR: This nanowire-embedded cloth can efficiently warm human bodies and save hundreds of watts per person as compared to traditional indoor heaters.
Abstract: Heating consumes large amount of energy and is a primary source of greenhouse gas emission. Although energy-efficient buildings are developing quickly based on improving insulation and design, a large portion of energy continues to be wasted on heating empty space and nonhuman objects. Here, we demonstrate a system of personal thermal management using metallic nanowire-embedded cloth that can reduce this waste. The metallic nanowires form a conductive network that not only is highly thermal insulating because it reflects human body infrared radiation but also allows Joule heating to complement the passive insulation. The breathability and durability of the original cloth is not sacrificed because of the nanowires’ porous structure. This nanowire cloth can efficiently warm human bodies and save hundreds of watts per person as compared to traditional indoor heaters.
375 citations
TL;DR: In this article, a literature review on determining the optimum thickness of the thermal insulation material in a building envelope and its effect on energy consumption was carried out, and a practical application on optimizing the insulation thickness was performed, and the effective parameters on the optimum value were investigated.
Abstract: Energy conservation is an increasingly important issue for the residential sector. Therefore, attention towards the thermal performance of building materials, particularly thermal insulation systems for buildings, has grown in recent years. In this study, a literature review on determining the optimum thickness of the thermal insulation material in a building envelope and its effect on energy consumption was carried out. The results, the optimization procedures and the economic analysis methods used in the studies were presented comparatively. Additionally, a practical application on optimizing the insulation thickness was performed, and the effective parameters on the optimum value were investigated.
337 citations
TL;DR: State-of-the-art developments of bioinspired thermal-management materials, including materials for efficient thermal insulation and heat transfer, and bioinspired materials for thermal/infrared detection, are highlighted.
Abstract: In the development of next-generation materials with enhanced thermal properties, biological systems in nature provide many examples that have exceptional structural designs and unparalleled performance in their thermal or nonthermal functions. Bioinspired engineering thus offers great promise in the synthesis and fabrication of thermal materials that are difficult to engineer through conventional approaches. In this review, recent progress in the emerging area of bioinspired advanced materials for thermal science and technology is summarized. State-of-the-art developments of bioinspired thermal-management materials, including materials for efficient thermal insulation and heat transfer, and bioinspired materials for thermal/infrared detection, are highlighted. The dynamic balance of bioinspiration and practical engineering, the correlation of inspiration approaches with the targeted applications, and the coexistence of molecule-based inspiration and structure-based inspiration are discussed in the overview of the development. The long-term outlook and short-term focus of this critical area of advanced materials engineering are also presented.
218 citations
References
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01 Jan 1980
TL;DR: In this article, the authors present an active and passive building heating system for solar thermal power systems, where the active system is designed by f--chart and the passive one by Utilizability Methods.
Abstract: FUNDAMENTALS. Solar Radiation. Available Solar Radiation. Selected Heat Transfer Topics. Radiation Characteristics of Opaque Materials. Radiation Transmission Through Glazing: Absorbed Radiation. Flat--Plate Collectors. Concentrating Collectors. Energy Storage. Solar Process Loads. System Thermal Calculations. Solar Process Economics. APPLICATIONS. Solar Water Heating----Active and Passive. Building Heating----Active. Building Heating: Passive and Hybrid Methods. Cooling. Industrial Process Heat. Solar Thermal Power Systems. Solar Ponds: Evaporative Processes. THERMAL DESIGN METHODS. Simulations in Solar Process Design. Design of Active Systems by f--Chart. Design of Active Systems by Utilizability Methods. Design of Passive and Hybrid Heating Systems. Design of Photovoltaic Systems. Appendices. Author Index. Subject Index.
9,391 citations
TL;DR: In this article, the authors present an active and passive building heating system for solar thermal power systems, where the active system is designed by f--chart and the passive one by Utilizability Methods.
Abstract: FUNDAMENTALS. Solar Radiation. Available Solar Radiation. Selected Heat Transfer Topics. Radiation Characteristics of Opaque Materials. Radiation Transmission Through Glazing: Absorbed Radiation. Flat--Plate Collectors. Concentrating Collectors. Energy Storage. Solar Process Loads. System Thermal Calculations. Solar Process Economics. APPLICATIONS. Solar Water Heating----Active and Passive. Building Heating----Active. Building Heating: Passive and Hybrid Methods. Cooling. Industrial Process Heat. Solar Thermal Power Systems. Solar Ponds: Evaporative Processes. THERMAL DESIGN METHODS. Simulations in Solar Process Design. Design of Active Systems by f--Chart. Design of Active Systems by Utilizability Methods. Design of Passive and Hybrid Heating Systems. Design of Photovoltaic Systems. Appendices. Author Index. Subject Index.
7,831 citations
TL;DR: The Solar Engineering of Thermal Processes (SEPTP) as discussed by the authors has become a classic solar engineering text and reference for students of solar engineering, solar energy, and alternative energy as well as professionals working in the power and energy industry or related fields.
Abstract: The updated fourth edition of the "bible" of solar energy theory and applications
Over several editions, Solar Engineering of Thermal Processes has become a classic solar engineering text and reference. This revised Fourth Edition offers current coverage of solar energy theory, systems design, and applications in different market sectors along with an emphasis on solar system design and analysis using simulations to help readers translate theory into practice.
An important resource for students of solar engineering, solar energy, and alternative energy as well as professionals working in the power and energy industry or related fields, Solar Engineering of Thermal Processes, Fourth Edition features:
Increased coverage of leading-edge topics such as photovoltaics and the design of solar cells and heatersA brand-new chapter on applying CombiSys (a readymade TRNSYS simulation program available for free download) to simulate a solar heated house with solar- heated domestic hot waterAdditional simulation problems available through a companion websiteAn extensive array of homework problems and exercises
798 citations
"Solar transparent insulation materi..." refers background in this paper
...The heat loss from top glass cover to ambient, Qt2 consists of the convective and radiative components and may be expressed as [69]: Qt2 = &2c + Qt2r (22) Qt2 = hJTp- Ta) + <7ec(rg- 71y) (23) where hw, the convective heat transfer coefficient from top cover to ambient is given by [69]: K = 5....
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...The (ta)b may be expressed by an approximate equation, which does not take into account the internal reflections between the honeycomb and the cover, as follows: (ta)b(q) = T1(0)-T2(0)-T3(0)-a(0) (28) U0) = TW^O) (29) where t1(q) is the transmittance based on reflection of the encapsulating cover plates, and is given by following [69]:...
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TL;DR: In this paper, the effect of sloping boundaries on thermal convection is studied theoretically and in the laboratory in the context of a model in which fluid is contained in a differentially heated rectangular box of small aspect ratio (depth/length), inclined at an angle δ to the vertical.
Abstract: The effect of sloping boundaries on thermal convection is studied theoretically and in the laboratory in the context of a model in which fluid is contained in a differentially heated rectangular box of small aspect ratio (depth/length), inclined at an angle δ to the vertical. Like its two limiting cases, Benard convection and convection in the vertical slot, a basic state which exists for low Rayleigh numbers becomes unstable as this parameter is increased. The types of instability and indeed the manner in which the motions become turbulent depend crucially on δ. In our work with water the following general picture of the primary instabilities applies:
For 90° > δ > 10° with the bottom plate hotter, the instabilities are stationary longitudinal convectively driven rolls with axes oriented up the slope. Near δ = 10° there is an upper and lower Rayleigh number cut off. If the Rayleigh number is too small diffusion damps the instabilities, but if it is too large they are damped by the development of a stable upslope temperature gradient in the mean flow.For 10° > δ > −10° (negative angles imply a hotter upper plate), transverse travelling waves oriented across the slope are the first instabilities of the mean flow. They obtain their kinetic energy via the working of the upslope buoyancy force.For - 10° > δ > −85° longitudinal modes are again observed. These are rather curious in that they may exist when the stratification is everywhere positive. The necessary energy for these modes comes out of the mean velocity field and out of the mean available potential energy.Agreement between the stability theory and the experiments is generally quite good over the whole range of δ, considering the approximations involved in finding a suitable basic flow solution.For Rayleigh numbers less than ∼ 106 turbulence is only possible for positive angles. For 85° > δ > 20° the development of unsteadiness involves the occurrence and the breaking of wavy longitudinal vortices in a manner reminiscent of the development of turbulence in cylindrical Couette flow.
257 citations
"Solar transparent insulation materi..." refers background in this paper
...Subsequently, the effect of cellular arrays on convection suppression was formulated in terms of the escalation in critical Rayleigh number [7-17]....
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01 Nov 1974
TL;DR: In this article, the spacing between the hot solar absorber and successive glass covers should be in the range 4 to 8 cm to assure minimum gap conductance, based on the theory and some experimental measurements.
Abstract: A useful solar-thermal converter requires effective control of heat losses from the hot absorber to the cooler surroundings. Based upon the theory and some experimental measurements it is shown that the spacing between the tilted hot solar absorber and successive glass covers should be in the range 4 to 8 cm to assure minimum gap conductance. Poor choice of spacing can significantly affect thermal conversion efficiency, particularly when the efficiency is low or when selective black absorbers are used. Recommended data for gap Nusselt number are presented as a function of the Rayleigh number for the high aspect ratios of interest in solar collector designs. It is also shown that a rectangular cell structure placed over a solar absorber is an effective device to suppress natural convection, if designed with the proper cell spacing d, height to spacing ratio L/d and width to spacing ratio W/d needed to give a cell Rayleigh number less than the critical value.
172 citations