Transparent Insulation Materials Research Articles

Compression and thermal conductivity tests of Cryogel® Z for use in the ultra-transparent cryostats of FCC detector solenoids

The Future Circular Collider (FCC) study includes the design of the detector magnets for the FCC-ee+ (electron-positron) collider, requiring a 2 T solenoid for particle spectrometry, and for the FCC-hh (proton-proton) collider, with a 4 T detector solenoid. For both solenoids and their cryostats, CERN is developing an innovative and challenging design in which the solenoids are positioned inside the calorimeters, directly surrounding the inner tracker. For this purpose, the cryostats must be optimized to have maximum radiation transparency. They are structured as a sandwich of thinnest possible metallic shells for achieving vacuum tightness, supported by layers of low density and highly radiation transparent insulation material, still providing sufficient mechanical resistance and low thermal conductivity. In this respect, thermal and mechanical analysis of innovative insulation materials are currently being carried out. The first material of interest, Cryogel® Z, is shaped as a flexible composite blanket, which combines silica aerogel with reinforcing fibers and a density of 160 kg/m3. It allows a 4 m bore, 6 m long FCC-ee+ detector solenoid cryostat with a total thickness of 250 mm. CERN has investigated the compression of Cryogel® Z under 1 bar equivalent mechanical load and its thermal conductivity between 10 K and room temperature, as well as the critical phenomena of thermal shrinkage and outgassing. We present the test results, as a first overview on the material.

Coupled transparent insulation system with low emissivity solar absorber: An experimentally validated building energy simulation study

A conversion of shortwave to longwave radiation heat transfer in building envelope system represents an substantial part in low-energy design campaing. For that reason, an experimental test sample of a novel solar façade element based on a Transparent Insulation Material (TIM) with a selective and a nonselective absorber was developed. The investigated element is a part of an opaque lightweight structure of a building envelope. The capability of one widely used Building Energy Simulation (BES) tool is analyzed in terms of its ability to model the performance of the TIM façade element. The good consistency between the simulation results and the experimental data obtained specifically via cooling period indicates that the reference simulation model based on high emisivity of solar absorber was reliable when predicting the energy performance of TIM based façade models. However, the low emissivity of solar absorbers in the façade cavity gives rise significant limitations. They were identified concerning the BES calculation methods and modeling principles. The computational results are significantly underestimated in case of low emissivity internal surface. The methodology developed in this study is expected to provide a reference for simulating the thermal and energy performance of TIM-based building elements with different solar absorbers.

First-principles investigation on electronic structure and solar radiation shielding performance of Tl<sub>0.33</sub>WO<sub>3</sub>

<sec>With energy-saving and emission-reduction have become the theme of today's social development, the theoretical design and research of novel transparent heat insulation materials for windows, which can save energy and improve the comprehensive utilization efficiency of solar energy, are particularly crucial.</sec><sec>In this paper, a calculation method based on DFT(density functional theory) is used to study the lattice parameters (the geometric structure of h-WO<sub>3</sub> crystal was optimized by calculation) electronic band structure, formation energy, and optical properties of pure hexagonal phase tungsten trioxide(h-WO<sub>3</sub>) before and after doping with Tl. The calculated results indicate that the lattice volume increases and the total system energy decreases to a negative value after Tl-doped h-WO<sub>3</sub>, while the system has better stability; The electron band structure changes greatly after doping, but the material still maintains n-type conductivity. In the meantime, the optical properties of the material also changed, h-WO<sub>3</sub> had no near-infrared absorption performance before Tl-doping, and Tl<sub>0.33</sub>WO<sub>3</sub> after Tl-doped had strong near-infrared absorption performance. On this basis, the solar radiation shielding performance of h-WO<sub>3</sub> before and after Tl doping has been studied. The results show that pure h-WO<sub>3</sub> has no solar radiation shielding performance, while Tl<sub>0.33</sub>WO<sub>3</sub> thin films after Tl-doped h-WO<sub>3</sub> have high transparency in visible light region and strong absorption in near infrared radiation. The calculation results provide a theoretical basis for the application of transparent thermal insulating material for windows of Tl-doped h-WO<sub>3</sub>.</sec>

Finite element analysis of heat transfer performance of vacuum glazing with low-emittance coatings by using ANSYS

As a new transparent insulation material, vacuum glazing with Low-E (low emittance) coating has drawn more and more attentions thanks to its excellent performances: outstanding thermal and sound insulations, anti-frosting, resisting wind press capacity, and good durability. However, a comprehensive analysis and evaluation on the heat transfer performance of Low-E vacuum glazing are still missing in the current literatures. In this work, the influences of various aspects on the heat transfer performance of Low-E vacuum glazing were analyzed based on the Finite Element Analysis (FEA) method, including thickness of substrate glass, width of the sealing edge, materials and spacing of support pillar array, and insulation frame structure. The simulated results show the following, 1) with the increase of the thickness of the substrate glass, the heat transfer coefficient of the Low-E vacuum glazing rises slowly in a linear trend. The larger the size of the whole piece of the glazing, the more slowly it rises; 2) the Low-E vacuum glazing heat transfer coefficient declines linearly with the decrease of the width of the sealing edge; 3) as the support pillar array spacing increases and the thermal conductivity of the support pillar array decreases, the Low-E vacuum glazing heat transfer coefficient decreases; 4) the use of thermal insulation frame structure can improve the insulation efficiency of the vacuum glazing. Experiments were carried out on a Low-E vacuum glazing, and the heat transfer coefficient of this vacuum glazing was determined by the Building Heat Resistance-III (BHR-III), an equipment for insulation performance testing. The simulated result matches well with the experimental result, with a relative deviation of 2.8%, which confirms the reliability of the simulation result. This work is expected to provide guidance for optimization design of Low-E vacuum glazing and its insulation performance evaluation.

The effect of changing surface emissivity on the natural ventilation rate of a narrow air cavity integrated in a transparent insulation façade

A transparent insulation material (TIM) can be incorporated in a building element in order to improve its thermal performance, including solar heat gain. However, some overheating protection needs to be implemented. The provision of natural ventilation in a façade cavity to avoid overheating, along with other potential techniques, could require a completely different approach to TIM integration in solar façade concepts. This paper concerns an analysis of the effect of different absorber emissivity behind a transparent insulation system. The emissivity changes are primarily studied in order to determine their effects on the overall radiation - natural convection heat transfer through a narrow façade air cavity. A comparative investigation was conducted using experimental full-scale dynamic outdoor tests and the building energy simulation (BES) approach. The thermodynamic response affected by the radiation - natural convection transfer is identified, specifically during the summer peak period, that corresponds to overheating. Depending on the ventilation regime, a low emissivity solar absorber inside a narrow air façade cavity may increase the cooling energy load and temperature response of a façade by 25 and 36%, respectively, in comparison with a high emissivity absorber. When the emissivity of the zone inside the cavity was changed, significant limitations were identified in the BES calculation methods for both vented and unvented cases.

Chameleon Building

The research lines that are outlined for the next few years identify the most promising innovation territory for the development of resilient envelopes in materials and construction systems. In the last two decades, this research lines has fuelled the development and then the entry on the market of different materials supported by a growing demand for resilience and characterized by the adoption of different approaches: from the design of the same material to the modification of some of its characteristics, obtained by technological transfer both within the same building sector, both from other sectors already tested, from the “eco-active” ones to obtain self-cleaning surfaces, up to PCM Phase Change Material, TIM Transparent Insulation Material, Aerogel, ETFE Ethylene, a polymer made of a translucent and resilient plastic film an air cushion that inflates and deflates according to weather conditions. To this, adds the strong contribution of SMART systems that produce sensitive and responsive envelopes that define its new resilient character. Another approach inherent in the adaptive requisite of buildings is that following the dictates of Biomimetic, it directs studies towards the realization of iridescent facades in the material-functional and language responses, to the different solicitations deriving from the contexts.Assuming nature as a model, measurement we study materials and components that react to environmental stimuli in an organic and passive way. These highly adaptive strategies could substantially contribute to the realization of resilient envelopes. The use of innovative materials and systems would therefore in a certain sense “tune” the building to the climate, in fact with the right sensors and controls the building is able to respond to weather conditions in real time.

Parametric analysis on the performance of flat plate collector with transparent insulation material

Abstract The transparent insulation materials (TIM) can effectively improve the performance of flat plate solar collector in cold weather. A three dimension numerical model of flat plate collector with TIM has been developed in this paper. The computational fluid dynamics (CFD) have been used to simulate the model. The Renormalization-group (RNG) k-e model and Discrete Ordinates (DO) radiation model were adopted. The influences of the environment conditions, mass flow rate, tilt angle and transmittance on the performance of the collector with TIM were analyzed. A good agreement was achieved between the CFD prediction and the previous experiment. The result shows that the collector with TIM is more efficient, when ambient temperature is low. For various wind speeds, the new collector's efficiency has a slightly change. The transmittance of TIM is a key parameter to achieve high performance for the collector. When the transmittance is below 80%, the collector with TIM has no the advantage of being good value. The optimum mass flow rate is 0.06 kg/s under corresponding conditions. The tilt angle of the collector with TIM has less effect compared with the conventional one.

Effect of the concentration ratio on energetic and exergetic performance of concentrating solar collectors with integrated transparent insulation materials

The effect of the concentration ratio on the performance of parabolic trough and central receiver collectors with integrated transparent insulation materials (TIMs) is analyzed in this work. A model based on optical, energy, and exergy analyses is developed to determine thermal and second law efficiencies of concentrated solar collectors as a function of the absorber temperature and concentration ratio. The results are compared with the respective traditional collector configurations without TIM. In general, high concentration ratios are fundamental to maintain high efficiencies. The incorporation of a TIM into concentrated solar collectors leads to higher thermal efficiencies at high operating temperatures even at low concentration ratios. An equivalent second law efficiency to that of the reference collector configuration can be achieved at lower concentration ratios by incorporating a TIM in parabolic trough or a TIM and a glass envelope in central receiver collectors. The idea of using a TIM deserves further exploration as it seems to be a promising alternative that contributes to a more efficient and cost-effective technology.

CFD investigation of a new flat plate collector with additional front side transparent insulation for use in cold regions

In cold environments, flat plate solar collectors are of limited value because high heat losses lead to low efficiency. The integration of polymethyl methacrylate (PMMA) sheet into flat plate collector is presented in this paper. The performance of this collector in cold weather was investigated using a three-dimension simulation model. A simplified experiment was conducted to verify the precision of numerical model and the simulation data can agree very well with practical ones. The effects of the thickness and location for PMMA sheet on the performance of collector efficiency following steady state were analyzed. The transmittance of transparent insulation material is the key parameter to achieve high performance for the collector. The optimum thickness of the transparent insulation material is 1 mm in simulated conditions and the best location of PMMA sheet was achieved. The result shows that the increase of the collector efficiency from the conventional collector is 11.3%, when reduced temperature difference is equal to 0.1 m2 °C/W and the ambient temperature is −20 °C.

Energy performance and economic analysis of a TIM-PCM wall under different climates

The application of an innovative translucent superinsulated latent heat storage wall, combining transparent insulation material and phase change materials (TIM-PCM wall), on the envelope of a typical office under different climates is evaluated. Energy and economic analysis related to this application are presented. The simulation process is carried out using an experimentally validated numerical model. The results show that the incorporation of the TIM-PCM wall, on the south orientation, is more efficient than the use of a double-glazed in all considered climates. The optimum TIM-PCM wall area is evaluated economically through life-cycle cost and payback period analysis. The purpose is to ensure effective performance of the wall in each climate and at the same time to ensure economic viability. The results show that, in polar and subarctic climates, the application of the TIM-PCM wall has a high economic value and the investment appears to be attractive, the payback period being 10.5 years and 7.8 years respectively. In Dras (continental climate), the use of the wall is found economically unfeasible due to low energy prices and high discount rates. At current prices, the TIM-PCM wall investment in Sacramento (Mediterranean climate) and Toronto (Humid continental) does not offer economic benefits.

A transparent insulation façade enhanced with a selective absorber: A cooling energy load and validated building energy performance prediction model

Solar thermal façade concepts for building integration have a relevant contribution in the field of renewable solar energy exploitation. This study is focused on an experimental analysis of a transparent insulation façade (TIF) concept and the options for the prediction of its performance using building energy simulation (BES) modelling. A TIF prototype based on a transparent insulation material (TIM) and a selective absorber is tested and compared with a nonselective type of absorber. An experimental study was conducted involving full-scale climatic chamber and dynamic outdoor tests. The proposed TIF concept with a selective absorber and its solar effective layers provides the same thermal performance as conventional types of thermal insulation. As the TIM integration is potentially limited by overheating phenomena, a maximum cooling energy load obtained by dynamic outdoor conditions provides its real outdoor performance. The results show that a significant difference is measured when compared with the nonselective absorber type. Finally, a detailed comparative investigation of the thermal performance of both TIFs was conducted using the BES method. When applying the low-e functionality of the solar absorber, significant limitations were found specifically concerning the surface radiant heat exchange with the low emissivity surface affecting the air cavity enclosed zone.

Life Cycle Assessment of Solar Façade Concepts Based on Transparent Insulation Materials

Contemporary architecture and construction industry are trying to cope with increasing requirements concerning energy efficiency and environmental impacts. One of the available options is the active utilization of energy gains from the environment, specifically solar energy gains. These gains can be utilized by, for example, solar walls and facades. The solar façade concept has been under development for more than a century. However, it has not achieved widespread use for various reasons. Rather recently the concept was enhanced by the application of transparent insulation materials that have the potential to increase the efficiency of such façades. The presented study evaluates the environmental efficiency of 10 solar façade assemblies in the mild climate of the Czech Republic, Central Europe. The evaluated façade assemblies combine the principles of a solar wall with transparent insulation based on honeycomb and polycarbonate panels. The study applies Life-Cycle Assessment methodology to the calculation of environmental impacts related to the life cycle of the evaluated assemblies. The results indicate that even though there are several limiting factors, façade assemblies with transparent insulation have lower environmental impacts compared to a reference assembly with standard thermal insulation. The highest achieved difference is approx. 84% (in favor of the assembly with transparent insulation) during a modelled 50-year façade assembly service life.

Thermal, energy and life-cycle aspects of a transparent insulation façade: a case study

Research and development in the façade engineering field highlights the need for comprehensive system solutions integrating advanced materials and renewable energy use. Presented study focuses on implementation of Transparent Insulation Materials (TIMs) in a façade concept. The idea is based on sensible use of (renewable) solar energy to reduce the heating demand of buildings. The concept integrates TIMs into a Transparent Insulation Façade (TIF) based on more common “solar wall” or “Trombe wall” systems enhanced with selective absorber (SA) functionalities. The study presents analysis of thermal, solar energy and environmental performance of the concept on a case study basis. Firstly, thermal analysis based on standard calculation is introduced to describe thermal and solar performance of the concepts. Secondly, energy balance calculations are used to compare the concepts with conventional façade systems. Finally, a Life-Cycle Assessment (LCA) evaluating the environmental impacts of the façade concept is introduced. The results show that the proposed concept performs better in both energy consumption and environmental impacts compared to a common facade with external thermal insulation. The TIF has higher heating energy demand than a common façade, however this is offset by up to 178 kWh⋅m−2⋅a−1 solar heat gains. The difference in environmental impacts (up to 80%) is also in favour of the TIF.

Polycarbonate multi-wall panels integrated in multi-layer solar façade concepts

Recent technological advances in transparent insulation materials’ (TIMs) production may have opened ways for new integration of these materials in buildings. This paper presents a study analysing several variants of façades incorporating TIMs on solar façade principles. The analysis is based on ongoing long-term full-scale experiments in Brno, Czech Republic. The paper introduces the test platform which is used for evaluation of specific aspects of integrated polycarbonate TIMs. The paper describes the experiment results, especially long-term thermal response and passive solar gain data. These data are applied for analysis of: influence of various polycarbonate-based TIMs on the real performance of the façades; influence of implementation of different solar absorbers on the performance of the proposed facades; effectivity of application of latent thermal energy storage (based on PCMs) as a part of heat accumulation layer and coupling of TIM with prismatic glass to enhance optical selectivity aspect. Presented results demonstrate for example significant influence of the type of solar absorber on the thermal performance of tested solar facades: the difference is up to 35% to 54%. Also the integration of prismatic glass coupled with simple two-wall polycarbonate panel can reduce solar penetration through components at the level comparable with the most complex six-wall panel.

Experimental study of solar powered ice maker using adsorption pair of activated carbon and methanol

The present study introduces an experimental work for a solar adsorption ice maker system (SAIMS) using working pair of activated carbon (AquaSorb 2000) and methanol. The isotherm and isobar characteristics of the used pair are investigated by using Dubinin-Raduskevich (D-R) equation then, the SAIMS is constructed and tested at real weather conditions of Qena, Egypt. The findings of the pairs reveal that it suitable for the solar adsorption ice making applications with adsorption capacity found to be 0.6935 kg of methanol per kg of activated carbon (AquaSorb 2000). The constructed SAIMS can produce about 0.4 kg of ice per kg of AquaSorb 2000 by using the acrylic sheets in the adsorption bed instead of glass or other bed covers. Also, the experimental results proved that by using the acrylic sheets with a good design of the adsorption bed and due to the enhancement of heat transfer and high adsorbent temperature, the mass of desorbed methanol and produced ice is increased. Therefore, both gross and net COP are improved in comparison with other previous studies with single, double and Transparent Insulation Material (TIM) in the adsorber.

Thermal behavior of a translucent superinsulated latent heat energy storage wall in summertime

This paper investigates the thermal performance of a translucent solar wall providing, concurrently, storage and restitution of heat, super thermal-acoustic insulation and daylighting to the interior environment. The wall is composed of glazing, silica aerogel used as a transparent insulation material (TIM) and glass bricks filled with fatty acid, an eutectic phase change material (PCM). To assess the TIM–PCM wall thermal behavior, experimentations were conducted in-situ in a full-sized test cell located in Sophia Antipolis, southern France. Experimental data shows that the tested wall is more effective in winter and might cause overheating during the summer mainly due to solar gains and un-cycling behavior of PCM which remains in liquid state. To enhance the energy performance of the wall in summertime, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers is developed. Then, the model of the wall is linked to TRNSYS software to assess the thermal performance of the whole building. The numerical model is validated experimentally and a good agreement is shown comparing the simulated values with the measured data for seven consecutive days in summer and winter. The importance of considering the natural convection effect in the liquid PCM is also demonstrated. Moreover, it was shown that shading devices can effectively reduce overheating while natural night ventilation decreases the indoor temperature without affecting the PCM performance since the outdoor temperature is always higher than the phase change temperature. The use of a glass with selective solar reflection properties depending on the season instead of the ordinary glazing is shown also to be very effective way to overcome the overheating problem. Finally, the TIM-PCM wall is tested under different climate conditions and passive solutions are given to ensure thermal comfort in summer season.

Smart Retrofit Solutions of Buildings toward a Low Carbon World

In this short communication, energy-efficient, eco-friendly and low-cost solutions for existing buildings are considered in a holistic manner toward low/zero carbon building concept of near future. Buildings are still responsible for about 40% of total primary energy consumption in the world, hence decisive measures need to be taken promptly due to growing significance of environmental issues driven by fossil fuel based energy use. Smart solutions addressed within the scope of this research aim at analyzing the energy consumption behaviour of a typical building from building envelope to the appliances utilised, then propose key technologies for urgent mitigation of energy use and drastic reduction of greenhouse gas emissions. For the external walls, aerogel and vacuum insulation panel based thermal superinsulation solutions are recommended owing to the superior thermal resistance ability of such materials (λ<0.01 W/mK for current commercial products). For glazed areas, aerogel glazing, vacuum glazing, solar pond glazing, PV glazing, Transparent Insulation Material (TIM) glazing and Phase Change Material (PCM) glazing concepts are introduced. About 60% of total heat losses from building fabric is attributed to window, which proves the significance of energy-efficient solutions on fenestration products. Depending on environmental and regional conditions, solar, wind and biomass oriented hybrid solutions can be considered for clean energy generation. Current payback period of such systems is below five years, which is promising. Especially thermally resistive PV glazing systems integrated with TiO2 nano coating are capable of producing more than 100 W from per m2 28 of cell area with 100% UV light blockage and self-cleaning feature. Polycarbonate based counter flow waste heat recovery systems are ideal for ventilation purposes with an average COP of about 3.5. For general heating and cooling purposes, air or ground source heat pump systems are found to be favourable for temperate and continental climatic conditions, respectively. Average COP of these systems is found to be greater than 3 in most cases, which is attractive. LED lighting systems are highly energy-efficient and cost-effective compared to the alternatives in market.

Performance prediction of a two-bed solar adsorption chiller with adaptive cycle time using a MIL-100(Fe)/water working pair – influence of solar collector configuration

The simulation studies of conventional small-scale adsorption chillers reported so far in literature incorporate a pre-determined user-defined cycle time which remains constant with the increasing number of cycles. This study presents the first attempt of the numerical simulation of a two-bed solar adsorption chiller with “adaptive” cycle time based on the temporal variations of temperatures and pressures existing inside the beds, the evaporator and the condenser. A water-stable metal organic framework (MOF), MIL-100(Fe), has been selected as the adsorbent while water has been chosen as the refrigerant. A flat-plate solar collector with three different glaze configurations, namely single-glazed (S-G), double-glazed (D-G) and single-glazed with transparent insulation material (TIM), has been employed. The performance of the two-bed adsorption chiller has been evaluated in terms of the variations of the specific cooling power (SCP), the coefficient of performance (COP) and the solar coefficient of performance (COPsc) with increasing number of cycles.

Glazing systems with Parallel Slats Transparent Insulation Material (PS-TIM): Evaluation of building energy and daylight performance

Being responsible for a significant proportion of total heat loss in façade dominated buildings, the design and specification of the envelope, particularly the building’s glazing system, is a key factor in determining overall energy consumption. To address this, an innovative double glazed façade system comprising parallel transparent/translucent plastic slats sandwiched between the glass panes to form a Parallel Slat Transparent Insulation Material (PS-TIM) system is proposed as a potential solution. This PS-TIM system reduces heat transfer between the glazing panes whilst maintaining access to solar radiation and daylight.The presence of the PS-TIM structure significantly affects the thermal and optical performance of the window system in which it is employed. This presents a further significant challenge when trying to predict its performance using dynamic building simulation approaches. Using a typical small office as a case study subject to varying climatic conditions, we investigate the thermal and optical behaviour of a range of PS-TIMs with respect to their daylight and energy performance. We find that when compared to a conventional double glazed system, the application of PS-TIMs can result in a more visually comfortable and uniformly lit environment, which might be desired in an office space, and, in the specific case of the small office under test, can result in a reduction in energy consumption of up to 35.8%. Furthermore, having explored the performance of the system in response to varying climatic conditions, we also present some advice as to how architects and engineers might apply PS-TIMs to window systems or glazed façades.

Experimental Analysis of Transparent Insulation Based on Poly-carbonate Multi-Wall Systems: Thermal and Optical Performance

The way for a new ideas and latest developments in research of various innovative materials are becoming the basis for a variety of potential combinations in future building components and facade concepts. Transparent insulation materials (TIMs) could predominantly be used with current concepts that are trying to replace conventional insulating materials in addition. Various polycarbonate multiwall systems are analyzed from thermal and optical point of view. Thermal and solar transmittance are experimentally determined. For the thermal transmittance, an inclined angle dependence is investigated with laboratory methods. On the other hand, the solar transmittance depending on the incident angle is observed, both at spectrophotometric laboratory and in-situ outdoor level. Obtained results demonstrate a relation between both material parameters studied and their real angular modes. Based on presented analysis, multi-wall polycarbonate building components may have a relevance for future facade concepts, especially when specific solar angular dependencies and certain thermal properties need to be considered.