Lower Emissivity Value Research Articles

Diesel/ biodiesel /silver thiocyanate nanoparticles/hydrogen peroxide blends as new fuel for enhancement of performance, combustion, and Emission characteristics of a diesel engine

In the present study, sunflower and soybean oil commixture with 50:50 V/V % had been used to produce biodiesel by using a homogeneously catalyzed transesterification. The influence of biodiesel blend, nano blended fuel, and nanoemulsion fuel blends on the combustion, performance, as well as emissions of DI diesel engine, had been examined in the laboratory at various engine loads and a steady speed of 1400 rpm. Volumetric proportions of fuel mixtures: D50B50N000 (50% diesel-50% biodiesel), D50B50N200 (D50B50 + 200 ppm silver thiocyanate AgSCN (SCP1∖), D50B50N200 + 2% hydrogen peroxide (H2O2), and D50B50N200 + 4%H2O2 were arranged to fuelling a one-cylinder engine. The exhaust emissions of the engine were compared at pure diesel fuel and biodiesel blend D50B50N000, which indicated a reduction in CO, UHC, and NOx emissions upon adding a 200-ppm of silver thiocyanate SCP1∖ as a nano additive. This reduction increased upon adding and increasing the volumetric percentage of H2O2 where the D50B50N200 + 4% H2O2 fuel blend has lower emission values. The results show that CO2 emissions for the investigated fuel blends were elevated than diesel fuel. The presence of nanosized AgSCN and H2O2 enhanced the combustion process because of elevated nanoparticle surface/volume ratio and the occurrence of micro-explosion phenomena of the sprayed fuel particles, which increased the in-cylinder pressure and heat release rate (HRR). A noticeable decrease in brake specific fuel consumption (BSFC) was observed owing to the positive effect of using nano biodiesel blend and nanoemulsion fuels. A consequent increment in brake thermal efficiency (BTE) was indicated for nano biodiesel blend and nanoemulsion biodiesel blend fuels, where D50B50N200 + 4%H2O2 has the highest BTE of 27.16% compared to all tested fuels. Exhaust gas temperature (EGT) values were evaluated and analyzed for all tested fuels.

Experimental investigation of burning of pulverized peat in a bidirectional vortex combustor

The paper reports on the results of experimental research of bidirectional vortex combustor operation at different modes. This combustor implements a new idea of burning solid pulverized fuel in a bidirectional swirling flow. The experimental results confirmed the thesis about a wide range of stable operation of the combustor, as well as its environmental friendliness: the values of exhaust emission of CO and NOx are significantly lower than those for the direct-flow combustor. Besides, such combustor can operate in two modes: as an igniter or stabilizer of boiler furnace, where it generates a stable high-enthalpy flame as well as an independent device with low emission values. A summary of research results defines that the most environmentally friendly operating mode is achieved at the net air-fuel equivalence ratio λΣ = 1.3 and the ratio of primary and secondary air mass flow rates n = 2.7.

Combustion and emission characteristics of isoamyl alcohol-gasoline blends in spark ignition engine

Nowadays, the evaluation of waste products has gained importance. The fusel oil, which is obtained as a waste product in sugar factories, has a high proportion of isoamyl alcohol. Alcohols having a high-octane number give lower emission values when used as fuel. In this study, isoamyl alcohol was used at high compression ratio (CR) to improve performance and emissions in a spark ignition (SI) engine. The experiments were performed at full load, different CRs (8.0:1, 8.5:1 and 9.0:1) and different speeds (2600, 2800, 3000 and 3200 rpm) using different fuels A0 (%100 gasoline), A10 (%10 isoamyl alcohol-%90 gasoline), A20 (%20 isoamyl alcohol-%80 gasoline) and A30 (%30 isoamyl alcohol-%70 gasoline). According to the obtained results, exhaust emissions decreased with using of isoamyl alcohol compared the using of gasoline at all CRs. With the use of A30, carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbon (HC) emissions decreased by approximately 12.2%, 35.6% and 6.45%, respectively compared to gasoline. The cylinder gas pressures (CGP) and heat release rates (HRR) were recorded for each CR and fuel blend. Moreover, by increasing the CR, brake thermal efficiency (BTE) increased about 2.67% with A20 compared to gasoline on 9.0:1 CR. Furthermore, torque and effective power also increased by 2.03% and 2.51% with A20, respectively.

Experimental Study of the Summation of Flicker Caused by Wind Turbines

Integration of wind energy into the grid faces a great challenge regarding power quality. The International Electrotechnical Commission (IEC) 61400-21 standard defines the electrical characteristics that need to be assessed in a Wind Turbine (WT), as well as the procedure to measure the disturbances produced by the WT. One of the parameters to be assessed are voltage fluctuations or flicker. To estimate the flicker emission of a Wind Power Plant (WPP), the standard establishes that a quadratic exponent should be used in the summation of the flicker emission of each WT. This exponent was selected based on studies carried out in WPPs with type I and II WTs. Advances in wind turbine technology have reduced their flicker emission, mainly thanks to the implementation of power electronics for the partial or total management of the power injected into the grid. This work is based on measurements from a WPP with 16 type III WTs. The flicker emission of a single WT and of the WPP were calculated. Low flicker emission values at the Point of Common Coupling (PCC) of the WPP were obtained. The flicker estimation at the PCC, based on the measurement from a single WT, was analyzed using different exponents. The results show that a cubic summation performs better than the quadratic one in the estimation of the flicker emission of a WPP with type III WTs.

Condition monitoring system for solar power plants with radiometric and thermographic sensors embedded in unmanned aerial vehicles

The photovoltaic solar energy industry is expanding, and there is therefore a need to increase and improve its maintainability, operating costs, availability, reliability, safety, life cycle, etc. The aim of this article is to design, develop and check a new condition monitoring system to detect dust in solar photovoltaic panels. The condition monitoring system uses a radiometric sensor connected to an Arduino platform. This novel approach is based on emissivity analysis produced over a surface and characterized with a low emissivity value when dust appears. A thermographic camera is also employed to validate the results provided by the radiometric sensor. The system is designed to be embedded in an unmanned aerial vehicle. Radiometric data is sent and analysed, Internet of Things is employed, and thermograms are stored for further processing. Several scenarios with a real solar panel are used in the experiments, in which the angles and distances of the sensors and surface conditions are studied. An analysis of the radiometric sensor provides accuracy results, and the presence of dust is identified in all scenarios.

Differences and Relationship Between Rhizosphere Characteristics and Methane Emissions of Double-cropping Rice Variety

Six field varieties of early rice and late rice were selected as test materials for field experiments to explore the difference in CH4 emissions among different rice varieties, and Static Obscura-Gas Chromatography was used to determine the CH4 gas. The results demonstrated a significant difference in the CH4 emissions flux between early and late rice varieties. The average yield of total fertility CH4 emissions was highest in Xiangzaoxian 24 and lowest in Zhuliangyou 819, with a difference of 34.6%. Of the late rice varieties, Tyou 15 was the highest and the Ziyou 299 was the lowest, with a difference of 33.9%. Differences in CH4 emissions and the greenhouse effect of unit yields between different double cropping rice varieties differed significantly. The cumulative CH4 emissions from early rice varieties ranged from 198.3-303.44 kg·hm-2, and the lowest emissions were from Zhuliangyou 819. The greenhouse effect per yield ranged from 0.67 to 1.40 kg·kg-1, and Luliangyou 996 had the lowest emission value. The late-season rice varieties exhibited significantly higher cumulative CH4 emissions compared to early rice, ranging from 291.93 to 388.28 kg·hm-2, and Ziyou 299 had the lowest emission value. The greenhouse effect of per yields rice varieties, while the late rice varieties were contrary to early rice. Reducing carbon and nitrogen concentrations in the rhizosphere and increasing Eh values could reduce CH4 emissions.

Waste to Energy: Response Surface Methodology for Optimization of Biodiesel Production from Leather Fleshing Waste

Background. The demand for diesel fuel is constantly increasing, requiring its alternate that could be sustainable, technically feasible, price competitive, and ecologically acceptable. Biodiesel is one of ecologically acceptable substitute for the conventional fuels. Methods. Sufficient lime fleshing waste was collected from Addis Ababa tannery share company. The limed fleshing waste in the wet condition was delimed using boric acid, dried, chopped, and subjected to Soxhlet extraction using petroleum ether solvent. The oil was treated by orthophosphoric acid and distilled water to remove gums. The pretreated oil was subjected to homogeneous base catalyzed transesterification. Response surface was used to optimize the process variables. GC-MS was used to see composition of the biodiesel produced. Result. The oil yield of the goat, hide, and sheep delimed fleshing wastes were 23.08%, 12.05%, and 26.7%, respectively. The conversion to biodiesel by KOH-catalyzed transesterification was achieved above 96% under optimum conditions: a methanol-to-oil molar ratio of 6:1, catalyst amount of 1 % w/w, and reaction temperature of 60°C for an hour reaction time. Conclusion. It was proven that fleshing wastes from tanneries whose storage and disposal are both troublesome and costly could be transformed to a fuel with low emission values and a performance close to diesel fuel.

Precious walls built in indoor environments inspected numerically and experimentally within long-wave infrared (LWIR) and radio regions

A thermographic non-destructive inspection conducted during the winter season on precious walls confined to an indoor environment (Baiocco room, L’Aquila, Italy) is illustrated herein. The use of a heat conveyor ad hoc selected has produced a particular benefit in terms of defect detection after the application of advanced algorithms because the thermal stimulus coming from an air heater hit the finishing layer under a laminar flow regime. Thermocouples registered both the heat-up and cool-down phases to confirm the numerical simulations conducted via Comsol Multiphysics® software. The results obtained by applying the principal component thermography (PCT) technique to raw data registered in the time domain were a priori studied through thermographic simulations. Defects were modelled on the basis of results already shown in a previous work centred on the Baiocco room, too. A comparison between the results obtained from PCT and the innovative sparse principal component thermography (SPCT) technique was also added to the discussion. The SPCT results show their benefits above all when they are supplemented with ground-penetrating radar results. The experimental analyses were conducted on a multi-layer wall called thereafter rectangular portal, in which the instant thermal conductance was experimentally measured. Subsurface cracks were detected using a long heating-up phase. This procedure is preferred by the Monuments and Fine Arts Department with respect to the use of flash lamps. Indeed, short energy pulses should be avoided on finishing layers having low emissivity values because producing spurious reflections affecting the thermographic results. A discussion on this point is also provided. On the basis of the data analysis, it is possible to say that the thermal waves should arrive at the interface between the masonry and its top layer in order to obtain a clear thermal map of the defects present at different depths. As shown, this goal can be realized through a smart solution based on: (a) the inverse knowledge of the aedicula via thermal analyses, (b) the best mesh to be selected for the numerical model, and (c) the optimal type of thermal stress to be delivered to the object under inspection.

A comparison of the effectiveness of voltage stability indices in an optimal power flow

Voltage stability is very important, as without it voltage collapse will occur. There is therefore a need to incorporate the consideration of voltage stability into the optimal power flow (OPF). This paper presents a comparison of the effectiveness of five voltage stability indices (VSIs) when incorporated in an OPF. The improved particle swarm optimization (IPSO) algorithm is used to solve the OPF problem. The five VSIs investigated are the L‐index, fast voltage stability index (FVSI), line stability index (Lmn), online voltage stability index (LVSI), and voltage collapse proximity indicator (VCPI). The effectiveness of each VSI is considered in the terms of the generation cost, emission, transmission loss, and voltage stability. The IEEE standard 14‐, 30‐, 57‐, and 118‐bus test systems are used for the comparison. It is found that considering each voltage stability index as part of the objective function for the OPF provided different values of generation cost, emission, transmission loss, and maximum loadability. The results suggest that FVSI and Lmn provide the minimum generation cost values for all test systems, while VCPI and LVSI provide lower emission values for most systems. VCPI gives the lowest transmission losses for all systems, and the L‐index provides the maximum loadability for most systems. Incorporation of these indices into the OPF can provide the optimal values in different terms, and the most suitable voltage stability index will depend on the situation and size of the system, which needs to be judiciously chosen. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Low infrared emissivity of the Cr39Ni7C/inorganic silicate coatings with excellent heat-resistant

Low infrared emissivity coatings with good heat-resistant property are prepared by using Cr39Ni7C powders and inorganic silicate as filler and binder, respectively. The effects of ball-milling time and heating temperatures on both the microstructure and crystallinity of Cr39Ni7C powders as well as the infrared emissivity of the coatings are detailedly explored. The results show that large spherical Cr39Ni7C particles change into smaller flakey particles gradually with ball-milling time extending to 70 h. Meanwhile, crystallinity of Cr39Ni7C powders enhances with temperature increasing from 300 °C to 700 °C. Contributed by the small flakey particles and enhanced crystallinity, the Cr39Ni7C coating could possess low emissivity value of 0.59 at room temperature, and it further reduces to 0.55 with the temperature rising up to 600 °C. Additionally, good thermal stability is obtained due to the SiOSi space network structure and the SiOM bonding between the coatings and substrates.

Combined experimental and computational approach for defect detection in precious walls built in indoor environments

In thermographic non-destructive evaluation (TNDE), the optimal thermal stimulus to be provided on precious coatings applied on ancient walls confined in indoor environments is a complex problem to solve particularly when low temperatures characterize the room where they were built. In fact, thermal stresses are always the concern of any restorer who is interested in determining both the positions and sizes of superficial and sub-superficial defects. In scientific literature, the use of lamps appears to be dominant, but when large surfaces must be inspected in situ, many problems could arise, such as environmental reflections, emissivity variations, and non-uniform heating, which cause false alarms in defect detections.In this study, the heating phase was carried out by using a wooden tunnel and an air heater. The main physical and geometrical characteristics of these two objects were optimized in order to stimulate the external coating (called “finishing layer” in this study) as homogeneously as possible. In fact, taking into account the very low temperature of the room which contains the inspected aedicule, the energy deposition (heating phase) is enhanced and the energy dispersion (cooling phase) is reduced (thanks to the tunnel) at the same time. This improves the heat transfer phenomenon along the z axis (i.e., the thickness of the wall).The detection of the defects was performed via higher-order statistics thermography (HOST) technique, which processes the thermal images resulting from the heating and cooling phases. Bearing in mind the low emissivity value of the canary grass (i.e., the finishing layer), the use of heating sources in front of it must be minimized; otherwise, spurious reflections can be recorded and then processed.In particular, a computational fluid dynamics (CFD) approach implemented via Comsol Multiphysics® computer program was used to validate the experimental setup. This was applied to a couple of cases in the Baiocco's room subjected to restrictions of the Superintendence for Historical, Architectural, and Environmental Heritage of the Abruzzo region (Italy) owing to its high artistic importance.The exact position of each defect was modelled after a combined visual-acoustical-thermal inspection. An expert restorer helped us in this task. This study is important because, to the best of our knowledge, the problem discussed above has not been solved yet by the scientific community involved in the field of cultural heritage. The results are first thoroughly discussed and second experimentally validated using a combination between thermocouples and ground penetrating radar (GPR) technique, while advantages and disadvantages of the proposed method are highlighted in view of a future perspective of the present work.

Spatio‐Temporal Differentiation of Life Cycle Assessment Results for Average Perennial Crop Farm: A Case Study of Peruvian Cocoa Progression and Deforestation Issues

SummaryThe application of spatially and temporally explicit information to increase result precision is gaining momentum in Life Cycle Assessment (LCA) studies. It is vital for the assessment of environmental impact of perennial crops with non‐productive years, grown in combination with shade crops. Available studies rely on differentiated life cycle inventory data for the inputs in LCA or application of adapted impact assessment methodologies. This study uses the identification of greenhouse gas emissions (GHG) hotspots (statistically significant clusters of farms with either high or low GHG emission values) estimated from average LCA results and assesses a relative deforestation risk in such hotspots. A total of 1892 farms in the Tocache province of San Martin region of Peru were evaluated between the year 2008 and 2010. Combination of average LCA results with farm size, age and deforestation progression allowed for the identification of areas and farms with a high relative risk of environmental impacts and potential deforestation. It was estimated that farms belonging to high‐GHG emission hotspots were twice more likely to expand their agricultural frontier and cause deforestation than farms in low‐GHG emission hotspots. Combining LCA with geo‐information systems and geostatistics is a viable path to explore the differentiation of assessment results, which might lead to faster, more accurate, and resource‐efficient ways to tackle environmental impacts while also accounting for important environmental impacts such as deforestation. Further research on the application of suggested approaches with other perennial crops and other geographical areas is needed.

Anti-icing of road surfaces using Hydronic Heating Pavement with low temperature

A traditional method to mitigate slippery conditions on a road surface is to spread out sand and salt. This method results in corrosion of the road infrastructures and damage to surrounding vegetation. A renewable alternative method for anti-icing the road surface is to use a Hydronic Heating Pavement (HHP). The HHP consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipe. The energy is harvested in summer and saved in seasonal thermal energy storages. The harvested energy, as the only source of energy, is released in winter for snow/ice melting. The aim of this study is to investigate the anti-icing performance of the HHP system during cold periods. A two-dimensional numerical model was developed to investigate how different design options, such as distance between the pipes, affect the efficiency of the HHP systems. The annual required energy for anti-icing and remaining hours of the slippery conditions on the road surface were numerically calculated using a finite element model. The numerical model was validated for two cases: (i) for a road without pipes using a one year measured data of an existing road and (ii) for a road with embedded pipes using an analytical solution. The validation results for a road without pipes showed that the mean annual temperature difference of the road surface is 0.28°C with standard deviation of 3.53°C between the measured data and numerical calculation. The validation results for the road with embedded pipes showed that the maximum relative error associated with the thermal resistance between the pipes and surface is less than 1% between the numerical model and the analytical solution. In order to investigate the anti-icing performance of the HHP system, the climate data from Östersund, an area in middle of Sweden, were selected. The results revealed that the anti-icing performance of the HHP system improves when the pipes are placed closer, the depth of embedded pipes is reduced, large pipe sizes are used and when the road surface has a lower emissivity value. Among all options, the distance between pipes has the most significant effect on improving the anti-icing performance, so changing the pipe distances from 400mm to 50mm results in approximately four times shorter hours of the slippery conditions on the road surface.

Methane, Black Carbon, and Ethane Emissions from Natural Gas Flares in the Bakken Shale, North Dakota.

Incomplete combustion during flaring can lead to production of black carbon (BC) and loss of methane and other pollutants to the atmosphere, impacting climate and air quality. However, few studies have measured flare efficiency in a real-world setting. We use airborne data of plume samples from 37 unique flares in the Bakken region of North Dakota in May 2014 to calculate emission factors for BC, methane, ethane, and combustion efficiency for methane and ethane. We find no clear relationship between emission factors and aircraft-level wind speed or between methane and BC emission factors. Observed median combustion efficiencies for methane and ethane are close to expected values for typical flares according to the US EPA (98%). However, we find that the efficiency distribution is skewed, exhibiting log-normal behavior. This suggests incomplete combustion from flares contributes almost 1/5 of the total field emissions of methane and ethane measured in the Bakken shale, more than double the expected value if 98% efficiency was representative. BC emission factors also have a skewed distribution, but we find lower emission values than previous studies. The direct observation for the first time of a heavy-tail emissions distribution from flares suggests the need to consider skewed distributions when assessing flare impacts globally.

Numerical Investigation of a Corrugated Heat Source Cavity: A Full Convection-Conduction-Radiation Coupling

In present study a numerical analysis of complex heat transfer (turbulent natural convection, conduction and surface thermal radiation) in a rectangular enclosure with a heat source has been carried out. The finite volume method based on SIMPLEC algorithm has been utilized. The effects of Rayleigh number in a range from 10⁸ to 10¹¹, internal surface emissivity 0≤ε˂1 on the fluid flow and heat transfer have been extensively explored. Detailed results including temperature fields, flow profiles, and average Nusselt numbers have been presented. In this investigation it has been tried to study the shape of heat source influence on heat transfer and fluid field in the considered domain. According to results in low emissivity values usage of circular obstacles is recommended. Although in high emissivity values using rectangular obstacles lead to more efficiency.

Thermal Vacuum Evaluation of Simulated Spacecraft Radiators with Discretized Emissivity Surface Properties

Incorporating variable emissivity electrochromic devices onto spacecraft radiators offers a unique potential for modulating passive heat rejection, but implementation challenges exist. Although high-/low-end states of these devices are readily achievable, uncertainties remain with reproducibility at intermediate states and also with stability in a thermal vacuum environment. An average intermediate heat rejection rate can be obtained by discretizing the radiator surface into mixed high- and low-emissivity values. We emulated this capability by constructing test articles with two fixed-emissivity states divided into four sections. Coupons were constructed from aluminum 6061 and stainless steel 304 to characterize performance variations resulting from differences in thermal conductivity. Tests were devised to maintain either a constant surface temperature or constant heat flux. The results showed that this approach provided a predictable area-averaged intermediate emissivity regardless of the material’s thermal conductivity or the heat rejection scheme used. When operating in a constant flux mode, however, the stainless steel coupon experienced larger lateral temperature gradients across the surface due to its lower thermal conductivity. Performance of a variable emissivity radiator must, therefore, take into account not only surface properties, but also consider the desired system heat rejection control scheme and localized thermal gradient tolerance.

Thermal performance of solar cooker with special cover glass of low-e antimony doped indium oxide (IAO) coating

Indium, cadmium and tin based transparent conducting oxide (TCO) films have low thermal emissivity values and these are suitable for energy efficient applications where controlling of thermal effect is an important factor. Among these films antimony doped indium oxide (IAO) coated glass has been explored to have resistivity ∼2×10−2Ωcm. The film is homogeneous and good adherence to glass even in large dimensions [500mm×500mm]. This film possesses emissivity ∼0.63 and it has been taken as the standard for the calculation of solar factor (gi) and absorbed solar energy reradiated and convected indoors (Ei) of transparent conducting oxide (TCO) films of 32 types. As calculated, the gi and Ei values of a TCO films are in the ranges 0.77–0.02 and 2.9–59Wm−2 respectively. Attempt has been made to use the IAO coated glass to improve glazing system in solar cooker with the principle that lowering of gi and Ei values would correspond to significant increase of heat insulation property. The thermal performance of solar cooker box having a cover of single layer low-e IAO coated glass was compared with the solar cooker box having a cover of uncoated double glaze soda lime silicate (SLS) glass initially and finally with the same solar cooker box with evacuated glazed cover maintaining vacuum (10−3atm) in the glazing system. Thermal performance of the solar cookers at ambient condition differs due to the variation of heat flow through glass cover with different glazing systems. The performance was promising for the solar cooker box with the cover of single glazed low-e IAO coated glass. The added advantages for domestic usage are low cost of production, relatively light weight and high mechanical durability along with relatively high thermal output.

Ice detection using thermal infrared radiometry on wind turbine blades

Abstract Wind farms are located in areas with a high probability of ice occurrence. Icing involves problems such as energy losses, mechanical failures and downtimes. The priority is to detect icing in order to avoid these problems. Icing detection is a complex procedure for example, low temperatures are not a guaranty of ice formation, and other variables may affect. Different techniques have been recently proposed to detect ice in wind turbine blades. They are mainly based on damping of ultrasonic waves on the blade surface, or measuring the resonant frequency of a probe. But these methods have some drawbacks that may cause the system to fail, e.g. the behaviour of ultrasonic waves in composite materials is difficult to predict due to different fibre orientations, and the ice detection by changes in the resonance frequency could lead to false alarms due to variations in working conditions. This paper takes advantage of the remote sensing techniques to propose a novel approach for icing detection without physical contact. The approach is based on the drastic emissivity change that it is produced over a surface characterized with a low emissivity value when ice appears. An experiment was conducted using a broad-band thermal radiometer and a section of a wind turbine blade. Radiometric temperature measurements were collected over the blade with and without an aluminium foil patch. The piece of blade was cooled down and different scenarios were considered, including frozen with and without ice. This study was completed with a sensitivity analysis of the approach to dust accumulation, accounting for real operation conditions. Results show the feasibility of this technique to detect ice formation and discern between frozen and icing conditions.

The spatial variability of methane emission from subtaiga and forest–steppe grass–moss fens of Western Siberia

Methane emission from the grass–moss fens of the Western Siberia subtaiga was studied using a static chamber method. It was established that CH4 flux median ± half of the interquartile range in the studied wetland ecosystems constituted 4.9 ± 2.9 mg of CH4/(m2 h). It was shown that such a high spatial variability of emission is caused mainly by the difference in the water table level. It was found that, in these observations, a higher water table level correlates with lower emission values. The causes of this phenomenon are discussed, and recommendations for conducting field studies for estimating the regional flux are given.

Multi-functional TiO2/Si/Ag(Cr)/TiNx coatings for low-emissivity and hydrophilic applications

Multi-functional (coatings with some additional functional properties such as high transparency, antireflection, hydrophilicity and antifogging) coatings are indispensable for the modern energy saving systems. In this regard, we deposited TiO2/Si/Ag(Cr)/TiNx multilayer thin films on soda-lime glass by using RF and DC magnetron sputtering to achieve a multi-functional thin film stack with the combination low-emissivity (low-e) and hydrophilicity properties in addition to the high transparency. Primary deposition of Ag(Cr)/TiNx was tried for the low-e effect and successfully obtained a very low emissivity value of 0.067, and then Si and TiO2 films with different bandgap were subsequently deposited to provide the hydrophilic properties. X-ray diffraction results revealed the anatase phase formation of TiO2 after annealing the films at 673K by using the rapid thermal annealing system. Rutherford Backscattering Spectrometry (RBS) was carried out to determine the chemical composition and elemental depth distribution. The multilayer stack exhibited superhydrophilicity with a water contact angle of about 5° after irradiation by UV light. A Heterojunction film with wide and narrow bandgap semiconductor materials was effective to improve the hydrophilicity. The films exhibited a high visible transmittance (∼85.5%, at 550nm) and low infrared transmittance (7%, at 2000nm) including low-e and superhydrophilicity.