Ambient Temperature Environment Research Articles

SiC and GaN Devices With Cryogenic Cooling

This article presents the cryogenically cooled application for wide bandgap (WBG) semiconductor devices. Characteristics of silicon carbide (SiC) and gallium nitride (GaN) at cryogenic temperatures are illustrated. SiC MOSFETs exhibit increased on-state resistance and slower switching speed at cryogenic temperatures. However, cryogenic cooling provides low ambient temperature environment and thus enables the SiC converter to operate at lower junction temperature to achieve higher efficiency compared to room temperature cooling. A cryogenically cooled MW-level SiC inverter prototype is developed and demonstrated the feasibility of operating high-power SiC converter with cryogenic cooling. GaN HEMTs exhibit more than five times on-state resistance reduction and faster switching speed at cryogenic temperatures which makes GaN HEMTs an excellent candidate for cryogenic power electronics applications. The significantly reduced on-state resistance of GaN devices provides the possibility to operate them at a current level much higher than rated current at cryogenic temperatures. A GaN double pulse test (DPT) circuit is constructed and demonstrated that GaN HEMTs can operate at nearly four times of rated current at cryogenic temperatures. Challenges of utilizing WBG device with cryogenic cooling are discussed and summarized.

Characterization of Nancy Grace Roman Space Telescope slitless spectrometer (grism)

We have published the optical design and early test results of the Roman Space Telescope grism spectrometer in previous SPIE proceedings. We report the follow-on activity of the spectral and radiometric calibrations, including the calibration methods, experiment designs, and test equipment calibration, such as the light source and detectors used in the test. The grism calibration includes the throughput versus wavelength, which is largely determined by the diffraction efficiency of the two diffractive surfaces. It also includes spectral resolution, point spread function, and relative radiometric measurements. The measured results are presented. The comparisons between the test data and the theoretical simulations are also presented. The tests and results presented are from the engineering test unit in ambient room temperature environment. The thermal/vacuum tests are planned to verify the results when the flight unit is ready.

Removal of bisphenol A by adsorption on organically modified clays from Burkina Faso

Four cationic surfactants with various length and number of long alkyl chains such as dodecyltrimethylammonium, tetradecyltrimethyl-ammonium, hexadecyltrimethylammonium and didodecyldimethyl-ammonium were intercalated at different concentrations into two natural clays from Burkina Faso via solid-state reaction. Each organoclay was used to explore bisphenol A (BPA) removal from water. Various factors including adsorbent dose, agitation time, concentration, surfactant loading levels, pH and temperature were evaluated. Further, pseudo-first and pseudo-second kinetics, Langmuir and Freundlich isotherms and thermodynamics of adsorption onto organoclays were investigated. The adsorption mechanism was perfectly described by pseudo-second-order kinetic model and Langmuir isotherm. Spontaneous and exothermic processes were associated with BPA removal. This study showed that both physisorption and chemisorption are involved in BPA adsorption. Adsorption capacities ranging from 88 to 127 mg/g were observed at ambient temperature and acidic environment. The ranking of organoclays sorption capacities depends on the surfactant loading level. The pH effect on the adsorption showed a remarkable decrease in the quantity of BPA removed when pH ≥ 10. The BPA amount adsorbed onto the organoclays was not varying significantly for pH < 10. Organoclays prepared via solid-state surfactant intercalation are as effective adsorbents for BPA removal from water as those prepared in aqueous solution through cation exchange.

Effects of Low Charge and Environmental Conditions on Diesel Generators Operation

In the context of electricity production in remote areas, the use of diesel generators, either alone or in hybridization with renewable energy sources, faces many technical problems. Indeed, the electrical instability that often characterizes the isolated networks, due to the fluctuating character of renewable resources and the high variability in the load profile, leads to the operation of the diesel generator in transient dynamic conditions, at low loads or outside prescribed environmental conditions. Furthermore, the extended operation of the diesel generator at low charge results in the condensation of combustion residues on the engine cylinder walls, which, after a certain time, increases friction, reduces the efficiency and increases fuel consumption. One way to solve this problem and to eliminate these deposits is to operate the engine at a higher speed until the operating temperature is reached. This paper explores the impact of the wind turbine penetration rate for hybrid wind–diesel systems and the effects of cold temperatures, high altitude, and other environmental operation conditions on diesel generators’ performances. We outlines the impacts of low load and environmental conditions such as ambient temperature, humidity, moisture, abrasive dust, cold and corrosive environments on the operation of modern diesel generators. The problem has been approached by examining the existing literature, researching damage cases, analyzing existing data, and assessing industrial experiences.

The Performance Simulation of The New R463A HFC/HFO/Carbon Dioxide Refrigerant with Lower GWP, As an Alternate Option for The R404A Refrigeration System

This study presents the performance simulation of the R463A that has been developed to be retrofitted to replace the R404A. The R463A is primarily composed of hydrofluorocarbons/hydrocarbon/carbon dioxide (HFCs/HCs/CO2). The R463A refrigerant (GWP=1494) is a non azeotropic mixture of R32 (36%), R125 (30%), R134a (14%), R1234yf (14%), and R744 (6%). It is composed of polyol ester oil (POE), and classified as a Class A1 incombustible and non-toxic refrigerant. The R463A has a higher cooling capacity (Qe) than the R404A, as it is composed of hydrofluorocarbons (HFCs) R32 and carbon dioxide (CO2) R744, and also has a lower global warming potential (GWP) than the R404A due to the hydrofluoroolefins (HFOs) by R1234yf. The properties of the R463A and R404A that uses the REFPROP and CYCLE_D-HX software, is in accordance to the CAN/ANSI/AHRI540 standard air-conditioning, heating, and refrigeration institute (AHRI). The normal boiling point of the R463A was found to be higher than the R404A by 23%, with a higher cooling capacity and a lower GWP value by 63% than the R404A. The critical pressure and temperature of the R463A was found to be higher than the R404A, i.e. it can be used in a high ambient temperature environment, and emits a higher refrigerant effect and heat reject with a lower global warming potential (GWP) than the R404A by 52%, due to its hydrofluoroolefins (HFOs) by R1234yf component. The COP of the R463A was found to be higher than the R404A by 10% under low temperature application.

Temperature Compensation Method for Raster Projectors used in 3D Structured Light Scanners.

Raster projectors are commonly used in many various measurement applications where active lighting is required, such as in three-dimensional structured light scanners. The effect of temperature on the raster projector, in some conditions, can lead to significant deterioration of the measurements performed with such a scanner. In this paper, the outcomes of several experiments concerning the effects of temperature on raster projectors are presented. The described research is focused on the thermal deformations of projected images caused by common thermal effects observed in projectors: those caused by the warming-up process and changes in ambient environmental temperature. A software compensation method is also presented. It is suitable for implementation in any existing measurement method that uses raster projectors. The results of performed verification experiments show that the developed compensation method can decrease the thermal drift of the projected images by up to 14 times in the ambient temperature range °C.

Effects of physical and chemical factors on pseudorabies virus activity in vitro

BackgroundPseudorabies (PR) is latent and can persist in infected sows for a long time, and thus, convalescent sows can carry the virus throughout life, causing severe economic losses to farmers and posing a tremendous challenge to PR prevention and control. Here, to investigate the biological characteristics of pseudorabies virus (PRV), a variety of physical and chemical factors were analyzed under controlled conditions.ResultsThe results showed that a high ambient temperature and dry environment led to faster virus inactivation. PRV had a certain resistance to weakly acidic or alkaline environments and was rapidly inactivated in strongly acidic or alkaline environments. The effect of ultraviolet (UV) radiation on PRV activity primarily depended on the frequency, intensity, and irradiation time of the UV exposure. Exposure to sunlight inactivated PRV via multiple factors, including temperature, sunlight intensity, UV intensity, and environmental humidity, and any shielding from sunlight strongly lowered the killing effect. Conventional disinfectants had a good disinfection effect on PRV.ConclusionsThe biological characteristics of different PRV strains are variable. Generally, the activity of PRV is affected by multiple factors, which can show both synergy and antagonism. Real-world conditions should be taken into consideration to guide pork production.

Changes in chemical and microbiological quality of semi-processed black soldier fly (Hermetia illucens L.) larval meal during storage

Edible insects are receiving attention as a protein source in the food and feed sector. However, successful commercialisation requires mass production matched with appropriate processing and storage techniques. The quality of dried and pulverised black soldier fly larvae stored in woven polypropylene (PP) sacks, polyethylene (PE) bags and plastic containers with screw lid (PL) in ambient and refrigerated environments was monitored over six months. Chemical indicators (oxidation, fatty acid profile), microbiological parameters (total viable counts, yeast and moulds,Enterobacteriaceae, presumptive coliforms,Salmonella) and colour change were examined. Temperature and relative humidity of the storage environments were monitored. In the ambient environment (temperature: 23.6±2.7 °C; relative humidity: 57.6±7.0%), chemical deterioration progressed 1.5 and 1.2 times faster in PP and PE, respectively, compared to PL. Refrigeration (temperature: 5.4±1.1 °C; relative humidity: 97±5.7%) exacerbated spoilage in the PP due to permeation of moisture through the woven strands, but slowed chemical deterioration by factors of 3.3 (PL) and 2.8 (PE). Likewise, based on the average counts ofEnterobacteriaceae and yeast and moulds, microbiological deterioration progressed 2.1 and 1.4 times faster in the PP and PE, respectively, while refrigeration retarded build-up of microbial loads by factors of 1.3-9.6. The presence ofSalmonella spp. in the experimental product indicates that due attention must be given to adequacy of processing and handling procedures for dried black soldier fly meal.

Epoxy/graphene film for lifecycle self-sensing and multifunctional applications

Graphene holds promise to provide polymers with multifunctionality such as electrical conductivity. However, pristine graphene is not processable in solvent and graphene oxide even after reduction lacks sufficient electrical conductivity and compatibility with polymers. This work reported an epoxy/graphene nanocomposite film that was synthesized by a facile approach, taking advantage of unique solution-processable graphene platelets (GnPs) that had high structural integrity as reflected by electrical conductivity of 1460 S/cm. A percolation threshold of electrical conductivity was found to be 0.63 vol% for the film. GnPs at 2 vol% improved the thermal conductivity and Young's modulus of epoxy by 117% and 101%, respectively. The film was then investigated as a multifunctional sensor. It can real-time monitor its lifecycle structure health, i.e. the measurement of not only curing parameters but the initiation, localization and evolution of damages spanning from curing to the end of service life. Being sensitive to ambient environmental temperature, the film was investigated as a thermal sensor. Its performance as a strain sensor proved satisfactory through a 20,000-cyclic fatigue test. The film not only self-sensed damage such as cracks but mapped out the corresponding locations. This methodology could lead to the development of cost-effective, high-performance sensors for life-cycle, self-sensing health monitoring for various bonding structures.

Seasonal acclimation of thermal performance in two species of reef-building corals

Thermal performance curves describe the relationship between temperature and the rate of biological processes. These relationships can vary among species and environments, allowing organisms to acclimatize to their local thermal regime. This study quantified the seasonal variation in the thermal performance of several coral and symbiont-dominated physiological traits for the thermally tolerant coral speciesPorites cylindricaand the thermally sensitive coral speciesAcropora valenciennesi. Photosynthesis rates, respiration rates, maximum photosystem II (PSII) quantum yield and electron transport rates were measured in winter and summer on coral fragments exposed to an acute temperature increase and decrease up to 5°C above and below the average seawater temperature in each season. Results showed that colonies ofA. valenciennesiacclimated primarily by shifting their optimal temperature to a higher temperature in summer, whereas colonies ofP. cylindricahad broader thermal breadth during summer. For symbionts within both species, performance was higher at all temperatures in summer, while the thermal optima and performance breadth remained unchanged. Despite these changes in thermal performance, the thermal optima of most traits did not match the ambient environmental temperature, but fell between the summer and winter temperatures. Overall, these results showed that both coral species were physiologically plastic in response to temperature change, but that there are constraints on the rate or capacity for acclimation that prevent a perfect match between the average temperature of the environment and the thermal optimum of the species.

Understanding the soot reduction associated with injection timing variation in a small-bore diesel engine

This study shows the in-cylinder soot reduction mechanism associated with injection timing variation in a small-bore optical diesel engine. For the three selected injection timings, three optical-/laser-based imaging diagnostics were performed to show the development of high-temperature reaction and soot within the cylinder, which include OH* chemiluminescence, planar laser–induced fluorescence of hydroxyl and planar laser–induced incandescence. In addition, detailed soot morphology analysis was conducted using thermophoresis-based soot particle sampling from two locations within the piston bowl, and the subsequent analysis of transmission electron microscope (TEM) images of the sampled soot aggregates was also conducted. The results suggest that when fuel injection timing is varied, ambient gas temperature makes a predominant effect on soot formation and oxidation. This is primarily combustion phasing effect as the advanced fuel injection moved the start of combustion closer to the top dead centre, and therefore, soot formation and oxidation occurred at elevated ambient gas temperature. There was an overall development pattern of in-cylinder soot consistently found for three injection timings of this study. The planar laser–induced incandescence images showed that a few small soot pockets first appear around the jet axis, which promptly grow into large soot regions behind the head of the flame marked planar laser–induced fluorescence of hydroxyl. The soot signals disappear due to significant oxidation induced by surrounding OH radicals. When the injection timing is advanced, the soot formation becomes higher as indicated by higher total laser–induced incandescence coverage, increased sampled particle counts and larger and more stretched soot aggregate structures. However, soot oxidation is also enhanced under this elevated ambient temperature environment. At the most advanced injection timing of this study, the enhanced soot oxidation outperformed the increased soot formation with both peak laser–induced incandescence signal coverage and late-cycle coverage showing lower values than those of more retarded injection timings.

Reduced thermal variability in cities and its impact on honey bee thermal tolerance.

Urbanization is one of the most significant land cover transformations, and while climate alteration is one of its most cited ecological consequences we have very limited knowledge on its effect on species’ thermal responses. We investigated whether changes in environmental thermal variability caused by urbanization influence thermal tolerance in honey bees (Apis mellifera) in a semi-arid city in central Mexico. Ambient environmental temperature and honey bee thermal tolerance were compared in urban and rural sites. Ambient temperature variability decreased with urbanization due to significantly higher nighttime temperatures in urban compared to rural sites and not from differences in maximum daily temperatures. Honey bee thermal tolerance breadth [critical thermal maxima (CTmax)—critical thermal minima (CTmin)] was narrower for urban bees as a result of differences in cold tolerance, with urban individuals having significantly higher CTmin than rural individuals, and CTmax not differing among urban and rural individuals. Honey bee body size was not correlated to thermal tolerance, and body size did not differ between urban and rural individuals. We found that honey bees’ cold tolerance is modified through acclimation. Our results show that differences in thermal variability along small spatial scales such as urban-rural gradients can influence species’ thermal tolerance breadths.

A method to describe the thermal property of pipe-embedded double-skin façade: Equivalent glass window

The pipe-embedded double-skin façade (PDSF) is a superior approach to decrease building cooling and heating load by using natural energy. With pipes embedded in the shading, the overheating problem in the conventional double-skin façade (DSF) can be eliminated. Unlike the traditional DSF or glass windows, the thermal performance of PDSF depends on the ambient environment and water temperature in the embedded pipes. Although the complicated heat transfer process of PDSF can be numerically solved, it is difficult for engineers to obtain the whole picture of the PDSF at first glance. To easily understand the thermal property of the PDSF, the overall heat transfer coefficient (U value), solar heat gain coefficient (SHGC) and equivalent ambient temperature of the PDSF are derived based on the thermal network. The heat transfer characteristic of the PDSF at different cooling water temperatures is compared with that of the conventional DSF. The results show that the three proposed indices can clearly reflect the thermal property of the PDSF: U value and SHGC reflects the influence of insulation and the transparency respectively, and the equivalent temperature reflects the integrated influence of water temperature and outdoor temperature. The typical PDSF has a higher U value than the DSF in the same structure. However, the SHGC of the PDSF is only 60% of that of the DSF. Although the equivalent ambient temperature depends on the outdoor temperature and water temperature, the weighting of the water temperature is 0.8, which indicates that the equivalent ambient temperature for the PDSF can reach a better level with the appropriate water temperature. Moreover, relatively warm water is suggested on sunny days to reduce the solar heat gain, since the solar heat gain is dominant in the total heat gain. Correspondingly, cool water is recommended for cloudy days to decrease the conductive heat gain.

Graphene supported ultrafine tin oxide nanoparticles enable conversion reaction dominated mechanism for sodium-ion batteries

Na-ion batteries are considered as promising alternatives for Li-ion batteries in electrochemical energy-storage. However, the lack of high performance anode materials severely plagues their practical application. In this work, we synthesized the SnO2@graphene (SnO2@G) nanocomposites through one-pot hydrothermal method, in which the ultrafine SnO2 nanoparticles (∼4 nm) evenly distributed on the graphene sheets surface. The synthesized SnO2@G delivered a Na storage capacity of 343 mAh g−1 at 100 mA g−1 after 100 cycles, with excellent capacity retention. Even at a low temperature of −20 °C, SnO2@G still maintains a specific capacity of 97 mAh g−1 after 100 cycles, making it both available for ambient and low temperature environment. The detailed Na-storage mechanism for SnO2@G is revealed. It is found that both conversion and alloying reaction contribute to sodium storage. The dominating contribution from conversion reaction is attributed to the ultrafine nanoparticles, which triggers the activity of conversion reaction of SnO2 with sodium. The study provides new insights for using SnO2 as the anode materials for Na-ion batteries.

Preparation and Photocatalytic Activities of Black TiO₂ in Vacuum and Ambient Temperature Environment.

The preparation conditions are important for the structure and properties of black TiO₂. In this paper, the black rutile TiO₂ with a particle size of approximately 5 nm was prepared in vacuum by the infrared nano-second laser sputtering deposition method. The study results indicated that the prepared black TiO₂ exhibited high light absorption from UV to near-infrared region. The lattice distortion and Ti3+ were responsible for the upward shift in the valance band, and the oxygen vacancy states were determined to be located about 0.7-1.18 eV under the conduction band, narrowing the band gap of TiO₂ from 3.2 eV to 2.1 eV. Although the black TiO₂ exhibited strong adsorption effects within the full spectrum and had a higher free carrier density, the presence of excess oxygen defects resulted in a higher recombination rate of the photo electron-hole pairs, which induced a poor photocatalytic performance of the black TiO₂. This work facilitates the understanding of the mechanisms mechanism of black TiO₂ formation via laser ablation, and emphasized the need for the controllability and quantification of oxygen vacancies.

Assessment of onset and progress in the high ambient environmental temperature influenced on rigor mortis in Tirunelveli district

Assessment of onset and progress in the high ambient environmental temperature influenced on rigor mortis in Tirunelveli district

Kocaeli Tarihi Cami Örnekleri Üzerinden Planlı Koruma Kapsamında Hasarsız Test Uygulamaları: Çoban Mustafa Paşa Camii, Fevziye Camii Ve Pertev Paşa Camii

The conservation of historical buildings via charters, general principles, methods for maintenance and repair of the buildings have been analysed in the international environment. Theories, approaches and conservation methods have been adopted along with the developing technology in relevance with the current conditions. Conservation is a process including consistent, coordinated and programmed activity of study, prevention (limiting situation of risk), maintenance (controlling the conditions of property) and restoration (direct intervention). In this regard, the significance of non-destructive tests on existing historical buildings –in the context of planned conservation- should be highlighted, and become widespread. In Turkey, which is extensively rich in historical building stocks, it is a difficult task to appraise the physical conditions of all historical buildings by non-destructive tests with a limited number of experts. On the contrary, appraisal of present conditions of building stocks and detailed diagnostics phase of the buildings are important in terms of conscious and sustainable conservation. The buildings under the effect of interior and ambient environmental conditions and decays developed on building envelope or structural elements causing from these conditions affect the structure and thermal comfort conditions in a negative way. Continuous monitoring of these actions causing decay and degradations prevent the structure to be under high risk and the necessity of performing heavy interventions on buildings. By the non-destructive test applications during monitoring, the buildings are prevented to be under high risks and the necessity for heavy interventions can be eradicated. In this research, Pertev Pasa Mosque -constructed by Architect Sinan-; Gebze Coban Mustafa Pasa Mosque -constructed in 1523 and known as the work of Architect Sinan but various names asserted as the architect of building according to resources-, and Fevziye Mosque -initially constructed by Architect Sinan in 1576 but then destroyed and re-constructed due to disasters in the past and finally heavily damaged on 17 August 1999 then re-constructed- are analysed. Three mosques are listed by national protection board and they were investigated without any damage to the buildings. All structures whose original construction dates back to 16th century were selected according to three criteria: Pertev Pasa Mosque and Fevziye Mosque are exposed to same climatic conditions due to their close locations to each other; on the other hand Fevziye Mosque display different material and construction system due to the subject of being reconstructed several times. Coban Mustafa Pasa Mosque, conserved well like Pertev Pasa Mosque in terms of material, construction system and architectural properties, is located in a different place with respect to others. The outcome and methods of the project 114K284, Non-Destructive Test Applications, in the Context of Planned Conservation, through Historical Mosques of Kocaeli: Coban Mustafa Pasa Mosque, Fevziye Mosque and Pertev Pasa Mosque”funded by TUBITAK, are presented in this paper. Temperature and relative humidity values of inside and ambient environments are were measured by dataloggers and probes for three mosques. The visual and quantitative data of the buildings were obtained to appraise degradation of building envelope and define micro-climatic conditions of the materials by Infrared Thermography and Ultrasonic Velocity Methods. Condensation risk in the mosques by logging inside and ambient environment temperature and relative humidity level were found high considering praying times. Existing and possible deteriorations and previous interventions were found via infrared thermography captures. Moreover, the voids inside the building envelope and qualitative properties of materials were revealed by tests.

Study on a novel portable urine analyzer based on optical fiber bundles

The portable urine analyzers play more and more important role in communities and families, However, the ambient light intensity and environment temperature may produce a relatively big influence on their test results. In this study, a novel portable urine analyzer with a new optical structure is presented. The optical structure, composed of optical fiber bundles, is raised to effectively reduce the influence of ambient light on test results, and hopeful lower the cost of urine reagent strips. Meanwhile, a temperature sensor is taken to measure the environment temperature in order to calibrate the test results of the analyzer. Additionally, some its components, including a micro-thermal printer, a wireless fidelity module, a secure digital card, are designed to be optional for further enhancing its performance. Consequently, the analyzer, which can detect fourteen-item indexes of urine, has good repeatability and measurement accuracy of more than 97%, and broad prospects for application.

Poikilothermic Animals as a Previously Unrecognized Source of Fecal Indicator Bacteria in a Backwater Ecosystem of a Large River.

Quantitative information regarding the presence of Escherichia coli, intestinal enterococci, and Clostridium perfringens in poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations of E. coli and enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB (E. coli and enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations of C. perfringens were observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources.IMPORTANCE The current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria (SFIB) Escherichia coli, intestinal enterococci, and Clostridium perfringens multiply significantly only in the guts of humans and other homeothermic animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that SFIB can also occur in high concentrations in poikilothermic animals (i.e., animals with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) in an alluvial backwater area in a temperate region, indicating that a reconsideration of this long-standing indicator paradigm is needed. This study suggests that poikilotherms must be considered to be potential primary sources of SFIB in future studies.

Numerical simulation of droplet evaporation characteristics of multi-component acetone-butanol-ethanol and diesel blends under different environments

Effects of ambient temperature, pressure and relative velocity between droplet and airflow on evaporation characteristics of multi-component droplet were investigated numerically. A recently proposed multi-component model was adopted in the present study by considering the pressure effects. The result shows that, present model predicts satisfactory results when compares with experimental data. Increasing ambient temperature especially promotes evaporation of low volatile components in ABE20. Ambient pressure influences ABE-diesel blends droplet evaporation differently under various ambient temperatures. For low ambient temperature environment, droplet evaporation rate decreases with ambient pressure increasing, especially for low diffusion coefficient components. However, evaporation characteristic shows an opposite tend under high ambient temperature environment, where evaporation rate increases with ambient pressure increasing. Additionally, increasing ambient pressure promotes maximum evaporation rate of high diffusion coefficient components. With temperature increasing, this promotion extends to low diffusion coefficient components. Finally, increase relative velocity between liquid and gas phase substantially enhances evaporation of high diffusion coefficient components in the mixture.