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Performance Evaluation of a Nanomaterial-Based Thermoelectric Generator with Tapered Legs
Get PDFA thermoelectric generator (TEG) converts thermal energy to electricity using thermoelectric effects. The amount of electrical energy produced is dependent on the thermoelectric material properties. Researchers have applied nanomaterials to TEG systems to further improve the device’s efficiency. Furthermore, the geometry of the thermoelectric legs has been varied from rectangular to trapezoidal and even X-cross sections to improve TEG’s performance further. However, up to date, a nanomaterial TEG that uses tapered thermoelectric legs has not been developed before. The most efficient nanomaterial TEGs still make use of the conventional rectangular leg geometry. Hence, for the first time since the conception of nanostructured thermoelectrics, we introduce a trapezoidal shape configuration in the device design. The leg geometries were simulated using ANSYS software and the results were post-processed in the MATLAB environment. The results show that the power density of the nanoparticle X-leg TEG was 10 times greater than that of the traditional bulk material semiconductor X-leg TEG. In addition, the optimum leg geometry configuration in a nanomaterial-based TEG is dependent on the operating solar radiation intensity
Comparison of the Critical Mass Flow Rates for Two Serpentine Designs of the Photovoltaic Solar Thermal Collector
Get PDFA recent analysis on the photovoltaic (PV) cell efficiency for the photovoltaic solar thermal collector (PVT), cooled by forced fluid flow, revealed that there is, in general, a critical mass flow rate that corresponds to the maximum PV cell efficiency for a PVT. The derived new equations are applicable for laminar and transition or turbulent flow regimes and could yield directly the critical mass flow rate as compared with existing methods that use repeated computational trials. To demonstrate further the generality of the method, this paper reports results on comparing the critical mass flow rates for two serpentine designs with different technical details, namely Design A and Design B, using the new equations. It is shown that Design A and Design B have critical mass flow rates of 0.041 and 0.014 kg/s, respectively. The corresponding Reynolds numbers are 4078 and 2785 for Design A and Design B, respectively. It is shown that the critical mass flow rate is different from one design to another. The importance of the critical mass flow rate is summarized
The Effects of the Solvent Choice of the Continuous Phase on the Poly(Urea-Urethane) Microcapsules Properties
Get PDFXylitol, a natural crystalline polyol, presents a cooling effect due to its negative heat of solution at 35 °C supported by humidity absorption, contributing to a fresh sensation when it dissolves. Since this material is sometimes in a liquid state, it cannot be incorporated in or onto a substrate without being protected. One of the strategies to protect the active substance may be forming a barrier layer at its surface, i.e., microencapsulation. The present work is devoted to studying the effect of continuous phase parameters affecting on encapsulation of xylitol with a poly (urea-urethane) shell through a two-step microencapsulation process. The first step is liquid-liquid dispersion either in toluene or Miglyol 812N, and the second step is microencapsulation by interfacial polymerization. The process can be used to control the size distribution of the microparticles, the thickness, and the chemical nature of the shell, which influences the release rate of the active substance. The choice of the continuous phase solvent (toluene or Miglyol 812N) required some changes in the formulation of the system, especially the HLB of the surfactant mixture, to obtain a stable emulsion with a narrow particle size distribution. The thermo-chemical and morphological characteristics of microparticles were studied by Fourier transform-infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), enthalpy of dilution, and scanning electron microscope (SEM). The microparticle size is governed by the emulsion step and the chemical composition of the organic phase. Most of the thermal properties are related to their porous structure and their chemical shell formation during the interfacial polymerization step
The Enrichment Conditions and Resource Potential of Marine-Continental Transitional Coal-Measure Shale Gas: A Case Study of the Permo-Carboniferous Systerm in the Huanghebei Coalfield of North China
Get PDF Coal-measure shale gas is considered to be an important unconventional oil and gas resource in coal measures. At the present time, coal-measure shale gas has not been well studied. However, in recent years, such potential resources have received increasing attention. In this research investigation, the coal measures of the Permo-Carboniferous Period in North China’s Huanghebei Coalfield were taken as the research object in order to evaluate the enrichment conditions and resource potential of the coal-measure shale gas. The results were as follows: 1) A variety of sedimentary environments were developed during the Late Paleozoic Era in the Huanghebei Coalfield region. Lagoon sediment had mainly developed in the Taiyuan Formation, which was conducive to the high-intensity development of shale. In addition, interdistributary bay-floodplain sediment had developed in the Shanxi Formation, which was also favorable to the development of shale; 2) The average value of the total organic carbon (TOC) in the shale of the Taiyuan and Shanxi Formations in the study area was found to be more than 2%. The main type of organic matter was Type II kerogen, followed by Type III kerogen. Furthermore, the thermal evolution degree of the organic matter was considered to be in the mature stage, which indicated a good hydrocarbon generation potential; 3) The gas bearing intervals of the shale in the Taiyuan and Shanxi Formations in the study area were mainly variegated shale, mudstone, carbonaceous shale, and silty mudstone (shale), which belong to the categories of ultra-low permeability and low porosity reservoirs; 4) The average gas content of mud shale in the Taiyuan and Shanxi Formations ranges between 0.645 and 3.34 m3/t. The shale tends to have large burial depths and well-developed caprock, which is conducive to the preservation of shale gas; 5) This study’s comprehensive analysis results showed that the mud shale in the Taiyuan and Shanxi Formations have good hydrocarbon generation potential. A favorable area was delineated in the middle of the Huanghebei Coalfield, and a NE-trending belt distribution was evident along the Pandian-Qihe-Biaobaisi. In summary, the three delineated perspective areas were determined to be the Dulangkou-Zhaoguan prospect area; Yuchengnan prospect area; and Sangzidian prospect area, respectively
A Review of Micellar Enhanced Ultrafiltration Technique in the Removal of Heavy Metals from Aqueous Solutions
Get PDFThe pollution of the aquatic ecosystems with heavy metal ions has become a global problem in recent years. Heavy metals normally occur in nature and are essential to life at trace levels. However, they can be toxic when their concentrations exceed the upper permissible limits. Heavy metal contaminated habitats have the ability to bioaccumulate in aquatic ecosystems, which, in turn, may enter into the food chain and lead to health problems. Therefore, it is necessary to remove these heavy metals from aquatic ecosystems. Several technologies are already in operation, but these conventional technologies involve high operational costs and may produce harmful impacts on aquatic ecosystems. Micellar enhanced ultrafiltration (MEUF) is an alternative technique to remove the trace concentrations of heavy metals from aquatic ecosystems. The uniqueness of MEUF is that it requires less energy due to low membrane cost and working pressure. Although various researchers have been carried out the MEUF study on the removal of heavy metal ions, few review papers indicate the factors on MEUF technique. That is the reason why this article focuses on reviewing of different parameters such as membranes, surfactants, operating conditions in the MEUF technique. In this technique, heavy metal ions’ removal even at lower concentrations has reached over 99%, which is evidently demonstrated in the presented review. The use of water-soluble ligands in combination with MEUF is a hybrid process to remove selectively and enhance the recovery of heavy metals. As understood in this study, an investigation is needed to treat highly concentrated solutions and real wastewater
Potential Surrogates for Evaluation of Decontamination Methods Under Field Study Conditions or BSL-2 Biosecurity Lab Conditions: A Review
Get PDF Surrogate species are commonly used to evaluate the ability of decontamination, sterilization, and/or disinfectant methods to sanitize bio-contaminated surfaces, equipment, facilities, soil, or water. As new decontamination technologies become commercialized there is an ongoing need to evaluate them using field studies, or on-site for large, stationary systems, to determine if they are more environmentally friendly, less expensive, or more effective than the current sanitation practices. This surrogate review compares potential surrogate species such as MS2 bacteriophage, Clostridium difficile, Bacillus subtilis, and Cytisus scoparius for their ability to accurately estimate the efficacy of decontamination, sterilization methods or commercial systems when evaluated under field conditions. Evaluation of decontamination systems, using field or on-site studies conducted under real-world conditions provides realistic estimates of sanitation and insights into potential risks to health or the environment. Multi-stage decontamination systems, or semi-sterilization methods, such as concentrated, or high-level, disinfectants, pressure washing equipment with steam, or extended ultra-violet (UV-C) radiation, require hard-to-kill surrogates, such as B. subtilis, to determine effective treatments. Use of multiple surrogates for decontamination or sterilization research alleviates several concerns about selecting a single surrogate species that may only perform well only under specific treatments or environmental conditions
Design and Analysis of a Flat Plate Solar Powered Ejector Refrigeration System
No full text The Ejector refrigeration system can operate using renewable energy such as solar or wasted heat. A mathematical model for an ejector refrigeration system powered by solar energy was developed. The Ejector refrigeration system depends on many factors, such as ejector geometry, NXP, and operating conditions. A flat plate solar collector is designed to predict the heat transfer performance for the whole system, and the primary factors affecting the heat transfer performance. Outlet temperature of 134.95 °C was achieved from the setup of five solar collectors (two square meters each) when the solar irradiance was 985.69 W/m2. The water needs total power of 5016 W to reach this temperature
Application of Arduino-Based Systems as Monitoring Tools in Indoor Comfort Studies: A Bibliometric Analysis
Get PDF Studies that require environmental measurements often struggle with the cost of monitoring equipment. Costs will increase as more variables are required. Thus, scientists have been increasingly relying on Arduino systems to overcome such a challenge. This paper aims to review the literature on the use of Arduino as a viable measurement tool in indoor comfort research. For this purpose, the results from three databases were compared: Web of Science, Scopus and ScienceDirect. Results from the Scopus search were then analyzed using VOSViewer according to three questions: (1) what is the state of the art and trends using Arduino; (2) how is Arduino being used in indoor environments; and (3) which are the main authors using the system and what are the most cited Arduino-related sources. The maps showed that the system is very versatile and offers the opportunity to strengthen multidisciplinary approaches
The Effect of Well Completion Fluid Loss on Productivity Evaluation in Tight Sand Gas Reservoir: A Case Study from East China Sea Gas Well
Get PDF Fluid loss is inevitable in the well drilling and completion, which may cause series of formation damage such as clay swelling, solid plugging and water blocking. In tight sand gas reservoir, water blocking has become the major damage factor for economical developing. In deliverability test, water blocking will bring an inaccurate productivity test result to affect the following development strategy. With the development of East China Sea gas field, well drilling is focusing on the deeper tight sand formation. The tiny pore throat and high capillary pressure can bring out serious water blocking damage during well drilling and completion. The damaged zone can mislead the resource assessment and productivity evaluation. In this paper, an exploration well X in East China Sea gas field is selected as the research target to investigate the water blocking mechanism and physical process during well drilling and completion process. This study compares the productivity performance of X well with fluid loss and no fluid loss models through numerical modeling approach based on the actual data. Sensitive studies are also performed in the simulation. Results show that the excessive fluid invasion pressure and lower matrix permeability will result in serious water blocking damage to mislead the resource assessment and productivity evaluation even in underbalanced well drilling. Interestingly, extending shut-in time can make the gas production rate quickly reach the peak value in the early production stage, while it can decrease the cumulative gas production in whole production process. This study can provide an avenue to initiate quantitative analysis on resource assessment, and gas productivity evaluation strategy after water invasion during the well drilling and completion in tight sand gas reservoir of East China Sea
Thermal and Compositional Analysis of Orange Essential Oil Obtained from Citrus Industry Waste
Get PDF During the production of orange juice, more specifically after the commercial extraction of fruit juice, other waste materials are generated, consisting of peel, pieces of membranes, pulp bagasse, juice vesicles and seeds. In this way, the final destination of the waste can become a problem when not managed correctly. Therefore, there are several possibilities for using these solid residues, as they present substances of great commercial interest. In this perspective, the present work evaluates the recovery of orange essential oil from the citrus industry waste using hydrodistillation. The oil obtained was characterized by acidic index, FTIR, GC / MS, TGA and DSC. The results exhibited that oil isolated by hydrodistillation has a similarity with cold-pressed orange oil. The chemical constitution of oil obtained from waste was almost the same as the commercial orange oil analyzed. However, the thermal behaviour presents a few differences in thermal stability and vaporization temperature between analysed essential oils. Therefore, this work produces an alternative to obtain a product with quality, high yields and added value that can be used in cosmetic and pharmaceutical industries