Showing papers on "Diffuser (sewage) published in 2018"

A Critical Review of the Factors Affecting Modeling Oxygen Transfer by Fine‐Pore Diffusers in Activated Sludge

Abstract: In this review, the factors affecting the transfer of oxygen in activated sludge processes using fine-pore diffusers for water resource recovery are critically discussed. In water resource recovery facilities, the energy required for aeration constitutes 50% to 80% of the total energy consumed by the plant. This critical review highlights the use of fine-pore diffuser aeration and emphasizes the significance of accounting for the following factors: diffuser aging and fouling, diffuser layout, diffuser type, selector benefits, local environmental conditions (temperature and atmospheric pressure), influent wastewater variability, dissolved oxygen control systems, and airflow rates. In our review, we were unable to find mathematical models that could be used to develop dynamic α-factor predictions and diffuser fouling predictions. Although the development of a model that considers all the factors that affect oxygen transfer efficiency (OTE) in activated sludge systems would be extremely valuable, the creation of such a model is outside the scope of this review.

Effects of air bubble size on algal growth rate and lipid accumulation using fine-pore diffuser photobioreactors

Abstract: Microalgae are a potential feedstock for biodiesel and aeration is a reliable method to improve the growth of microalgae. Previous studies revealed the influence of bubbles on a variety of microorganisms, yet so far few studies have focused on the effects of bubble size on microalgal lipid production. In this study, four different fine-pore diffusers that could produce different bubble sizes were used for aeration in the photobioreactors. The equivalent diameters (de) of the bubbles in the four systems were 1.5 mm, 2.5 mm, 3.5 mm and 6.0 mm, respectively. The system with de = 3.5 mm obtained the highest biomass productivity (104.1 mg·L−1·d−1), which was 12% higher than that with de = 1.5 mm. However, the lipid content in the system with de = 1.5 mm was 30% higher than that for de = 3.5 mm, and it also achieved the highest lipid productivity of 30.4 mg·L−1·d−1. Results from transmission electron microscope indicated that there is more starch in the cells when de = 3.5 mm and more lipid droplets in the cells when de = 1.5 mm. The largest bubble size was not beneficial for supplementing CO2 to the algae, which may have limited the growth. Therefore the air bubble size of de = 1.5 mm is the best when using aeration as a strategy for enhancing lipid productivity, since it could provide appropriate external stress for lipid accumulation, but did not greatly inhibit the growth of microalgae.

Air flow characteristics of a room with air vortex diffuser

Abstract: The air diffuser is a very important component of any ventilation system, and the comfort level of ventilated space occupants depend among many other factors on properly designed and choice of diffusers. At present a large number of diffusers are produced to meet a different kind of requirements. One of the most efficient and very popular types of the diffuser is the vortex diffuser in which air flow has angular as well as translational velocity components. This paper investigates experimentally airflow characteristics of vortex ceiling diffuser and its effect on airflow in a ventilated space. Two thermal comfort criteria namely: mean age of the air and ventilation effectiveness have been used to predict the comfort zone inside the room. Effect of supply air velocity on the flow field is investigated and hence the on comfort and energy consumption. The results show that significant amount of energy can be saved by using vortex diffuser in reference to the other diffusers type. The values of the velocity decay coefficient were compared for different diameters of vortex diffuser.

Numerical and Experimental Investigations on Aerodynamic Behavior of the Ahmed Body Model with Different Diffuser Angles

Abstract: Due to many restrictions applied by the necessity of fulfilling dimensional analysis in a numericalexperimental research and also the limits in experimental facilities a Low Reynolds Number simulation seems to be widespread. In this paper, effects of the diffuser angle on the aerodynamic behavior of the Ahmed body have been investigated for low Reynolds number flows. Numerical simulations were performed by solving the Reynolds Averaged Navier-Stokes (RANS) equations combined with different turbulence models. The Finite Volume Method (FVM) is used for simulations in Fluent 6.3.26 Software. The main objectives of the study are to improve the aerodynamic design of the body, analyzing the flow field to understand the nature of these improvements and reaching a suitable and reliable experimental-numerical setup for such a flow. Finally, it was concluded that the SST k-ω turbulence model with transitional flow corrections is the best choice. From the flow simulation and obtained experimental data, it was concluded that that drag coefficient is a function of three main phenomena. Results showed that the drag coefficient has its minimum value at a specific diffuser angle (8◦) and further increases in the angle lead to higher drag coefficient. On the other hand, the lift coefficient constantly decreases by increasing the diffuser angle. In order to show the validity of the numerical results, experimental data were obtained by measuring the drag and lift coefficients of scaled standard Ahmed body and a model with the diffuser angle of 8 degrees in a wind tunnel. Results confirmed that improvement of drag and lift coefficients occurs when diffuser region is considered for the Ahmed body. In addition, the flow field around the body was studied in detail to show the effects of the diffuser geometry on the aerodynamic characteristics of the body.

3D Fluorescence Microscopy with DiffuserCam

Abstract: We propose a lensless diffuser-based microscope for 3D fluorescence microscopy from a single exposure. We use compressed sensing and a local convolution model to account for the system’s spatially-varying point spread functions in a computationally efficient manner.

Intermittent micro-aeration control of methane emissions from an integrated vertical-flow constructed wetland during agricultural domestic wastewater treatment.

Abstract: It is very important to control methane emissions to mitigate global warming. An intermittent micro-aeration control system was used to control methane emissions from an integrated vertical-flow constructed wetland (IVCW) to treat agricultural domestic wastewater pollution in this study. The optimized intermittent micro-aeration conditions were a 20-min aeration time and 340-min non-aeration time, 3.9 m3 h−1 aeration intensity, evenly distributed micro-aeration diffusers at the tank bottom, and an aeration period of every 6 h. Methane flux emission by intermittent micro-aeration was decreased by 60.7% under the optimized conditions. The average oxygen transfer efficiency was 26.73%. The control of CH4 emission from IVCWs was most strongly influenced by the intermittent micro-aeration diffuser distribution, followed by aeration intensity, aeration time, and water depth. Scaling up of IVCWs is feasible in rural areas by using intermittent micro-aeration control as a mitigation measure for methane gas emissions for climate change.

An investigation of centrifugal compressor stability enhancement using a novel vaned diffuser recirculation technique

Abstract: The main centrifugal compressor performance criteria are pressure ratio, efficiency, and wide flow range. The relative importance of these criteria, and therefore the optimum design balance, varies between different applications. Vaned diffusers are generally used for high-performance applications as they can achieve higher efficiencies and pressure ratios, but have a reduced operating range, in comparison to vaneless diffusers. Many impeller-based casing treatments have been developed to enlarge the operating range of centrifugal compressors over the last decades but there is much less information available in open literature for diffuser focused methods, and they are not widely adopted in commercial compressor stages. The development of aerodynamic instabilities at low mass flow rate operating conditions can lead to the onset of rotating stall or surge, limiting the stable operating range of the centrifugal compressor stage. More understanding of these aerodynamic instabilities has been established in recent years. Based on this additional knowledge, new casing treatments can be developed to prevent or suppress the development of these instabilities, thus increasing the compressor stability at low mass flow rates. This paper presents a novel vaned diffuser casing treatment that successfully increased the stable operating range at low mass flow rates and high pressure ratios. Detailed experimental measurements from a high pressure ratio turbocharger compressor stage combined with complementary CFD simulations were used to examine the effect of the new diffuser casing treatment on the compressor flow field and led to the improvement in overall compressor stability. A detailed description of how the new casing treatment operates is presented within the paper.

Intelligence design method for three-dimensional vaned diffusers in a centrifugal compressor:

Abstract: This paper presents a multi-objective optimization-based intelligence design method for the design of the three-dimensional vaned diffuser for a given centrifugal compressor. This design method con...

High-pressure ratio centrifugal compressor with two different fishtail pipe diffuser configurations

Abstract: To improve fishtail pipe diffuser outflow uniformity, deswirlers and splitters are added inside and after fishtail pipe diffuser passages for a compact centrifugal compressor. The influence of cloc...

Improving energy efficiency and fouling mitigation for membrane bioreactor in Al-Rustamiyah sewage treatment plant based on hydrodynamics

Abstract: In Al-Rustamiyah sewage treatment plant in the east of Baghdad city, capital of Iraq, the membrane bioreactor suffering from a severe biofouling problem. The main reason for this problem is inefficient and inadequate aeration process. The objective of this work is to control fouling and to improve the energy efficiency of the submerged membrane bioreactor. Fouling control is achieved by optimizing the two-phase hydrodynamic parameters (air bubble diameter and shear stress), while energy efficiency improved through analysis of flow field. An experimental rig similar to real plant was built, and several operating and design parameters were experimentally tested. The parameters were air flow rate (1–9 L/min), membrane sheets spacing (3, 5, and 7 mm), and air diffuser design (pipe diffuser and disk diffuser). The bubble sizes were measured experimentally using high-speed camera. It was found that larger bubbles were produced at narrow channels between the membrane sheets. Optimization using computational fluid dynamic with ANSYS FLUENT was employed; the results showed that a bubble diameter of 2.5 mm had a slug flow pattern, resulting in better energy saving for a 3 mm space between membrane sheets with a 5 L/min air flow, while maximum shear stress obtained was (4 Pa). Nutrients removal results from synthetic sewage were 97.32, 79.68, and 13% for COD, NH3–N, and PO 4 −3 , respectively, at 6 days retention time. The results obtained are quite significant in practice because it contributes to improve the efficiency of membrane bioreactor in Al-Rustamiyah sewage treatment plant.

Biomimetic Design Inspired Sharkskin Denticles and Modeling of Diffuser for Fluid Control

Abstract: While sharkskin surface roughness has been hypothesized but remains yet controversial to be capable of achieving turbulent flow control and drag reduction, sharkskin-inspired “riblets” have been reported to be an effective biomimetic design (BMD). Here we address an integrated study of biomimetic riblets inspired by sharkskin denticles by 3D digitizing. Diffuser vanes with BMD sructures were fabricated using the precision cutting and BMD diffusers were assembled. Diffuser’s fluid control was evaluated to confirm the effect of the BMD on fluid control. Our results indicate that the morphological feature in sharkskin denticles likely play a critical role in passively controlling local turbulent flow and points to the potential of denticle-inspired biomimetic riblets for turbulent-flow control in aquatic vehicles as well as other fluid machinery.

LED lamp, oven, and microwave oven

Abstract: An LED lamp includes: a heat sink; a light-emitting module positioned on the heat sink, the light-emitting module including an LED unit positioned on the heat sink, a reflection cup, and a first diffuser covering the reflection cup, the reflection cup encircling the LED unit and defining at least one first ventilation hole; a heat-conducting support positioned on the heat sink and encircling the reflection cup, the heat-conducting support defining at least one second ventilation hole; and a second diffuser secured to and clamped by the heat-conducting support.

Laser projection device, TOF (Time Of Flight) depth camera and electronic apparatus

Abstract: The invention discloses an electronic apparatus, a TOF (Time Of Flight) depth camera and a laser projection device. The laser projection device includes a lens cone, a diffuser and a protective cover;the lens cone comprises a first surface and a second surface which are opposite to each other; an accommodating cavity passing through the first surface and the second surface is formed in the lens cone; and a mounting groove communicated with the accommodating cavity is formed in the first surface; the diffuser is mounted in the mounting groove; the protective cover is mounted on one side of thefirst surface of the lens cone, wherein the one side of the first surface is far away from the second surface; and the diffuser is sandwiched between the protective cover and the bottom surface of the mounting groove. According to the laser projection device, a condition that glue is adopted to fix the diffuser to the lens cone can be avoided, therefore, the glue can be prevented from volatilizing into a gaseous state, so that the influence of the diffusion of the gaseous glue and the solidification of the gaseous glue onto the surface of the diffuser on the microstructure of the diffuser canbe avoided; and a condition that the diffuser falls off from the lens cone due to the reduction of a bonding force which is further caused by the aging of the glue that connects the diffuser and thelens cone can be avoided.

Flow Characteristics of an Ultracompact Serpentine Inlet with an Internal Bump

Abstract: An ultracompact serpentine inlet, which contains a compact diffuser as short as 2.3 times the exit diameter, is experimentally and numerically studied. An internal bump is introduced to red...

Method and device for testing minimum ignition energy of combustible dust/combustible gas mixture

Abstract: The invention discloses a method and device for testing the minimum ignition energy of a combustible dust/combustible gas mixture. The device comprises a quartz glass tube, an ignition electrode, a diffuser, a copper sleeve, a base, a high-voltage discharging device, an ignition electrode joint seat, a gas storage tank, a first air inlet valve, a second air inlet valve, a third air inlet valve, afourth air inlet valve, a first compressed gas bottle, a second compressed combustible gas bottle, a control valve, a blind flange, an explosion venting valve and a vacuum pump, wherein the quartz glass tube is vertically fixed at the base through bottom threads; the ignition electrode is fixed at the lower part of the quartz glass tube through the ignition electrode joint seat and the copper sleeve; and the diffuser is used for raising dust covering the surface of the diffuser up through airflow so as to form dust cloud. By improving a gas distribution technique and a powder spraying technique, the uniform distribution of the combustible dust/combustible gas mixture in air is realized in the ignition moment, so that the minimum ignition energy of the combustible dust/combustible gas mixture can be accurately detected.

Composite particles comprising quantum dots and methods of making the same

Abstract: Composite particles comprising quantum dot light emitters, a nonvolatile liquid ligand system, and hydrolyzed organometallic metal oxide precursor, wherein the quantum dot light emitters and the nonvolatile liquid ligand system are collectively present in the composite particles in an amount of at least 30 weight percent. Composite particles described herein are useful, for example, in films (e.g., remote phosphor diffuser films). Remote phosphor diffuser films are useful, for example, in LCD displays.

High-efficient aeration tank for treatment of domestic sewage

Abstract: The invention discloses a high-efficient aeration tank for treatment of domestic sewage. The high-efficient aeration tank comprises a tank body, a fixing mount, a water inlet pipe, an aeration tray, ablower and a water discharging pipe; the top of the tank body is fixedly connected with a fixing mount, a side wall of the fixing mount is fixedly connected with a support, and the support is rotatably connected with a nozzle; the lower surface of the fixing mount is fixedly connected with a second motor, a shaft extension of the second motor is fixedly connected with a rotating shaft, the lowerend of the rotating shaft protrudes into the tank body, the rotating shaft is fixedly connected with a diffuser plate, and the lower end of the rotating shaft is fixedly connected with the aeration tray; sewage is discharged into the tank body by means of through holes on a spreader plate, the through holes on the spreader plate are distributed in radial distribution, and a sprinkling range of thesewage is increased; when the sewage is sprayed, the nozzle is swung up and down, so that the sprinkling range of the sewage is further enlarged; the blower is used, and air is discharged into bottomsewage from aeration heads; when the aeration tray is rotated, a hairbrush is used for cleaning the aeration heads, agitator arms are used for breaking bubbles, so that air and the sewage are fully contacted.

Vehicle grille assembly

Abstract: A vehicle grille assembly is provided herein. The grille assembly includes a panel sealingly coupled to a substrate and defining a cavity therebetween. A light source is disposed within the cavity. A diffuser is disposed between the light source and a portion of the panel.

Micro-turbojet engine for additive manufacturing

Abstract: The invention discloses a micro-turbojet engine. The micro-turbojet engine comprises a casing and a radial diffuser, wherein the radial diffuser is connected with the head of the casing, and both theradial diffuser and the casing are integrally manufactured by adopting an additive manufacturing technique. According to the micro-turbojet engine, both the casing and the radial diffuser are integrally manufactured by adopting the additive manufacturing technique, so that the processing is facilitated, the weight is reduced advantageously, and the processing and maintenance cost and difficulty are reduced advantageously.

Microfiltration Membrane Assisted CO2 Diffuser for Algae Cultivation

Abstract: The aim of this paper is to cover on the feasibility of using algae as an alternative to capture CO 2 . As such, comparison between a membrane diffuser and a bubble diffuser in terms of its performance in the cultivation of algae has been made. This work utilized PVDF flat sheet membrane with only air and pure CO 2 as the feed gas and the diffusion method used was compared between membrane diffuser and a bubble diffuser. In the experiment, the feed gas flows through the membrane diffuser in which the algae suspension utilized the CO 2 for its growth. The biomass contents of four different samples have been determined using the dry weight of the algae suspension samples, which is obtained by drying the samples in an oven overnight at 105˚C. The algae suspension with the membrane diffuser was able to remove CO 2 feasibly while showing better performance with respect to algae cultivation in comparison to the bubble diffuser. Results showed the maximum average biomass content of the samples that used membrane diffuser had higher value of 0.325 g/L when a 1:1 ratio of air and CO 2 was used in the feed stream and 0.275 g/L when using pure air as the feed stream. Thus, it has been shown that membrane diffuser is better than a bubble diffuser owing to its larger effective surface area.

Aroma diffuser and aroma diffuser control system

Abstract: The invention provides an aroma diffuser and an aroma diffuser control system. The aroma diffuser comprises a first communication module, a control module and an execution module, wherein the controlmodule is connected with the first communication module and the execution module, the first communication module receives user physiological data acquired by a mobile terminal and transmits the user physiological data to the control module, the control module receives the user physiological data, generates control commands according to the user physiological data and transmits the control commandsto the corresponding execution module, and the execution module receives the control commands and correspondingly adjusts running parameters of the aroma diffuser according to the control commands. The aroma diffuser is intelligently adjusted in a humanized and personalized manner according to the user physiological data.

Real scale experimental study for performance evaluation of unidirectional air diffuser perforated panels

Abstract: Nowadays, there is an increasing emphasis on indoor air quality due to technological evolution and the fact that people spend most of the time in enclosed spaces. Also, energy efficiency is another related factor that gains more and more attention. Improving air distribution in an enclosure can lead to achieve these goals. This improvement can be done by adjustingthe air terminals position, theredimensions or the air diffuser perforations. The paper presents the study of 8 types of panels with different perforations shapes. The systems were characterized by flow, pressure loss and noise. Usualand special geometries were chosen, all having the same flowsurface. The perforated panels were mounted in a unidirectional air flow (UAF)diffuser, also called a laminar air flow (LAF)diffuser, that is placed in a real scale operating room (OR) in our laboratory.The purpose of this study is to determine whether changing the shape in the perforated panels can improve the technical parameters of the diffuser.

Additive manufacturing system and method of forming an object in a powder bed

Abstract: An additive manufacturing system including a housing configured to contain a powder bed of material, and an array of laser emitters having a field of view. The array is configured to melt at least a portion of the powder bed within the field of view as the array translates relative to the powder bed. The system further includes a spatter collection device including a diffuser configured to discharge a stream of gas across the powder bed, and a collector configured to receive the stream of gas and contaminants entrained in the stream of gas. The collector is spaced from the diffuser such that a collection zone is defined therebetween, and the spatter collection device is configured to translate relative to the powder bed such that the collection zone overlaps with the field of view of the array.

Aerodynamic Shape Optimization of Diffuser Augmented Wind Turbine Shrouds Using Asynchronous Differential Evolution

Abstract: An adaptable numerical scheme for the aerodynamic shape optimization of axisymmetric diffuser-augmented wind turbine shrouds is demonstrated in this work, using an asynchronous and parallel version of a Differential Evolution (DE) algorithm. The simulation of the incompressible flow field about each candidate geometry is succeeded by means of an in-house Computational Fluid Dynamics (CFD) solver, that has been developed based on the specially modified, by the artificial compressibility approach, Navier-Stokes equations, expressed in non-dimensional form, for 2D-axisymmetric frames of reference. The discretization of the computational domain is made with 2D hybrid unstructured meshes, composed by both triangular and quadrilateral elements, combined with a node-centered finite-volume scheme, while the Free-Form Deformation (FFD) technique is applied, for both the parameterization of the design geometry and the morphing of the computational mesh. The required data transfer between the DE algorithm and the CFD solver is accomplished with appropriate text files, while the parallel implementation is achieved utilizing the Message Passing Interface (MPI) library functions. Further acceleration of the optimization procedure is succeeded by the combination of the DE with surrogate models, in order to replace the costly CFD-based evaluations of the candidate solutions with fast, but approximate estimations of their cost function.

Performance Enhancement of Window-Type Air-Conditioning Units

Abstract: In this work, the performance of window-type air-conditioning units was improved. The study was achieved by adding a diffuser at the compressor outlet. An experimental investigation was carried out...

Combined Methods in Preliminary Micro Scale Gas Turbine Diffuser Design – a Practical Approach

Abstract: Micro scale gas turbines are low cost, simplified versions of full scale jet engines. A unique feature of their design are centrifugal compressor impellers that are selected from automotive low cost, high quality turbocharger components. The present article is dedicated to the practical design of a micro scale centrifugal compressor diffuser that suits a reduced scale, turbojet engine. The idea of using a simplified method comes from the requirement from fast geometry generation for a prototype design. The chosen approach is suitable when the time is crucial and available resources are limited. The chosen simplified analytical model is based on turbomachinery physics. The obtained results are verified by detailed data from successful designs such as KJ66, MW54 and TK50. For a prototype design, GT60 results where compared with a numeric simulation in the ANSYS CFX environment. The difference in isentropic efficiency, numerical prediction in comparison to compressor flow map was less than 3%.This is acceptable for preliminary calculations due to the difference in compressor stator design.