Internal Fan Research Articles

Design of closed loop for reproduction of gas-dominated hydrate flow.

The study presents a novel setup for measuring the flow regime of hydrate particles in a gas-dominated flow, which is of interest for applications such as natural gas transportation. A closed-flow loop, driven by a novel internal fan, enables continuous observation of hydrate particle behavior in a gas flow. The experimental setup allows the production and insertion of HFC134a gas hydrate particles with diameters of 10-50μm into the gas flow loop via a bypass loop. The performance curve of the internal fan is validated, and its suitability for achieving the required flow speed (5m/s) is demonstrated. Through an observation window using camera systems, the flow regime of glass beads is successfully visualized and analyzed. To validate the experimental data, a coupled computational fluid dynamics-discrete element method model is used to simulate the particle flow density distribution. The study findings demonstrate the effectiveness of the experimental setup in characterizing the flow regime of hydrate particles in a gas-dominated flow.

Analisa Mesin Pengering Makanan Food Dehidrator Menggunakan Sensor Thermostat Berbasis Hybrid

The process of drying food is done in the traditional way, by drying it in the hot sun, but the traditional drying method makes the food unhygienic. Several factors can influence the drying results of food ingredients, including temperature and drying time. Using optimal drying temperatures and times can reduce the level of damage caused by the drying process. This research aims to obtain an analysis of a food dehydrator drying machine using a hybrid-based thermostat sensor that can optimally condition the temperature and time factors in the drying process, the hyfood dehydrator machine system uses a dehumidification method, there is a heat recovery mechanism that recycles heat to open new air, thus saving 60-70% of fresh air preheating energy consumption. Hot air moving in the room dries the material. It is known that the test result data was analyzed by calculating the accuracy values, down to the relative distance values. The results of the comparison process are used as validation of the output values ​​produced by the temperature measuring instrument. The measurement results of the Digital Thermostat Sensor are in accordance with the datasheet and have a high level of accuracy. So the Digital Thermostat Sensor measuring instrument can be used as a measurement tool. With an internal fan, thermostat, and time settings on this device, you only need to set the right heat according to the type of food you want to dry. The shelves in the cupboard consist of drying trays that can maximize the drying process

Experimental investigation and analysis of cooling performance of solar thermoelectric refrigerator

Nowadays, a potential alternate source of renewable energy for heating and cooling purposes is solar thermal energy. In remote areas electricity problems, the solar cooling and heating are very useful for living. The present research is focus to develop a solar thermoelectric refrigerator (STER) by using thermoelectric module based on principles of Peltier effect (creating cold and hot zone). Inside the refrigerator compartment, the cold side zone of the thermoelectric module is used for refrigeration. However, the rejected heat from other hot side of module to ambient surrounding through heat sinks and fans. The experimental model considers a steel aluminium box of dimension 200 × 195 × 300 mm3 having two thermoelectric (TE) modules and two heat sink with cooling fan to investigate the performance evaluation of solar thermoelectric refrigerator. The STER unit utilises a 100 W solar panel. The experimental result of double module with internal fan shows that the STER unit reduces room temperature of 33 °C to 4.1 °C in 44 min with coefficient of performance (COP) of 0.61. Therefore, the present novel refrigeration system is augmented for domestic and medicine storage purpose in remote area with economically viable and environmental friendly.

Application of Nanotechnology in a Novel Air Purifier for Remediation of Airborne Pathogen and to Prevent the Spread of COVID-19

The spread of COVID-19 occurs via airborne transmission. With a constant and variable spread of COVID-19, indoor air-quality has become a major concern all over the world. People who are infected with COVID can release particles and droplets of respiratory fluids that contain the SARS CoV-2 virus into the air when they exhale (e.g., quiet breathing, speaking, singing, exercise, coughing, sneezing). Once infectious droplets are exhaled, they move outward from the person (the source) into the surrounding environment; these droplets carry the virus and transmit infection. Indoors, the very fine droplets and particles will continue to spread through the air in the room or space and can accumulate. Harmful pathogenic organisms like fungi, bacteria and viruses, as the one responsible for causing contagious diseases like the ongoing pandemic of COVID-19 can also be successfully destroyed and neutralized. We have developed and studied the efficiency of the AFL Mini Sanifier II® in a simulated environment of a fiberglass chamber using various types of meters to assess the suspended particulate matter (PM) in the ambient air. We also report the development of a novel face mask that was assessed for safety measures and further improvement by the researchers in the West Texas A&M University. The mask is user friendly and portable, equipped with a small internal fan that supplies a continuous air to the user preventing the suffocating effect caused by the other masks. The novel mini air purifier is equipped with the advanced nanotechnology that cleans and sanitizes both the air and surfaces and subsequently has been shown to reduce common allergy, asthma and hay fever related symptoms. This mask and the mini air purifier function in an advanced way to combat all forms of airborne pathogens including the bacteria, viruses, mold spores and harmful Volatile Organic Compounds (VOC) present in the air.

Aeropropulsive assessment of engine installation at cruise for UHBPR turbofan with body force fan modelling

The overall propulsive performance of an aircraft with podded nacelles depends on the interaction occurring between the wing body and the propulsor. With the tight installation required for Ultra-High Bypass Ratio (UHBPR) turbofans, the engine and airframe flows are more coupled, resulting in a mutual interference that can affect the working condition of the turbomachinery and the wing flow. In the paper, we employ a fully coupled fan stage model based on a body force method to evaluate the performance of an ultra-high bypass ratio turbofan in a nominal and closely-coupled installation position, along the cruise phase of a long-haul flight at Mach number 0.85. By comparing the results obtained with a standard powered-on representation based on one-dimensional static boundary conditions, we assess the effect of the engine/airframe coupling on the aerodynamics and propulsive forces. The major differences occur on the discharge flow, on the internal fan nozzle duct and on the jet/wing interaction, due to the nonuniform fan stage outlet status in the body force simulations. The net vehicle force deviates from 1% to 1.6%, according to the position and the cruise phase. The sensitivity of the propulsive forces to the change of installation position, instead, is in general consistent for the two methods. The discrepancy can be much larger if the 1D boundary conditions are not corrected for true engine operating points arising under installation, exceeding 8% in the tighter assembly for the net vehicle force.

Lithological and structural anatomy of an unusually well exposed strike-slip fault pressure ridge in the Nanjieshan, western China

We combine field observations, drone photogrammetry, and petrographic and XRD analysis to document the internal lithological and structural variability of an exceptionally well-exposed strike-slip fault pressure ridge, in the northern Tibetan foreland. The ridge exposes alternating dm-m thick discolored zones of fault gouge, breccia, and cataclasite likely reflecting the original Riedel shear array and progressive widening of the fault zone as comminution, fluid pressures, mineral alteration, and strain hardening and weakening processes evolved and migrated vertically and laterally within the core. The principal fabric defines an internal foliation fan, and sinistral, oblique-thrust faults bound the ridge supporting a transpressive squeeze-up origin. Outcrop- and micro-scale grain size reduction, gouge formation, and calcite precipitation suggest that thermal pressurization, mechanical lubrication, fault-valve fluid cycling, and periodic gouge zone lock-up may have been important factors controlling fault slip behavior and seismic energy release. Local variations in the distribution and thicknesses of brittle fault rocks, strain intensity, alteration mineralogy and fault core fabrics are a sobering reminder that a single 2-dimensional exposure across any regional fault system will fail to capture the complex petrological, mineralogical, mechanical and rheological heterogeneity that is typical of an evolving intraplate strike-slip fault system, especially where it reactivates an older fault/shear zone.

Parametric study of a novel combination of solar chimney and radiative cooling cavity for natural ventilation enhancement in residential buildings

The application of radiative cooling (RC) is expanding to a diverse research field, with some current studies trying to apply RC for natural ventilation. One proposed strategy is to use RC for the enhancement of solar chimney (SC) ventilation, and this strategy has been proven in a dry temperate climate. However, geographical locations and other design parameters may affect the performance of this natural ventilation strategy, and the conditions in which SC-RC ventilation performs best need to be investigated. This parametric study examines the performance of a novel SC-RC ventilation with six different parameters. The six parameters are the RC emitter's convection cover, building's thermal mass, RC cavity gap, internal heat gain, climate, and fan usage. Transient 2D computational fluid dynamics (CFD) simulations with Ansys Fluent were conducted to analyse the SC-RC ventilation's optimal design and working conditions. A convection cover on the RC emitter, a thermal mass wall material, a smaller RC gap, and a relatively low internal heat gain help the SC-RC achieve a cooler room and higher ventilation flow rate. Overall, the novel SC-RC ventilation performance is better than a conventional SC, except in humid climates. In dry climates, the SC-RC has the potential to create a maximum 2 °C temperature reduction, with a daily average room temperature of 0.56 °C lower than ambient. This cooling performance of the passive SC-RC ventilation is better than the fan-assisted SC-RC. Also, the SC-RC can achieve a daily average of 2.1 ACH, which is 0.4 ACH more than the conventional SC.

Toxic YouTubers “hated” by Doctor Who? Animating multiphrenic incarnations of Not My Doctor anti-fandom

This article considers how popular/spreadable misogyny enters into Doctor Who fans’ discourse communities via fan-cultural appropriation, mixing external political and internal fan discourses. This can oppose fannish communal norms such as “convivial evaluation” and “ante-fandom”. The theoretical perspective taken in the article combines work on toxic fandom with anti-fandom to thus understand fan toxicity as “multiphrenic”, i.e. drawing on multiple discourses and self-investments, including responding to its own anti-fans. The article goes on to examine YouTube voiceover-commentary videos from one communally-prominent Whotuber representing Not My Doctor anti-fandom, showing how they use devices such as the acousmetre and “stripped down” subjectivity to open a projective space for toxic fandom and enact a flat affect characterising what is termed “performative rationality”. Crucially, leftwing narratives of toxicity and hate are completely inverted to the extent that Doctor Who and the BBC are presumed, without evidence, to “hate” straight white male conservative fandom.

Identifying the contribution of charge effects to airborne transmission of aerosols in confined spaces

Aerosols in indoor air have various adverse effects on human health. Considering the use of forced ventilation and fan mixing (individually and in combination), the variation in charge number and their effects on aerosol transmission in confined spaces were explored in this study with the distinction of particle sources. In the case of sources originating from the external space, natural penetration acquires a greater number of negative charges. Forced ventilation of a confined space acts on the fate of particles in the neighboring confined space, while the internal fan has a negligible effect on both the number concentration and charge number of particles in the exterior. The combination of forced ventilation and fan mixing increases charge numbers, altering the lifetime of particles in the external regional environment by deposition or adsorption, particularly for neutralized particles. In the case of sources originating from the interior area, application of an internal fan weakens the ventilation effect from forced ventilation, resulting in internal particle loss by depositing on internal surfaces due to electrostatic charge, increasing the potential risk of resuspension. Additionally, source origin is associated with particle fate, and the charge generated under the action of external forces contributes to the transmission pathways and the fate of the particles in the air. This study investigates the transmission pathways and the fate of aerosols from the perspective of charge number, hopefully contributing to an in-depth understanding of the transmission mechanisms of toxic substances in confined spaces with aerosols as carriers.

Analysis of Selected Operating States of the Line Start Synchronous Reluctance Motor Using the Finite Element Method

The article presents the results of work on an effective numerical study of selected transient states of a low-power electrical machine. The object of detailed research was a synchronized squirrel-cage induction motor. Its ability to work at a synchronous speed was enabled by obtaining reluctance torque, caused by an imposed asymmetry between the direct and quadrature reluctances of the rotor. The difference between the reluctances was achieved by changing the rotor geometry by milling additional deep grooves. The modifications of the rotor did not damage the continuity of the rotor cage. Imposed lots were arranged symmetrically around the rotor circumference. In order to study the performance of the modified motor, a parameterized, numerical model of the machine was developed to evaluate the impact of the geometry of the slots. The developed three dimensional (3D) model of the electromagnetic phenomena in the studied magnetic circuit employs the finite element method (FEM). The model takes into account the saturation of the machine’s magnetic circuit and the skew of the rotor cage bars as well as the mechanical equilibrium of the terrain system including the moment of inertia and frictional torque in the bearings as well as the load torque resulting from the operation of the internal fan. The simulation study concerned the starting process of the machine under different values of the load. The influence of the supply voltage phase angle at the moment of start-up and the initial position of the rotor in relation to the stator was investigated. In order to calibrate the model, tests of the physical object were performed. The corrections introduced concerned the magnetization characteristics of the magnetic circuit. The results obtained confirm the correctness of the adopted strategy of testing the operational properties of the considered engine.

A Novel Approach to Identifying How Equipment Disrupts the Airflow Patterns in the Operating Room.

A decrease in the infection rates in the operating room (OR) is attributable to advances in sterile technique; heating, ventilation, and air-conditioning (HVAC) filtration; and limiting the number of people entering and leaving the OR. However, some infection complications after open heart procedures have been linked to the discharge fans of surgical equipment, most notably from the LivaNova 3T. We believe that surgical infection within the OR may also be due to other devices with internal fans. The purpose of this study was to 1) identify surgical equipment with an internal fan and see how they affect the airflow in an OR, 2) use the equipment to positively affect airflow to possibly reduce the risk of surgical site infections, and 3) bring attention to the HVAC system ability to exchange air throughout the OR. By using a fog machine and multiple camera angles, we identified the devices that have an effect on the airflow. We saw that the direction of the intake vent of specific devices can change the direction of airflow and possibly help to remove air. Last, we showed how the current HVAC air exchange rate might not be enough to remove contaminated air within the OR. Understanding intake and discharge vents for all equipment is important because sterile contamination and wound infection may be minimized or mitigated completely by simply repositioning a few devices.

Exfiltrating data from air-gapped computers via ViBrAtIoNs

Air-gap covert channels are special types of covert communication channels that enable attackers to exfiltrate data from isolated, network-less computers. Various types of air-gap covert channels have been demonstrated over the years, including electromagnetic, magnetic, acoustic, optical, and thermal.In this paper, we introduce a new type of vibrational (seismic) covert channel. We observe that computers vibrate at a frequency correlated to the rotation speed of their internal fans. These inaudible vibrations affect the entire structure on which the computer is placed. Our method is based on malware’s capability of controlling the vibrations generated by a computer, by regulating its internal fan speeds. We show that the malware-generated covert vibrations can be sensed by nearby smartphones via the integrated, sensitive accelerometers. Notably, the accelerometer sensors in smartphones can be accessed by any app without requiring the user permissions, which make this attack highly evasive. We implemented AiR-ViBeR, malware that encodes binary information, and modulate it over a low frequency vibrational carrier. The data is then decoded by malicious application on a smartphone placed on the same surface of the air-gapped computer (e.g., on a desk). We discuss the attack model, provide technical background, and present the implementation details and evaluation results. Our results show that using AiR-ViBeR, data can be exfiltrated from air-gapped computer to a nearby smartphone on the same table, or even an adjacent table, via vibrations. Finally, we propose a set of countermeasures for this new type of attack.

Aerodynamic optimization of forward-curved blade centrifugal fan characterized by inclining bionic volute tongue

The profile and axial designs of a volute tongue have great influences on the internal flow conditions and aerodynamic performance of a forward-curved blade centrifugal fan. In order to achieve a high quality of internal flow fields and fan aerodynamic performance, we propose an inclined bionic volute tongue (IBVT) described with rotation angle and scale coefficient at the front and back walls of the volute, which varies the profile of the volute tongue and the distance between the impeller and the volute tongue in the axial direction. Meanwhile, an adaptive pseudo expected improvement matrix (APEIM) parallel multi-objective efficient global optimization (EGO) algorithm is developed by introducing a flexible number of added points for each iteration of optimization on account of the optimization problem itself. On this basis, IBVT is optimized to maximize the fan aerodynamic performance in terms of total pressure efficiency and static pressure rise by virtue of numerical simulation. The results show that the developed APEIM parallel multi-objective EGO algorithm is capable of accurately and efficiently finding the Pareto front solutions. IBVT is considered to have the effectiveness of aerodynamic performance improvement for a forward-curved blade centrifugal fan. Within the fan with IBVT, the flow fields in the axial direction become more uniform with the dimension reduction of the inactive zone around the front span. The impeller-volute tongue interaction is greatly improved with the decreases of reversed and recirculated flow coefficients. IBVT also benefits the reduction of flow losses in the volute. By adopting the analysis of variance (ANOVA), the aerodynamic performance of the fan is highly affected by the rotation angle and scale coefficient of IBVT at the front wall of the volute. This work is helpful to guide the design of the volute tongue for a forward-curved blade centrifugal fan.

Fans arrangement analysis in oil forced air natural cooling method of power transformer radiator

The cooling of radiators in power transformers employing natural oil-air forced method is the purpose of this study. Two modes used for cooling fans, namely vertical and horizontal placement, will be compared as well. Four sets of radiators have been studied in this research, and in each set, 14 fins and three fans with a diameter of half a meter have been used. The fans will be arranged such that three of them will be placed under the radiator (in vertical position) in the first case, while in the second case, they will be located in one side of the radiator (in horizontal position). The results derived from the comparisons indicate the superiority of the horizontal mode in heat transfer against the vertical mode. Furthermore, it is notable that if the internal fan is disconnected, the cooling can be enhanced with the help of some existing points in the vertical mode. The improvement in heat transfer rate can be observed through locating the vertical fans optimally, once compared to the horizontal placement. The lower reliability of the vertical mode can be detected once the side fans are disconnected, while in any cases, the heat transfer superiority is achievable for horizontal mode. That is because, the disconnection of one of the fans, leads to the negligence of the radiators major parts in the vertical mode.

Enhancing clean cooking options in peri-urban Kenya: a pilot study of advanced gasifier stove adoption

Kenya has experienced a decade of relative prosperity with consistent economic growth and minimal political tension. GDP is growing by 3% annually and poverty rates are declining. Despite these gains, Kenya still has a lot of ground to cover to achieve the Sustainable Development Goals (SDGs) by 2030. SDG7, which aims to ‘Ensure access to affordable, reliable, sustainable and modern energy for all’, exemplifies both Kenya’s achievements and the challenges that remain. Access to grid-based electricity and LPG have grown rapidly. However, over 90% of Kenyans still rely on polluting fuels like wood, charcoal and/or kerosene for some or all of their cooking needs. Substantial effort is needed to ensure all Kenyans have access to clean cooking options by 2030. We present the results of a pilot study in which gasifier-based pellet stoves were introduced in 150 peri-urban households. The stoves include an internal fan that improves combustion efficiency and reduces emissions by 90%–99% relative to charcoal and fuelwood in traditional devices. A subset of participants received stoves with ‘Pay-as-You-Cook’ (PAYC) hardware, which relies on pre-paid RFID card to activate the stove’s internal fan, allowing vendors to sell the stove below cost and recoup losses through pellet sales. We find that people were willing to include pellet stoves in their cooking routines and, in many cases, pellets displaced polluting fuels. We also find that PAYC hardware did not negatively impact adoption: PAYC users had higher daily rates of fuel consumption and reported higher willingness to pay for the stove than non-PAYC users. However, stoves were not used exclusively. Instead, people stacked pellets in combination with other cooking options, with pellets contributing to 12%–40% of their cooking needs (inter-quartile range). Though the project did not successfully overcome all of the barriers necessary to achieve long-term adoption of advanced pellet stoves, the results demonstrate that pellets could contribute to a portfolio of cleaner options.Social media abstract:In a pilot project, clean-burning ‘pay-as-you-cook’ pellet stoves were stacked with LPG and polluting fuels.

Experimental and numerical investigations on effect of blade trimming on aerodynamic performance of squirrel cage fan

The impeller of squirrel cage fan exerts great effects on the internal flow fields and fan aerodynamic performance. On the premise of maintained impeller-volute tongue distance and production cost reduction, this paper proposes a blade trimming method focusing on axial modification of blade inlet in an attempt to improve the impeller flow condition and further the aerodynamic performance of squirrel cage fan, which is divided into blade full trimming and part trimming. Aerodynamic performance tests and numerical simulations are performed to explore the effect of blade trimming on the fan aerodynamic performance and the related flow mechanisms. The results show that the blade trimming with proper trimming parameter enables the fan to achieve higher fan aerodynamic performance in terms of total pressure efficiency and static pressure rise, between which full trimming is preferable to part trimming. With the optimum full trimming of blade, the axial distributions of mass flow at the impeller inlet and outlet become more uniform. The dimension of inactive zone near the front span is decreased. On the blade pressure surface, the forces are reduced with obvious improvement of gradients near the front span and back span. A better match between impeller and volute tongue is achieved as the decreases of reversed flow coefficients at the impeller inlet and outlet and recirculated flow coefficient in the volute.

Preliminary investigation of performance and temperature distribution of thermoelectric cooler box with and without internal fan

Thermoelectric cooler is one type of refrigeration system that is environmentally friendly because it does not use refrigerants which have potential damaging the ozone layer. In this study, an experimental performance of thermoelectric refrigerator using fan and without fan is presented. The result shows that the cold side temperature decreases from 25.5 degree C to -5 degree C for 37 watt (with fan) and 25.5 degree C to -7.5 degree C for 37-watt without fan. Using 43-watt power supply, the cold side decreases from 25 degree C to -5 degree C for fan usage, and from 26 degree C to -7.5 degree C in 60 minute and 75 minutes, respectively. Using fan for cold sink inside the cabin will distribute the cabin temperature of cool box evenly and also increase the capability of heat transfer performance of cooler box of thermoelectric. Maximum average COP is 0.103 and achieved by 37-watt power supply with cold sink fan.

Effects of flux chamber configuration on the sampling of odorous gases emissions

Flux chambers are commonly used to measure emission rates of odorous compounds at passive liquid surfaces in wastewater treatment plants. Different flux chambers configurations are found in the literature and the main concern regards to the mixing inside the chamber, which is linked to impact on the overall mass transfer between emitting surface and headspace, and the sampling recovery efficiency. However, aspects related to the airflow and mass transfer inside the chambers influence the measured emission rates. The mass transfer coefficients in the liquid and gas phases are functions of the friction velocity on the liquid surface. This work investigates the airflow and odorous compounds transport (with different Henry’s law constants) inside a flux chamber using Computational Fluid Dynamics, to determine the influence of inlet airflow rate (2, 5 and 10 L min−1), inlet configurations (4, 6 and 8 inlet holes) and the inclusion of internal fans on the surface friction velocity and emission rate. The results showed a complex flow inside the chambers and a concentration field that reaches steady state after 6 residence times. The use of an internal fan promoting downward flow increased turbulence and produced values of friction velocity at the liquid interface closer to those found in the near surface flow in the boundary layer, whereas all other configurations tested showed much lower values of friction velocity. Therefore, the use of a fan is recommended.

Research on Thermal Characteristics of Internal Ventilated Paths in Compact Medium High- Voltage Motor Based Fluid Network Decoupling

Aiming at the problem that it is difficult to model and analyze the thermal effect of large motors as a whole, a method based on fluid network decoupling is proposed to solve the global thermal effect of large motors. Taking YJKK500-4 2500-kW compact medium-sized high-voltage motor as an example, combined with the internal structure and the actual size of the motor, and using the flow-heat coordination mechanism and the fluid network, the whole internal ventilated paths of motor are divided into four equal pressure regions: end, stator-rotor, end, and internal fan according to the magnitude of pressure. The reasonable basic assumptions and boundary conditions are selected to link each region, which can avoid the problem that the inlet boundary condition is difficult to give. After that, the internally ventilated paths are modeled and analyzed, and the fluid flow and temperature in each region of the internally ventilated paths are obtained. Combined with the experimental data, the calculation results are all within the error. The rationality and correctness of the method used in the paper are confirmed, which solves the problem that the ordinary computer cannot calculate the huge model of large motor and provides a basis for the calculation of similar motor in the future.

Developing of a ventilation system for residential houses with solar air heater

Ventilation of buildings in winter period, especially in cold climatic conditions, requires rather big quantity of heat for preheating the ventilation fresh air. Consequently, an average low-income family pays a tangible cost for ventilation of apartments. To provide low cost ventilation of houses it is becoming attractive the use of solar energy for preheating the outside fresh air, before its supplying into the house. For this purpose, cheap solar air heaters are needed. To solve this problem a simple and cheap construction of solar air heater was developed, which is the main part of the ventilation system. The system consists of air heating solar collectors, installed on the roof of the house, warm air distribution ductwork, internal air circulation ducts and air-circulating fan. In summer period, the system is used only during nighttime period for circulating outside colder air through the internal space of the house. Such operation allows cooling internal air and as well the constructions of the house. As a result, the house accumulates nighttime natural cold for using it at daytime cooling purposes. Presentation includes the scheme, explanation of operation and method for design of suggested ventilation system. Analysis proved the energy efficiency and cost effectiveness of the new system.