Varying Air Flow Research Articles

Heat Transfer Parameterization towards Enhancing Shelf Life of Vegetables in Low Cost Cold Chain with FACCC

India is the second-largest vegetable producing country after China. It is observed that there is a huge loss of vegetables due to the lack of low-cost cold chain for its storage & transportation after harvesting from agriculture land to vegetable market. The shelf life of these vegetables is less due to poor temperature control during transportation and storage. If vegetables are not maintained at their prudent temperature, then they will lose their potency, which will lead to enormous economic loss. Therefore, it is observed that temperature control of vegetables and their heat transfer characteristics are a major factor to maintain potency and increase their shelf life. This paper proposed a low-cost design of FACCC for temperature control of vegetables during transportation and storage with the help of Chillers. Further, the effect of air velocity on heat transfer rate and Nusselt number of various vegetables was evaluated to predict the performance of FACCC for enhancing the shelf life of vegetables.Thermophysical characteristics of these vegetables have been calculated at different air flow rate with the help of Reynolds analogy as a function of Stanton Number, Reynold’s Number and Prandtl Number.The airflow rate was maintained between 0.2065 m/s - 0.413 m/s inside FACCC. Experimental study reveals that the average Nusselt Number of these vegetables lies in the range of 57.9 - 115.74 and the range of Surface heat transfer coefficient is 54.48-108.96 W/m2K. Validation of FACCC performance has been done by comparing the heat transfer rate and Nusselt number from published literature. These results are obtained by temperature control of vegetables by varying air flow rate through four fans fitted inside FACCC. It results in higher shelf life due to favourable maintenance of thermodynamic parameters such as surface heat transfer coefficient, Nusselt number, Reynold number and preferable temperature for specific commodities.Thus, the proposed FACCC model can be an effective tool for enhancement of low-cost cold chain for vegetables in future.

Enhanced efficiency of the brushless direct current motor by introducing air flow for cooling

A brushless direct current (BLDC) motor has high reliability and a long life because it eliminates mechanical friction, and compensates for the defects of a direct-current (DC) motor by removing the brush and commutator. Compared to a DC motor, BLDC motor has the excellent efficiency because there is no voltage drop or friction loss of the brush. However, when the motor is operated for a long time with a high output, the internal motor temperature rises, and the copper-winding temperature increases. The temperature rise of the internal motor affects the resistance of the copper winding and the performance of the permanent magnet. This study investigates the efficiency of a 500 W BLDC motor with a varying air flow rate. The temperature rise and efficiency of the BLDC motor are studied by applying inlet flow rates of 0, 30 and 50 L/min during a 20 min load test. The temperature rise is very high at 0 L/min and the efficiencies are calculated as 81.9%, 82% and 82.7%. This study can be used as a basic study on the optimal air flow rate to the internal motor.

Biomedical system to evaluate pulmonary function in patients with post-stroke hemiparesis

Abstract Introduction: Stroke is a neurological disorder considered the second major cause of death worldwide, leading to severe respiratory dysfunctions, evident in reduced respiratory muscle strength and the presence of muscle imbalances that directly affect the pulmonary mechanics of these patients. Objective: Evaluate the possible metric properties of a biomedical system, the IBI. Method: the study was conducted with 25 hemiparetic stroke patients of both sexes, using a manovacuometer, peak flow, and SG IBI for respiratory measurements. Results: Moderate to strong correlations were observed between the IBI biomedical system and peak flow and manovacuometer measurements, which were smaller than the predicted values. Conclusion: The results suggest that the IBI biomedical system is potentially valid for pulmonary function measurement, sensitive to air flow variations and generates maximum respiratory pressure. As such, it is an important resource for prescribing intensity and controlling progression in pulmonary rehabilitation.

Gas distribution mapping and source localization using a 3D grid of metal oxide semiconductor sensors

The difficulty to obtain ground truth (i.e. empirical evidence) about how a gas disperses in an environment is one of the major hurdles in the field of mobile robotic olfaction (MRO), impairing our ability to develop efficient gas source localization strategies and to validate gas distribution maps produced by autonomous mobile robots. Previous ground truth measurements of gas dispersion have been mostly based on expensive tracer optical methods or 2D chemical sensor grids deployed only at ground level. With the ever-increasing trend towards gas-sensitive aerial robots, 3D measurements of gas dispersion become necessary to characterize the environment these platforms can explore. This paper presents ten different experiments performed with a 3D grid of 27 metal oxide semiconductor (MOX) sensors to visualize the temporal evolution of gas distribution produced by an evaporating ethanol source placed at different locations in an office room, including variations in height, release rate and air flow. We also studied which features of the MOX sensor signals are optimal for predicting the source location, considering different lengths of the measurement window. We found strongly time-varying and counter-intuitive gas distribution patterns that disprove some assumptions commonly held in the MRO field, such as that heavy gases disperse along ground level. Correspondingly, ground-level gas distributions were rarely useful for localizing the gas source and elevated measurements were much more informative. We make the dataset and the code publicly available to enable the community to develop, validate, and compare new approaches related to gas sensing in complex environments.

Experimental studies on the performance of mobile air conditioning system using environmental friendly HFO-1234yf as a refrigerant

In this work, the experimental investigation on the performance and exergy analysis of mobile air conditioning system with suction line heat exchanger using environmental friendly HFO-1234yf was carried out under varied evaporator air flow rates. The performance was compared with existing HFC-134a results. The performance analysis showed that the cooling capacity and the coefficient of performance of the system with HFO-1234yf were lower than that of the HFC-134a by upto 2–11%. The power consumption and the volumetric efficiency of the compressor with HFO-1234yf were found to be 14.02% and 11.2% higher than that of HFC-134a. From the exergy analysis, it was observed that the major exergy destruction occurred in the compressor, followed by the condenser, evaporator, thermostatic expansion valve, and suction line heat exchanger for both refrigerants. The exergy efficiency of the system with HFO-1234yf was 2.4–12.6% lower than that of HFC-134a. From this study, it was observed that the losses experienced in the compressor, thermostatic expansion valve and evaporator lead to poor performance with HFO-1234yf.

Air spreading through wetted cellulose membranes: Implications for the safety function of hydraulic valves in plants.

Plants transport water against the risk of cavitation inside xylem vessels, called "embolism." As one of their hydraulic strategies, pit membranes composed of cellulose fibers have been known as safety valves that prevent the spreading of embolism towards adjacent xylem vessels. However, detailed observation of embolism spreading through a pit membrane is still lacking. Here, we hypothesized that the pit membranes normally remain to be wetted in xylem vessels and noticed in particular the hydraulic role of water film on air spreading that has been overlooked previously. For the hydrodynamic study of the embolism spreading through a wetted pit membrane, we investigated the penetration and spreading dynamics of air plugs through the wetted cellulose membrane in a channel flow. Air spreading exhibits two types of dynamics: continuous and discrete spreading. We elucidated the correlation of dynamic characteristics of air flow and pressure variations according to membrane thickness. Our study speculates that the thickness of pit membranes affects the behaviors of water film captured by cellulose fibers, and it is a crucial criterion for the reversible gating of further spreading of embolism throughout xylem networks.

Experimental characterization of the impact of unsteady airflows on tracer gas measurement

Natural ventilation induces several issues when trying to measure airflows. Low pressure differences that drive natural airflows are very sensitive. A small pressure drop introduced by an airflow-meter would significantly affect the flow pattern. Furthermore, for window aired buildings or rooms, the implementation of a protocol to characterize the flow through a window is practically hard to implement and often poorly reliable. For these reasons, tracer gas methods are widely used to measure natural airflows. They do not interfere with the flow path, as they do not require any other instruments than concentration sensors. The principle is to inject a tracer gas inside a chamber and to observe the evolution of the concentration of the tracer gas. The knowledge of the emission rate of the gas, as well as its concentration evolution allows describing the airflow.Unfortunately, tracer gas methods are highly sensitive to the measurement noise, which is likely to be significant for concentration sensors. Most used methods, in the literature, use regression techniques to reduce the measurement noise. However, the regression implies steady airflows during the measurement, which should theoretically discard natural airflows. For lack of better methods, these techniques are often used in natural conditions, regardless of the variation of airflows. The present paper experimentally assess the impact of variable airflows on the accuracy of most common tracer gas methods, namely the constant injection and the concentration decay methods. The experiment was implemented in a laboratory cell, taking advantage of a controllable extract fan to simulate natural airflows, while allowing the direct measurement of the airflow in the extract duct. This value provides the reference value for the comparison of tracer gas methods results. Insights are also given, using signal-processing techniques to improve the reliability of tracer gas methods under variable airflows.

A Novel Device for Simultaneous Measurement of Nostril Air Flow Pressure and Temperature using Fiber Bragg Grating Sensor

This paper presents the design, development, calibration and demonstration of non-invasive, Nostril Pressure and Temperature Measurement Device (NPTD) employing Fiber Bragg Grating (FBG) sensors for the simultaneous, accurate and real-time measurement of nostril air flow pressure and temperature which can aid in clinical diagnosis of nasal dysfunction and associated nose disorders. The unique design of NPTD enables the comfortable measurement of randomly varying air flow pressure and temperature of both the nostrils simultaneously. To calibrate the pressure and temperature readouts of NPTD, suitable and in-house calibration techniques have been devised and adopted. The NPTD developed can provide certain critical features such as breathing pattern, rate of respiratory, individual nostril temperature/pressure, nostrils dominance pattern, body core temperature etc., which can aid clinicians in early diagnosis of breathing problems associated with heart, brain and lung malfunctioning. The developed NPTD is simple in design, practically implementable robust, EMI proof and non-electric, which are obligatory features for any clinical diagnostic tool used in a hospital environment.

Growth region characterization of carbon nanotubes synthesis in heterogeneous flame environment with wire-based macro-image analysis

Identification of carbon nanotube (CNT) growth region is paramount in a heterogeneous environment of flame to ensure an improved yield and growth rate. Previously, the growth region analysis in flame synthesis has been done based on repetitive scanning electron microscope (SEM) characterization that tends to be costly and time-consuming for a large heterogeneous environment. A systematic evaluation of the experimental method for growth region characterization is very limited. Therefore, the present study provides a detailed sensitivity and accuracy evaluation of a simple wire-based macro-image analysis (WMA) method for the measurement of steady-state and temporal change of growth region size for multiwalled carbon nanotubes (MWCNT) in a methane diffusion flame with varied air flow rate at atmospheric condition. The WMA method was developed to simplify the MWCNT deposit region identification using the image produced by digital single-lens reflex (DSLR) camera and post-processed using baseline data that was gathered through a one-time SEM analysis. Pure nickel wire was positioned in the flame with a stainless-steel wire grid placed on top of the substrate wire to redistribute the flow field. The MWCNT deposit region that is confined in the fuel-rich region at the inner side of the flame sheet shifts toward the flame centerline with the increase of the air flow rate from 1 to 10 slpm due to the shift of the flame sheet in the same direction. The inception and growth of MWCNT are consistently observed together with the formation of amorphous carbon layer, which has been verified based on detailed SEM analysis. The formation of amorphous carbon layer happens due to the higher rate of carbon supply compared to that of the carbon diffusion rate in nickel catalyst for CNT growth. These phenomena serve as the fundamental basis of the present WMA method. At 10 mm above the burner, the WMA method at steady state successfully detected the change in size and spatial distribution of deposit region by a factor of 2.28 and 2.68 respectively at varying air flow rate with ± 0.5 mm accuracy. The present method demonstrated high sensitivity to capture the temporal change of the deposit region length within the exposure time for the growth rate measurement of the deposit region. More than twofold increase in effective growth rate was successfully captured at a high air flow rate due to the change in equivalence ratio from rich to stoichiometry that promotes the increase in heat release rate. The present flame setup was able to produce a widest CNT deposit region with an optimum growth rate at 6 slpm air flow rate. High-resolution transmission electron microscopy (HRTEM) analysis verified that the synthesized CNT is hollow with multiwalled internal structure and Raman spectroscopy analysis indicated that crystallinity level of the produced MWCNT is relatively constant with the change in air flow rate.

Airflow simulation and inlet pressure profile optimization of a grain storage bin aeration system

The quality and conservation of grains depends directly on the storage system. Storage problems and inefficiency can lead to significant losses of the stored product, and high expenditure in energy and resources. To minimize these losses, an adequate and efficient aeration system is important, covering a uniform airflow throughout the grain mass domain. In order to have a good aeration system, a mathematical model and software were developed to simulate the distribution of 3D airflow in horizontal bulk storage bins during the aeration process under nonhomogeneous and anisotropic conditions. The criterion of evaluation of the specific airflow and the criterion of optimization of the aeration system were incorporated in the model. With the results, it was possible to perform the analysis of the air pressure, global and local specific airflow rate, and air velocity throughout the grain mass domain. Pressure data were obtained on a real storage system. The data obtained in the simulation were validated with observational, showing good agreement. Observational data of the pressure at different depths of the grain mass were obtained. An optimized aeration inlet air pressure profile was proposed, aiming at greater uniformity of the local specific flow distribution. The proposed theoretical air inlet profile allowed an 85.3% decrease in the airflow variation, but an 150% increase in maximum inlet air pressure at the centre of the storage bin was necessary. It could be used as a guideline for a new aeration system design.

Can the inhalation exposure of a specific worker in a cross-ventilated factory be evaluated by time- and spatial-averaged contaminant concentration?

Industry implies economic growth; however, outdoor and indoor air pollution generated by industrial activities represents a widespread problem for the environment and human beings. In terms of human health, indoor air quality assessment has become essential in a society where people spend most of their time in indoor dwellings, as in the case of industry workers. Because indoor air quality is strongly affected by the outdoor environment, especially under natural ventilation conditions (e.g., cross-ventilation), a comprehensive analysis that includes outdoor atmospheric-urban environment is needed to reproduce realistic scenarios. In this context, computational fluid dynamics (CFD) is a useful tool. To perform a precise analysis of the inhalation exposure of factory workers to potential gas-phase contaminants in the working environment (i.e., inhaled dose of contaminants and potential effects), the human body and respiratory tract need to be integrated in the analysis. Therefore, in this study, we performed an integrated occupational inhalation exposure/toxicology assessment in a factory building that applies a computer simulated person (CSP), a virtual human respiratory tract and integrated physiologically-based toxicokinetic (PBTK) model to predict tissue dosimetry distribution. Outdoor airflow variation was transported into the enclosure through an hourly change in wind pressure coefficient to calculate transient ventilation rate and indoor contaminant concentration between 08:00 and 17:00 h. Thereafter, the time-averaged contaminant concentration calculated at the nares of the human body was employed in a steady state calculation of airflow and contaminant distribution inside the virtual respiratory tract. Subsequently, we predicted adsorbed contaminant in the first layer of tissue of the human airways; highest adsorption took place in the nasal cavity. Finally, based on the results of the comprehensive coupled numerical analysis performed using the CFD-CSP-PBTK model, we quantitatively discussed differences between the inhalation exposure concentration and representative contaminant concentration in the factory space (e.g., time and volume-averaged concentration).

Static Flame Stability of Circumferentially Arranged Fuel Port Inverse Jet Non-Premixed Flame Burner

ABSTRACT This paper presents experimental studies on flame appearance and static flame stability characteristics of inverse jet flame (IJF) using a circumferentially arranged fuel port (CAFP) burner by following two different methods, namely, Protocol I and Protocol II. In the case of Protocol I, experiments are conducted for a fixed air flow rate, by varying fuel flow rate whereas, in the case of Protocol II, by varying air flow rate for a fixed fuel flow rate. In Protocol I, the flame is lifted off from the burner rim unlike in Protocol II. Moreover, the flame base becomes unstable at higher fuel flow rate before the occurrence of flame liftoff for Protocol I. Momentum flux ratio (MFR) and overall equivalence ratio parameters are considered to obtain insights on the phenomenon with variation of flame liftoff height in CAFP-based IJF burner. An attempt has also been made to analyze the hysteresis effect on the flame liftoff. In contrast to the normal jet diffusion flame, the hysteresis effect is observed at lower MFR, and is absent particularly when the base flame gets strongly anchored to the burner rim for higher MFR. On the other hand, in Protocol II, with an increase in air velocity, the inverse jet diffusion flame is no longer diffusion controlled, rather mixing controlled. In addition, the flame blowoff for Protocol I is attributed to occurrence of leaner overall equivalence ratio obtained by reduction of fuel flow rate whereas global strain rate governs flame blowout for Protocol II. In addition to flame blowout and liftoff, the main flame for Protocol II experiences local extinction and re-ignition at certain conditions with increase in the global strain rate at certain threshold value. In addition, semi-empirical correlations based on Peclet number for main flame extinction, flame blowout and flame blowoff are proposed in the present study which can be employed for designing CAFP-based IJF-based combustor system.

Oscillating flow rig for air turbine testing

Oscillating water column (OWC) devices equipped with an air turbine are the most extensively studied and possibly the most reliable wave energy converters (WEC). Self-rectifying air turbines are usually employed, being the key element of the power-take-off system. Experimental testing the air turbine in realistic operating conditions is a fundamental step in turbine and WEC development. These turbines are, by definition, operating under oscillating airflows. The present paper describes the development of a novel test-rig designed to test self-rectifying air turbines under both steady and variable unidirectional airflows, and subsequent demonstration tests performed on an axial-flow impulse turbine. A real-time hardware-in-the-loop flow controller was implemented, providing the means to not only experimentally characterise the turbine's performance under realistic wave conditions, but, as importantly, to develop new advanced turbine-generator control strategies that further increase overall efficiency and survivability. Results show that a unidirectional oscillating-flow test-rig with a calibrated fan and fast-actuating valve system can adequately reproduce airflows that are characteristic of an OWC air turbine's operational regime. The hardware-in-the-loop simulator implemented in an oscillating-flow test-rig appears as an innovative, integrated solution for turbine testing in realistic operating flow conditions, but in a laboratory-controlled environment at a small fraction of the costs.

Evaluation of Titration Method on Determination of Ozone Concentration produced by Dielectric Barrier Discharge Plasma (DBDP) Technology

Determination of the ozone concentration produced by a reactor is very important. The titration method is an analytical chemical method with high accuracy still in use. Research on titration for measurement of ozone concentration generated by a generator at a given flow rate has been done. Ozone is produced by a dielectric barrier discharge plasma reactor. The reactor is formed with a cylindrical-cylindrical electrode configuration made of stainless steel wire mesh. Evaluation of ozone concentration of titration method was done by varying air flow rate between 4-15 liter/min. The titration time is varied between 3-12 minutes. Voltage source was used a high-voltage AC with variation between 6 - 11 kV. The greater the air flow rate the resulting ozone concentration will decrease. The concentration of ozone obtained is smaller with a large tear time at the same voltage and flow rate. From the results of this study, the time of titration in determining the concentration of ozone is not required larger, at 3 minutes has given the best results. The long of titration time probably the ozone dissolve and saturated in the titrant (KI) and released into the air again.

Correlation of regional deposition dosage for inhaled nanoparticles in human and rat olfactory

BackgroundNose-to-brain transport of airborne ultrafine particles (UFPs) via the olfactory pathway has been verified as a possible route for particle translocation into the brain. The exact relationship between increased airborne toxicant exposure and neurological deterioration in the human central nervous system, is still unclear. However, the nasal olfactory is undoubtedly a critical junction where the time course and toxicant dose dependency might be inferred.MethodComputational fluid-particle dynamics modeling of inhaled nanoparticles (1 to 100 nm) under low to moderate breathing conditions (5 to 14 L/min – human; and 0.14 to 0.40 L/min – rat) were performed in physiologically realistic human and rat nasal airways. The simulation emphasized olfactory deposition, and variations in airflow and particle flux caused by the inter-species airway geometry differences. Empirical equations were developed to predict regional deposition rates of inhaled nanoparticles on human and rat olfactory mucosa in sedentary breathing. Considering, breathing and geometric differences, quantified correlations between human and the rat olfactory deposition dose against a variety of metrics were proposed.ResultsRegional deposition of nanoparticles in human and the rat olfactory was extremely low, with the highest deposition (< 3.5 and 8.1%) occurring for high diffusivity particles of 1.5 nm and 5 nm, respectively. Due to significant filtering of extremely small particles (< 2 nm) by abrupt sharp turns at front of the rat nose, only small fractions of the inhaled nanoparticles (in this range) reached rat olfactory than that in human (1.25 to 45%); however, for larger sizes (> 3 nm), significantly higher percentage of the inhaled nanoparticles reached rat nasal olfactory than that in human (2 to 32 folds). Taking into account the physical and geometric features between human and rat, the total deposition rate (#/min) and deposition rate per unit surface area (#/min/mm2) were comparable for particles> 3 nm. However, when body mass was considered, the normalized deposition rate (#/min/kg) in the rat olfactory region exceeded that in the human. Nanoparticles < 1.5 nm were filtered out by rat anterior nasal cavity, and therefore deposition in human olfactory region exceeded that in the rat model.ConclusionRegional deposition dose of inhaled nanoparticles in a human and rat olfactory region was governed by particle size and the breathing rate. Interspecies correlation was determined by combining the effect of deposition dosage, physical\\geometric features, and genetic differences. Developed empirical equations provided a tool to quantify inhaled nanoparticle dose in human and rat nasal olfactory regions, which lay the ground work for comprehensive interspecies correlation between the two species. Furthermore, this study contributes to the fields in toxicology, i.e., neurotoxicity evaluation and risk assessment of UFPs, in long-term and low-dose inhalation exposure scenarios.

CFD study on particle grouping under an oscillatory flow in a wavy duct

Particle grouping that arises from temporal and spatial variation of air flow is a promising method to facilitate agglomeration and removal of aerosol. We conduct a computational investigation on this phenomenon under an oscillatory flow in a wavy duct using a discrete phase method. This setup is simple and practically feasible. The grouping behavior is affected by the flow Reynolds number, duct wavelength, angular frequency of oscillation, ratio of minimum to maximum duct diameter and velocity ratio. Three different regimes are identified: no grouping, stable/strong grouping and unstable/weak grouping. It is found that a moderate delay of flow response to the imposed pulsations is critical for grouping. Among the investigated values for the periodicity parameters, the strongest grouping takes place when the duct wavelength is four times the maximum duct diameter, and the angular frequency of oscillation is five times the reciprocal of characteristic flow time. Moreover, an increase in the velocity ratio and a decrease in the diameter ratio further enhance the grouping behavior under otherwise identical conditions. Due to the flow complexity in this realistic setup, the criterion for particle grouping is different from that based on an ideal 1D standing wave flow field in the literature.

Microwave Plasma Gasification Performance of Sawdust

In this study, the gasification performance of the pine tree sawdust and hornbeam sawdust at varied air flow rate and microwave plasma power are investigated. In each case, 250g sawdust are dosed to gasification reactor. The effects of power and air flow rate on syngas composition and reactor temperature are studied. The sawdust contents are examined by ultimate and proximate analysis. The heating value of the fuels are measured as 21353 kJ/kg for hornbeam sawdust and 17942 kJ/kg for pine tree sawdust by bomb calorimeter. The syngas content is substantially proportional with the content of the fuel. The variation of local temperatures during the gasification is of great importance on the process. The temperature is increased by increasing the power and the conversion performance of sawdust is enhanced. Air flow rate has a reverse effect on both magnitude of the temperate and syngas yield. The temperature in gasifier increase %54 in case of 50 sL/min and approximately %80 in case of 100sL/min by increasing power from 3 kW to 6 kW. CO, CH4 and H2 conversion increase by increasing the power while CO2 conversion decreases by power. Unlike to the effect of power, increase of air flow rate from 50 to 100 sL/min enhances CO2 conversion, with a reduction in the conversions of CO, CH4 and H2.

Dual-Modality Electrical Tomography for Flame Monitoring

Electrical capacitance tomography has been widely used in flame monitoring. In this paper, a dual-modality electrical tomography system was developed for imaging of flame admittivity distribution, including conductivity and permittivity distributions. An admittance measuring circuit was developed to obtain both resistance and capacitance of the flame impedance, and a Calderon method-based reconstruction algorithm was developed, which could be used to directly reconstruct the cross-sectional images of both conductivity and permittivity in the flame. The 2-D and 3-D phantoms were modeled in simulation to validate the feasibility of the developed system and algorithm. Experiments were carried out to monitor a Bunsen burner flame with varied air flow rates. Both simulation and experimental results were confirmed that the developed technique has not only reconstructed the cross-sectional distribution of admittivity in the flame but also revealed variations in flame admittivity with height. In addition, it was discovered that the conductivity and permittivity distributions in the flame were affected by the air flow rates. Therefore, the system can be used to monitor the conductivity and permittivity distributions in the flame and, hence, can further help study the combustion mechanism.

Seasonal Variations in Airflow Over the Namib Dune, Gale Crater, Mars: Implications for Dune Dynamics

AbstractDune length scale airflow modeling provides new insights on eolian bedform response and complex near‐surface 3‐D wind patterns not previously resolved by mesoscale models. At a 1‐m surface resolution, Curiosity wind data are used to investigate the eolian environment of the Namib dune on Mars, providing improved seasonal constraints on grainfall, grainflow activity, and ripple migration. Based on satellite images, airflow patterns, and surface shear stress, enhanced eolian activity, and slipface advancement occurs during early springtime. Autumn and winter winds are also favorable to eolian activity, but minimal movement was detected in satellite images overlapping with wind data. During the summer, the migration of large stoss ripples on the Namib dune may augment sediment deposition on the slipface. These results provide a better understanding of the overall migration pattern of the Namib dune, which can be extrapolated to other dunes in the Bagnold Dune Field.

Mapping of Nonconformities that Impact the Performance of Cooling Towers: Refinery Case

The current world outlook of supply and demand for basic inputs, such as in the case of water, has created an alarming situation for all of society, especially the industrial sector. Cooling Towers are the equipment responsible for the removal of heat from a stream of hot water from an industrial process and at the same time they are the most water-consuming equipment in the industry. Their good performance is directly linked to the sustainable consumption of water present in the environment. In this context, audits for the mapping of nonconformities encountered frequently in tower operation become a useful tool to increase the efficiency of the equipment. As a step in this mapping and work objective, discussions were carried out on two irregularities commonly identified in operation, such as: (1) variation of the water feed load; (2) variation of air flow, in addition to its main causes and impacts on the operation and efficiency of the equipment. Actual data were obtained for the case study of a tower located in Petroleum Refinery in Brazil. The controlled variable chosen for the study was the outlet water temperature of the tower. The model used to identify the output temperature is based on Merkel's theory, using the Tchebeycheff method for numerical integration. Therefore, with the variations carried out, it is possible to verify the direct influence on the outlet temperature and to identify possible causes of the irregularities addressed in the study.