Effect Of Fan Speed Research Articles

Effect of turbulent fluctuation on the ignition of millimeter particle: Experimental studies and numerical modelling with a new correlation of nusselt number

Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is essential. In this work, to study the effect of turbulent fluctuation on ignition time, millimeter coal particles are subjected to a specific flow field, generated in a furnace with symmetric fans. A one-dimensional model with the new proposed correlation and the Ranz-Marshall (R-M) correlation for Nu (Nusselt number) is established to simulate the coal ignition process. In addition, the effects of fan speed, temperature, particle diameter, particle distance and coal type on the ignition time are investigated. It is found that an increase in fan speed from 0 to 3000 rpm leads to a particle Reynolds number Rep increase from 0 to 22.5, and a turbulent particle Reynolds number Ret∗ increase from 0 to 71.5. With a consideration of the fluctuation effect, the new correlation of Nu gives a better prediction of ignition time compared to the R-M correlation. Moreover, the ignition time is revealed to decrease with an increasing fan speed and an elevating temperature. While the ignition time shows merely an initial boost with enlarging particle distance, it exhibits a linearity with the term of particle diameter dp1.3–1.7 and Reynolds numbers (Nu∗/Nu)–0.6 (Nu∗ is turbulent Nusselt number). Based on this relationship, the difference of predicted ignition time is calculated at different Rep and Ret∗. It is shown that at low Rep or high Ret∗ values, the new correlation should substitute for the R-M correlation.

Analysis of cyclic frosting and defrosting of a vehicle heat pump

Heat pumps are used for energy-efficient heating in electric vehicles. If ambient air is used as a heat source, frost may form on the surface of the exterior heat exchanger at low ambient temperatures. If significant amounts of frost accumulate, the heat exchanger performance degrades and it must be defrosted. The aim of this work is the energy analysis of a heat-release-controlled vehicle heat pump with a direct flat tube evaporator in cyclic frosting and defrosting operation. The effects of fan speed and number of refrosting phases on the heat quantity released per frosting phase are analyzed on a laboratory test rig. The experiments show that the heat quantity released decreases with lower fan speed and increasing number of frosting phases. Defrosting operation parameters are also examined using the test rig and it is found that shorter defrosting times can be achieved at higher compressor speeds and larger expansion valve openings. A numerical model of the heat pump in cyclic frosting and defrosting operation is developed and validated using test rig data. An average relative deviation of less than 7% is determined between the model and experimental data. The heat pump is then integrated in a prototypical vehicle and the model is calibrated with experimental data from test drives. A numerical study of the validated vehicle heat pump model in cyclic frosting and defrosting operation shows a maximum increase of the mean total electric power consumption of 33% between dry air and saturated moist air at an ambient temperature of 0 °C. At an ambient temperature of -10 °C the mean total electric power consumption increases by 17% from dry air to saturated moist air conditions.

Comprehensive efficiency analysis of air-cooled vs water-cooled electric motor for unmanned aerial vehicle

The efficiency of an electric motor for an unmanned aerial vehicle can reduce when its temperature exceeds the working temperature. In this paper, air- and water-cooling methods for electric motors in unmanned aerial vehicles are proposed and comprehensively compared. The effects of fan speed, water flow speed, and convection heat transfer coefficient on the outer surface of the electric motor on the cooling capacity of the electric motor are discussed. A comprehensive performance evaluation factor for the cooling method of the motor is proposed. Results show that when the fan speed increased from 800 to 2000 rpm, the cooling efficiency increased by 27.78% for the air-cooled motor, whereas when the inlet flow rate of cooling water increased from 0.1 to 0.9 m/s, the cooling efficiency increased by 67.47% for the water-cooled motor. The comprehensive performance of the water-cooled motor reached the highest level with a velocity of 0.7 m/s. The convection heat transfer coefficient increased from 5 to 25 W/(m2·K), and the cooling efficiency increased by 22.93% and only 2.77% for the air- and water-cooled motors, respectively. These findings can provide guidance for designing highly efficient electric motor cooling equipment for unmanned aerial vehicles.

Machine Learning-Based Investigation of the 3D Printer Cooling Effect on Print Quality in Fused Filament Fabrication: A Cybersecurity Perspective

Additive manufacturing (AM), also known as three-dimensional (3D) printing, is the process of building a solid object in a layer-wise manner. Cybersecurity is a prevalent issue that appears more and more frequently as AM becomes popular. This paper focuses on the effect of fan speed on the printing quality and presents a plugin called Fan Speed Attack Detection (FSAD) that predicts and monitors fan speeds throughout the printing process. The goal of the plugin is to prevent cybersecurity attacks, specifically targeting fan speed. Using the proposed FSAD, any fan speed changes during the printing process are evaluated to see whether the printer can sustain the abnormal fan speed change and still maintain good print quality.

气吸式排种器的气流场特性试验研究

The vacuum seed metering device absorbs seeds by using the negative pressure generated by vacuum air flow. Therefore, it is of great significance to study the variation law of pyrolysis gas flow field to improve its seed metering performance. In this paper, the common disc and composite disc were selected as the research objects and tested on the indoor test-bed. The negative pressure was measured by U-type barometer, and the effects of fan speed, suction hole size, seed hole structure and air chamber thickness on the air flow field were studied. Firstly, the influence of fan rotation frequency on vacuum chamber negative pressure is studied, and the variation law of negative pressure in vacuum chamber and fan port of common disc and composite disc under the same frequency is compared. Secondly, the suction holes in the vacuum chamber were numbered, the negative pressure distribution of the suction holes was measured, and the influence of the number and diameter of the suction holes on the negative pressure of the vacuum chamber was studied. Finally, the negative pressure was measured at the distance of 0 to 10 mm from the suction hole to study the effect of seed hole structure on the air flow field. Moreover, increase the additional thickness of the vacuum chamber from 0 to 40 mm to study the influence of the chamber thickness on the distribution of the gas flow field. This paper makes a comprehensive experimental analysis on the influencing factors of air flow field of air suction seed metering device, necessary for future design of air suction seed metering device.

Testing and Analysis of the Extractor of a Sugarcane Chopper Harvester

Abstract. Performance tests were carried out on the primary extractor of a Chenhan 4GQ-130 sugarcane chopper harvester to improve the harvesting quality, increase the economic benefits, and reduce the harvesting cost. The tests were designed to identify the relationships of three performance indexes (impurity rate, cane loss, and power consumption) to the main influencing factors (fan speed, air speed, and feeding rate of sugarcane). Single-factor tests showed that fan speed was positively correlated with air speed and pressure. The high feeding rate of 3 kg s-1 had a higher impurity rate than the low feeding rate of 2 kg s-1. The average power consumption was higher at the high feeding rate than at the low feeding rate. However, the results of a 2 × 3 factorial experiment showed that feeding rate did not have significant effects on the impurity rate, cane loss, and power consumption (p > 0.1). It also showed that fan speed had no significant effect on the impurity rate (p > 0.1). However, at a significance level of a = 0.05, fan speed had a highly significant influence on cane loss and power consumption (p < 0.01). Compared to the feeding rate, the effect of fan speed on each performance index was more significant. Fan speed was important for the impurity rate, cane loss, and power consumption. The interaction of feeding rate and fan speed was not significant. Therefore, the optimal fan speed should be determined for a suitable feeding rate, air speed, and air pressure, which determines the extractors’ optimal performance. Keywords: Air speed and pressure, Cane loss, Fan speed, Feeding rate, Impurity rate, Power consumption.

Grain Sieve Loss Fuzzy Control System in Rice Combine Harvesters

The main working parts of the cleaning device of a rice combine harvester can be controlled by an established control strategy in real time based on the monitored grain sieve loss. This is an efficient way to improve their cleaning adaptability, since as a consequence, the main working parameters of combine harvesters can automatically adapt to crop and environment changes, and the corresponding cleaning performance can be improved. To achieve the target of cleaning control based on the monitored grain sieve loss, a fuzzy control system was developed, which selected S7-1200 PLC as the main control unit to build the lower computer hardware system, utilized ladder language to complete the system compilation, and used LabVIEW 14.0 software to design the host–computer interface. The effects of fan speed, guide plate angle, and sieve opening on the grain sieve loss and grain impurity ratio have been investigated through a large number of bench tests. The relevance level of the operating parameters on the performance parameters has been determined also, and finally, a fuzzy control model was developed for the cleaning system. The experiment results indicated that the designed fuzzy control model can control the cleaning section settings, such as fan speed and guide plate angle automatically, and reduce the grain sieve loss to some extent.

Determining Seed Cotton Mass Flow Rateby Pressure Drop across a Blowbox

<abstract> <b><sc>Abstract. </sc></b>A seed cotton mass flow rate sensor would offer useful feedback for gin managers and provide a critical input for advanced process control systems. Several designs of seed cotton mass flow rate sensors have been evaluated in the laboratory, but none have found acceptance in commercial gins. The objectives of this research were to develop a system for predicting seed cotton mass flow rate based on the pressure drop measured across a blowbox; investigate the effect of pipe diameter, cultivar, moisture content, feed rate, and fan speed on this relationship; and provide recommendations for developing a prototype system for testing in commercial gins. A negative pressure pneumatic conveying system was constructed with a variable-speed feed control and fan. The inlet air velocity, blowbox pressure drop, temperature, and relative humidity were recorded during testing. A model was developed to predict the seed cotton mass flow rate based on the blowbox pressure drop, air velocity, air density, and pipe cross-sectional area. The model was calibrated by conveying a known mass of seed cotton through the system and integrating the model over this time. Mean absolute error in predicting seed cotton mass was 7.35%. Cultivar and moisture content had no effect on the model regression coefficients. Significant differences existed between the regression coefficients of different feed rates; however, these only occurred at mass flow ratios much larger than those achieved in commercial gins. The effect of fan speed was small and likely not practically significant. Measuring the pressure drop across a blowbox is a suitable basis for further development of a seed cotton mass flow rate sensor for commercial gins.

Effects of Fan Speed on Rotating Stall Inception and Recovery

An implicit, time-accurate 3D compressible Reynolds-averaged Navier-Stokes (RANS) solver is used to simulate rotating stall inception and recovery, the so-called rotating stall hysteresis, in the case of a modern fan geometry. In the first instance, rotating stall was simulated for 70%, 80%, and 90% fan speeds using a whole-annulus fan model with a variable-area nozzle downstream. As the fan speed is increased, the stall cells also increase in size but their number decreases. One large stall cell is predicted to rotate along the annulus at 80% and 90% speeds, while there are three smaller cells at 70% speed. In all cases, the reverse flow is confined to the near-tip region and the rotating stall does not develop into a full-span stall because of the fan blade’s high-aspect ratio. To simulate stall recovery, the nozzle area was increased gradually at 70% and 90% speeds and the flow was seen to recover from rotating stall to reach an unstalled operating condition. The recovery process was found to be affected by the fan speed. At 70% speed, the large disturbances decay first to form almost symmetric stall cells. Thereafter, the stall cells shrink into smaller ones as the mass flow rate increases further. At 90% fan speed, a single stall cell rotates along the annulus, the disappearance of which results in recovery. An attempt has been made to explain the dependence of the stall inception and recovery patterns on the fan speed.

Deposition and Air Speed Patterns of Air-carrier Apple Orchard Sprayers

Semi-dwarf apple trees were treated with foliar micronutrients using two different forms of orchard air-carrier sprayers. The effects of fan speed, travel speed, and spray emission patterns on in-canopy air speed and spray deposition were evaluated. The FMC Economist fan outlet air speed did not significantly affect deposit patterns. Deposit levels and patterns were influenced by changes in the spray emission pattern and by the position of the fan and nozzle manifold assembly. An 8% difference in the output between the upper and lower half of a nozzle manifold on the FMC Economist sprayer did shift, although not significantly, the vertical spray deposition in the canopy. The raised fan and nozzle manifold assembly of the Friend Air Kadet II produced the best vertical distribution of spray deposits. Increasing travel speed from 0.9 to 1.3 m/s did not significantly decreased air speed within the trees. In-canopy air speed measurements followed patterns similar to the spray deposits but there was not a good correlation between air speed and one-pass spray deposit.