Fan Speed Research Articles

Optimization of Heat Dissipation for Fan Cooling Solution

Abstract Today’s ECUs (Electronic Control Units) face a high-power density mounted in a very small volume due to miniaturisation, available space, and weight limitations. For this reason, the resulting heat dissipation has become increasingly difficult to manage and continuous efforts are being made to optimize thermal management in this direction. This paper shows an improvement in heat dissipation by finding an optimal configuration between the fan speed and the distance between the cooling fins using the Design for Six Sigma methods. The focus was on finding a reliable transfer function that could predict the influence of the identified critical design parameters. Two transfer functions were derived and analysed in parallel; one based on Design of Experiments (DoE) and another based on simplified thermal theory. The accuracy of the transfer function and predictions were compared with the results of thermal simulations performed in the Ansys Icepack program. This shows that the use of the DoE method based on a small number of simulations is sufficient to estimate the behaviour of the ECU, without using a more complex theoretical approach.

Temperature control system on greenhouse effect gaplek dryer

Gaplek is a processed product of cassava that requires a drying process to remove the water content in cassava. Solar thermal energy can be used for the drying process of gaplek by using a greenhouse effect drying system. However, the greenhouse effect drying system using solar thermal energy is very dependent on weather conditions and temperature that is difficult to control. Therefore, a temperature control system is proposed in this study by utilizing Pulse Width Modulation (PWM) to control the exhaust fan speed. Thus, the temperature can be maintained according to the drying standard of processed cassava products. In this study, a temperature control system has been successfully created that is able to maintain the temperature in the drying room according to the drying standard, namely at a temperature of 50℃ to 60℃ when tested in three different locations, namely, Sukamaju Village, Kaligunting Village, and Sumberejo Village which have shown optimal drying temperature.

A Knowledge-Based System for Intelligent Control Model of Rice and Wheat Combine Harvester

The intelligent regulation and control strategies for rice and wheat combine harvesters’ operation are lacking and the rule of parameter matching is fuzzy in China, around these issues. The dynamic correlation control law among the parameters of rice and wheat, cleaning operation parameters of combine harvesters, the cleaning loss rate and impurity rate, and so on are studied. The intelligent control model for the rice and wheat combine harvester is established based on case-based reasoning (CBR). According to different rice and wheat varieties, water content and other rice and wheat properties, the control scheme of cleaning fan speed, air distributor plate angle and upper sieve opening with low cleaning impurity rate and cleaning loss rate is provided. Through the development of web-based cleaning intelligent control expert system and experimental evaluation, the feasibility and effectiveness of the CBR method in the intelligent control filed of rice and wheat combine harvesters are verified.

A two-layer framework for optimal control of battery temperature and microgrid operation

Battery energy storage is an essential component of a microgrid. The working temperature of the battery is an important factor as a high-temperature condition generally increases losses, reduces useful life, and can even lead to fire hazards. Hence, it is indispensable to regulate the temperature profile of the battery modules and packs properly during its operation. In view of this, a two-layer optimal control and operation scheme is proposed for a microgrid with battery energy storage. In the first layer, an optimal control model is formed to derive the optimal control policy that minimizes the control efforts, consisting of the fan speed and battery current magnitude, in order to achieve a reference value of temperature in the battery module. In the second layer, the system operator of the microgrid performs an optimal power flow to search for the optimal reference for temperature and the corresponding operating current of the battery that minimizes the operation cost of the entire microgrid system. This two-layer scheme offers a great computational benefit that allows for large-scale integration of batteries. A case study is performed on the proposed two-layer framework to illustrate its performance.

Assessment of airflow and heat transfer around a thermal manikin in a premise served by DOAS and ceiling fans

Ceiling fan improves thermal comfort and reduces air-conditioning energy consumption in super low energy buildings operated at warmer room air temperature with increased air movement. This paper investigated the characteristics of airflow generated by the ceiling fans around a thermal manikin body, and the convective heat transfer caused by the airflow distribution through experiment and CFD for standing and seated postures. The standing and seated postures showed almost the same convective heat transfer for the whole-body, but the contribution of mean velocity and turbulence components were different. Turbulence intensity (median value and dispersion) of the seated posture was higher, and the dispersion range reaches between 20 and 84% despite the average velocity being relatively low compared to the standing posture when the fan speed exceeds 100 rpm. The convective heat transfer coefficient for the whole-body caused by the ceiling fan was 32–75% of the horizontal air flow cases of previous studies at inflow air speed under 1.1 m/s for both postures. On the other hand, under ceiling fan flow the heat transfer coefficient at the lower body of the manikin remains relatively low compared to horizontal flow even at increased fan speeds. This difference potentially leads to a different thermal sensation in corresponding body parts between the ceiling fan flow and the horizontal flow situations.

Improving the nonlinear control performance of the supply fan at air handling units using a gain scheduling control strategy

Due to its nonlinear nature, the supply fan at air handling units with the controller tuned at the design condition tends to be aggressive and oscillate under partial load conditions. The objective of this paper is to develop and validate a gain scheduling control strategy to improve its nonlinear control performance. First, a control-oriented model, which does not require numerous physical parameters and extensive test data, is developed to study the nonlinearity of the fan system. Based on the theoretical model and experimental verifications, the issue of an aggressive response with a conventional fixed-gain controller is caused by the fact that the system gain is proportional to the ratio of the duct static pressure to the fan speed. To address the issue, a scheduling function of the measurable duct static pressure and fan speed is proposed to be included in the conventional fixed-gain controller to compensate for the fan system gain variation. The gain scheduling control strategy is found to approximately maintain the identical control performance under all operation conditions. Most importantly, the gain scheduling control strategy can be readily implemented without intensive computation and additional measurements, showing a promising potential in industrial applications.

Flow Analysis of Various Inlet Velocity Profiles on Indoor Temperature for Energy Conservation of HVAC System Using CFD

Energy conservation has been the most popular topic of the modern world. Heating, Ventilation and Air Conditioning (HVAC) systems consume approximately 10 % of the total energy of world. In order to improve the efficiency of HVAC systems, two dimensional (2D) room with inlet, outlet and heat source has been modeled. ANSYS Fluent has been used for numerical analysis of air flow in a 2D room. User Defined Functions (UDFs), which are coded in C language and hooked in ANSYS fluent, have been used for recording temperature variations and for heat generation within 2D room. Besides studying velocity fields and temperature distributions within indoor environment under specified boundary conditions, reference region for comparative analysis is also selected during Steady State (SS) numerical simulations. During transient analysis, temperature variations of a selected location are recorded for four different scenarios under varying inlet velocity profiles i.e. three for 0°, 30°, 60° angle with 1.3661 m/s velocity and fourth 0° with 2.7322 m/s velocity. Temperature profile of reference region after 1500 sec of transient simulations are compared with the steady state. Temperature profile of the scenario once the air is injected at 30° closely matched with the steady state temperature profile of the selected region. Time for attainment of SS temperature is also measured and compared after transient simulations. SS temperature value was attained twice, first at 240 seconds when the air was injected at 0° with 2.7322 m/s and secondly at 522 seconds when inlet air entered at velocity of 1.3361 m/s at 30°. The power consumption by increasing the fan speed is much higher as compared to the power consumed for changing direction only.

Experimental investigation of the simultaneous effect of using phase change material/plate-fin heat sink on thermal performance of a power supply unit

In this paper, a thermal management system of a personal computer power supply unit (PSU) is experimentally investigated. The simultaneous use of a passive cooling system such as PCM with a fan that is an active cooling system can improve performance and increase the lifetime of the PSU. Three cases with different volume fractions of fins have been fabricated. To investigate the effect of the fan on the thermal performance of the PSU, the experiments carried out at a minimum and maximum fan speed. The chosen PCM for this study, CaCl2.6H2O , is an inorganic salt-hydrate. According to the different operating conditions of the PSU, the input heat fluxes to the heat sink are variable. The results show that with simultaneous of fan/PCM, the average reduction in the steady temperature of the PSU circuit at the minimum and the maximum fan speeds are 12.8 (°C) and 12.4 (°C), respectively. The results indicate that increasing the number of fins does not have a favorable effect on the thermal performance of the PSU. On the other hand, using of a passive cooling system like PCM can be effective in reduction the dimensions and energy consumption of the fan.

Research on performance of liquid drive fan cooling system for hydrogen fuel cell forklift

Due to the large energy consumption as well as poor controllability and other problems, the traditional cooling system has not been able to adapt to the development needs of construction machinery with the continuous upgrading of emission regulations. This paper introduces a hydraulic driven fan cooling system based on pilot operated electro-hydraulic proportional valve. In order to make the whole machine quickly reach the temperature required in the best working condition when the construction machinery starts working, controlling the fan at a lower speed can reduce the heat dissipation and save energy. The electronic control system will adjust the motor speed in time when the temperature of the fluid rises, and control the temperature in the best temperature range required. A one-dimensional simulation model of this stepless speed control system is established to predict the parameter sensitivity of the electro-hydraulic proportional valve and the dynamic performance of the system. The simulation shows that the fan speed of the system can reach the required speed in only 5s at the extreme high temperature of 40 °C; the fan input power of the system accounts for 65% of the system input power at −30 °C and reaches 80% at 40 °C. Three-dimensional simulation shows that the fan-front temperature-controlled cooling system for forklift truck has high heat dissipation efficiency and can be applied to other heavy machinery products.

PROTOTYPE SISTEM PENGATURAN KECEPATAN KIPAS DC OTOMATIS MENGGUNAKAN SENSOR PIR, SENSOR ULTRASONIK, SENSOR DHT11 BERBASIS MIKROKONTROLER ARDUINO UNO DAN NODEMCU

fan is always ordinary thing at home, human needs fan for comfortable while rest, and lower the temperature of the body if the weather is too hot. But fan brings adverse effect like, the experience pain in certain parts of the body, for example,stiffness due to being exposed to a wind blow of the fan that is always strong against the body.The purpose of making this prototype is to automatically adjust the fan speed based on the distance from the fan to the human. by using an ultrasonic sensor, by using Passive Infrared sensor, we can automatically turn off without pressing any button so that the fan can turn on, and there is also a DHT11 sensor which can make us know the room temperature and humidity of the room being occupied, the fan will automatically turn off if it does not detect humans within 1 minute 40 seconds, in this project we can also turn on or turn off the fan if you really want to turn it on even though no one is in front using the Blynk application, and the temperature and room will also appear on the Blynk application, the microcontroller used is ArduinoUno, and NodeMCU as intermediary for the internet

Neural network and adaptive neuro‐fuzzy inference system modeling of the hot air‐drying process of orange‐fleshed sweet potato

The primary objective of this study is to determine the hot air drying characteristics and nutritional quality of orange-fleshed sweet potato (OFSP) in a convective dryer. Three temperatures (323.15, 333.15, and 343.15 K) and fan speed levels (0.5, 0.9, and 1.3 m/s) were used. A rehydration study of dried OFSP was also carried out. Modeling and prediction of experimental moisture data were done using artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS) models. The result showed that the drying rate and rehydration ratio were significantly (p < .05) affected by drying temperature and fan speed levels. The effective diffusivity (Deff) of the samples ranged from 2.5 × 10–9 to 4.25 × 10–9 m2/s, and it was found to increase with temperature and fan speed. Protein and fat content appeared to be strongly influenced by drying processing variables, whereas other properties appeared to be insignificant. ANFIS showed better modeling ability than ANNs in predicting the experimental moisture data of OFSP with R2 and RMSE values of .99786 and 0.0225 respectively. In conclusion, the findings from this research will be useful in product optimization and process monitoring of hot air drying of OFSP, in establishing its drying temperature and fan speed. Practical applications Dried orange-fleshed sweet potato (OFSP) is utilized as a precursor to many industrial goods and feedstock in the food industry. Establishing the process conditions for drying of OFSP is very important for product adaptability by industries. Modeling the drying kinetic data is useful for developing controls for industrial dryers. Mathematical models have been used in time passes, although they lack the robustness to combine several process variables at time. Therefore, this study applied robust artificial intelligence tool; artificial neural networks, and adaptive neuro-fuzzy inference system (ANFIS) in the prediction of the drying curve of OFSP. Also, the study shows how the process variables affect the quality of the chips. ANFIS showed better prediction ability, and thus can be used in developing robust control systems for industrial drying of OFSP.

Comparative study of purifications technologies and their application to HVAC systems

Nowadays, there is a growing demand to guarantee indoor air quality in buildings. This study presents a solution that combines hygrothermal control and purification of the air supplied to occupied spaces, in which the control and purification system is integrated into the air distribution ductwork. Among all the air purification technologies, not all of them are suitable to be used in the residential and tertiary sector along with already installed HVAC systems. In this study, a review of the state of the art of technologies is made and the major purification techniques are analysed and compared, i.e., negative ionization, ozone, ultraviolet light, photocatalytic oxidation, and high-efficiency filtration. The comparison is focused on key aspects such as the use with occupation, whether there is a biocide or not, whether it can be used with HVAC units, costs, and maintenance. Finally, an effective and viable purification solution for HVAC systems is presented. It consists of a compact device based on the ionization technology. An ionizer device is placed in the air in-take of ducted HVAC units that is capable of remotely controlling the main operating parameters of the HVAC equipment (switching on and off, operating mode, fan speed, and setpoint temperature) while reducing the suspension time of fine particles in the air. Various studies carried out in Airzone laboratories have empirically shown that the use of this device results in a 47% reduction in the maximum concentration of particulate matter of 2.5 µm or PM2.5 and up to a 55% reduction of the time these particles are suspended in the air.

Pressure Drop Caused by Diverting Flow in Cooling System and Its Optimization

One solution to reduce the cooling system noise generated by construction machinery is to drive the fan at low speed while ensuring the flow rate required for the cooling system. An approach to achieve this is to reduce the pressure drop that occurs in the flow path in the cooling system. Using CFD is effective for estimating the three-dimensional spatial pressure drop characteristics of the system, but the mechanism of pressure drop that occurs in the three-dimensional flow field has not been clarified. In this study, the flow field around the axial flow fan placed in the cooling system enclosure is visualized, and the mechanism of pressure drop that occurs in the three-dimensional flow field considering the actual configuration is clarified. With the default exhaust port, we found that portions of the fan outlet flow divert significantly inside the enclosure and are exhausted at exhaust port outlets located some distance away from the fan. With the optimized exhaust port, there are few diverting flow and the flow in the enclosure is discharged in a shorter route than the default exhaust port, so the pressure drop is reduced and the flow rate is increased. Hence, by expelling the flow at the exhaust port via the shortest path without allowing it to mix chaotically inside the enclosure, the flow rate can be increased using the same fan speed.

Assessing Mitigation Strategies to Reduce Potential Exposures to Indoor Particle Release Events

Airborne transmission is a major concern for many infectious pathogens, including the novel coronavirus. Ventilation is the principal engineering method used to control airborne health hazards in buildings. Understanding potential air pollution hazards are a particular concern for highly populated indoor environments, such as workplaces and classrooms. This study discusses the results of ventilation testing in a university classroom which contains two fan coil units as the primary HVAC system. A particle nebulizer was used to release aerosol particles into the air, and multiple particulate measuring devices were placed strategically around the room to measure the particle concentration over time. An exponential particle decay rate is determined from the data and converted to a particle concentration half-life, which ranged from over 60 minutes down to under 10 minutes. We then assess how quickly the particles were removed by ventilation systems with varying conditions, including the addition of both high- and low-cost portable mitigation devices into the classroom. Our results indicate that a low-cost unit, made of a simple box fan with a MERV13 filter taped to it, may perform as well at removing particles from a room as a high-cost HEPA filter unit, owing to a tradeoff between filtration efficiency and the number of air changes per hour. As is observed in numerous other studies, the particle concentration half-life in each classroom setup decreases as the mechanical air changes per hour increases from about 1.3 to 9.3. These results are used to evaluate the potential personal exposure risk associated with various classroom ventilation setups. Our results indicate that, when compared to running the fan coil units on low fan speed, operating on a high fan speed reduces potential exposure by 22% and using a portable HEPA filter in the room reduces potential exposure by 66%.

Movement law of the threshing material in threshing and cleaning machine for plot-bred wheat

In order to clarify and enhance the work performance of the threshing and cleaning machine for plot-bred wheat and further reduce the grain retention in all working areas in the machine, in this study, a discrete element model for the threshing material of plot-bred wheat and a gas-solid coupling simulation model for the machine were established by ensuring all the harvesting criteria for the machine. Then numerical simulation was completed on the movement process of the threshing material in the threshing and cleaning machine for plot-bred wheat, the movement law and motion trajectory of all components of the threshing material were explored, and the impact forms of unreasonable work parameters on the separating and cleaning process were analyzed. First, four working areas were divided in the threshing and cleaning machine for plot-bred wheat. Under gas-solid flow coupling effect, the number variation of threshing material in each working area was analyzed under the effect of gas-solid coupling, and the operation characteristics of “no retained seeds and convenient cleaning” of the threshing machine for plot-bred wheat were further improved. The verification test results showed that, when the feeding amount of wheat was 0.30 kg/s, the rotation speed of the shaft of the tooth-type threshing cylinder was set to 1350 r/min, the rotation speed of the winnower was set to 500 r/min, the rotation speed of the residue absorption fan was set to 1000 r/min, the average total loss rate in threshing of the sample machine was 0.56%, and average impurity rate of the threshing material was 5.26%, average damage rate in threshing was 0.68%. In the test, the status of material discharged from the residue absorption fan outlet and bottom of the cyclone separator was similar to that of the simulation results, showing that it was feasible to use the method of gas-solid coupling to simulate the movement law of threshing material in the threshing and cleaning machine for plot-bred wheat. Keywords: plot-bred wheat, threshing and cleaning machine, computational fluid mechanics, discrete element, numerical simulation, test DOI: 10.25165/j.ijabe.20221503.7194 Citation: Dai F, Song X F, Shi R J, Guo W J, Zhao Y M, Wang F, et al. Movement law of the threshing material in threshing and cleaning machine for plot-bred wheat. Int J Agric & Biol Eng, 2022; 15(3): 100–106.

Numerical simulation and experiment of grain motion in the conveying system of ratooning rice harvesting machine

The mixtures, grains, and residues in the ratooning rice harvesting machine need to be conveyed forward, backward, upward, and downward. Due to such operations, often accumulation and blockage take place at the intersection of a horizontal-vertical screw conveyor, resulting in low efficiency, high power consumption, and even grain damage. In this study, a CFD-DEM approach was applied to address the above problems. Firstly, a pneumatic conveying device was designed for ratooning rice, and then the motion of the rice grains and airflow field was analyzed in detail. The effects of different cross-sectional heights and lengths of the contraction section related to the mixing cavity were examined. Finally, the three-factor quadratic regression orthogonal rotational combination method was adopted in the experiment, and the fan velocity, filling coefficient, and speed of the horizontal screw conveyor were taken as test factors. The results showed that with the increasing cross-sectional height of the contraction section in the mixing cavity, the grain velocity decreased and the dispersity increased. With increasing length of the contraction section in the mixing cavity, the area of the high-speed airflow zone increased and the diffusion effect was enhanced. At the fan velocity of 2700 r/min, the filling coefficient was 0.41, the speed of the horizontal screw conveyor was 1173 r/min, and the outlet flow optimization index was the highest, which was 45.9% higher than that obtained without airflow. Keywords: ratooning rice, screw conveyor, grain motion, harvesting machine, CFD-DEM DOI: 10.25165/j.ijabe.20221503.6681 Citation: Liu W J, Luo X W, Zeng S, Zang Y, Wen Z Q, Zeng L, et al. Numerical simulation and experiment of grain motion in the conveying system of ratooning rice harvesting machine. Int J Agric & Biol Eng, 2022; 15(3): 103–115.

Model Predictive Control of Induced Draft Cooling Towers in a Large Scale Cooling Plant

We study the problem of designing a model predictive control strategy for multiple induced draft cooling towers. The common objective of the cooling towers is to regulate the outlet water temperature of the common collection basin to the desired set point. Each cooling tower can be operated in different modes (bypass, showering, ventilation) to meet the heat rejection requirement. To deal with the interacting dynamics and logic, we propose a model predictive control strategy based on mixed integer programming (MIP) which accounts for the changing weather conditions and active heat load to simultaneously determine the best operational mode and optimal fan speed for each cooling tower. Dwell time constraints are added to avoid excessive switching between different operational modes. Although the proposed formulation can account for different operational efficiencies of the cooling towers, an adaptive penalty is designed to balance the run time among identical cooling towers. The inherent over-actuated structure of the cooling process is exploited to provide robustness against the unavailability of an operational mode of a cooling tower. The efficacy of the proposed approach is demonstrated on experimentally validated models of induced draft cooling towers. Simulation results show significant performance improvements and energy savings over conventional heuristic solutions.

Experimental Modal Analysis of Radiator Fan Module to Predict its Influence of Structural Characteristics on Vibration and Noise Contribution

Among many accessories of a passenger car, engine cooling Radiator Fan Module (RFM) is an important source of noise and vibration. Modal parameters provide the basis for the noise generation mechanism and noise propagation phenomena. The objective of the current research work is to characterize RFM through its modal behavior to investigate the contribution of structural vibration to noise radiation during its operating state. Hence, the experimental modal analysis and the noise measurement of RFM were carried out. Additionally a finite element modal analysis of RFM was performed to validate the finite element model that can be used for vibro-acoustic and computational fluid dynamic studies. Below 500 Hz total of eight critical modal frequencies, three for fan and five for shroud are determined and between 500 Hz to 2000Hz seven modes for fan and fifteen modes for shroud were dedermined. From the correlation study, it is witnessed that the contribution of modal behaviour for noise radiation is observed with 20 dB(A) variation below 500 Hz, along the diagonal grid points whereas beyond 500 Hz the variation was negligible. Importantly, blade passing frequencies corresponding to the fan speeds between 500 to 3000 rpm were compared with resonance frequencies obtained and they do not conicide with modal frequencies.

Application of ADMM to robust model predictive control problems for the turbofan aero-engine with external disturbances

&lt;abstract&gt;&lt;p&gt;In this paper, we investigate a class of optimal control problems for turbofan aero-engines considering external disturbances. The alternating direction method of multipliers (ADMM) is embedded in the framework of robust model predictive control (RMPC), which is not only able to reach a predetermined value of the engine fan speed, but is also developed to maintain the robustness of the engine control system. First, to consider the optimal control strategy for the worst-case scenario, this optimal control problem is formulated as a minimum-maximum convex optimization problem with constraints. Second, through a transformation technique, the problem can be equivalently described by a variational inequality, which is then transformed into a quadratic programming (QP) problem using a proximal point algorithm (PPA). Finally, the ADMM algorithm is used to solve a series of optimization subproblems based on the structural characteristics of the model. Computational examples illustrate the solution efficiency and robustness of the improved algorithm (RMPC-ADMM).&lt;/p&gt;&lt;/abstract&gt;

Flow Disturbing to Enhance Heat Transfer Inside a Duct: an Experimental Study

In the present experimental work, the effect of air circulation on increasing heat transfer rates within the duct was studied. Three air circulation speeds are implemented: 2400, 1800, and 1200 rpm. In addition, the effect of the distance between the heat source and the location of the circulating fan on heat transfer rates was investigated using three different distances: 20, 40, and 60 cm. The Exhaust fan, placed at the outlet of the duct, changed its speed to three values: 2850, 2140, and 1425 revolutions per minute. The Reynolds range ranged from 65,000 to 175,000. The results showed that the best thermal performance is achieved when the exhaust fan speed, air circulation speed, and the distance between the heat source are 1425 rpm, 2400 rpm, and 60 cm, respectively.