Fan Flow Rate Research Articles

Chair Fans as Energy Efficient Strategy to Aid Localized Ventilation

Nowadays, the air conditioning industry is deviating from the conventional mixing ventilation technique towards localized ventilation. Displacement ventilation and ceiling personalized ventilation are localized systems presenting a high potential in insuring good indoor air quality while reducing the energy consumption compared to mixing ventilation. In this work it is proposed to enhance their performance by assisting them with chair fans controlling the behavior of occupants’ convective plumes. Computational fluid dynamics models were developed to simulate office spaces ventilated by displacement ventilation and ceiling personalized ventilation equipped with chair fans. The Lagrangian technique was adopted to track particle trajectories to determine particle behavior after generation from occupant respiratory activity. A parametric study was conducted to assess the effect of chair fan flow rate on each system performance in terms of indoor air quality. Recommendations were given to reduce cross-infection between occupants for both types of localized systems studied with reduced energy consumption. The total chair fans flow rate was optimized for both cases to insure acceptable indoor air quality resulting in significant energy savings. It was found that the optimal total chair fans flow rate per occupant was approximately 14 L/s when assisting displacement ventilation while it was 10 L/s when aiding ceiling personalized ventilation.

Design of the external forced air cooling control strategy for the bulb tubular turbine generator based on multi-objective optimization

The compact internal structure of the bulb tubular turbine generator (BTTG) leads to poor ventilation and heat dissipation capability (VHDC). It will result in high-temperature faults and lead to losses for the hydro-power station, if the staff at the hydropower station fail to promptly regulate the external forced air cooling for effective heat dissipation. Thus, a specific and effective ventilation control strategy (VCS) is of utmost importance for the operation of the BTTG. In this study, the finite element method (FEM) was employed to solve the magnetic-flow-thermal coupled field of a 24-MW BTTG. The distribution characteristics of electromagnetic losses and their impact on the temperature field were revealed. Experimental validation was conducted to verify the effectiveness of the numerical results. The response surface methodology (RSM) was employed to design an experimental plan by building upon this foundation. Integrated with a multiobjective genetic algorithm (MOGA), an optimal relationship between ambient temperature, fan flow rate, and heating components’ temperature was established. This relationship serves as the optimized ventilation control strategy for the BTTG. This research provides a theoretical framework for the formulation of operational guidelines to ensure the safe operation of generators.

Analysis of various design parameters of a desert cooler

ABSTRACT Aside from climatic parameters, the cooling potential of a desert cooler is influenced by fan flow rate, pad thickness, and pad packing factor, all of which are referred to as cooler parameters. In this study, a general equation for determining cooling potential in terms of cooler parameters is proposed and validated. An equation has been devised to determine the combination of fan flow rate (FFR) and pad area required to meet a given heating load. The equation aids in the sizing of coolers for a desired room temperature in various climates. The size of the cooler tank is determined by the rate of water evaporation. In this investigation, we evaluated the influence of different fan flow rates on the rate of water evaporation. It is seen that at a typical set of climatic parameters and for a given pad (1 m2, 350 m2/m3, 10 cm thick), the cooling potential of the cooler increases by increasing fan flow rate (. Furthermore, increasing pad area reduces the amount of fan flow rate required for a given heating load, allowing one to select the appropriate combination of fan flow rate and pad area. Higher fan flow rates increase the running cost, while increasing pad area raises the initial investment cost. The pad area needed (10 cm, 350 m2/m3) for the composite climate of Delhi at a 0.35 m3/s FFR, is roughly 66.7% less than that for the hot climate of Jodhpur for 4 kW heating load.

Performance of an oxygen-consuming inerting system for an aircraft fuel tank with RP-3 aviation fuel in flight

Aircraft fuel tank inerting system is an important guarantee for flight safety. A novel oxygen-consuming inerting system-3CIS (low-temperature controllable oxygen-consuming catalytic inerting system) was proposed and studied with RP-3 aviation fuel. Based on the designed inerting system, the mathematical model of the system in flight was established based on the conservation law of mass and energy. The system performance under different flight conditions was firstly analyzed, and the effects of the initial fuel loading, fan flow rate and preheating temperature on the system performance were studied. Meanwhile, a test bench was built to verify the correctness of the established model. The following conclusions can be drawn from the results: The 3CIS can reduce the oxygen concentration in the fuel tank quickly to prevent fires and suppress explosions. What's more, the inerting time is the longest when the fuel tank is initially empty if all other system conditions are the same. Therefore, it is suggested the no-load state should be used for the system parameters design for the purpose of maximum safety. As for the influence of key parameters on system performance, the inerting rate increases with the increase of fan suction flow and preheating temperature, and low fan flow rate during the climb and cruise stages and high fan flow rate during descent are suggested for the control system designing. Finally, a regenerator is recommended when designing the system since it can effectively reduce the preheating power and cooling power of the system.

A numerical evaluation of a novel recovery fresh air heat pump concept for a generic electric bus.

Since the outbreak of the worldwide COVID-19 pandemic, public transportation networks have faced unprecedented challenges and have looked for practical solutions to address the rising safety concerns. It is deemed that in confined spaces, operating heating units (and cooling) in non-re-circulation mode (i. e., all-fresh air mode) could reduce the airborne transmission of this infectious disease, by reducing the density of the pathogen and exposure time. However, this will expectedly increase the energy demand and reduce the driving range of electric buses. To tackle both the airborne transmission and energy efficiency issues, in this paper a novel recovery heat pump concept, operating in all-fresh air mode, was proposed. The novelty of this concept lies in its potential to be applied to already manufactured/in-service heat pump units as it does not require any additional components or need for redesigning the heating systems. In this concept, the cabin exhaust air is directed to pass through the evaporator of the heat pump system to recover part of the waste heat from the cabin and to improve the efficiency of the system. In this paper, a 0D/1D coupled model of a generic single-deck cabin and a heat pump system was developed in the Simulink environment of MATLAB (R2020b) software. The model was run in two different modes, namely the all-fresh air (as a baseline and a recovery heat pump concepts), and the air re-circulation mode (as a conventional heat pump concept with a 50% re-circulation ratio). The performance of these concepts was investigated to evaluate how an all-fresh air policy could affect the performance of the system, as well as the energy-saving potential of the proposed recovery concept. The performance of the system was studied under different ambient temperatures of −5 °C, 0 °C, and 5 °C, and for low and moderate occupancy levels. Results show that implementing the all-fresh air policy in the recovery and baseline concepts significantly improved the ventilation rate per person by at least 102% and at most 125%, compared to the air-re-circulating heat pump. Moreover, adopting the recovery concept reduced the power demand by at least 8% and at most 11%, compared to the baseline all-fresh air heat pump, for the selected fan and blower flow rates. The presented results in this paper along with the applicability of this concept to in-service mobile heat pumps could make it a feasible, practical, and quick trade-off solution to help the bus operators to protect people and improve the energy efficiency of their service.

Effect of recirculation zones on the ventilation of a public washroom.

Air-borne transmission can pose a major risk of infection spread in enclosed spaces. Venting the air out using exhaust fans and ducts is a common approach to mitigate the risk. In this work, we study the air flow set up by an exhaust fan in a typical shared washroom that can be a potential hot spot for COVID-19 transmission. The primary focus is on the regions of recirculating flow that can harbor infectious aerosol for much longer than the well-ventilated parts of the room. Computational fluid dynamics is used to obtain the steady state air flow field, and Lagrangian tracking of particles gives the spatial and temporal distribution of infectious aerosol in the domain. It is found that the washbasin located next to the door is in a prominent recirculation zone, and particles injected in this region take much longer to be evacuated. The ventilation rate is found to be governed by the air residence time in the recirculation zone, and it is much higher than the timescale based on fully mixed reactor model of the room. Increasing the fan flow rate can reduce the ventilation time, but cannot eliminate the recirculation zones in the washroom.

Investigation of mechanical ventilation for cooling in high-rise buildings

Cooling-related energy consumption is growing rapidly in buildings. High-rise buildings usually have high cooling loads and cooling-related energy consumptions. Reducing the cooling load of high-rise buildings is critical for decreasing cooling-related energy consumption and peak electricity demand. Due to their cold climates, ventilative cooling (VC) is available for a long time throughout the year in Canada and Northern Europe, not only during shoulder seasons, but also in summer periods. Mechanical ventilation is an option for providing VC and reducing high-rise cooling load. However, the mechanical ventilation system in high-rise buildings is typically designed and used for maintaining indoor air quality, rather than for removing indoor heat. This study aims to use the mechanical ventilation system for VC in high-rise buildings and explore the associated energy saving approaches. Energy models of components in the cooling system were developed. Based on the models developed, different energy saving approaches were proposed, including applying the optimal control method, using energy efficient fans, and increasing nominal fan flow rates. A case study was conducted on an institutional high-rise building to validate the models developed and evaluate the proposed energy saving approaches. It was found that with energy efficient fans, applying the optimal control method and increasing the nominal ventilation flow rate can achieve energy savings for cooling. Increasing the optimal nominal ventilation rate further does not significantly increase energy savings. The conclusions of this study provide vital information regarding high-rise VC for new building design and HVAC system retrofit in existing buildings.

Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment.

Controlled pressure method (CPM) testing is a building-specific diagnostic tool for vapor intrusion (VI) pathway assessment which offers advantages over traditional pathway assessment approaches. By manipulating the building pressure conditions, the CPM creates the worst-case VI impact and provides rapid insight into the type of vapor source(s). The primary barrier to general acceptance and use of this tool is the need for definitive guidance on test design parameters, such as the indoor-outdoor pressure difference (or exhaust fan flow rate), CPM test duration, exhaust fan location, and air sampling location(s) and conditions. This study focused on a systematic evaluation of each of these factors, which then led to the formulation of proposed CPM testing guidelines. The results suggest that CPM tests should be conducted with both negative and positive pressure indoor-outdoor differentials of about 10-15 Pa, and the tests should last for at least nine indoor air exchanges for negative pressure difference testing and four indoor air exchanges for positive pressure difference testing. Although exhaust fan intake sampling is sufficient to provide critical information to assess impacts during negative pressure testing, adding room-specific indoor air sampling to both negative and positive pressure difference testing can provide insight into vapor entry locations and indoor source contributions.

EXPERIMENTAL STUDY OF SOLAR AIR HEATER USING OF PHOTOVOLTAIC CELLS

In this paper, we are studying about solar air heater. The solar air heater are consisting the several component such as flat glass, collector, D.C. fan, photovoltaic cells and electrical storage system. In this study we are achieving the various type of outlet temperature with the help of D.C. fan and various Mass air flow rate using of simple absorber trays forced convection.

Effect of air supplementation on the performance of an onboard catalytic inerting system

In this work, a catalytic inerting process with an external air supplement was proposed. Based on the molar flow rate of the pumped air in the fuel tank, the flow relationship of each gas component after flowing through the catalytic reactor was derived. The mathematical model of the gas concentration variation in the gas phase space of the tank was established by considering the mass conservation equation and gas equilibrium dissolution relationship, and the core fuel tank model was verified using existing experimental data. The performances of the inerting system for aviation fuels, such as JP8, RP3 and RP5, with and without an external air supplement were compared and studied, and the influence of the key parameters on the performance of the system was determined. The results indicated that the presence of an air supplement can accelerate the process of inerting; a higher fuel vapor pressure corresponds to the requirement for a larger air supplement ratio, which means that more inert gas flow is generated by the reaction and the O2 concentration of the tank decreases more rapidly. For example, when the inerting system of RP5 has a catalytic efficiency of 0.8, the O2 concentration in the gas phase of the tank decreases to 9%; the time required for this process without and with the air supplement is 7.55 min and 0.77 min, respectively. Under the same conditions, the highest inerting rate is for RP5, followed RP3 and JP8. In addition, with the air supplement, the inerting time of the RP3 and RP5 fuels is reduced with the increase of the catalytic efficiency. A larger fuel loading rate corresponds to a smaller gas phase space volume and less inerting time. The inerting time is inversely proportional to the fan flow rate, that is, when the flow rate of the fan increases by N times, the inerting time decreases to 1/N times the original value. Therefore, when designing an onboard catalytic inerting system, the inerting performance can be improved by providing an external air supply, and the influence of the key parameters, such as the catalytic performance, fuel loading rate and fan flow, on the system performance should be considered.

Heat Transfer Improvements in a Solid Fueled Boiler and Modeling of Pressure Differences by Artificial Neural Network

Bu çalışmada, duman borularının çapı 42 mm, baca çapı 230 mm ve su giriş ve çıkış çapları 65 mm olan 125.000 kcal/h ısı kapasiteli katı yakıtlı kazanda, 4 farklı tipte şerit türbülatör kullanılarak ısı transferinin iyileştirilmesi incelenmiştir. Kazandaki duman borularının tümüne yerleştirilen türbülatörlerle deneyler yapılmıştır. İlk olarak içerisine türbülatör yerleştirmeden deneyler yapılmıştır. İkinci adımda ise duman boruları içerisine türbülatörler yerleştirerek her tip için ayrı ayrı deneyler yapılmış ve ısı transferi hesaplanmıştır. Deneylerde fan debisi damper yardımıyla değiştirilerek Reynolds sayısı 1800 ile 2800 arasındaki değerlerde hesaplamalar yapılmıştır. Isı transferi iyileştirmesi için yapılan türbülatörlü deneyler, türbülatörsüz deneylere göre ısı transferinde en az % 44, en fazla % 82 oranında artış sağlanmıştır. Hesaplamalar sonucu elde edilen basınç farkı değerleri için yapay sinir ağı (YSA) kullanılarak tahminsel bir model elde edilmiştir. Elde edilen modelin hata analizleri yapılmış ve basınç değerlerini başarılı bir şekilde tahmin ettiği gösterilmiştir.

Ultrafine particle cleaning performance of an ion spray electrostatic air cleaner emitting zero ozone with diffusion charging by carbon fiber

A novel electrostatic precipitator (ESP)-type small air cleaner with an ion spray charger was developed and evaluated. Unlike conventional ESP air cleaners, the charger is located at the rear of the collection stage. Ions are emitted into ambient space by the fan of the air cleaner, and airborne particles are charged by nearby ions through a diffusion charging mechanism. A carbon fiber ionizer without a grounded metal plate was installed as the charger to minimize ozone emission. The novel air cleaner had a particle clean air delivery rate (CADR) for 0.3-μm particles of 0.863 m3/min at a fan flow rate of 2.0 m3/min and applied voltages of – 5 kV to the ionizer and collection plate. As the size of the particles increased from 0.25 to 1 μm, particle CADR increased from 0.6 to 1.6 m3/min. Near-zero ozone emission was generated in a closed chamber (30.4 m3), and the concentration decreased from an initial background level of 2.39 ppb–1.29 ppb after 12 h of continuous operation. Our study showed a close relationship between particle CADR and the number of charges per particle, and the number of charges per particle matched well with theoretical predictions based on diffusion charging theory. The particle CADR of ion spray ESPs was 3.63 times higher than that of a high-efficiency particulate air (HEPA) filter air cleaner of similar volume. In an actual environment (56.43 m3), the particle CADR was 0.798 m3/min, similar to the chamber test.

Investigating measurement variation of modified low-cost particle sensors

Particulate matter (PM) has demonstrably increased rates of cardiovascular and respiratory related disease; thus, a low-cost sensor that accurately measures PM is desirable including for smaller and more private environments such as residential homes. The low-cost Dylos and the Utah Modified Dylos Sensor (UMDS) have been shown to be highly correlated with references instruments for measuring particle counts and aerosol concentrations, which makes them useful tools for air quality studies. An analytical calibration equation (calibration) is used to describe the linear relationship between the UMDS and a reference instrument, providing the best estimate of PM concentrations when the UMDS is operated. In this study, an investigation of measurement variation of a UMDS was performed using a low-cost calibration technique to determine differences between the brand new UMDS pre-calibration equation (Prec), a contaminated UMDS post-calibration equation (Postc), and a cleaned UMDS clean calibration equation (CC). The UMDS were calibrated against a high-grade aerosol spectrometer (Grimm model 1.109) as a reference instrument. Calibrations took place in a home or office environment. Counts per volume units from the UMDS were matched to the Grimm's for comparison. The investigation of the UMDS for measurement variation was performed for the approximate estimates of PM2.5 by using the small bin (i.e. ≥0.50 μm) subtracted from the large bin (i.e. ≥2.5 μm), and for total particulates by using the large bin. Linear regressions were performed between the UMDS and the Grimm per calibration event, which produced R2 values and slopes that were indicative of measurement variation. Data exceeding the upper limit of quantification (ULOQ) of 106,000 particles/liter and the lower limit of quantification (LLOQ) of 4 particles/liter were excluded from statistical comparison. R2 values greater or equal to 0.70 were used to assess measurement variation as a quality control standard for valid comparisons. A rank sum statistical test between calibration comparisons was performed. Prec/Postc and Prec/CC had significant differences indicating measurement variation. Postc/CC did not have any significant differences; cleaning the UMDS had no effect and did not demonstrate measurement variation. Reasons for measurement variation may include instrument contamination (dust/dirt), hardware degradation, altered fan flow rates, and potentially inadequate cleaning of the UMDS. Future work may investigate the rate of measurement variation in order to develop a recommended re-calibration schedule in order to maintain the most accurate estimates of PM for UMDS in long-term operation.

Analysis of Air Distribution at Molecular Sieve Vessel In RDE System Based On Fan Flow Rate Variation Using Aerosol Density Testing Facility

The Experimental Power Reactor uses the type of pebble bed fuel and helium gas as its primary coolant. Therefore, to maintain and maintain the quality of helium as a coolant in accordance with predetermined requirements helium purification system is designed. One part of the main component of this helium purification system facility that serves to absorb CO2 and CH4 is molecular sieve vessel. FASKERA is a test facility used to measure the density level of aerosols in a space in real time. To optimize the FASKERA’s performance, the characterize of its airflow rate distribution is needed. The purpose of this study is to know the airflow rate homogenous distribution in the FASKERA using fluent 6.3. The fan flow rate varied with speed 20 m/s and 25 m/s. Based on the simulation result of CFD that has been done, it can be concluded that the profile the airflow distribution within FASKERA by using a fan air flow rate of 20 m/s resulted in a more homogeneous air flow rate distribution compared to a fan air flow rate of 25 m/s, this is because the resulting drag force area is fewer and the spatial distribution area of the two airflows is evenly distributed in the chamber.

냉각 팬의 유동 특성을 고려한 압출적층형 3차원 프린터 노즐부의 열-유동 연계 해석

For 3D printing of high-strength polymers, such as PC (Polycarbonate) and PEI (Polyetheimide), the temperature of the nozzle should exceed the melting temperature of the high-strength materials. At the same time, the temperature of the transfer part, composed of the shaft extruder and the Teflon hose, should be cooled below the glass transition temperature and below the limit temperature of the transfer part. In this study, we analyzed the effect of the flow rate of the cooling fan when the extruder nozzle is heated to 300oC. We compare the natural convection environment, in which the cooling fan is not operated, and the forced convection condition, in which the cooling fan is operated, and analyze the effect on the cooling fan flow rate. The simulation considered the heat transfer in the air and the nozzle, as well as the flow characteristics of the air.

The benefit of kitchen exhaust fan use after cooking - An experimental assessment

Cooking is one of the main sources of indoor air pollutants, and may even exceed the contribution from outdoor sources. This pilot study examines the use of different flow-rate fans during cooking and tests whether continuing to run the fan after cooking significantly improves pollutant removal rates and integrated exposures. Tests were carried out in the Canadian Centre for Housing Technology's twin research houses, in Ottawa, Ontario. We completed the same cooking protocol 60 times on a gas stove, testing 6 different flow rates on three different over-the-range exhaust fans, while continuously measuring UFP, PM2.5, NO2, and NO. The fan was operated during cooking for all tests and then either turned off or left on after cooking for the duration of the three hour test. We estimated decay rates, source emission rates, and integrated exposures to measured pollutants following the cooking test. The results showed that while leaving the fan on after cooking generally increased decay rates, it had a relatively small effect on integrated exposures compared to the effects of fan flow rate and the specific fan used during cooking. For PM2.5, the effect of running an exhaust fan for 15 min after cooking was similar in magnitude to the impact of a 100 cfm increase in the flow rate used while cooking: both were associated with a decrease in 15-min integrated exposure of roughly 3 μg m−3. This suggests that one can partially compensate for a low flow rate exhaust fan by continuing to run the fan after cooking.

Axial Fan Performance under the Influence of a Uniform Ambient Flow Field

In their application to air-cooled condensers, axial fans are often subject to the detrimental influence of ambient flow fields at their inlet or outlet. While effects have been investigated mostly under perpendicular cross-flow conditions on fans operating as part of an array in their target design point, this study aims at examining the integral influence of uniform ambient flow fields on a single axial fan over a wide operating range. For this purpose, a wind tunnel fan test rig has been designed and assessed. Multiple angles between uniform ambient flow field and fan axis are examined in their integral influence on the characteristic curve of two distinct industrial axial fans with varying inlet modifications. Increasingly with the fan flow rate, perpendicular inlet cross-flow was found to always have a detrimental influence on fan performance. The straight bladed fan reacted less sensitively than the forward skewed fan, and the adverse cross-flow influence could be reduced with an inlet guard grille and with short conical shroud extensions. Cross-flow at the fan outlet showed potential static fan pressure increases at low flow rates.

Advances in developing a new test method to assess spray drift potential from air blast sprayers

Drift is one of the most important issues to consider for realising sustainable pesticide sprays. This study proposes and tests an alternative methodology for quantifying the drift potential (DP) of air blast sprayers, trying to avoid the difficulties faced in conducting field trials according to the standard protocol (ISO 22866:2005). For this purpose, an ad hoc test bench designed for DP comparative measurements was used. The proposed methodology was evaluated in terms of robustness, repetitiveness and coherence by arranging a series of trials at two laboratories. Representative orchard and vineyard air blast sprayers in eight configurations (combination of two forward speeds, two air fan flow rates, and two nozzle types) were tested. The test bench was placed perpendicular to the spray track to collect the fraction of spray liquid remaining in the air after the spray process and potentially susceptible to drift out of the treated area. Downwind spray deposition curves were obtained and a new approach was proposed to calculate an index value of the DP estimation that could allow the differences among the tested configurations to be described. Results indicated that forward speed of 1.67 m/s allows better discrimination among configurations tested. Highest DP reduction, over 87.5%, was achieved using the TVI nozzles in combination with low air fan flow rate in both laboratories; conversely, the highest DP value was obtained with the ATR nozzles in combination with high air fan flow rate. Although the proposed method shows a promising potential to evaluate drift potential of different sprayer types and nozzles types used for bush and tree crops further research and tests are necessary to improve and validate this method.

Evaluation of nitrous oxide as a substitute for sulfur hexafluoride to reduce global warming impacts of ANSI/HPS N13.1 gaseous uniformity testing

The ANSI/HPS N13.1–2011 standard requires gaseous tracer uniformity testing for sampling associated with stacks used in radioactive air emissions. Sulfur hexafluoride (SF6), a greenhouse gas with a high global warming potential, has long been the gas tracer used in such testing. To reduce the impact of gas tracer tests on the environment, nitrous oxide (N2O) was evaluated as a potential replacement to SF6. The physical evaluation included the development of a test plan to record percent coefficient of variance and the percent maximum deviation between the two gases while considering variables such as fan configuration, injection position, and flow rate. Statistical power was calculated to determine how many sample sets were needed, and computational fluid dynamic modeling was utilized to estimate overall mixing in stacks. Results show there are no significant differences between the behaviors of the two gases, and SF6 modeling corroborated N2O test results. Although, in principle, all tracer gases should behave in an identical manner for measuring mixing within a stack, the series of physical tests guided by statistics was performed to demonstrate the equivalence of N2O testing to SF6 testing in the context of stack qualification tests. The results demonstrate that N2O is a viable choice leading to a four times reduction in global warming impacts for future similar compliance driven testing.

A Study of the Evaluation of Products by Industrial Design Students

The objective of this study is to provide industrial design students with a comprehensive approach of product evaluation during the course of a research project. During the design evaluation stage, a student often encounters vague information since the attributes of product design demands are usually not quantifiable. Therefore, one of the important topics during the product development processes is to allow a student to carry out design evaluations effectively. The fuzzy Analytic Hierarchy Process (AHP) was utilized in this study to assess product designs and resolve the problems that might occur during product assessments. The purposive sampling technique was used in the questionnaire survey. By assigning a weighted value to each of the evaluation criteria, the case study verified the feasibility of the proposed design approach in fan designs. A total of 52 questionnaire copies were distributed. 36 copies of them were collected and the return rate is 77%. Among them, 28 copies were from the engineers and 8 copies were from people in the relevant industries. 22 copies were from males and this accounts for 61%. On the other hand, 14 copies were from females and this accounts for 39%. The results indicated that the weight of efficiency which is the secondary constituent element is the highest. Under the constituent element of efficiency, the weight of fan flow rate is 0.592 which is the highest. The defuzzification of efficiency is 0.744 which is the optimal value among the indices of various factors. The defuzzified value of Design No.4 after defuzzification is 0.682 which is the optimal one among four design candidates. The results of this study demonstrated the feasibility of the proposed design approach. New fan styles can be effectively created by implementing this design approach. This approach allows the entire evaluation process to be more precise. The combination of these approaches is not only practical and objective, but also is capable of assisting a student in making a decision under complicated and uncertain circumstances. This makes a design task definite and better clarified and also enhances a student’s learning competitiveness by supplying a good reference during the follow-up stage of product design assessments.