Fan Airflow Rate Research Articles

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.

Toward a new method to classify the airblast sprayers according to their potential drift reduction: comparison of direct and new indirect measurement methods.

Drift is one of the most important issues to consider for realising sustainable pesticide sprays. This study proposes an alternative indirect methodology for comparative measurements of drift reduction potential (DRP) generated by airblast sprayers, aimed at overcoming the practical inconveniences and drawbacks of standardized ISO 22866:2005. A test bench in the absence of target crop and wind was employed to measure drift potential values (DPVs). A variation to the proposed method that introduced a crop between sprayer and test bench device was considered to study the canopy effect (absence/presence) and to validate the method. In parallel, direct spray drift measurements (ISO 22866) were performed to obtain the drift value (DV). A representative vineyard airblast sprayer was evaluated in four configurations (a combination of two fan airflow rates and two nozzle types). The configurations tested under the three methods (direct and indirects) were classified according to achieved drift reduction percentages (ISO 22369-1:2013) and compared. Indirect methods discriminated DPVs from different nozzles (conventional, air induction) and fan airflow rate (high, low) combinations. Indirect methods also showed that despite crop influence on drift amount, target absence has a negligible effect when used specifically for DRP determination/classification. In fact, identical DRP final classifications were achieved for the two methodologies tested. Alternatively, all tested configurations resulted in lower DR values following the ISO 22866 field method, which caused different final classifications due to the high dependence of results on external factors. The alternative test bench methodology, characterized by the absence of target crop and calm of wind, was considered feasible for comparative measurements of airblast sprayer DRP. © 2019 Society of Chemical Industry.

Minimization of fan energy consumption in ventilation and (or) air-conditioning systems as an optimization calculus of variations

The article presents an optimization calculus of variations of fan energy consumption in ventilation and (or) air-conditioning systems. It defines an air flow rate function that depends on the time of operation in the defined room size, starting conditions and the function of hazardous substances emission rate in the room. The differential form of air flow rate dependence on density of hazardous substances allows to establish a connection between air pollution in the room and a fan air flow rate, i.e. fan energy consumption. Creating a fan energy model experiment in the room in different conditions allows to minimize energy consumption to 5–30% depending on existing conditions.

Numerical simulation study of BIPV/T double-skin facade for various climate zones in Australia: Effects on indoor thermal comfort

Maintaining indoor thermal comfort is crucial for the health and productivity of building occupants. Building envelope plays a major role in influencing the impact of outdoor climate and controlling the indoor thermal conditions. In this paper, comparative analysis of indoor comfortable temperature for four different types of building-integrated photovoltaic/thermal (BIPV/T) building models in a range of climate zones in Australia was conducted using TRNSYS simulation tool. In terms of system operational mode, the four types of BIPV/T building facade systems include a building-integrated photovoltaic single-skin facade (SSF), non-ventilated BIPV/T double-skin facade (BIPV/T-DSF), naturally ventilated BIPV/T-DSF and fan-assisted BIPV/T-DSF. In addition to the operational modes of the facade systems, two types of semi-transparent PV glazing with different visible light transmittance (VLT) were respectively applied to the models as external window glazing. The numerical results showed that the naturally ventilated BIPV/T-DSF with lower VLT (27%) PV glazing maintained a relatively better indoor temperature for the hot climatic conditions compared to the other operational modes, while the non-ventilated BIPV/T-DSF with higher VLT PV glazing (37.5%) offered more comfortable indoor temperature (i.e. 20 to 26 °C for office hours) for the cold climates in Australia. On the other hand, the naturally ventilated BIPV/T-DSF could basically maintain comfortable indoor temperatures from 22 to 27 °C during office hours without mechanical systems for the peak summer times for cool temperate climates in Australia. Moreover, it was found that the thermal insulation effect of semi-transparent PV glazing hardly affected indoor operative temperature in the ventilated modes of the BIPV/T-DSF. According to the sensitivity analysis, the change of U-value of internal window of the DSF would significantly lead to the change of indoor thermal comfort in both ventilated operational modes, but very few changes for the non-ventilated DSF. The variation of cavity depth had distinct impact on the indoor thermal comfort for fan-assisted DSF but slightly affected that of other modes. In addition, the changes of opening ratio for the ventilating louvers and fan airflow rate of the DSF also had a degree of influence on indoor thermal comfort for naturally ventilated DSF and fan-assisted DSF respectively.

シーリングファンの簡易空調設計に関する研究 (その4）シーリングファンの風量と設置間隔が室内気流分布に及ぼす影響

シーリングファンの簡易空調設計に関する研究 (その4）シーリングファンの風量と設置間隔が室内気流分布に及ぼす影響

Ground Deposition and Airborne Spray Drift Assessment in Vineyard and Orchard: The Influence of Environmental Variables and Sprayer Settings

Spray drift assessment encompasses classification of the capacity of each sprayer/technology/setting combination to reduce or avoid the spray drift risk, as well as drift measurement to define buffer zones mandated during pesticide application. Compounding the challenge of these tasks is the great variability of field evaluation results from environmental conditions, spray application technology, canopy structure, and measurement procedures. This study, performed in Spanish context, evaluates the effects of different parameters on comparative measurements of ground and airborne spray drift employing the ISO22866:2005 protocol. Four configurations of air blast sprayers, derived from two fan airflow rates and two nozzle types (conventional and air-induction), were tested in orchard and vineyard at late growth stage. Spray drift curves were obtained, from which corresponding Drift Values (DVs) were calculated using an approximation of definite integral. Both sprayer settings and environmental variables statistically affect spray drift total amounts and result variability. PCA analysis showed that nozzle type and wind speed characteristics explained 51% and 24% of the variance, respectively. In particular, mean wind direction influence ground sediments (Pr < 0.01) and maximum wind speed strongly influence airborne drift value (Pr < 0.0001). The wind characteristics concealed the influence of adopted fan airflow rates on final spray drift assessment results. The effect of uncontrollable environmental conditions makes objective and comparative tests difficult.

Validating a Multi-Port, Averaging Pitot Tube for Measuring Fan Airflow Rates

A multiport averaging Pitot tube (MAPT) system was evaluated for measuring airflow rates from large agricultural fans in confined poultry facilities. The MAPT system consisted of a copper tube with multiple pressure ports along its length to respond to the velocity pressure profile across the full fan diameter. The tube was connected to a low-pressure transducer that provided a differential voltage signal, which was recorded by a data logger, in response to fan airflow. The best performance was observed when the tubes were positioned on the intake of a test fan and operated with pressure ports facing the downstream direction of the fan. The responses of two tube lengths were calibrated in measuring airflow delivered by a 91- or 122-cm diameter wall-mounted exhaust fan by comparing measurements to a Fan Assessment Numeration System (FANS) used as a reference. There was a strong linear relationship between the square root of voltage outputs from the MAPT pressure sensor and the reference FANS air velocity readings. Linear regression equations were used to compute flow rates of additional fans using MAPT measurement. Airflow rates based on MAPT measurement were highly correlated with the reference FANS values with mean deviation less than 3% and 9% for 91- and 122-cm diameter fans, respectively. The MAPT system is particularly useful for applications such as farm energy audits that require fast and easy estimates of airflow from large, wall-mounted agricultural exhaust fans.

The impact of operating pressure on residential bathroom exhaust fan performance

This study quantified the performance impact of increasing operating pressure on residential bathroom exhaust fans based on the comparative analysis of airflow, efficacy, and loudness on more than 80 different residential bathroom exhaust fans with alternate current motors. The fan performance data were measured in a well-instrumented laboratory environment that includes a calibrated nozzle airflow chamber and a six-microphone reverberant sound chamber. Fan airflow rates, efficacies, and loudness were experimentally determined to investigate the impact of external static pressure (ESP) on fan performance at the rating pressure of 0.1in. w.g. (25Pa) and the higher field-observed pressure of 0.25in. w.g. (62.5Pa). An analysis of results showed that fan performance was strongly affected with increasing the ESP. For example, when the ESP was increased from 0.1 to 0.25in. w.g. (25–62.5Pa), the average value of fan airflow rate decreased by 19%, efficacies were penalized by 16%, and the loudness increased by 75%.

Evaluation of ventilation performance and energy efficiency of greenhouse fans.

In order to investigate fan performance in fan-ventilated greenhouses (Urbana, USA), the effects of guard screen and loose belts on fan ventilation airflow and power consumption in greenhouse operations were examined with four belt-driven fans as trial subjects. The Fans Assessment Numeration System was used to measure the airflow rate. Temperature, relative humidity and power consumption were also monitored. Results show there were significant differences in the airflow rate between the fans with a cleaned and uncleaned guard screen [P is less than 0.05]. Power consumption also differed significantly even with the same cooling effect in greenhouse. When fan belts were adjusted to the proper tension, the fan speed and airflow rate were 13.1% and 30.1% higher than those of original belts, respectively. The daily average power consumption for the fan with the original loose belts was 20.4% higher than that with the adjusted belts when the pad was not working and 24.2% higher with pad working. The ventilation performance of fans with identical specifications showed a variation by up to 13.0% in terms of the ventilating efficiency ratio. These results demonstrated that fans should be cleaned routinely, and belt tension should be checked to ensure that fan performance meets specifications. This can reduce the power consumption in greenhouses for environmental control. Moreover, reordering fan staging, so that the most efficient fans are used in areas of greatest demand, can also reduce ventilation energy costs. DOI: 10.3965/j.ijabe.20150801.014 Citation: Zhang Z, Gates R S, Zou Z R, Hu X H. Evaluation of ventilation performance and energy efficiency of greenhouse fans. Int J Agric & Biol Eng, 2015; 8(1): 103－110.

Parametric analysis of air–water heat recovery concept applied to HVAC systems: Effect of mass flow rates

In the last three decades, the world has experienced enormous increases in energy and fuel consumption as a consequence of the economic and population growth. This causes renewable energy and energy recovery to become a requirement in building designs rather than option. The present work concerns a coupling between energy recovery and Heating, Ventilating and Air Conditioning HVAC domains and aims to apply heat recovery concepts to HVAC applications working on refrigeration cycles. It particularly uses the waste energy of the condenser hot air to heat/preheat domestic water. The heat exchanger considered in the recovery system is concentric tube heat exchanger. A thermal modeling of the complete system as well as a corresponding iterative code are developed and presented. Calculations with the code are performed and give pertinent magnitude orders of energy saving and management in HVAC applications. A parametric analysis based on several water and air flow rates is carried out. It was shown that water can be heated from 25 to 70°C depending on the mass flow rates and cooling loads of the HVAC system. The most efficient configurations are obtained by lowering the air flow rate of the condenser fan.

Investigations on a virtual airflow meter using projected motor and fan efficiencies

Airflow measurements are not as accurate as needed in air-handling units due to space and cost limitations of physical meters. Generally, the airflow in an air-handling unit is propelled by a fan driven by a motor and, hence, the airflow rate is related to fan-motor system performance, which can be affected by other measurable variables, such as fan head and motor power. Theoretically, a virtual airflow meter can be developed to virtually obtain the airflow rate from measured fan head and motor power along with projected motor and fan efficiency models. Because variable frequency drives have been widely installed in HVAC systems, a comprehensive motor efficiency model is needed to project motor efficiency under variable frequency and voltage. At the same time, an in situ fan efficiency curve needs to be projected through a calibration process corresponding to actual fan head measurement. This article explores a theoretical model of virtual airflow meters in order to identify the relationship of fan airflow rate with measurable fan head, motor power, and power frequency and voltage; then, demonstrates a procedure to implement a virtual airflow meter and validate the virtual fan airflow meter through an experiment. The results show that airflow measurements from the virtual airflow meter match very well with a conventional duct mounted airflow meter with an standard deviation of 0.0177 m3/s (37.5 cubic feet per minute [CFM]) for instant measurement and 0.0142 m3/s (30.1 CFM) for a 5-min moving average with the measured airflow range between 0.45 m3/s (950 CFM) and 0.70 m3/s (1,480 CFM).

Electricity Generation from a Solar Parabolic Concentrator Coupled to a Thermoelectric Module

The concept of generating electricity from the sun's energy using a parabolic concentrator and a thermoelectric (TE) module is presented in this study. The proposed TE solar concentrator was composed of a parabolic dish collector with an aperture of 1.5 m that was used to concentrate sunlight onto a receiver plate with an area of 10 × 10 cm2. One BiTe-based TE module installed on the receiver plate was used to convert the concentrated solar thermal energy directly into electric energy. A rectangular fin heat sink coupled with a fan was used to release heat from the cold side of TE module and a tracking system was used to continuously track the sun. The effects of fan orientation and air flow rate were investigated. Under maximum heat flux, the TE module was able to produce 1.32W at 0.42 m3/min of the air flow rate (pushing air), corresponding to 2.89% conversion efficiency. The proposed concept seems to be reliable and merits further investigation.

Evaluation of seed dressing dust dispersion from maize sowing machines

The present study analysed the constructive and operative parameters of pneumatic seeders and researched and assessed possible technical solutions for limiting the unwanted dispersion of dust from seed dressing during sowing of maize seeds. Tests were made on several maize pneumatic seeder models. The air flow rates and the air velocities at the fan outlet were assessed, the sizes of the areas contaminated with the material from the maize seeds was evaluated and the air velocities along the contour of the sowing machines were measured. Results showed that by decreasing the fan air flow rate by 30% it was possible to consistently reduce the size of the area contaminated by seed dressing dust while maintaining a good quality of seeding. They also showed that the technical solutions proposed by the seeder manufacturers reduced the environmental contamination with the pesticide-containing dust by more than 90%.

An optimal design for axial-flow fan blade: theoretical and experimental studies

The technique of inverse design problem (IDP) for optimizing the three-dimensional shape of an axial-flow fan blade based on the desired airflow rate is presented in this work. The desired volume flow rate of air can be obtained from the airflow rate of the existing axialflow fan by multiplying it with a constant which is greater than unity. The geometry of the redesigned fan blade is generated using numerous design variables, which enables the shape of the fan blade to be constructed completely; thus the technique of parameter estimation for the inverse design problem can be used in this study. Results show that with the redesigned optimal fan blade, the airflow rate of fan can be increased, thereby improving the performance of the axial-flow fan. Finally, to verify the validity of this work, the prototypes of the original and optimal axial-flow fan blades are fabricated and fan performance tests are conducted with these blades on the basis of the AMCA-210-99 standard. The algorithm used in the present study can be applied to the blade design problem in any propulsion and power systems.

Thermal Environmental Control of High-Rise Layer Houses in California

The ventilation systems of two high-rise layer houses in California were monitored from 10/25/07 to 10/31/09 (m/d/y) for the National Air Emission Monitoring Study to facilitate the calculation of air pollutant emission rates. The ventilation systems, building structural design, feeding systems, and manure management practices of the houses were identical. Each house had approximately 32,500 laying hens in cages on the second floor (layer room) and was mechanically ventilated in cross-flow fashion with 12 sidewall single-speed exhaust fans on the first floor, consisting of two 91 cm fans and ten 122 cm fans. The fan rotational speeds, differential static pressure, temperature, relative humidity, and the evaporative misting system of each house and outside weather variables were continuously monitored. All 24 fans were evaluated with a portable fan tester three times during the two-year test. Fan airflow models were developed from in situ fan test data to calculate the fan airflow rates based on house differential static pressure and fan rotational speeds. The results showed that the fan performance factors of the 91 cm and 122 cm fans were 75% and 84% of the airflows, respectively, of new unused fans. The daily mean dry standard house ventilation rate averaged 47 m3 s-1 at dry standard conditions and ranged from 12 to 88 m3 s-1. The daily mean hen-specific ventilation rates averaged 5 m3 h-1 hen-1 and ranged from 1.3 to 9.8 m3 h-1 hen-1. Relative uncertainties of the hourly mean hen-specific ventilation rates averaged ±4.8% and ranged from ±2.9% to ±8.8%. The house differential static pressures ranged from -35 to -10 Pa 92% of the time. The layer room temperatures were controlled by adjusting the ventilation rate, which generally increased with ambient temperature. The evaporative misting system decreased the layer room temperature by up to 8°C from the ambient, or barn inlet, air temperature while contributing to an increase of up to 3.8 g kg-1 in the house humidity ratio relative to barn inlet conditions.

Technical Note: Upstream vs. Downstream Placement of FANS Device to Determine Ventilation Fan Performance in Situ

Accurate ventilation rate (VR) data are essential to maximizing the quality of aerial emission measurements. The Fan Assessment Numeration System (FANS) has been widely used by U.S. researchers in measuring aerial emissions from mechanically ventilated livestock and poultry facilities. The FANS device is used to measure airflow rates of ventilation fans in situ, thereby developing fan performance curves under field conditions. The FANS device was originally intended to be placed upstream of the fan to be calibrated. However, certain field situations make it impractical to apply the FANS device as such. This study was conducted to assess use of the FANS device downstream of a ventilation fan, with the gaps between the FANS device and the discharge cone of the exhaust fan sealed using a non-permeable fabric. Nine exhaust fans (1.22 or 1.32 m diameter) in laying hen and turkey houses were tested with the FANS device placed upstream and downstream for a building static pressure range of 10 to 40 Pa. The results revealed that downstream placement of the FANS device yielded 0.6% 0.4% to 4.0% 0.9 % (mean SE) higher but not significantly different (P > 0.28) VR values as compared to upstream placement for the exhaust fans tested. This magnitude of discrepancy is considered acceptable for in situ measurement of fan performance.

Canopy Gas Exchange Measurements of Cotton in an Open System

A portable, open transparent chamber system for measuring canopy gas exchanges was developed and tested. Differentials between incoming and outgoing atmospheric H2O and CO2 concentrations were used to calculate canopy transpiration (E) and net assimilation (A) at 10‐s intervals using solenoid valve actuated sample lines connected to an infrared gas analyzer. A programmable data logger controlled fan speed and air flow rate to control daytime chamber air temperature to within 0.5°C of ambient air temperature. To validate the mass balance equations used to calculate E, the chamber was positioned over sealed soil potted cotton (Gossypium hirsutum L.) plants which were placed on a weighing scale. A second scale was used to measure E of cotton plants outside the chamber to quantify potential chamber effects. A wide range of crop canopy leaf areas and soil water contents were created with greenhouse‐grown plants for these comparisons. Data analysis indicated agreement between chamber E measurements and the internal weighing scale (R2 = 0.93), as well as comparison between the internal and external scales (R2 = 0.88) across wide ranges of soil water contents and canopy leaf area. Transpiration ranged from near zero at night to 900 g (H2O) h−1 during the day. Bias estimates of E for chamber vs. internal scale and the internal vs. external scale were −6.0 and 4.6 g (H2O) h−1. With minor chamber effect, the chamber accurately estimates E for many field applications such as comparison of canopy gas exchanges and water use efficiencies among irrigation treatments.

Investigation of nitrous acid concentration in an indoor environment using an in-situ monitoring system

An in-situ measurement system for the determination of nitrous acid (HONO) was developed and used at an indoor residential environment. The system uses a diffusion scrubber to sample gaseous HONO and the peroxynitrite-induced luminol chemiluminescent method to quantify the amount of HONO. In this system, the detection limit of HONO, estimated as three times the noise level of the scrubbing solution blank, was 120 pptv for a 2-min integrated sample. Indoor HONO and NO x concentrations were determined for 7 days in the living room of an apartment with a gas range for cooking in the kitchen. Close examination of the relationships among HONO, NO, and NO 2 concentrations during both the background and combustion periods confirm that the observed HONO was formed not only by direct emission from gas combustion, but also from heterogeneous reactions of NO 2 with H 2O on indoor surfaces. The average ratio of HONO to NO 2 over the study period was 0.12 ± 0.05. The HONO/NO 2 concentration ratio was 0.04–0.08 during the combustion period, whereas it was 0.10–0.25 after combustion had stopped. This suggests that HONO was generated through different production processes, both during combustion and after the completion of combustion. The controlled combustion experiments indicate that the burning rate is an important factor to determine the peak HONO concentration. In darkness, HONO had a nearly constant removal rate for all of the combustion experiments, whereas the removal rates of NO and NO 2 depended on the burning rates of the gas range. Combustion experiments conducted at the fixed burning rate setting show also that ventilation decreased HONO concentration. This indicates that the airflow rate of the range hood fan is an important factor to control the concentration of indoor air pollutants.

A Modified T-Method Simulation for Multi-fan Duct Systems

In this study, we introduce the Modified T-Method which can be applied to the prediction of the flow distribution in multi-fan duct systems. Introduction of individual flow routes enables the division of a complicated multi-fan ductwork into a set of simultaneous single-fan subsystems. The present method was tested on the single-fan duct system presented in the ASHRAE handbook. The test system consisted of several branches and a fan. Our results showed good agreement with those published. Also, we tried another approach, in which the symmetry of a two-fan duct system was investigated. Verification was accomplished successfully by the analysis of a two-fan duct system that yielded physical consistency. In order to evaluate the utility and capability of the title method, a bathroom ventilation system in a 20-storey residential building was selected as an example of an application. Under the typical design conditions, the air flow rate of each exhaust fan at the balance point was predicted successfully and it was shown that such information can lead to an engineering estimate for the system performance as a whole. While some deficiencies in ventilation were found in bathrooms on the lower floors with 6mmAq-rated exhaust fans, they disappeared over the building as a whole by using fans of enhanced static pressures, 7 and 8mmAq. Finally, the work has demonstrated that this method is likely to be useful for the design of multi-fan duct systems.

Multi-fault detection and diagnosis of HVAC systems: an experimental study

The objective of this study is to detect faults due to multiple element failures in HVAC systems occurring concurrently. To classify and detect single as well as multiple faults, measurements were made of supply air temperature, OA-damper position, supply fan pressure, indoor temperature and airflow rate in a variable air volume heating ventilating and air conditioning test facility. Experimental results show that three types of patterns emerge in the analysis of multi-fault problems. To solve the multi-fault problem, a new strategy based on pattern classification and the use of residual ratios is presented. It is shown that the residual ratio can be used to diagnose and accurately identify and detect multiple-faults occurring in HVAC systems. Copyright © 2005 John Wiley & Sons, Ltd.