Volumetric Air Flow Rate Research Articles

Compressor Scheduling and Pressure Control for an Alternating Aeration Activated Sludge Process—A Simulation Study Validated on Plant Data

Aiming at reducing their emissions, wastewater treatment plants (WWTP) seek to reduce their energy consumption, where a large amount is used for the aeration. The case plant, Grindsted WWTP uses an alternating aeration strategy, with a common air supply system facilitating the process in four aeration tanks and thus making optimisation challenging. In this work, a nonlinear model of the air supply system is designed, in which multiple key parameters are estimated by data-driven optimization. Subsequently, a model-based control strategy for scheduling of compressors and desired airflow is proposed, to save energy without compromising the aeration performance. The strategy is based upon partly static- partly dynamic models of the compressors, describing their efficiency in terms of system head and volumetric airflow rate. The simulation study uses real plant data and shows great potential for improvement of energy efficiency, regardless of the aeration pattern in any of the four process tanks, and furthermore contributes to a reduction in compressor restarts per day. The proposed method is applicable to other WWTP with multiple compressors in the air supply system, as this study is conducted using first principle models validated on data from the daily operation.

Two-way layout factorial experiments of spatial point pattern responses in mineral flotation

Factorial experiments are well-understood when the given observations are outcomes of random variables. However, when we observe spatial point patterns in each combination of factors cells, the methodology is much less developed. Motivated by a real problem of locations of bubbles in a mineral flotation experiment where the interest is analysing if the spatial distribution might be affected by frother concentrations and volumetric airflow rates, we develop an approach for statistical testing of two-way factorial experiments for spatial point patterns. We describe the point patterns through the K-function, a second-order summary statistic, and develop a set of new Fisher-based statistics using weighted means. For inference by Monte Carlo, we use random permutations of weighted residuals depending on the null hypothesis. We conduct simulation experiments to demonstrate the performance of the new test statistics and present the results of the real problem.

Improvement of nisin production by using the integration strategy of co-cultivation fermentation, foam fractionation and pervaporation

In this work, an integrated strategy of fermentation and separation was developed to improve nisin production. During fermentation, the acidification of fermentation liquid would hinder the synthesis and maturation of nisin inside strain cells. First, Saccharomyces cerevisiae (S. cerevisiae) was co-cultivated with Lactococcus lactis subsp. lactis (L. lactis) to overcome above obstacle. Experimental results indicated that lactose could be used as the substrate carbon source of co-cultivation fermentation. When inoculation ratio of L. lactis and S. cerevisiae was 102:1, nisin titer and ethanol concentration in the fermentation liquid were 3436.3 ± 171.8 IU/mL and 5.9 ± 0.2 mg/mL, respectively. Subsequently, glucose (500 g/L) was supplied into the culture at 24 h for further increasing nisin yield through the quorum sensing of microorganisms. Foam fractionation was used to recover nisin from fermentation liquid. Under the conditions of volumetric air flow rate 40 mL/min, pore diameter of gas distributor 180 μm and initial coupling time of fermentation and foam fractionation after sugar supplementation 9 h, enrichment ratio and recovery percentage of nisin reached 5.8 ± 0.2 and 63.1 ± 2.8%, respectively. Through integrating pervaporation after sugar supplementation for 9 h, permeate concentration and recovery percentage of bioethanol were 367.2 ± 16.5 mg/mL and 76.2 ± 3.4%, respectively. The total nisin titer was 4593.2 ± 206.6 IU/mL.

CFD Study on MR-deDuster As a Fine Particle Emission Control

Reynolds stress model (RSM) is known to demonstrate the closest approximation with experimental data and appraised as the most reliable turbulent model for the flow field in a cyclone simulation against other models. In this study, computational fluid dynamics (CFD) with RSM was used to simulate MR-deDuster, which is a newly developed multi-cyclone for fine particle emission control with axial inlet entry. The flow field characteristics of velocity contour and particle trajectories inside the cyclone were profiled while particle cut-diameter (dpc) of the unit was predicted based on fractional collection efficiency. Throughout the simulation, three different inlet velocities represented by their respective volumetric air flow rates (Q) ranging from 0.27 to 0.35 m3/s were applied and the results were plotted accordingly by referring to the value of these Qs. The velocity flows are almost identical for every unit of the cyclone in MR-deDuster system with the highest velocity of 33 m/s was found at the end of the vortex finder operated at 0.35 m3/s. This is crucial to ensure that each unit is operated in similar mode to get optimum performance of the system. Meanwhile, discrete phase model was used to estimate the particle trajectories in the flow. By releasing a certain number of inert particles at the cyclone’s inlet, fractional collection efficiency plot could be determined using the ratio of tracked particles trapped and released through the outlet. This study indicated that the predicted dpc of MR-deDuster was 1.85 and 2.05 μm for the highest and lowest Q respectively. The former represents the highest inlet velocity which is able to attract more of fine particle deep inside the bottom of the cyclone compared to the latter. Thus, the predicted fractional collection efficiency of 100% was achieved for particle larger and equal to 10 μm in size at the highest volumetric air flow rate or inlet velocity. The importance of inlet velocity in reducing the dpc which simultaneously increase the performance of a cyclone is illustrated in this study as successfully demonstrated by the CFD software.

Extrudate dehydration rate increase by modernization of the extruder vacuum chamber

This paper proposes to upgrade the vacuum chamber of the extruder to enhance the impact of thermovacuum effect on extrudate due to dispensing air into the working volume of the vacuum chamber of the extruder. An air valve is installed in the upgraded extruder chamber. This valve allows faster removal of the wet steam with the extrudate surface. Analytical expressions, which allow determining the volumetric flow rate of intake air of the machine in the vacuum chamber and determining its influence on the basic design and technological parameters of the system, were obtained. The obtained results can be useful and taken into account in the process of subsequent theoretical studies of extruders with a vacuum chamber and will improve the efficiency of machines that perform thermal vacuum extrusion of plant materials.

Foam fractionation for the separation of SDBS from its aqueous solution: Process optimization and property test

Foam fractionation is an adsorption bubble separation technique allowing recovery and immediate reuse of surfactants. This work was aimed at investigating the variations in recovery efficiency and physicochemical property of sodium dodecyl benzene sulfonate (SDBS) through multiple foam fractionation operation. First, a suitable SDBS concentration of 0.05 g/L was determined for preparing feeding solution. Subsequently, effects of volumetric air flow rate, height ratio of liquid phase and foam phase, and pore diameter of gas distributor on recovery efficiency of SDBS were investigated, respectively. Response surface methodology (RSM) was used to optimize the operating conditions of foam fractionation for separating SDBS. Under the conditions of volumetric air flow rate 80 mL/min, height ratio of liquid phase and foam phase 1:2, and pore diameter of gas distributor 0.180 mm, enrichment ratio and recovery percentage of SDBS were 134.83 ± 6.74 and 63.43 ± 3.17%, respectively. In repetitive separation experiments, the maximum separation number of recovered SDBS by foam fractionation was 3. Experimental results of surface activity and foam properties of recovered SDBS solution suggested that the interfacial adsorption and desorption processes had induced the structural transition and irreversible aggregation of SDBS molecules after multiple foam fractionation operation.

Numerical and experimental analysis of a tube-and-fin cross-flow heat exchanger with a controlled non-uniform inflow of gas

The paper presents results of numerical and experimental analyses of a fin-and-tube air-water heat exchanger. The analysed device is a one-row heat exchanger with finned elliptical tubes. The aim of the analyses is to investigate the impact of a controlled non-uniform inflow of air on the heat exchanger performance. The heat exchanger was modelled numerically using the ANSYS Fluent program. The developed model was applied to simulate the heat exchanger operation in the conditions of the uniform inflow of air. Cases of an uncontrolled non-uniform inflow of gas were investigated experimentally, using a purpose-designed test station. On the experimental test station the effect of a controlled non-uniform air inflow was also achieved by placing appropriately shaped inserts in the air inlet duct, directing the air partially to the region of the water inlet header. By controlling the gas inflow, it was possible to significantly enhance the heat exchanger performance. The results of the multivariate numerical analyses conducted for the adopted parameters of the mediums (air and water volumetric flow rates and water temperature) show that the heat exchanger performance can be improved by up to almost 5% compared to a variant with a natural non-uniform air inflow taking place in the exchanger under consideration.

Türkiye’de Doğalgazın Tüketildiği Mahallerde Kullanılan Havalandırma Menfezlerin Optimizasyonu

Doğalgaz kullanılan dairelerde TS 7363 standardına göre sabit kanallı havalandırma sistemi olarak cam menfezi veya 150 cm2’lik havalandırma sistemlerinin kullanılmasının zorunluluğu araştırılmıştır. Türkiye’de kullanılan evsel gaz yakıcı cihazlarda A tipi bacasız cihaz (ocak) ve C tipi denge bacalı cihaz (hermetik kombi) ikilisi kullanıldığı görülmüştür. Hermetik cihazlar temiz havayı dışarıdan alıp kirli havayı dışarıya verdiği için iç hava kalitesine etkisinin olmadığı ancak bacasız gaz yakıcı cihazların (daireler için ev tipi ocakların) iç hava kalitesini etkileyip etkilemediği araştırılmıştır. Örnek il olarak Türkiye’nin en soğuk illerinden biri olan Erzurum seçilmiştir. Menfezden geçen havanın hacimsel debisi ANSYS-Fluent paket programı yardımıyla hesaplanmıştır. Havalandırma menfezinden ortama giren taze hava miktarının yanma için ihtiyaç duyulan taze hava miktarından 90 kat fazla olduğu bulunmuştur. Bu sonuç tüketicilerin 150 cm2’lik havalandırma menfezlerinin önemli miktarda enerji kaybına neden olduğu iddiasının doğru çıkartmaktadır. Dairelerde sabit kesit alanlı havalandırma menfezi yerine kullanılan yakıcı cihazların çeşidine ve mevsim şartlarına bağlı olarak değişken kesitli menfez kullanımı önerilir.

Thermo-hydraulic study in a shell and tube heat exchanger using rod inserts consisting of wire-nails with air injection: Experimental study

Recently, air bubbles injection with utilizing insets inside the tubes for enhancing heat transfer performance in shell and tube heat exchanger STHEs has achieved a great interest. In this study, air was injected by the simple method in tube sides where wired nails-circular rod inserts (WNCR) are presented with water tube side flow rate TSFR changed from 14 LPM to 18 LPM and water shell side flow rate is kept constant at a typical value of 18 LPM. Two configurations of inserts with different distance between the nails (10 cm and 5 cm) are employed with three different air volumetric flow rates AVFR of 1, 2, and 3 LPM. Effects of inserts only, inserts in conjunction with air injection, and air injection only on thermal parameters (i.e. number of transfer units NTU, effectiveness ε, and overall heat transfer coefficient U) and hydraulic performance (indicated in pressure drop Δp) are studied and discussed. Moreover, exergy efficiency and thermal hydraulic parameter are also presented and studied. Results indicated that inserts are more pronounced than air injection for all performance parameters. Moreover, the second type (insert B) of inserts has more influence than the first one (insert A). Percentage enhancements in performance parameters are within the ranges of 31%–131% for insert A, 43%–177% for insert B, 33%–143% for injection with insert A, 44%–184% for injection with insert B, 2%–19% for air injection only with insert A, and 1%–23% for insert B. Finally, air injection only gives a small effect on heat exchanger performance parameters (less than 5%) for performance parameters such as NTU, Δp, and thermal hydraulic parameter.

Heat and mass transfer in a honey dehydrator with closed air circulation

The article contains the results of research on transient heat and mass transfer processes occurring in a honey dehydrator with the capacity of 30 kg of honey with closed air circulation with volumetric flow rates V˙a = 0.01–0.03 m3s−1. The research was carried out different rotational speeds of the honey mixer ns = 120-270 rpm, without and with preheating of the honey. The article presents heat and mass balance equations for the considered process of honey dehydration, the values of heat transfer and mass transfer coefficients between honey and air were determined. The values obtained are respectively α = 5-25 Wm−2 K−1, β = 0.001–0.035 kg m−2s−1. The reduction of mixer speed from ns = 270 rpm tons = 120 rpm was accompanied by an increase in average heat and mass transfer coefficients of approx. 30% and 52%, respectively. The tripled volumetric flow rate of air(V˙a1/ V˙a2 = 3) resulted in an increase in heat and mass transfer coefficients – on average by 80% and 140%, respectively. Preheating the honey allows to increase the amount of removed water by 30%. The paper presents the general dimensionless expressions allowing for the calculation of heat and mass transfer coefficients.

Maillard reaction products for strengthening the recovery of trans-resveratrol from the muscat grape pomace by alkaline extraction and foam fractionation

In this study, the recovery of trans-resveratrol (trans-Res) from the muscat grape pomace had been investigated by alkaline extraction and foam fractionation with the assistance of Maillard reaction products. First, the conjugates of soy protein isolate (SPI) and dextran (Dex) were prepared by Maillard reaction, and they were characterized by SDS-PAGE and FTIR. The suitable Maillard reaction period of 10 h was determined by measuring glycation degree of SPI, foam stability and browning degree of reaction solution. Fluorescence spectrum showed that trans-Res could be assembled with SPI-Dex conjugates through intermolecular interaction. Response surface method (RSM) was used to establish the nonlinear multivariate relationship between process variables and response, thereby optimizing operation conditions. Response surface method (RSM) had been used to optimize the extraction conditions of trans-Res from the muscat grape pomace. The extraction percentage of trans-Res reached 88.2% under the optimal extraction conditions of temperature 80 °C, NaOH concentration 12 mM, SPI-Dex conjugates concentration 5.5 g/L and extraction time 86 min. Then, the supernatant of extracting liquor was separated and used to perform foam fractionation as the feeding solution. The SPI-Dex conjugates would play a role of collector for entraining trans-Res into the foam phase. At 30 °C of temperature, 150 mL/min of volumetric air flow rate, 0.3 M/kg of ionic strength and 400 mL of loading liquid volume, the recovery percentage and enrichment ratio of trans-Res were 90.3% and 6.2, respectively. Stability test results showed that SPI-Dex conjugates contributed to maintaining the stable structure of trans-Res by generating aggregates during foam fractionation.

RESEARCH OF THE FUNCTIONING AND OPTIMIZATION PROCESS OF THE STRUCTURAL-TECHNOLOGICAL PARAMETERS

Domestic and foreign scientists in recent years have performed a considerable amount of scientific research on the biological justification of optimal combinations of microclimate parameters required for the normal development of animals. However, the results of the studies do not allow one to specify the optimal parameters for different species of animals, taking into account their age, sex, weight and level of feeding. While it is possible to specify rather wide limits of change of temperature and relative humidity of air at which productivity is maximum, and technical and economic efficiency is approximately the same. Providing microclimate regulations in livestock premises is associated with significant costs of electricity and heat, which is about 17% of the producers' costs. To create a microclimate in livestock premises based on the above technological parameters and the analysis of the design features of the recuperators, two design and technological schemes of the three-pipe recuperator, which differ in the directions of movement of air flows, are proposed. The purpose of the research is to increase the efficiency of the technological process of functioning of the three-pipe recuperator for livestock premises by substantiating its structural and mode parameters. The results of theoretical studies of pneumatic losses in the three-pipe recuperator determined the dependence of pressure and power losses on the length of the air duct of the three-pipe recuperator, the radius of the external duct and the volume flow rate of air. As a result of theoretical studies, a mathematical model of the heat transfer process in a three-pipe heat exchanger was developed, with condensation in it, which allows to determine the temperature distribution of air flows by its length and its thermal capacity. The results of theoretical studies of the process of heat transfer in the design and technological schemes of a three-pipe recirculator with counter-current and direct-current showed that the counter-current variant is more effective. Optimization of the results of theoretical studies allowed us to determine the dependence of the design parameters of the three-pipe heat exchanger on the volumetric flow rate of air, subject to the highest useful thermal power.

Design and development of a machine for continuous popping and puffing of grains.

Popping/puffing have been traditionally practiced for enhancing storage life, improving organoleptic properties and ease of incorporation in ready-to-eat-foods. Currently, batch type sand and electric popping/puffing machines involving conduction mode of heat transfer are employed. The major drawbacks of these methods are high-energy consumption, scorching of grains, non-uniform product quality, contamination (by sand/ash) and problems in scale-up. Since fluidization is known to increase heat and mass transfer, a continuous fluidized popping/puffing machine (capacity 10-20kg/h) involving convective mode of heat transfer is designed/developed. Hot-flue gas generating from burning of LPG was used as the eco-friendly fuel. Process parameters such as expansion ratio, fluidization velocity, terminal velocity, carry over velocity, bulk density and voidage were estimated for un-popped and popped/puffed rice, maize, jowar (sorghum) and paddy. Fluidization and carry over velocities for these grains were in the range of 4.18-5.78m/s and 2.15-6.18m/s, respectively. Based on the terminal velocity of the grains and volumetric air flow rate of the blower, fluidization chamber diameter was arrived. Chamber diameter of 0.15m was found to be sufficient to generate required air velocity of 6.89m/s which met the fluidization and carry over velocities of popped/puffed grains. The designed fluidization chamber was analyzed for heat and mass transfer during popping/puffing. Convective heat and mass transfer coefficients were estimated to be in the range of 103-187W/m2°C and 0.124-0.162m/s, respectively. Theoretical values for total heat and mass transfer were similar to the experimental values.

Temperature analysis in flighted rotary drums and the influence of operating parameters

Flights in rotary drums are used to improve the mixing and the heat transfer. They lift particles out of the solid bed to shower them as curtains through the gas phase of the drum. The number of particles and their distribution are influenced by several operational parameters. An indirectly heated flighted rotary drum was designed and constructed to conduct experiments relating transverse particle motion to heat transfer. Batch experiments divided into heating and cooling periods were performed with glass beads as reference material. The axial, circumferential and radial temperature distributions were measured. It was found that increasing the rotational speed as well as the volumetric airflow rate leads to quick temperature changes, while an increase in the filling degree results in a gradual decrease of the temperature drop during cooling.

Measurement of multifractal character of bubble paths using image analysis

The trajectory of the virtual mass centers of sequentially departing gas bubbles in water flow has been analyzed in this study. The bubbles were generated from a brass nozzle of 1 mm inner diameter in a glass tank (300 × 150 × 500 mm3), filled with distilled water maintained at 21 ± 1 °C. A three-mirror system was used to obtain two frames of the workspace in a single shot of a Phantom v1610 high-speed camera. A three-dimensional computer reconstruction algorithm was developed, which consisted of a blur filter, canny edge filter, region of interest (ROI), and Kalman filter. This algorithm was used to obtain the coordinates of the center of mass of each individual gas bubble. We analyzed the bubble trajectories obtained for three different air volumetric flow rates. A multifractal analysis was used to evaluate the gas bubble dynamics. The wavelet transform modulus maxima method was used to obtain the singularity spectra of the bubble paths. The local Hölder exponent value proved that the gas bubble motion trajectories tended to behave in a deterministic and chaotic manner. In addition, the sensitivity of the chaotic bubble paths to small- and large-scale fluctuations of the lateral bubble displacement was investigated. In conclusion, the proposed approach allows us to distinguish between deterministic chaotic dynamics and the stochastic evolution of bubble paths.

Experimental and numerical heat transfer analysis of heat-pipe-based CPU coolers and performance optimization methodology

This paper presents an experimental and numerical heat transfer analysis of heat-pipe-based CPU coolers and a performance optimization methodology. The first part of the study focuses on the performance of two commercial HP-based CPU coolers under inclination angles of 0°, 90° and 180°. The results show that the 90° orientation provides the best thermal performance. The influence of heat pipe orientation on the performance of the entire system is obscured due to the much higher thermal resistance on the air-side of the cooler. A fourfold increase in air volumetric flow rate has only a minor effect on the cooling performance enhancement with a reduction of the thermal resistance from 0.11 K W−1 to 0.074 K W−1 at the highest heating power. In the second part of the study, heat transfer numerical simulations of the finned part of a cooler were performed and validated using experimental results. The output of the simulation is a 2-D temperature field, which is used as an input for the optimization methodology based on fin effectiveness and fin efficiency. Optimizing the fin geometry by removing unnecessary material yielded a 23% increase of the fin efficiency and decreased the weight of a fin by approx. 30%, proving the usefulness of the proposed methodology, which helps reduce costs, weight and development time of finned HP-based coolers.

DESIGN AND FABRICATION OF PORTABLE ATMOSPHERIC WATER SEQUESTRATOR AS AN OFF-GRID WATER SYSTEM

The lack of access to clean water has been one of the major issues in water-stressed countries. In this study, the design and fabrication of a prototype portable atmospheric water sequestrator device was carried out and tested for its ability to harness available water vapor in the atmosphere. The system utilized the concept of Peltier effect in Peltier units as a new way to liquefy atmospheric water. MATLAB® was used to investigate effects of different parameters namely humidity ratio, volumetric air flow rate, and Peltier surface temperature on water generation. Results showed that humidity ratio exhibited the highest significance among the parameters. Furthermore, the highest water production was found to be 7.643 mL at a Peltier surface temperature of 4 ºC, air flowrate of 24 ft3/min, and humidity ratio of 0.021. Moreover, the physico-chemical characteristics of the water produced was well under the Philippine standards and can be classified into Public Water Supply Class I. KEYWORDS: Design and fabrication, portable water sequestrator, Peltier effect, water generation

Моделювання процесу витрат повітря у камері пневмомарзана ротаційного висікального модуля

Equipment for the manufacture of cardboard products is constantly being improved. New sections for die cutting are being designed. As well as devices for carrying out technological processes of die-cutting and cutting down of cardboard products. The tendency to improve the rotational method of trimming and die cutting of sheet materials is increasing. The main problem in the design of die cutting equipment is the quality of the processes performed.The advantages of the rotary die cutting sections include high productivity. Therefore, improving this process is very important. This article deals with the technological process of cutting in the knife-counter—knife zone. The problem of the interaction of cutting actuators is considered. The use of pneumatic systems greatly simplifies the die cutting process.An advantage of the pneumatic die cutting module is that it can be integrated into the transport system. This combination of conveyor and rotary module allows for curved separation of cardboard sweep.The aim of this study is to simulate the technological parameters of the process of cutting cardboard reamers in a pneumatic system. The calculation was carried out by computer aided design.Accordingly, in the working area of die cutting of the pneumatic system, the air pressure changes. Therefore, temperature parameters of air are important parameters. As previous studies have shown, air temperature can affect the performance of the rotary die cutting module. With increasing temperature, the required air flow rate increases to maintain the required working pressure. This is directly related to a decrease in air density with increasing temperature.Improving the geometry of the nozzle of a pneumatic system is an important study. A partial drop in pressure in the working areas of the die cutting can lead to a decrease in the quality of material processing.The basis of the work is research on the influence of air flow and its temperature variables as a characteristic working fluid. Additional studies carried out using the SolidWorks computer-aided design system show the dependence of the air volumetric flow rate on its variable temperature in the working area of the pneumatic rotary die cutting section.

Tekhnologicheskiy raschet innovatsionnogo flyuidizatsionnogo skoromorozil'nogo apparata dlya plodoovoshchnoy produktsii

If the company is faced with the problem of freezing quickly a large batch of smallsized products such as berries, fruits and vegetables of small size (or cut into small pieces), mushrooms, shrimps, etc., then the best solution can not be found than the use of fluidized quickfreezing machines. Of course, the cost of this equipment is slightly higher than, for example, freezing chambers, however, the reduction of freezing duration several times improves considerably the final product quality as regards both its appearance and nutrient content. These machines may differ by sizes, performances and capacities. It is these characteristics that form their final value. But, purchasing this equipment one should focus, first of all, not on the price but on the tasks to be solved. An innovation fluidized quickfreezing machine has been computed and designed for freezing smallsized and smallfraction products in a dense suspended air flow. The calculation of operational parameters for freezing green pears, as an example, is given. The thermophysical properties of pears have been investigated, a machine for pears shock freezing have been designed. The results from studies testified the influence of product properties and the entire technological process on the freezing process as well as on the power efficiency of the fluidized machine as a whole. The calculation method offered allows determining the optimal rate of air motion in the loading compartment, the duration of product freezing, the area and sizes of the grid, the capacity and sizes of the machine, the coefficient of heat transfer from the freezable product, as well as the volumetric air flow rate through the grid and the heat load on the refrigeration equipment of the machine.

Considerations About the Required Volumetric Air Flow Rate Inside an Office Room with One Occupant – Case Study

Abstract In the construction process of modern buildings, the aim is to achieve maximum comfort within minimum energy consumption. One of the ways to achieve this requirement is the accurate determination of the volumetric flow rate of fresh air, necessary to ensure the required indoor air quality. This study begins with the experimental determination of carbon dioxide (CO2) concentration in an office room with one occupant performing three types of activities with different levels of physical intensities. Based on these measurements, a methodology for the precise determination of the volumetric air flow rate is presented. This method was compared with another one that takes into account body parameters and is considered in this study as the most accurate. The required outdoor air flow rate for the experimental room was also determined based on the present legislations of five different countries. Comparing all the studied methods and considering as refence the method based on body parameters, it was found that the accuracy of the values is influenced by the physical intensity of the activity and that most methods generally underestimate the amount of required fresh air.