Improving the estimation of methodological errors in reproducing the volumetric air flow rate by reference critical nozzle

Metrologiya ◽  
2021 ◽  
pp. 4-30
Author(s):  
V. I. Chesnokov
Keyword(s):  
Kinetic Energy ◽  
Flow Rate ◽  
Gas Flow ◽  
Flow Model ◽  
Air Flow ◽  
Operating Conditions ◽  
Initial Kinetic Energy ◽  
Methodological Error ◽  
Air Flow Rate ◽  
Critical Nozzle

In the development of the previously obtained results a more accurate estimate of the methodological error in reproducing the volumetric air flow rate by reference critical nozzle is given, associated with the choice of the gas flow model and due to taking into account the initial kinetic energy of the flow at the nozzle inlet. Based on improved flow model an analytical evaluation of the methodological error in reproducing the volumetric air flow rate by reference critical nozzle, which is due to a change in the humidity of the working air, has been carried out. It is shown that the methodological error in reproducing the volumetric air flow rate by reference critical nozzle, associated with a change in the air humidity, as well as the analogies methodical error caused by the existence of the initial kinetic energy of the flow, must be taken part in accuracy characteristics at the real operating conditions of the standard volumetric air flow rate using critical nozzles.

scholarly journals The effects of operating conditions on the performance of a direct carbon fuel cell

2013 ◽  
Vol 34 (4) ◽  
pp. 187-197 ◽  
Author(s):  
Andrzej Kacprzak ◽  
Rafał Kobyłecki ◽  
Zbigniew Bis
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Gas Flow ◽  
Air Flow ◽  
Operating Conditions ◽  
Cell Performance ◽  
Fuel Particle ◽  
Air Flow Rate ◽  
Direct Carbon Fuel Cell ◽  
Fuel Particles

Abstract The influences of various operating conditions including cathode inlet air flow rate, electrolyte temperature and fuel particles size on the performance of the direct carbon fuel cell DCFC were presented and discussed in this paper. The experimental results indicated that the cell performance was enhanced with increases of the cathode inlet gas flow rate and cell temperature. Binary alkali hydroxide mixture (NaOH-LiOH, 90-10 mol%) was used as electrolyte and the biochar of apple tree origin carbonized at 873 K was used as fuel. Low melting temperature of the electrolyte and its good ionic conductivity enabled to operate the DCFC at medium temperatures of 723-773 K. The highest current density (601 A m−2) was obtained for temperature 773 K and air flow rate 8.3×106 m3s−1. Itwas shown that too low or too high air flow rates negatively affect the cell performance. The results also indicated that the operation of the DCFC could be improved by proper selection of the fuel particle size.

scholarly journals Air flow model development and application in a complex combined sewer system

2020 ◽  
Vol 82 (8) ◽  
pp. 1687-1700 ◽  
Author(s):  
Hasan Zobeyer ◽  
David Z. Zhu ◽  
Stephen Edwini-Bonsu
Keyword(s):  
Flow Rate ◽  
Flow Model ◽  
Air Flow ◽  
Model Development ◽  
Iterative Solution ◽  
Momentum Equation ◽  
Air Flow Rate ◽  
Sewer System ◽  
Combined Sewer ◽  
Combined Sewer System

Abstract A steady-state air flow model was developed and applied in a complex combined sewer system in the city of Edmonton, Alberta, Canada. The model solves the continuity at each junction and the momentum equation for the links coupled with dropshaft and other manholes. The dropshaft pressure gradient is computed using the dropshaft equation and air flow rate through manhole pickholes is computed considering the opening as an orifice. A leakage factor is used as a calibration parameter to represent the area through which air can leak from the manholes into the neighborhood. The model uses an iterative solution algorithm with a forward sweep for the continuity and backward sweep for the momentum equation. An underrelaxation is applied to update pressure in each iteration for model stability. The model was calibrated and validated by using the measured air flow rate and manhole pressure in the sewer network, with good results. An analysis of the air flow characteristics shows that a significant amount of air is brought into the system due to a large headspace in the upstream trunk but over 70% of this air is released into the neighborhood due to reduced headspace in the downstream trunk.

scholarly journals Experimental Study and Performance Analysis of a Portable Atmospheric Water Generator

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 73 ◽  
Author(s):  
Wei He ◽  
Pengkun Yu ◽  
Zhongting Hu ◽  
Song Lv ◽  
Minghui Qin ◽  
...  
Keyword(s):  
Flow Rate ◽  
Reference Model ◽  
Air Flow ◽  
Operating Conditions ◽  
Water Yield ◽  
Air Humidity ◽  
Air Flow Rate ◽  
Thermoelectric Coolers ◽  
And Performance ◽  
The Impact

Found in some specific scenarios, drinking water is hard for people to get, such as during expeditions and scientific investigations. First, a novel water generator with only two thermoelectric coolers (Model A) is designed for extracting water from atmospheric vapor and then experimentally studied under a small inlet air flow rate. The impact of operating conditions on surface temperatures of cold/hot sides and water yield are investigated, including the air flow rate and humidity. Alternately, to determine the super performance of Model A, a comparative experiment between Model A and a reference model (Model B) is carried out. The results suggest that both the cold/hot temperature and water yield in Model A increases with the humidity and air flow rate rising. Seen in comparisons of Model A and Model B, it is found that, at an air humidity of 90% and air flow rate of 30 m3/h, the total water yield was increased by 43.4% and the corresponding value reached the maximum increment of 66.7% at an air humidity of 60% and air flow rate of 30 m3/h. These features demonstrate the advantage of Model A especially in low air humidity compared to Model B.

scholarly journals Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers

2015 ◽  
Vol 47 (1) ◽  
pp. 69-85 ◽  
Author(s):  
Marek Kalenik
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Operating Conditions ◽  
Water Delivery ◽  
Air Flow Rate ◽  
Analysis Of Results ◽  
Delivery Pipe ◽  
Air Lift

Abstract: Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L) of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

Evaluation of numerical modelling for a compact down-hole subsea gas-liquid separator for high gas content

2009 ◽  
Vol 49 (1) ◽  
pp. 433
Author(s):  
Shakil Ahmed ◽  
Mohamed Nabil Noui-Mehidi ◽  
Jamal Naser's ◽  
Gerardo Sanchez Soto ◽  
Edson Nakagawa
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Volume Fraction ◽  
Air Flow ◽  
Gas Content ◽  
Water Mixture ◽  
Air Flow Rate ◽  
Flow Rates ◽  
High Efficient ◽  
Liquid Separator

This paper describes the computational fluid dynamics (CFD) modelling of a laboratory scale gas-liquid separator designed for high gas content. The separator consists of two concentric pipes with swirl tube in the annular space between the pipes. The gas-liquid mixture comes tangentially from the side inlet and the system works with a combination of gravity and centrifugal forces to achieve a high-efficient gas-liquid separation. Three dimensional transient multi-phase fluid flows were solved to predict the velocity and volume fraction of each phase. The standard k- turbulence model was used for turbulence closure. The performance of the gas-liquid separator was visually established for a range of gas flow rates (271–495 L/min), with volume fraction (VF) =0.874–0.985 by observing the liquid carry over (LCO) regime where liquid was carried out in the gas stream. The liquid and gas flow rates at which the LCO was observed defines the upper operational range of the separator. Air-water mixture was used in the numerical simulations to keep consistent with the experiments. The pressure between the inlet and exit was validated against the experiments for different air-water flow rate combinations. The values were matched reasonably well for high air flow rate (495 L/min, VF=0.985) but were under-predicted for low air flow rate (271 L/min, VF=0.874). The air and water were mixed upstream of the inlet in the experiments and the pressure was measured at the start of the inlet. In case of numerical simulation the air and water were mixed at the inlet. This might cause the deviation of pressure when the air flow rate was low.

scholarly journals Air Flow Model for Mixed-Mode and Indirect-Mode Natural Convection Solar Drying of Maize

2020 ◽  
Vol 10 (2) ◽  
pp. 1
Author(s):  
Isaac N. Simate
Keyword(s):  
Natural Convection ◽  
Flow Rate ◽  
Mixed Mode ◽  
Flow Model ◽  
Air Flow ◽  
Solar Drying ◽  
Air Flow Rate ◽  
Thermal Buoyancy ◽  
Early Stages ◽  
Grain Moisture

An air flow model for mixed-mode and indirect-mode natural convection solar drying of maize to help understand the factors that influence air flow in the dryer is presented. Temperatures at various sections of the dryer obtained from drying experiments were input to the air flow model to predict the respective thermal buoyancies. The air flow rate was determined by balancing the sum of the buoyancy pressures with the sum of the flow resistances in the various sections of the dryer. To validate the model, the predicted air flow was compared with measured air flow from experiments. For both the mixed-mode and indirect-mode, the biggest driver of the air flow is the thermal buoyancy created in the collector, while the grain bed is the dominant pressure drop. Thermal buoyancy on top of the grain bed is largely responsible for the variation in air flow, translating into low mass air flow during the early stages of drying when grain moisture is high, and higher air flow in the later stages when grain moisture is low. The heating of the grain bed by direct radiation in the mixed-mode translates into a slightly higher air flow rate than the indirect-mode. The implications are that a thinner grain bed results in shorter drying time as it has a higher air flow rate than a thicker one. To mitigate the low air flow at the early stages of drying, the collector length should be appropriately designed for a desired air flow.

A review of pilot-scale studies of bottom and surface velocities within air-agitated circular and rectangular vessels

1990 ◽  
Vol 17 (2) ◽  
pp. 243-251
Author(s):  
David W. Machina ◽  
Jatinder K. Bewtra
Keyword(s):  
Flow Rate ◽  
Design Parameter ◽  
Fluid Velocity ◽  
Air Flow ◽  
Operating Conditions ◽  
Surface Velocity ◽  
Air Flow Rate ◽  
Dimensionless Numbers ◽  
Power Requirement ◽  
Compressor Power

The use of bottom or surface fluid velocity within air-agitated circular and rectangular vessels has been studied as a possible design parameter to achieve a specified scale of agitation. Experimental data are presented in terms of five dimensionless numbers involving the fluid velocity, the depth of fluid in the vessel, the elevation of the diffuser above the vessel floor, the air flow rate, and the compressor power required. Design equations are obtained for a total of 506 physical observations with a ring diffuser around the perimeter of a circular vessel, a pipe diffuser at the centre of a circular vessel, and a line diffuser at the centre line or end wall of a rectangular vessel. The applicable range of variables for each equation is provided. It is shown that both bottom and surface velocities increase with an increase in air flow rate or compressor power requirement for a specified fluid depth. For a constant air flow rate and fluid depth, the surface velocity always exceeded the bottom velocity. The surface and bottom velocities are related to operating conditions in different water and wastewater treatment units in which a specified degree of uniformity of the vessel contents has to be maintained in order to keep a specified particle in suspension. The sensitivity analysis of the model revealed that the fluid depth was the most important design parameter in controlling the velocities within air-agitated vessels. Key words: bottom velocity, surface velocity, velocity gradient, degree of uniformity, air-agitated rectangular vessels, air-agitated circular vessels.

scholarly journals A Analisa Kinerja Pembangkit Listrik Dual-Fuel Kapasitas 40 Kw Berbasis Gasifikasi Limbah Sabut Kelapa Di PT. Indonesia Power Pesanggaran Bali

Jurnal METTEK ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 26
Author(s):  
A.A Ngurah Wisnu Kusuma ◽  
I Gusti Bagus Wijaya Kusuma ◽  
A.A.I.A.S Komaladewi
Keyword(s):  
Flow Rate ◽  
Diesel Fuel ◽  
Power Plants ◽  
Gas Flow ◽  
Air Flow ◽  
Dual Fuel ◽  
Air Flow Rate ◽  
Coconut Fiber ◽  
Air Inlet ◽  
Fiber Consumption

Telah dilakukan penelitian tentang kinerja pembangkit listrik dual-fuel 40 kW berbahan bakar solar dan bahan bakar hasil gasifikasi dari limbah sabut kelapa. Penelitian ini bertujuan untuk mengetahui konfigurasi laju alir udara pembakaran (AFR) terhadap daya keluaran mesin diesel dan penghematan minyak solar yang dihasilkan. Pengukuran dilakukan dengan mengukur konsumsi bahan bakar solar, laju alir gas produser, daya genset, dan konsumsi sabut kelapa pada bukaan valve inlet udara pembakaran setengah dan penuh dengan pemberian beban listrik 0-100%. Data menunjukan bahwa konfigurasi laju alir udara pembakaran (AFR) yang baik digunakan adalah bukaan setengah dan kinerja mesin diesel dual-fuel menggunakan bahan bakar biomassa sabut kelapa mampu mengurangi konsumsi solar sebesar 41.4% Research on the performance of 40 kW dual-fuel power plants with diesel fuel and gasification fuel from coconut fiber waste. This study aims to determine the configuration of combustion air flow rate (AFR) on diesel engine output power and saving diesel fuel produced. Measurements were made by measuring diesel fuel consumption, producer gas flow rate, generator power, and coconut fiber consumption at the opening of the half and full combustion air inlet valve by providing 0-100% electric load. Data shows that the configuration of the combustion air flow rate (AFR) good to use is the half openings and the performance of dual-fuel diesel engines using coconut fiber biomass fuel can reduce diesel consumption by 41.4%

scholarly journals Empirical Thermal Performance Investigation of a Compact Lithium Ion Battery Module under Forced Convection Cooling

2020 ◽  
Vol 10 (11) ◽  
pp. 3732
Author(s):  
Akinlabi A. A. Hakeem ◽  
Davut Solyali
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Air Flow ◽  
Lithium Ion ◽  
Operating Conditions ◽  
Battery Pack ◽  
Performance Criteria ◽  
Maximum Temperature ◽  
Air Flow Rate ◽  
Worst Case

Lithium ion batteries (LiBs) are considered one of the most suitable power options for electric vehicle (EV) drivetrains, known for having low self-discharging properties which hence provide a long life-cycle operation. To obtain maximum power output from LiBs, it is necessary to critically monitor operating conditions which affect their performance and life span. This paper investigates the thermal performance of a battery thermal management system (BTMS) for a battery pack housing 100 NCR18650 lithium ion cells. Maximum cell temperature (Tmax) and maximum temperature difference (ΔTmax) between cells were the performance criteria for the battery pack. The battery pack is investigated for three levels of air flow rate combined with two current rate using a full factorial Design of Experiment (DoE) method. A worst case scenario of cell Tmax averaged at 36.1 °C was recorded during a 0.75 C charge experiment and 37.5 °C during a 0.75 C discharge under a 1.4 m/s flow rate. While a 54.28% reduction in ΔTmax between the cells was achieved by increasing the air flow rate in the 0.75 C charge experiment from 1.4 m/s to 3.4 m/s. Conclusively, increasing BTMS performance with increasing air flow rate was a common trend observed in the experimental data after analyzing various experiment results.

scholarly journals Ammonia nitrogen removal and recovery from acetylene purification wastewater by air stripping

2017 ◽  
Vol 75 (11) ◽  
pp. 2538-2545 ◽  
Author(s):  
Lei Zhu ◽  
DeMing Dong ◽  
XiuYi Hua ◽  
Yang Xu ◽  
ZhiYong Guo ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Air Flow ◽  
Ammonia Nitrogen ◽  
Operating Conditions ◽  
H2so4 Solution ◽  
Air Flow Rate ◽  
Air Stripping ◽  
Experimental Conditions ◽  
N Removal

Ammonia nitrogen (NH4-N) contaminated wastewater has posed a great threat to the safety of water resources. In this study, air stripping was employed to remove and recover NH4-N from acetylene purification wastewater (APW) in a polyvinylchloride manufacturing plant. Investigated parameters were initial APW pH, air flow rate, APW temperature and stripping time. The NH4-N removal by air stripping has been modeled and the overall volumetric mass transfer coefficient (KLa) of the stripping process has been calculated from the model equation obtained. In addition, the ability of H2SO4 solution to absorb the NH3 stripped was also investigated. The results indicated that under the experimental conditions, the APW temperature and its initial pH had significant effects on the NH4-N removal efficiency and the KLa, while the effects of other factors were relatively minor. The removal efficiency and residual concentration of NH4-N were about 91% and 12 mg/L, respectively, at the optimal operating conditions of initial APW pH of 12.0, air flow rate of 0.500 m3/(h·L), APW temperature of 60 °C and stripping time of 120 min. One volume of H2SO4 solution (0.2 mol/L) could absorb about 93% of the NH3 stripped from 54 volumes of the APW.

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