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 Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

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.

Prediction of alpha factor values for fine pore aeration systems

2008 ◽  
Vol 57 (8) ◽  
pp. 1265-1269 ◽  
Author(s):  
S. Gillot ◽  
A. Héduit
Keyword(s):  
Flow Rate ◽  
Oxygen Transfer ◽  
Air Flow ◽  
Domestic Wastewater ◽  
Aeration Tank ◽  
Air Flow Rate ◽  
Factors Affecting ◽  
Domestic Wastewater Treatment ◽  
Alpha Factor ◽  
The Impact

The objective of this work was to analyse the impact of different geometric and operating parameters on the alpha factor value for fine bubble aeration systems equipped with EPDM membrane diffusers. Measurements have been performed on nitrifying plants operating under extended aeration and treating mainly domestic wastewater. Measurements performed on 14 nitrifying plants showed that, for domestic wastewater treatment under very low F/M ratios, the alpha factor is comprised between 0.44 and 0.98. A new composite variable (the Equivalent Contact Time, ECT) has been defined and makes it possible for a given aeration tank, knowing the MCRT, the clean water oxygen transfer coefficient and the supplied air flow rate, to predict the alpha factor value. ECT combines the effect on mass transfer of all generally accepted factors affecting oxygen transfer performances (air flow rate, diffuser submergence, horizontal flow).

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.

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.

An analytical study to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system

2019 ◽  
Vol 41 (4) ◽  
pp. 507-516
Author(s):  
Fa-Li Ju ◽  
Liying Liu ◽  
Xiaoping Yu
Keyword(s):  
Mechanical Ventilation ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Air Flow ◽  
Ventilation System ◽  
Theoretical Expression ◽  
Air Flow Rate ◽  
Rate Testing ◽  
Fan Speed ◽  
The Impact

Based on air flow rate testing of each branch fan in a distributed fan ventilation system under different branch air duct inlet static pressures, the conclusion can be drawn that there is a branch fan air flow rate deviation phenomenon. The air flow rate of the branch fan increases with the branch air duct inlet static pressure at the same branch fan speed, and the branch fan hinders the air flow rate in some cases. In this study, a theoretical expression of the deviation of the branch air duct design air flow rate was established, and the influencing factors of the deviation were determined to include the branch air duct resistance characteristics, branch fan performance, and branch air duct inlet pressure ratio. A graphic analytical method for determining the deviation of the branch fan design air flow rate was also proposed. Both methods can provide a theoretical basis for calculating and analysing the deviation of the branch fan design air flow rate in a distributed fan ventilation system. Practical application: This paper provides new data on the performance of a distributed fan ventilation system. Our results could be used to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system. Crucially, we not only propose two types of methods that can be applied to predict deviations of the air flow rate in a distributed fan ventilation system caused by the branch air duct inlet static pressures but also obtain the factors that are important for understanding the true impact of the deviation of the branch fan air flow rate. This study lays an important foundation for the design and operation of building mechanical ventilation systems.

The Impact of Air Flow Rate on Photobioreactor Sparger/Diffuser Bubble Size(s) and Distribution

2013 ◽  
Author(s):  
Anil R. Kommareddy ◽  
Gary A. Anderson ◽  
Stephen P. Gent ◽  
Ghazi S. Bari
Keyword(s):  
Flow Rate ◽  
Bubble Size ◽  
Air Flow ◽  
Air Flow Rate ◽  
The Impact

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 AUTOMATION CONTROL SYSTEM OF TECHNICAL CONDITION OF GAS TURBINE ENGINE COMPRESSOR

2019 ◽  
pp. 121-128
Author(s):  
Микола Сергійович Кулик ◽  
Володимир Вікторович Козлов ◽  
Лариса Георгіївна Волянська
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Static Pressure ◽  
Air Flow ◽  
Gas Turbine Engine ◽  
Technical Condition ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Turbine Engine ◽  
Flow Duct

The article is devoted to one of the approaches to the construction of an automated system for solving the problems of diagnostics and monitoring of the flow duct of aircraft gas turbine engines and gas turbine plants. Timely detection of faults and subsequent monitoring of their development in operation are possible thanks to automated systems for assessing the technical condition of engines. This is particularly relevant in operating conditions as the knowledge of the technical condition of the engine is necessary in any engine maintenance system allows  to choose the content and timing of maintenance, repair of the flow duct of gas turbine engines and gas turbine plants, as well as commissioning. The engineering technique, which can be applied at performance of maintenance and at stages of tests and debugging of aircraft engines, is considered. The automated system implements a method of measuring the air flow through the compressor and a technique for assessing the technical condition of the compressor by the relative change in air flow. To determine the air flow rate through the gas turbine engine, it is sufficient to measure only static pressure values in the flow part. The static pressure receivers are not located in the flow part and do not obscure it, and thus do not affect the compressor gas dynamic stability margin. The inspection area is selected for measuring in the flow duct of the air intake. Static pressure in the maximum and minimum cross sections of the chosen area is measured; the maximum cross-section area of the flow duct, the total temperature of the air flow is measured outside the air intake.  To determine the air flow rate, the functional dependence of the air flow rate on the static pressure is used. The algorithm for monitoring and diagnosing the operating condition of the engine is based on a comparison of the actual values of air flow rate with the air flow rate determined during the control tests or when using a mathematical model adapted for this gas turbine engine. The positive effect of the using of the proposed automated control system of technical condition is that the air flow rate measured under operating conditions will significantly increase the objectivity of the control of the operation and technical condition of the gas turbine engine.

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