Air Inlet Opening Research Articles

Numerical investigation of a novel cooling vortex tower using Relap5 computer code

The main objective of this work consists of modeling, simulation and analysis of the kinematic, dynamic and thermal characteristics of airflow through a novel vortex tower model carried out at the Nuclear Research Center of Birine (Algeria). This work is a contribution to a project aiming to study and design a vortex tower prototype based on an airflow heated by the secondary circuit of a nuclear reactor. The purpose of this process is to use the lost energy, traditionally transferred to the environment to cool a facility, to generate an additional amount of electrical energy. The main issue to be resolved in this study is to identify the appropriate location in the flow path where the flow characteristics are the most suitable to recover the maximum electrical energy using a turbo generator.The work presented in this paper is to investigate the airflow characteristics and predict the behavior of the vortex tower model using Relap5 system code in spite of the chaotic nature of the flow in such geometry. In addition, a parametric study is carried out in order to identify the effect of some parameters on the tower performance such as the air inlet velocity ranging from 0.01 to 0.3 m/s and the number of inlet openings varied from 1 to 8.Vortex model geometry is created and nodalized according to Relap5 system code modeling guidance and requirements. The developed model was qualified against experimental and numerical results available in the literature in terms of velocity quantities, as well as with an analytical calculation using the mass balance, a good agreement was obtained. The analysis of the simulation results showed that the selected tower configuration presents good characteristics with a maximum air velocity of 5.5411 m/s at a height of 0.560 m from the base (inlet section). The simulation highlighted clearly the contribution of the inlet parameters and the number of inlet openings to the enhancement of the vortex tower performances. The investigations revealed that an increase in air inlet velocity until 0.3 m/s leads to an increase of air velocity at the narrowing point of the tower attaining a maximum of 16.217 m/s. Furthermore, the results also showed that the maximum airflow velocity increases by 87 % when the number of air inlet openings is varied from 1 to 8.

A Study on the Thermal Performance of Air-Type BIPVT Collectors Applied to Demonstration Building

Research on existing air-type PVT (photovoltaic/thermal) collectors has mainly focused on improving the efficiency of the collector itself and on using the energy produced by the collector in heating and cooling facilities and building energy. The first consideration in an air-type PVT system applied to a building facade is the collector arrangement and the flow path considering the collector performance. It is necessary to design the flow inside the air-type BIPVT (building integrated photovoltaic/thermal) collector so that it runs smoothly so as not to cause a dead space and a pressure drop inside the collector, which deteriorate the thermal performance. This study analyzed the thermal characteristics of an air-type BIPVT collector applied to a demonstration building (educational buildings) according to the air flow path and inlet opening ratio. For this purpose, the uniformity of the airflow in the collector was compared through the NX computational fluid dynamics (CFD) program, and the acquired thermal calories and thermal efficiency of the BIPVT collector were compared and analyzed. Based on the simulation results, the temperature and thermal characteristics of the BIPVT collector were compared.

Interaction effect of room opening and air inlet on solar chimney performance

Solar chimney has been frequently adopted in buildings to save energy by enhancing the natural ventilation. Although its optimization studies have been frequently taken previously, most of them have focused on the configuration of solar chimney but ignored the air inlet, even though its significant influence has already been confirmed. The interaction between the air inlet and room openings (e.g. window and door) is critical to improving the solar chimney performance, but the related interaction mechanism is still not known. Interaction of room opening and air inlet on solar chimney performance was analysed under both natural ventilation and smoke exhaustion modes. Numerical results of 19 scenarios were first validated by reduced-scale experiment tests. Another 25 numerical scenarios for full-scale solar chimney room with different heights of air inlet (0.1–2.3 m) and window (0.6–1.8 m) were analysed. It was known from numerical results that the height of window shows limited influence on flow rate under natural ventilation mode but the obvious effect on both flow rate at the air inlet and the total flow rate (both window and air inlet) under smoke exhaustion mode, especially when the window centre is higher than wall centre. Scenario, when both the window and air inlet are at the vertical centre of the wall, shows the best performance of both natural ventilation and smoke exhaustion. An empirical model was also developed to predict the flow rate through the air inlet under smoke exhaustion. Critical conditions for air inlet to exhaust smoke were determined which happens when the neutral plane is almost no lower than the window centre.

Transparent Elemental Facade with an Integrated Ventilation Unit for a High-Rise Building – Development and Experimental Verification

Abstract The article documents the development of a modular transparent elemental facade. The cooperative development was realized in two areas, i.e., the development of facade ventilation units for an under-pressure ventilation system and experimental verification in a laboratory of a facade panel and optimization of its acoustic parameters. The task of controlled ventilation in modern residential buildings is to ensure the optimum quality of the interior environment and fulfill hygienic and thermal technical requirements that guarantee the comfort of the users. The paper discusses the development and experimental verification of atypical vertical ventilation units of an under-pressure controlled ventilation system for a residential high-rise building. A recommended concept for the facade´s details has been developed in relation to the ventilation system. Conceptual designs of alternatives to the air inlet openings of an under-pressure controlled ventilation system for the apartments with an atypical vertical geometry were proposed. An optimized alternative to air inlet openings in the bottom level of a vertical pilaster with the function of an air distribution channel for a ventilation system has been selected and developed. Laboratory experiments have verified the physical properties of the optimized alternative ventilation units of the under-pressure controlled ventilation system in their development cycle. The hydrodynamic regime of the air inlet openings of the controlled ventilation system has been verified by experimental research in a laboratory large rain chamber. The aerodynamic regime of a naturally controlled ventilation system was verified by experimental research in a large laboratory pressure chamber. The acoustic properties of the naturally controlled ventilation system were verified by experimental research in a laboratory´s acoustic chambers. The verified parameters of the ventilation units of the under-pressure controlled ventilation obtained by the experiment were compared with the design parameters. An experimental assessment of the mechanical, thermal and acoustical parameters of the elemental modular facade was carried out in a laboratory. At the end of the article, the results and conclusions of the laboratory experiment are summarized.

Enhancing the performance of vehicle cooling modules using diffusers

In this work, numerical results focused on the enhancement of water-air heat exchanger thermal performance are presented. New designs consisting of using diffusers between the front end openings of the vehicle and the first exchanger facing the airflow are suggested. The diffuser will reduce the velocity magnitude but over a larger area through the exchanger. This will reduce the air velocity non-uniformity upstream the exchanger and then increase its thermal performance. An in-house code is established to evaluate the thermal performance of the exchanger based on known parameters; namely, the ratio of the area of the air inlet opening to the area of the exchanger, the distance between the air inlet opening and the first exchanger at its downstream, the angle of the diffuser, and the water and air mass flow rates. It was shown that the thermal performance of the exchanger can be enhanced by up to 67% when the diffuser is present depending on the configuration.

A Review Paper on CFD Analysis of Tri-sector Air Preheater for different Primary Air Inlet Opening

A Review Paper on CFD Analysis of Tri-sector Air Preheater for different Primary Air Inlet Opening

An Image Based Mathematical Model for the Propagation of Fan Noise in a Plenum with Large Side Openings

This paper presents another application of an images group model for a special enclosure geometry and source orientation. A previous work outlined the concept via application to a special tight-fitting enclosure. Application of the concept to a fan plenum requires different mathematical descriptions for the image groups. This paper describes the sound reverberation inside a sound enclosure with mostly open sides where the primary noise sources are the air inlets and exhausts of axial type fans located at the top of the enclosure, the sound transmission through the air inlet openings, and the radiation to wayside positions. The main reverberation between the floor and ceiling is determined with an image based mathematical model. The model considers how the main reverberant part image group is amplified by its images from two parallel bulkheads and any side wall frame members. The method of images approach allows the hard surfaces of an untreated plenum to be represented by perfectly reflecting surfaces with zero sound absorption coefficients, thus not requiring any estimate or measurement for these surfaces. Numerical results show excellent comparison to experimental results for an actual plenum. The image model is also shown to be significantly more accurate than the standard large room diffuse field reverberant model.

Development and Experimental Verification of Ventilation Units for Under Pressure Ventilation System

Task of controlled ventilation in modern residential buildings is to ensure optimum quality of interior environment and fulfill hygienic and thermal technical requirements guaranteeing comfort of user. The paper discusses development and experimental verification of atypical vertical ventilation units of under pressure controlled ventilation system for residential high-rise building. Recommended concept of solution to façade detail in relation to ventilation system. Conceptual designs of alternatives of air inlet openings of under pressure controlled ventilation system for apartments of atypical vertical geometry. Optimized alternative of air inlet openings in the bottom level of vertical pilaster with function of air distribution channel for ventilation system. Laboratory experimental verification of physical properties of optimized alternative of ventilation units of under pressure controlled ventilation system in their development cycle. Hydrodynamic regime of air inlet openings of controlled ventilation system – laboratory experimental research in large rain chamber. Aerodynamic regime of natural controlled ventilation system – laboratory experimental research in large pressure chamber. Acoustic properties of natural controlled ventilation system – laboratory experimental research in acoustic chambers. Comparison by the experiment of verified parameters of ventilation units of under pressure controlled ventilation with design parameters.

New Façade Ventilation Units of under Pressure Controlled Ventilation System

Task of controlled ventilation in modern residential buildings is to ensure optimum quality of interior environment and fulfill hygienic and thermal technical requirements guaranteeing comfort of user. The paper discusses development and experimental verification of atypical vertical ventilation units of under pressure controlled ventilation system for residential high-rise building. Recommended concept of solution to façade detail in relation to ventilation system. Optimized alternative of air inlet openings in the bottom level of vertical pilaster with function of air distribution channel for under pressure controlled ventilation system. The paper discusses laboratory experimental verification of physical properties of optimized alternative of ventilation units of under pressure controlled ventilation system for high-rise residential building in their development cycle. Boundary conditions of physical designing of envelope structures for load of wind-driven rain and their modifications for high-rise building in the locality of Bratislava. Hydrodynamic regime of air inlet openings of controlled ventilation system – maintaining water impermeability of air inlet openings of the ventilation system under the effect of wind-driven rain – laboratory experimental research in large rain chamber, its results and necessary construction modifications of elements of ventilation units. Aerodynamic regime of natural controlled ventilation system – quantification of volume of air flow rate through ventilation units in dependence to air pressure difference - laboratory experimental research in large pressure chamber. Acoustic properties of natural controlled ventilation system – quantification of index of air impermeability of controlled ventilation system in open and closed position - laboratory experimental research in acoustic chambers. Comparison by the experiment of verified parameters of ventilation units of under pressure controlled ventilation with design parameters.

Model Experiment on Smoke Tower Part 3 Flow of Smoke and Air in the Anteroom in Case of Large Air Inlet and Smoke Outlet Openings

Model Experiment on Smoke Tower Part 3 Flow of Smoke and Air in the Anteroom in Case of Large Air Inlet and Smoke Outlet Openings

Natural Ventilation in Workshop with Different Horizontal Arrangement of Heat Source

The natural ventilation in a heating workshop with different horizontal arrangement of heat source was numerically simulated based on computational fluid dynamics (CFD) method. Realizable k- turbulent model was used to calculate the air flow and temperature distribution. Simulation results showed that the horizontal arrangement of the heat source in the workshop influenced heavily the air flow and temperature distribution. When the heat source was placed at the workshop centre, the heat distribution factor was minimal, the average air temperature at operation zone was lowest and the hot air exhausting velocity was highest, the air flow field and temperature distribution was reasonable for the natural ventilation. When the heat source was placed to be close to the air inlet opening, the fresh air would travel a short path and directly rise to exit and the fresh air did not reach to the right part of the workshop, leading to a possible accumulation of pollutant emission there. When the heat source was placed at the right side of the workshop, the benefit would be that the possible pollutant could be taken away by the air flow, however, the ventilation rate decreased.

Numerical study of smoke extraction for adhered spill plumes in atria: Impact of extraction rate and geometrical parameters

In case of fire in an atrium, a smoke and heat control (SHC) system can be designed to improve safety inside the atrium. An important design criterion is the smoke free height in the atrium. This smoke free height is the result of a number of parameters, of which the fire heat release rate (HRR), the SHC extraction mass flow rate, the position of the extraction device or opening and the size and position of openings for make-up air are of primary importance. In the present paper, an extensive numerical study, based on computational fluid dynamics (CFD), is presented in which these parameters are varied. The presence of a downstand or balcony is not covered in the study at hand. From the results, a correlation is presented for adhered spill plumes in atria without downstand, relating the smoke extraction rate to the smoke free height in the atrium. The smoke layer in the atrium is illustrated to become multi-dimensional beyond a certain threshold value of the smoke extraction rate and existing correlations, which do not take this phenomenon into account, are not conservative. The position and exact size of the make-up air inlet openings are shown not to affect the observations, as long as the openings are sufficiently large.

Numerical Simulation of the Natural Ventilation in Workshop with Different Air Inlet Openings

The authors numerically simulated the natural ventilation in an industrial workshop with heat sources by computational fluid dynamics (CFD) method when the height of air inlet opening was set different values. The flow and temperature fields in the workshop were simulated by realizable k-e turbulent model combined with a Discrete Ordinate (DO) radiation. Results showed the height of air inlet opening strongly influenced the flow and temperature fields in the workshop. When the height of air inlet opening increased, the natural ventilation was improved and more fresh air flowed into the workshop. When the height of air inlet opening increased from 1.7 meters to 3 meters, the temperature in the operation zone of the workshop dropped. When the height of air inlet opening increased from 2.7 meters to 3.7 meters, the temperature in operation zone did not change much, while the temperature in the upper zone of the workshop dropped. The heat distribution factor decreased first with the height of air inlet opening and then increased again. When the height of air inlet opening was 3 meters, the heat distribution factor was minimal.

Particle–Gas Mass Transfer in a Spouted Bed with Adjustable Air Inlet

Spouted bed equipment has the potential of producing high-quality particulate materials with reduced energy consumption and environment impact. Particle-to-gas mass transfer was investigated in a spouted bed with a novel design of two rotating drums placed symmetrically in the apparatus to create air inlet openings of adjustable width, so that fluidization can be adapted to the requirements of each product and process. The mass transfer coefficients between particle surface and gas were derived from first-period drying experiments with porous, nonhygroscopic material by assuming perfect back-mixing or, alternatively, ideal plug flow of the gas. Respective Sherwood numbers were empirically correlated and found to be superior to the Sherwood numbers of conventional fluidized beds or conventional spouted beds.

2階機械給排気方式及び床下給気方式についての実験と数値計算 : 住宅用ハイブリッド換気システムの性能評価に関する研究 その2

For the purpose of complementing the lack of ventilation airflow rate on the 2nd floor, the mechanical supply for the 2nd floor with passive exhaust system and the crawl space supply with hybrid exhaust system were suggested. Experiments and long-term numerical analysis were carried out for evaluating the system performance. As the results, the followings are reported; About the forth system, airflow rate of mechanical supply showed close connection to the balance of ventilation airflow rate. High building air-tightness and large amount of fan airflow rate for the 2nd floor are desirable for cold climate area especially. In the case of crawl space supply with hybrid exhaust system, good balance of ventilation airflow rate was obtained by adjusting the air inlet opening area on the 1st floor and the crawl space temperature. According to the calculation result for hybrid ventilation system, no correlation was shown with regional climate differences. It was found that airtight building needed larger air inlet opening area on the 1st floor for the balance of ventilation airflow rate.

Air inlet and outlet silencer structures for turbine

Both air duct inlet silencers and air duct outlet silencers for use with a stationary gas turbine are disclosed. The inlet silencer comprises a vertically extending duct structure having an upper section with a plurality of vertically extending sides and a top cover. Air inlet openings are formed in the vertically extending sides and an air outlet is formed at the bottom end for connection to the air intake housing of the turbine. An elongate, central airflow defining member is substantially cylindrical for a major portion of its length and extends downwardly from the top cover and past the air inlets. This member has a perforated sheet metal exterior and contains sound attenuating material. Airflow passages extend from the inlet openings towards the outlet with each defined by at least one interior wall. Each passageway bends substantially downwardly so that the bottom section extends vertically. The outlet silencer includes first and second series of splitters with each series forming smaller air passageways.

Noise muffler for an air blower

The noise generated by onrushing air which is produced by an air blower for use in conjunction with pneumatic conveying equipment is substantially reduced by directing the air flow through an enclosed housing from an air inlet opening to an air outlet opening mainly via hollow tubular members made of air pervious material shaped in a snake-like or serpentine fashion between the air inlet and the air outlet openings.

Fixed geometry controlled entrainment ventilated convergent nozzle and method

A combination convergent jet engine aircraft nozzle (86, 142, 146) and a ventilation tube (88, 136, 144) are fixed in place and have no moving parts. Ambient air is entrained through duct inlets (96, 140, 154, 160), through the nozzle walls, through hollow struts (90, 138), the struts supporting and being connected to a hollow central tube (102, 144) or a plurality of tubes (136), to adjacent the downstream end of the nozzle to mix at takeoff with the jet forming gas exhaust. The ducts (102, 136, 144) are positioned with respect to the nozzle exhaust so that entrained ambient air flows into the gas exhaust during takeoff and so that the ambient air flow is substantially restricted or shut off during cruise flight. Ambient air inlet openings (160) are formed as a porous surface, the holes through the surface being generally in the shape of louvers (166) of which downstream end portions (174) are depressed inwardly of the outer wall surface of the nozzle to provide a minimum drag along the outer nozzle periphery during cruise flight and at takeoff. A method of positioning and fixing the outlet end of a noise suppressor within a convergent nozzle so that entrained ambient air flows into the gas exhaust during takeoff to substantially reduce the engine noise and so that ambient air is substantially restricted or is shut off entirely during cruise flight. The method in which ambient air is entrained in a noise suppressor within a convergent nozzle and is exited downstream adjacent the nozzle downstream end to mix with the gas exhaust during takeoff to suppress the engine noise, and at cruise flight substantially restricting or shutting off the ambient air through the noise suppressor by turning engine exhaust gas toward the noise suppressor axis downstream of the ambient air exit.

Water-cooled internal combustion engine with a sound-absorbing cover

In order to improve in a simple manner the ventilation of a water-cooled internal combustion engine having a sound-absorbing cover, a suction device is provided at the air inlet opening of the cover, the suction device containing a suction port in the low pressure area of the radiator/fan assembly. By specific placement of several air inlet openings a variety of cooling requirements may be met.

Model Experiment on Smoke Tower Part 2 Flow of Smoke and Air in the Anteroom in the Case of Upper Smoke Outlet and Lower Air Inlet Openings

Model Experiment on Smoke Tower Part 2 Flow of Smoke and Air in the Anteroom in the Case of Upper Smoke Outlet and Lower Air Inlet Openings