Inlet Window Research Articles

Evaluation of Free Cooling Technique at the Telecom Cell Site in Ghana

Air Conditioning (AC) is the primary source of cooling in a typical Cell Site (CS) although it consumes a large quantity of electricity. Excessive energy consumption due to air conditioning increases the operational expenses of telecommunication companies. Therefore, network operators have attempted various techniques to reduce the exorbitant cost of a cell site’s high-power consumption. A Free Cooling (FC) System is one such approach. This paper uses computer modeling to investigate how the FC System will function at a CS in Ghana for 12 hours (from 6 pm to 6 am). A shelter with dimensions of 3 m × 2.47 m × 2.45 m (L × B × H) is used in the study, with three window positioning scenarios (different window heights), namely: (a) an inlet window 0.5 m high, and the outlet window 1.5 m high, (b) an inlet window and outlet window both 1.0 m high and (c) an inlet window 1.5 m high, and the outlet window 0.5 m high. The analysis revealed that the shelter with inlet and outlet windows at the same height has the most efficient heat dissipation potential. Furthermore, at a set temperature threshold of 25 °C, the annual percentage share for the two operating modes is approximately 67% for AC and 33% for FC in 2020, 76% for AC and 24% for FC in 2021, and 61% for AC and 39% for FC in 2022. However, when the set temperature threshold is increased from 25 °C to 30 °C, the annual percentage share is approximately 0.01% for AC and 99.9% for FC in 2020, 0% for AC and 100% for FC in 2021, and 1% for AC and 99% for FC in 2022. Thus, the proportion of free cooling increases as the set temperature threshold is raised, indicating potential energy savings. It could be concluded that in Ghana, installing a cell site with an FC system and setting the temperature of its control system to 30 °C or higher will result in significant energy savings.

Study of the inertial separator of the clover thresher with a pneumatic loader

The clover thresher with a pneumatic loader, having an inertial louvered counterflow separator, is characterized by a simple design and operation, reliability and durability, convenient arrangement with other elements of the pneumosystem and relatively low hydraulic resistance. The wedge-shaped sedimentation chamber (separator) with a horizontally displaced discharge opening towards the inlet window is equipped with a louvered partition installed at the junction of the inlet and outlet windows. To determine the basic design parameters of the inertial louvered counterflow separator of the clover thresher, the authors experimentally studied the hull of meadow clover with a humidity of 12 to 14% of the following composition: 57.4% of beans with seeds; 16.6% of free seeds; 25.0% of light impurities; 1.0% of heavy impurities. As a result, the main design parameters of the separator have been determined: the length of the louver grille is 210 mm, the pitch, length, angle of installation of the louver plates are 40mm, 50 mm, 30°, respectively, the height of the inlet and outlet windows of the separator is 120 and 280 mm, the height of the outlet windows of the louver and counterflow cleaners is 190 and 80 mm, the depth of the discharge pipe of the sedimentary chamber is 570 mm. The efficiency of the pneumatic loader when feeding 300 kg/h: the amount of released heavy impurities - 100%, light impurities -33.6%, loss of full-fledged seeds to waste - 0.8% hydraulic resistance - 196 Pa. The research results give grounds to recommend this design for application.

An Assessment of Orientation on Effective Natural Ventilation for Thermal Comfort in Primary School Classrooms in Enugu City, Nigeria

The current harsh climatic and high thermal conditions observed across the globe due to climate change is a challenge for indoor thermal comfort in buildings. In most developing nation, educational buildings where formal teaching and learning is conducted are designed to function without mechanical ventilation in an attempt to save energy costs hence relying solely on Natural ventilation. However, the effects of orientation on effective natural ventilation in educational buildings in the hot-humid tropical environments have not been adequately explored. The aim of this study was to investigate the effect of orientation of the classroom buildings with respect to cardinal and wind directions on effective natural ventilation desired for thermal comfort in buildings of public primary schools in the city of Enugu, Nigeria. It adopted a combination of experimental and descriptive survey research design. Instruments for data collection were two thermo-anemometer data logging device (AZ 9871) for determining both indoor and outdoor temperatures, wind velocities and relative humidity of classrooms of selected 60 public primary school building in the metropolis based on stratified sampling technique. Data analysis was done using linear regression analysis, the global coefficient of ventilation and building orientation standards. The research results showed that there was a correlation between classroom building orientations and effective natural ventilation coefficient and that the mean natural ventilation efficiency of 80% above the 60% global ventilation efficiency standard was achieved. In addition, orientation of classroom buildings in terms of inlet window planes to the dominant wind direction had positive significant effect on natural ventilation efficiency, invariably influencing the thermal comfort conditions of the investigated classrooms. The research concludes that adequate attention should be given to the orientation in classroom buildings especially in the hot humid tropical environments by architects and building designers to ensure thermal comfort is achieved for effective teaching and learning.
 Keywords: Building orientation, Natural ventilation, Tropical environment, Classroom buildings, Thermal comfort

FINDING THE TRAJECTORYOF MOVEMENT OF A MATERIAL PARTICLE ON THE INNER SURFACE OF A VERTICAL CYLINDER AT THE SIDE SUPPLY OF MATERIAL

The movement of material particles on the inner surface of the cylinder takes place in cyclones. Due to the complexity of the aerodynamics of the process, theoretical developments can not be used as a basis for calculating the design and efficiency of their operation. Because of this, a number of simplifications are allowed in the theoretical provisions, as a result of which the calculated data do not coincide with the experimental data. The use of modern software products, which have great graphics capabilities, allows you to get new results in solving such problems in the form of high-quality graphic illustrations. The aim of the study is to determine the motion of a material particle that enters the inner surface of a vertical cylinder with a given initial velocity. A number of simplifications were introduced in the calculations: air resistance, the effect of particles on each other, their size, etc. were not taken into account. Accompanying Frenet and Darboux triangles were used to find the trajectory. Differential equations of motion of a material particle on the inner surface of a vertical cylinder are compiled. The equations are solved using the MatLab system. It is established that the velocity of particles that fall on the inner surface of the cylinder decreases to a certain value, and then begins to increase. For specific conditions (coefficient of friction and radius of the cylinder), the value of the minimum speed to which the movement of particles is slowed down is approximately the same and does not depend on the value of the initial speed. This means that there is a minimum value of the initial velocity at which the particle will not slow down when it hits the surface of the cylinder. Since particles with different coefficients of friction at the initial stage of their movement on the cylinder are poorly scattered on its surface, for the effective operation of the cyclone you need to make an inlet window of sufficient size in the vertical direction.

Sprayer for chemical treatment of vineyards and orchards

The authors have developed an improved sprayer for two-way chemical treatment of vineyards and orchards. The research aims to justify the design scheme and parameters of the sprayer. The proposed sprayer is equipped with a centrifugal fan, which directs air flow from the inlet window to two opposite sides. The distributor is designed as a truncated cone with an inlet nozzle on its small base and outlet nozzles equally spaced on its large base and connected to sprayers by flexible hoses of equal length. It is established that the diameter of the centrifugal fan wheel 630 mm, number of fan wheel rotations 1500 r/min, diameters of large and small distributor base as a truncated cone 90 mm and 18 mm respectively, the diameter of each nozzle set on its large base 3 mm, cone height 100 mm, number of atomizers 20 pieces and working liquid pressure in the system 0.40-0.45 MPa is provided a uniform distribution of working liquid.

JUSTIFICATION OF CHANGE IN CASE OF VACUUM PUMPS

Milk production is closely related to the milking process. The operations that are involved in this process require high responsibility and are quite laborious. The economic efficiency of the milking process depends not only on the qualifications of the operators, but to a large extent is determined by the technical perfection of the means of mechanization that are used. After all, the vacuum pump, which is part of any milking installation, has a significant impact on the productivity of the latter. The operation of the executive elements of the milking machines, as well as the transportation of milked milk, depends on the amount of air taken. The perfect design of the vacuum pump affects the energy consumption of the milking process. The analysis of vacuum pumps used in the technological process of machine milking is made. Research and literary sources indicate that mechanical rotary vacuum pumps are most widely used, this is explained by a number of technical and economic indicators. The specific energy consumption of a rotary vane vacuum pump depends on the value of the set working vacuum and the rotor speed. In most rotary vane vacuum pumps, the housing design provides for the movement of air through the inlet pipe to the inlet port and does not fill the space between the two blades as much as possible. If the air is escaping, it cannot be quickly emitted through the outlet window. These disadvantages are eliminated by the fact that a transverse groove is located at the end (in the direction of movement of the rotor) of the inlet window. To effectively remove air from the pump, the outlet window, at the beginning (in the direction of the rotor movement), has a transverse groove, the dimensions of the grooves are 4/5 of the width of the vacuum pump housing and less than 1/2 of the width of the corresponding window. The proposed design of the body of the vacuum pump makes it possible to increase the productivity by 7-12% and reduce the power consumption for the drive by 8-10%, in addition, there is a decrease in the heating of the body to 67-74 °С.

Effects of Water Intake Layout along the Wharf Shoreline on Ships

Abstract The construction of a water intake along the wharf shoreline can realise the intensive and comprehensive utilisation of the shoreline. However, since the water intake will increase the lateral flow at the wharf and also the hydrodynamic forces on ships, it will bring risks to ships mooring and leaving. The effects of the water intake on ships are studied using a physical model, numerical model and standard formulas. The results show that it leads to an increase of the hydrodynamic forces acting on the ship when the standard formulas are used to calculate the forces without considering the water level difference between the two sides of the ship. The results of the physical model are closer to the real situation. Measures that can effectively reduce the influence of the water intake on ships are proposed by increasing the distance between the wharf front and the front of the water intake as well as the depth of the water inlet windows.

Experimental identification of pressure drop characteristics at the shell side of an intermediate heat exchanger inside a prototype generation-IV sodium-cooled fast reactor

The flow characteristics at the shell side of a prototype intermediate heat exchanger (p-IHX) in a prototype generation-IV sodium-cooled fast reactor (PGSFR) were investigated experimentally in this study. The shell side of the p-IHX consisted of an inlet window, tube bundles, grid plates, and an exit flow channel. Two different test facilities were newly constructed to identify the pressure drop characteristics due to the complicated configuration with minimized scaling distortion. An intermediate heat exchanger test loop for PGSFR (iHELP) was constructed to characterize the flow resistance of the tube bundle regions with the grid plates and inlet window. The iHELP test section with a slab-shaped cross section was manufactured with a 1/29.6 vol scale ratio by preserving the height of the p-IHX. The hydraulic diameter at the tube bundle regions, the porosity of the grid plates, and the configuration of the tube bundles were conserved. In addition, the Reynolds number was preserved, which determined the flow rate conditions for the iHELP experiments. To investigate the pressure drop characteristics of the exit flow channel (EC), an intermediate heat exchanger test loop for the exit flow channel (IEC) was built with a 1/5 linearly reduced length scale by preserving the geometry of the flow path based on the EC of the p-IHX. The Euler number was conserved with a 1/8 Reynolds number ratio corresponding to a 1/1 flow velocity ratio to the p-IHX for dynamic similarity. By using each test facility the experimental pressure drop data satisfying the experimental uncertainty requirements were obtained separately for the bundle and exit channel regions. The pressure drop at the shell side of the p-IHX under a wide range of flow rate conditions was determined by using the pressure drop results from the iHELP and the IEC test facilities, which would be useful in improving and validating the pressure drop correlations in the IHX design computational code (SHXSA).

Numerical Optimization of Aperture Absorbing Loads of Liquid Calorimeters for High-Power Microwave Pulses

Frequency-domain numerical modeling is performed and disc-shaped wide-aperture absorbing loads of calorimeters with a working liquid based on ethyl alcohol, which are designed to measure the energy of highpower microwave pulses, are optimized using the finite element method and the Nelder–Mead gradientless procedure. The possibility of using caprolon and polycarbonate as a load casing material with a corrugated inlet window together with low-pressure high-density polyethylene is investigated. The results of calculations significantly refined the results obtained earlier using a computational technique based on the finite-difference time-domain method for a simplified model of the absorbing load.

Acoustical Benefits of Plenum Window as Facade Device – A Parametric Study

Rapid population growth and economic development have led to serious noise pollution in densely populated cities. As the noise level keeps on increasing, opening windows for natural ventilation has become nearly not possible, especially in urbanized residential areas. Plenum window is the modification of a partially opened double glazing window system to the staggered inlet and outlet window openings which can provide better sound protection to the building and at the same time can allow certain degree of natural ventilation across it. A series of full-scale laboratory measurements were carried out in order find out the relationship between the important parameters and the acoustical performance of plenum window. From the measurement results, plenum window can attenuated at least 10 dBA traffic noise without treatment inside the window system. It is found that window opening sizes and overlapping width have significant effects on the acoustical protection of plenum window.

Computational Study of Indoor Pollutant Dispersion of an Apartment

Objectives: Indoor Air Quality (IAQ) is very important for the health of human beings. Proper ventilation of apartment can improve IAQ. The objective of the study is to analyse the pollutant dispersion behaviour inside the fluid domain at fixed boundary conditions. Methods/Statistical Analysis: A 2BHK apartment has been taken for study. The fluid domain of apartment has been simulated in the Computational Fluid Dynamics (CFD) software “ANSYS Fluent 16.2”. Four inlet doors, four inlet windows, one outlet door, one outlet window and two ventilations from toilets were taken in the apartment. Seven inlet pollutant sources at the middle of the bottom of each enclosed area i.e. drawing/dining room, master bedroom, bedroom 1, kitchen, toilet 1 and toilet 2 have been considered. The methane gas is selected as the pollutant in the study. The k-epsilon (2 equations) model has been used and methane-air mixture has been taken for species transport. Findings: The methane mass fraction has been studied at different planes and at different locations of the domain. It was observed that the pollutant dispersion phenomena were varying at different locations and with this the highest methane mass fraction zone have been discussed. Application/Improvements: Simulated model can be useful in urban management and planning to find the best geometrical configurations of infrastructure, especially residential, to achieve proper and effective ventilations. Present model can also be more effective with environmental wind tunnel validations.

EFFECT OF THE FILL VENTILATION WINDOW ON PERFORMANCE OF A NATURAL DRAFT COOLING TOWER SUBJECTED TO CROSS-WINDS

Various aerodynamic design elements and technics (wind deflectors, wind walls, etc.) are utilized for improvement of the thermal efficiency of the natural draft cooling towers, particularly in conditions of cross wind. One of the technical methods, proposed by engineers of Belarus Academy of Sciences, is installation of the ventilation window in the center of the fill. This method is substantiated by the fact that the flow of cooling gas obtains maximum temperature and humidity near the center of the under-fill space of cooling tower and, as a consequence, performs minimal heat exchange. The influence of the fill ventilation window and wind deflectors in the inlet windows of the cooling tower on its thermal performance in condition of cross-wind is investigated in the paper numerically. The cooling tower of the “Woo-Jin” power plant (China) 150 m of the height and 114 m of the base diameter was taken as a prototype. The analogy (equivalence) between the heat and mass transfer was taken into consideration, which enabled us to consider single-phase flow and perform complicated 3D simulation by using modern personal computers. Heat transfer coefficient for the fill and its hydrodynamic resistance were defined by using actual data on total flow rate in the cooling tower. The numerical model and computational methods were tested and verified in numerous previous works. The non-linear dependence of the thermal performance of the cooling tower on wind velocity (with the minimum in vicinity of Ucr ~ 8 m/s for the simulated system) was demonstrated. Calculations show that in the condition of the average wind speed the fill ventilation window doesn’t improve, but slightly decrease (by 3–7 %) performance of the cooling tower. Situation changes in the condition of strong winds Ucw > 12 m/s, which are not typical for Belarus. Utilization of airflow deflectors at the inlet windows of cooling tower, conversely, increases thermal performance of the cooling tower on 10–12 % for the wide range of winds exceeding 2 m/s. Results of the investigation may be helpful for optimal design of natural draft and perspective “hybrid” cooling towers.

Salman Farsi Dam reservoir, a successful project on a karstified foundation, SW Iran

The Salman Farsi Dam is constructed on the Ghareh Aghaj River at the northern limb of Changal Anticline, SW Iran. The anticline is composed of the calcareous Asmari Formation (AF) sandwiched between two marly formations, the Pabdeh–Gurpi (PGF) and Razak (RF). The AF is divided into three units: lower (LAF) marl and limestone, middle (MAF) karstified limestone, and upper (UAF) marl and marly limestone. The dam is constructed on the MAF, and the reservoir is in direct contact with the MAF, UAF and RF. A huge relict cave was discovered during excavation of grouting galleries in the MAF. In this research, the potential leakage passage (PLP) is defined as parts of the karst aquifer located lower than the normal water level (NWL) of reservoir, in which the reservoir water has potential to be leaked toward downstream, assuming no grout curtain construction. The PLP is composed of the inlet windows, transfer passage, and discharge zones. At the Salman Farsi Dam, the PLP is determined by three alternative schematic models considering hydrogeological and geological settings. At this dam site, the grout curtain was properly designed from the MAF toward the downstream LAF, at the narrowest part of the PLP and bypassing the huge cave. The grout curtain was successful in blocking the PLP based on the negligible leakage, and high differences between water level in the pair piezometers at the upstream and downstream sides of the grout curtain. It is recommended to determine the PLP in future dam construction in karst terrains.

Effect of Inlet Window Deflectors on the Performance of a Natural-Draft Cooling Tower Subjected to Crosswinds

The effect of inlet window deflectors on the performance of a natural draft cooling tower subjected to a crosswind was studied numerically. Three patterns of the inlet window deflectors with different setting angles (62, 72, and 82 degrees) were tested under various crosswind velocities. The assumption of heat and mass transfer equivalence was adopted for simulation. A numerical model was developed and verified by comparison with experimental data. The simulations show that the 72-degree inlet window deflectors are efficient in a wide range of crosswind velocities. The effect of the number of deflectors was also investigated and the link between the velocity profile and the critical wind velocity was clarified. It was shown that the use of deflectors in the inlet window increases the thermal efficiency of a cooling tower up to 8.6% at wind velocities greater than 2 m/s and does not exhibit any effect at the wind velocities close to critical wind velocity. The investigation may be helpful in optimal design of natural draft and “hybrid” cooling towers.

Numerical Investigation on the Effects of Human Movements on Smoke Propagation in Building Fire

This work aims at analyzing the dynamics mechanism of airflow and fire spread, especially for the effects of human movements on smoke propagation. A numerical investigation method composed of fire parameters and a smoke propagation analysis is proposed in this paper. The diversifications of flow field when human moves are the main part of the smoke propagation analysis, which is based on the dynamic mesh method of computational fluid dynamics. The numerical results show that the movements of human may cause great changes to the velocity and temperature fields in the building. The high temperature and toxic gas follows the human's movement and lead to a great change to the risk distribution in the risk region by promoting the heat transfer effects of convection between the gases with different temperatures. These movements also lead to a farther spread of the cool air that getting through the inlet window, which decreases the average temperature in the room. These effects should be taken into the consideration for the formulation of evacuation routes.

Experimental and numerical investigation of the tracer gas methodology in the case of a naturally cross-ventilated building

This paper presents the investigation of a naturally cross-ventilated building using both experimental and numerical methods with parameter being the incidence angle of the wind to the openings of the building. The experimental methodology calculates the air change rate based either on measurements of the inlet velocity profile, the outlet velocity profile or the descending rate of the tracer gas mass concentration using the decay method. The numerical investigation is based on the solution of the governing Reynolds averaged Navier–Stokes equations in their full three dimensional expression, focusing on the time dependent character of the induced flow field. The numerical results are compared with corresponding experimental data for the three aforementioned experimental methodologies in the case of a full-scale building inside a wind tunnel. The numerical investigation reveals that for large incidence angle the flow is governed by an unsteady character regarding especially the regions close to the inlet and outlet windows. It is concluded that velocity measurements in the inlet window are of high accuracy when the flow in this region has a steady character, whilst the decay method is depicting the effective air change rate in a control volume and not the intended one. Finally, conclusions about the air change rate spatial distribution in the control volume of the building are provided as a function of the incidence angle, revealing that its accuracy as a method for measuring the intended aeration rate depends significantly on the mixing of gas within the control volume of the building.

Dynamic simulation of accidental closure of intermediate heat exchanger isolation valve in a pool type LMFBR

In a pool type liquid metal cooled fast breeder reactor (LMFBR), core and other internals such as pumps, heat exchangers are immersed in a pool of sodium. Heat exchange from primary sodium circuit (pool) to secondary sodium circuit (loop) is through four intermediate heat exchangers (IHX) immersed in primary sodium pool. Each IHX is provided with a sleeve valve at its primary sodium inlet window for the purpose of isolating the shell side of IHX from the sodium pool. With such a provision, an inadvertent partial or complete closure of a sleeve valve of one of the IHX during normal operation of the reactor has been considered as a design basis event for the reactor. One dimensional transient thermal hydraulic models of the primary and secondary sodium circuits have been developed to study the thermal hydraulic consequences of such an event. The main areas of concern in the plant and the availability of safety parameters for the detection of the event have been evaluated.

Temperature Difference between the Cooled and the Noncooled Parts of an Electrolyte in Capillary Electrophoresis

Joule heating always accompanies electrophoresis and unavoidably leads to a temperature increase of the electrolyte. The elevated temperatures are known to adversely affect the quality of separation and detection. To minimize the temperature increase in capillary electrophoresis (CE), Joule heat is removed by actively cooling the capillary. However, there are always small parts of the capillary, such as its inlet, outlet, and detection window, which are not actively cooled. The noncooled capillary inlet has been recently proven to have an elevated temperature which is high enough to significantly affect CE-based quantitative affinity analyses. The temperature difference between the cooled and noncooled regions has never been determined due to the lack of a suitable method. Here, we report on the first experimental determination of temperature in the cooled part of the capillary and the noncooled inlet region of the capillary. We found that, under typical CE conditions, with a low-conductivity run buffer, the temperature in the noncooled inlet exceeded the temperature in the cooled region by more than 15 °C. High-conductivity buffers are anticipated to have even greater temperature differences between the noncooled and cooled capillary parts. Our results strongly suggest the potential effect of the noncooled capillary regions on the quality of CE-based analyses, which cannot be ignored. The simplest way to avoid potential errors is to move the sample to the cooled region by pressure or by applying a low electric field.

New agitated and thermostatized cell forin situmonitoring of fast reactions by synchrotron SAXS

A thermostatized and agitated sample cell for synchrotron small-angle X-ray scattering (SAXS) measurements of liquid samples (homogeneous or heterogeneous) has been developed. The cell is composed of a compact main body with inlet and outlet windows for the beams of light. The volume of the cell is approximately 0.8 ml and the distance between the windows is 5 mm to allow accurate SAXS measurements. The cell is thermostatized by means of a jacket that surrounds the sample holder and it is connected to a thermostatic bath. In addition, the cell has a top and a bottom lid that allow easy cleaning and maintenance without demounting the optical windows. The cell has been used to run SAXS measurements of liquid samples and, for the first time, a mini-emulsion polymerization reaction has been monitored by SAXS.

Temperature monitoring of the lead bismuth eutectic flow in the MEGAPIE target

Introduction. An Electromagnetic Pumps System for the MEGAPIE target has been developed, produced and tested at the Institute of Physics, University of Latvia, during the recent two years in the framework of the MEGAPIE-TEST Project (MEGAWatt Pilot Experiment – TESTing) funded within the Euratom 5 Framework Programme as an implementation of transmutation technology [1]. The EMPS operates being submerged in lead bismuth eutectic (LBE), whose temperature fluctuates depending on the proton beam trip in the range 220–380◦C with the temperature changing rate 5–10◦C/s. The electromagnetic pump system is responsible for the lead bismuth eutectic flow in the MEGAPIE target. Stop of the flow, e.g., as a result of the channel plugging with He bubbles, leads to local overheating of the proton beam inlet window and very likely to its disintegration. Therefore, monitoring of the flow during the target operation is a very important task. Results of original electrodynamics and thermo hydraulic calculations of the electromagnetic pump system are presented in the report. These results assume the procedure of lead bismuth eutectic flow monitoring through electrical regimes for electromagnetic pumps and lead bismuth eutectic temperatures measurements. The procedure is based on the strong correlation between the lead bismuth eutectic temperature at the EMPS inlet and outlet, the flow rate and the electrical regime for the pump. A special PC code, which allows controlling the intensity of the lead bismuth eutectic flow in the EMPS channel at steady and transient temperature regimes of the target operation, has been developed and proposed. There are recommendations on the PC code adoption for the MEGAPIE target control system at the end of the presentation.