Journal articles: 'Recirculation fan'

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Borghei, Leila, and Ramin Haghighi Khoshkho. "Effects of Wind on Hot Air Recirculation (HAR) Behavior." Applied Mechanics and Materials 110-116 (October 2011): 2067–74. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2067.

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The air-cooled condenser system is impacted greatly by many factors such as the wind speed, the direction of wind and arrangement of site equipments. This paper concentrates on the hot air recirculation phenomenon and its dependence on ambient winds are numerically simulated by using the computational fluid dynamics code, FLUENT. In this paper, two different wind directions (case A and case B) and wind speeds are considered: Results show that the hot air recirculation increases with the increment of velocity speed. Case A has a critical wind direction angle. Wind causes an air temperature increase at the fan inlet due to hot air recirculation, resulting in the deterioration of the heat transfer performance. The hot air recirculation is the main factor responsible for the reduction of heat rejection rate. In case A, fan inlet temperature is higher than case B. The peak value of the HAR occurs at 9 m/s in case A.

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Faulkner, David, William Fisk, and John Walton. "Energy Savings in Cleanrooms from Demand-Controlled Filtration." Journal of the IEST 39, no. 6 (November 1, 1996): 21–27. http://dx.doi.org/10.17764/jiet.2.39.6.k8792h8164vk5218.

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In cleanrooms, very low particle concentrations are maintained by recirculation of air at a high rate (e.g., 600 room air volumes/hr) through highly efficient air filters. Results are reported in a Class M3.5 (Class 100) cleanroom with 28 m2 (300 ft2) floor area, where significant energy savings were realized by controlling the rate of air recirculation through the filters in response to real-time measurements of particle concentrations. An inexpensive, $2500, optical particle counter was used to measure particle concentrations. The effect of varying the recirculation airflow rate on particle concentrations was investigated. Changes in recirculation fan speeds of 10 percent or greater did not cause a noticeable particle release from filters or resuspension from indoor surfaces. With new automatic control systems in operation, there were occasional, usually fewer than 10/day, nonconsecutive l-min episodes in which the particle concentration exceeded Class M3.5 (Class 100) status. Depending upon the choice for baseline energy use, the energy consumption of the recirculating fans was reduced by 60 to 80 percent, and the estimated payback period for a 90 m2 (1,000 ft2) Class M3.5 (Class 100) cleanroom is from 1 to 4 yr.

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Li, Xiangjun, Stephen Spence, Hua Chen, Wuli Chu, and Lee Gibson. "Flow Control by Slot Position and Noise Baffle in a Self-Recirculation Casing Treatment on an Axial Fan-Rotor." International Journal of Rotating Machinery 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/9509212.

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To address the situations where the casing treatment needs to be used to stabilize axial compressors through strong recirculation, this paper initiated a CFD study to investigate how the flow could be suitably controlled in the casing treatment to minimize the efficiency penalty and increase the flow range. A counter-swirl self-recirculation casing treatment was first designed on a low speed axial fan rotor as a baseline case. Then three different slot positions and the influence of including the noise baffle were numerically studied. Based on the understanding of their coeffects, the shorter noise baffle was considered and it was found that the highest efficiency was achieved in the case of the upstream slot when the length of baffle was suitably adjusted to balance the incoming flow and recirculation. The largest flow range was achieved by locating the slot at the most downstream position and using a 50% length baffle since it suitably controlled the recirculating flow and relieved the separation at the low-span region. An optimization study showed that the optimum length of the baffle for efficiency was always larger than for the flow range. Both of the two optimum values reduce as the slot moves downstream.

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KIM, HWA-YOUNG, SUNG-HOON YOON, SEUNG-JAE MOON, JAE-HEON LEE, HOSEON YOO, and YUN-CHUL IM. "A STUDY ON THE FAN EFFICIENCY DECREASE ON THE BACKWARD FLOW IN AN AXIAL FAN WITH ADJUSTABLE PITCH BLADE." International Journal of Air-Conditioning and Refrigeration 18, no. 02 (June 2010): 101–7. http://dx.doi.org/10.1142/s2010132510000216.

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In this study, a numerical study has been carried out to analyze the factors of the efficiency decrease at backward flow situation in an axial fan with adjustable blades. The analysis is done with the pitch angle of 36° on the forward flow and of -26° on the backward flow. The numerical results show that the air flow rates of the pitch angle of 36° and -6° are calculated to be 285 cubic meter per min (CMM) and 212 CMM, respectively. The results are similar to the experimental results by Chang et al.1 The results had the maximum error of 10.6% compared with the experimental results. The fan efficiency decrease is caused by the fact that the axial fan used for this study was designed for the forward flow. As the results, the pitch angle of -26° has induced the recirculation around the impeller blade, impeller cover and downstream. This recirculation caused the large decrease in total pressure coefficient. This turned out to be the main cause of the efficiency decrease.

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Dilin, P., T. Sakai, M. Wilson, and A. Whitfield. "A computational and experimental evaluation of the performance of a centrifugal fan volute." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 212, no. 4 (June 1, 1998): 235–46. http://dx.doi.org/10.1243/0957650981536763.

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A detailed experimental study of the performance of two radial-flow fan volutes has been carried out at the Science University of Tokyo. This included a volute with a full tongue, such that no recirculating flow occurred, and the same volute but with the tongue cut back to allow flow recirculation. Detailed velocity and pressure distributions at a wide range of azimuth angles were obtained experimentally and are presented. At the University of Bath a computational model, using the k-e turbulence model, has been used to predict the internal flow of both volutes, with particular attention given to the tongue flow. Predicted flow separation at the volute tongue has been demonstrated experimentally through laser sheet studies at the Science University of Tokyo. The performance of the volutes is discussed and the computational fluid dynamics (CFD) analysis is used to recommend design improvements for the volute.

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Wang, Lidong. "SEARCHING UNGROUND FAN INDUCED RECIRCULATION IN A COMPLICATED MINE VENTILATION NETWORK." Stavební obzor - Civil Engineering Journal 27, no. 1 (2018): 104–13. http://dx.doi.org/10.14311/cej.2018.01.0009.

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Shriwas, Mahesh, and Felipe Calizaya. "Automation in detection of recirculation in a booster fan ventilation network." International Journal of Mining Science and Technology 28, no. 3 (May 2018): 513–17. http://dx.doi.org/10.1016/j.ijmst.2018.04.009.

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Mutama, K. R., and A. E. Hall. "The Experimental Investigation of Jet Fan Aerodynamics Using Wind Tunnel Modeling." Journal of Fluids Engineering 118, no. 2 (June 1, 1996): 322–28. http://dx.doi.org/10.1115/1.2817380.

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Jet fan aerodynamic behavior was investigated using wind tunnel modeling. Conditions were created to simulate mine and vehicular tunnel ventilation where these fans are finding increased application. Results showed that the ability of a jet fan to entrain air depends on its proximity to the tunnel wall. Moving the jet fan toward the wall increased the initial pressure drop below ambient in a significant length of the tunnel. This increased the volume of air entrained despite the existence of a large recirculation eddy or back flow whose size diminished as the jet fan was traversed toward the tunnel axis. When the jet fan was located at the tunnel axis the flow was very unstable close to the walls of the tunnel and it had a tendency to reverse itself with periods coinciding with the jet oscillation behavior. The complete set of measurements obtained are suitable for CFD code validation and modeling.

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Chen, Q. G., Y. C. Zhang, F. Li, X. Z. Kong, and X. H. Luan. "Effects of anti-recirculation ring on performance of an automotive cooling fan." IOP Conference Series: Materials Science and Engineering 52, no. 4 (December 20, 2013): 042008. http://dx.doi.org/10.1088/1757-899x/52/4/042008.

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Коновалов, Дмитро Вікторович. "ЗАСТОСУВАННЯ ГАЗОДИНАМІЧНОГО ОХОЛОДЖЕННЯ В СИСТЕМАХ РЕЦИРКУЛЯЦІЇ ВІДХІДНИХ ГАЗІВ СУДНОВИХ ДИЗЕЛІВ." Aerospace technic and technology, no. 7 (August 31, 2019): 81–86. http://dx.doi.org/10.32620/aktt.2019.7.11.

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There are many ways and methods to reduce exhaust gases emissions on modern ships. One of the most effective ways to reduce NOx and SOx emissions is to use of exhaust gas recirculation (EGR technology). The EGR system disadvantage is an increase in back pressure through additional pressure losses in the scrubber and heat ex-changer, which entails an engine fuel efficiency deterioration. Creating a reliable and efficient heat exchanger for cooling recirculation gases is a complex task due to deposits and pollution emitted by these gases. In the pre-sent work, the jet apparatus effectiveness named aerothermopressor is analyzed in the scheme with exhaust gases recirculation of the ship low-speed two-stroke engine. Aerothermopressor is a two-phase jet for contact disperse cooling, in which by increasing the heat from the gas stream the gas pressure and cooling are increased. The calculation of the characteristics of the engine was carried out, both in nominal, and in operating modes and in all possible range of partial loads. The installation of the aerothermopressor before the scrubber is pro-posed, which allows reducing engine thermal load. Increasing the pressure in the aerothermopressor by 0.2-0.4 ∙ 105 Pa (6-12 %) allows reducing the back pressure in the gas exhaust system and thus reducing the load on the exhaust gas recirculation fan and when the engine load is higher than 75% in the cold zone, the fan is not need-ed, which additionally allows to reduce the specific fuel consumption. The parameters of the exhaust gases that are going to be recirculated and the processes of their gas-dynamic cooling in the aerothermopressor are based on the developed technique and program using the thermodynamic and gas dynamics equations. The proposed scheme-design solution allows at a high environmental friendliness of the existing exhaust gas recirculation sys-tem to provide a certain reduction in specific fuel consumption. It was determined that the engine specific fuel consumption has been decreasing when the aerothermopressor is used to Dge = 2.5-3.0 g/(kW·h) (1.5-1.7%).

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Oh, H. W., and K.-Y. Kim. "Mean streamline performance analysis of mixed-flow fan impellers covering the low flowrate characteristics." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 215, no. 4 (June 1, 2001): 513–18. http://dx.doi.org/10.1243/0957650011538640.

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The mean streamline analysis using the empirical loss correlations has been developed for performance prediction of industrial mixed-flow fan impellers in the present study. New simple, but effective, models for the additional Euler input work characteristic and a suction recirculation loss due to internal flow reversal under the low flowrate conditions are proposed in this paper. Comparison of overall performance predictions with six sets of test data of mixed-flow fans is accomplished to demonstrate the accuracy of the proposed models. Predicted performance curves by the present set of loss models agree fairly well with experimental data for a variety of mixed-flow fan impellers over the entire operating conditions. The prediction method presented herein can be used efficiently in the conceptual design phase of mixed-flow fan impellers.

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Omar, Mohd Amal Asrol, Wirachman Wisnoe, and Azman Bakri. "Flow Characteristics of a Servco Fume Cupboard." Applied Mechanics and Materials 393 (September 2013): 753–58. http://dx.doi.org/10.4028/www.scientific.net/amm.393.753.

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A fume cupboard is equipment used to carry out chemical reaction process in its working chamber. A suction fan takes air or gas from the working chamber and releases it outside. When the air or gas is flowing from the inlet to the outlet, some recirculation zones may be formed depending on the internal shape design of the fume cupboard. This recirculation zone may create back flow that can be the cause of leakage. Leakage happens when airborne contaminants escape through inlet of the fume cupboard to the user breathing zone and the surrounding air in the room. To have a good fume cupboard, the recirculation zone needs to be minimised. In this paper, the flow characteristic of a Servco fume cupboard will be presented as a result of computational fluid dynamics (CFD) simulation using κ-ω turbulence model. The results are presented in terms of velocity components at different cross sections of the fume cupboard.

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Farfán, Ricardo Fabricio Muñoz, Telly Yarita Macías Zambrano, Vicente Paúl Zambrano Valencia, and Victor Manuel Delgado Sosa. "Design and construction of a cold production simulator system: chiller." International journal of physical sciences and engineering 3, no. 3 (November 25, 2019): 31–40. http://dx.doi.org/10.29332/ijpse.v3n3.367.

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The design and construction of a cold production system from the ice water submitted by a mechanical direct expansion system contributing to the development of knowledge in the area of air conditioning were carried out. Among the technical design parameters, a direct expansion system with cooling capacity of 9000 BTU/Hrs, R134 refrigerant gas to a turbine for the work of the Fan Coil of ½ Hp of force 220 V was selected, as was the fan motor of the cooling tower as fundamental means for heat transfer. The recirculation pumping system is carried out by pumps of 0.37 kW of power and a maximum flow of 40 l/min. For both the evaporator sump (cold) and the condenser sump (hot). The work stage is given in two independent circuits, the Fan Coil system is connected to the evaporator sump and the cooling tower, in turn, is connected to the condensation system for proper operation and achieve condensation temperatures of 35 ° C and in case of having water requirements in the cold sump, the tower is connected by means of an electromagnetic valve for its supply.

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Nowak, Bernard, and Jan Piątek. "Verification of Mathematical Description of Changes in Air Temperature and Humidity in Headings Ventilated with Auxiliary Ventilation System/Weryfikacja Metematycznego Opisu Zmian Temperatury I Wilgotności Powietrza W Wyrobiskach Przewietrzanych Lutniciągiem Tłoczącym Z Dadatkowym Wentylatorem O Zmienianej Prędkości Obrotowej." Archives of Mining Sciences 59, no. 2 (June 1, 2014): 529–51. http://dx.doi.org/10.2478/amsc-2014-0039.

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Abstract The article presents verification of the mathematical model which was developed in earlier works, describing, through distributions of temperature, specific humidity, and flow rate of both fresh and exhaust air in the dead end headings ventilated with forcing duct line ventilation system, the climatic conditions existing in those headings. On the route of the considered duct line, an additional fan with a variable rotational speed was installed in order to avoid recirculation of the air between the inside of the duct line and the heading. The task of this auxiliary fan is an increase in the volumetric flow rate of fresh air at the mine face. The above-mentioned verification was based on a comparison of the calculation results obtained from the numerical solution of ordinary differential equations of the first order and algebraic equations with the results of measurements carried out in the selected mine heading. Wide comparative material was obtained by changing the location of the auxiliary fan in the duct line for a given heading length, and the heading length itself. 14 research variants were obtained in this way, in which, in addition to the already mentioned temperatures and humidity of the air, also the rotor speeds of the auxiliary fan were compared. The results of calculations and measurements have been presented in a graphical form. Their comparison was carried out using statistical methods.

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Skoneczna-Łuczków, Joanna, and Włodzimierz Ciesielczyk. "Exergetic Analysis For A Complete Node Of Fluidised-Bed Drying Of Poppy Seeds." Chemical and Process Engineering 36, no. 4 (December 1, 2015): 437–47. http://dx.doi.org/10.1515/cpe-2015-0031.

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Abstract The article presents an experimental-theoretical analysis of fluidised-bed drying of poppy seeds directed on minimisation of energy. The analysis was performed for a complete drying node incorporating a heat exchanger and a fan. Two complementary factors were used in the exergetic evaluation: exergy efficiency and unit consumption of exergy. An analysis of drying in stationary bed was carried out for comparison purposes. Results of the exergetic analysis can become a basis for innovative works focused on decreasing energy consumption of a technological node being analysed, e.g. by the use of recirculation of fluidising-drying medium.

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Devle, Milind, Ankur Garg, and Darci Cavali. "Thermal management of machine compartment in a built-in refrigerator." MATEC Web of Conferences 240 (2018): 05005. http://dx.doi.org/10.1051/matecconf/201824005005.

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In general a multi-door refrigerator machine compartment comprises of fan, condenser, compressor, control box, drain tray, and drain tubes. The performance of machine compartment depends upon the efficiency of heat extraction or heat exchange from heat generating components such as condenser and compressor. The efficiency of heat exchange can be improved by addressing two major factors, namely (1) Air bypass and (2) Hot air recirculation. The hot air recirculation in the machine compartment for builtin multi-door refrigerator configuration is the focus of this study. The results from Computational Fluid Dynamics (CFD) simulations show that efficiency of heat exchange for built-in application is lower than that for free-standing configuration. Recirculation of hot air and reduction in airflow are the two major factors which contribute towards the variation in machine compartment performance. The CFD simulations were coupled with Partial Factorial Design of Experiment (DoE) approach to systematically investigate the effect of variables such as (a) side gap and top gap between kitchen cabinetry and the refrigerator, (b) the baffle/flap (i.e. back and bottom of machine compartment) on the performance effectiveness of machine compartment. The results of the simulation provided critical design improvement directions resulting in performance improvement. Furthermore, the CFD simulation results were also compared to test data and the results compared favourably.

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Palacio-Caro, Iván D., Pedro N. Alvarado-Torres, and Luis F. Cardona-Sepúlveda. "Numerical Simulation of the Flow and Heat Transfer in an Electric Steel Tempering Furnace." Energies 13, no. 14 (July 15, 2020): 3655. http://dx.doi.org/10.3390/en13143655.

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Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times.

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Wagner, Patrick Hubert, Zacharie Wuillemin, Stefan Diethelm, Jan Van herle, and Jürg Schiffmann. "Design and Experimental Realization of a Steam-Driven Micro Recirculation Fan for Solid Oxide Fuel Cell Systems." ECS Transactions 91, no. 1 (July 10, 2019): 187–93. http://dx.doi.org/10.1149/09101.0187ecst.

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Melendres, Ariel Verzosa, and Rolan Pepito Vera Cruz. "Absorption of Water Vapor Using Superabsorbent Polymer Composite Material." Key Engineering Materials 858 (August 2020): 129–39. http://dx.doi.org/10.4028/www.scientific.net/kem.858.129.

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The ability of superabsorbent polymers (SAP) to absorb water vapor was studied. A multilayer composite material was prepared where SAP particles were spread in the fluffy fibrous layer located in the middle of the composite structure. Distribution of SAP within the composite material permits air to pass through its porous structure effectively hence allowing efficient contact of air with SAP. SAP was able to decrease the relative humidity of air of a 3-L cabinet from 96% relative humidity (RH) to 52% and 49 % (RH) in 18 hours using 2 g and 4 g of SAP respectively. Study on the water vapor absorption ability of SAP placed together with pure water in a closed cabinet was conducted with and without convective air transport effect. Convective air transport was done by activating the 12 V fan allowing air recirculation speed at rates corresponding to constant voltage settings of 6 V and 12 V. Higher SAP water vapor absorption rate was obtained at higher air recirculation speed. SAP particles swelled after water vapor absorption with slight decrease in the porosity of composite material as observed through the digital microscope.

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Przydróżny, E., A. Przydróżna, and S. Szczęśniak. "Energy efficient setting of supply air temperature in dual-duct dual-fan ventilation systems with extract air recirculation." Thermal Science and Engineering Progress 5 (March 2018): 69–85. http://dx.doi.org/10.1016/j.tsep.2017.10.006.

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Futawatari, Naoki, Yosuke Udagawa, Taro Mori, and Hirofumi Hayama. "Improving Prediction Accuracy Concerning the Thermal Environment of a Data Center by Using Design of Experiments." Energies 13, no. 18 (September 4, 2020): 4595. http://dx.doi.org/10.3390/en13184595.

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In data centers, heating, ventilation, and air-conditioning (HVAC) consumes 30–40% of total energy consumption. Of that portion, 26% is attributed to fan power, the ventilation efficiency of which should thus be improved. As an alternative method for experimentations, computational fluid dynamics (CFD) is used. In this study, “parameter tuning”—which aims to improve the prediction accuracy of CFD simulation—is implemented by using the method known as “design of experiments”. Moreover, it is attempted to improve the thermal environment by using a CFD model after parameter tuning. As a result of the parameter tuning, the difference between the result of experimental-measurement results and simulation results for average inlet temperature of information-technology equipment (ITE) installed in the ventilation room of a test data center was within 0.2 °C at maximum. After tuning, the CFD model was used to verify the effect of advanced insulation such as raised-floor fixed panels and show the possibility of reducing fan power by 26% while keeping the recirculation ratio constant. Improving heat-insulation performance is a different approach from the conventional approach (namely, segregating cold/hot airflow) to improving ventilation efficiency, and it is a possible solution to deal with excessive heat generated in data centers.

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Wagner, Patrick Hubert, Zacharie Wuillemin, David Constantin, Stefan Diethelm, Jan Van herle, and Jürg Schiffmann. "Experimental characterization of a solid oxide fuel cell coupled to a steam-driven micro anode off-gas recirculation fan." Applied Energy 262 (March 2020): 114219. http://dx.doi.org/10.1016/j.apenergy.2019.114219.

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Canepa, Edward, Andrea Cattanei, and Fabio Mazzocut Zecchin. "Leakage Noise and Related Flow Pattern in a Low-Speed Axial Fan with Rotating Shroud." International Journal of Turbomachinery, Propulsion and Power 4, no. 3 (July 10, 2019): 17. http://dx.doi.org/10.3390/ijtpp4030017.

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The effect of rotational speed and pressure rise on the leakage flow noise radiated by a low-speed axial fan, provided with rotating shroud, has been systematically investigated. The flow in the gap region has been studied by means of particle image velocimetry (PIV) measurements taken in the meridional plane. At low blade loading, the leakage flow is restrained close to the rotor ring and, at higher loading, it forms a wide recirculation zone. In the latter conditions, an unsteady flow separation likely takes place in the blade tip region which may be observed in the instantaneous flow field only. The leakage flow noise generally increases with the blade loading, but is non-monotonic, as the overall sound pressure level (OASPL) growth is interrupted by local minima; such a trend is qualitatively independent of the rotational speed. As the loading increases, the sound pressure level (SPL) spectrum shows important modifications, since the characteristic frequency of the subharmonic narrowband humps related to the leakage noise decreases; furthermore, height and width of the humps vary non-monotonically. Such a complicated behavior is likely related to the modifications in the leakage flow pattern and also to the appearance of the flow separation at the blade tip.

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Parker, David B., Kenneth D. Casey, Richard W. Todd, Heidi M. Waldrip, Gary M. Marek, Brent W. Auvermann, Thomas H. Marek, et al. "Improved Chamber Systems for Rapid, Real-Time Nitrous Oxide Emissions from Manure and Soil." Transactions of the ASABE 60, no. 4 (2017): 1235–58. http://dx.doi.org/10.13031/trans.12151.

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Abstract. Nitrous oxide (N2O) emission rates have traditionally been measured using non-flow-through (NFT), non-steady-state (NSS) chambers, which rely on measuring the increase in N2O concentration in the sealed chamber headspace over time. These flux measurements are very labor- and time-intensive, requiring three to four gas samples collected over a 30 to 60 min period, followed by laboratory N2O measurement with a gas chromatograph (GC) and subsequent flux rate calculation. The objective of this research was to develop and evaluate improved, real-time flux chamber designs that rapidly quantify N2O emissions from manure and soil. The first chamber system consisted of six square 0.95 m2 chamber pans. The chamber pans were mounted on a rail system to facilitate controlled indoor/outdoor laboratory research at a pilot scale. An aluminum lid was moved among the chamber pans. A second portable chamber system with a circular footprint (0.49 m internal dia.) was designed for use in field measurements. With both systems, N2O concentrations were measured each second with 0.1 ppb resolution by recirculating sample air through a real-time continuous N2O analyzer with return flow into the recirculating-flow-through (RFT-NSS) chamber. Performance and observational data are presented for different chamber vent designs, sealing mechanisms between the chamber pan and lid, recirculation pumps, and presence/absence of an internal fan that mixes headspace air within the sealed chamber. As examples of the repeatability and precision of the methodology, ten consecutive flux measurements were obtained using moist manure (32.6% wet basis water content, WCWB) within a 15 min period in which chamber pans were fitted with lids for 60 s and removed for 30 s. The mean calculated N2O flux was 43.08 ±0.89 mg N2O m-2 h-1. Using dry manure (WCWB = 10.8%), five consecutive flux measurements showed a very low, but consistent, flux that averaged 0.025 ±0.0016 mg N2O m-2 h-1. Five case study experiments demonstrate the usefulness of these chamber systems and highlight discoveries and lessons learned to enhance future research efforts. Major discoveries and observations include: (1) installation of a small internal fan within the chamber lids decreased N2O fluctuation over small time periods, allowing precise measurement of manure N2O fluxes as low as 0.0073 mg N2O m-2 h-1 during a 60 s measurement period; (2) two distinct N2O peaks were observed at 1 and 21 d following the addition of water to manure (initial WCWB = 32.6%), with the second peak accounting for 83% of the total N2O emitted over 45 d; and (3) there was notable diurnal variation in N2O fluxes due to temperature variation, even when the manure was dry (WCWB = 10.8%). These flux chamber systems proved to be more rapid, precise, and repeatable than traditional flux chamber methods and offer promise for future greenhouse gas emissions research on manure and soil. Keywords: Cattle, Chamber, Diurnal, Fan, Feedlot, Greenhouse gas, Manure, Precision.

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Minko, V. A., N. S. Kobelev, V. M. Kretova, V. N. Kobelev, V. Yu Amelin, and A. D. Soloviev. "INNOVATIVE SOLUTIONS OF ADSORPTION CLEANING RECIRCULATING AIR FOR ELECTRIC TESTS OF ELECTRIC PRODUCT TESTS." Proceedings of the Southwest State University 22, no. 6 (March 27, 2019): 103–10. http://dx.doi.org/10.21869/2223-1560-2018-22-6-103-110.

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The purpose of the study of this work: to provide a scientific justification for the energy-saving device to maintain the normalized parameters of the recirculated air in special “clean” rooms, to derive formulas for calculating the adsorption material during the operation of the installation. The novelty of the constructive solution is protected and confirmed by patents of the Russian Federation for the invention. Methods. The volume of adsorbent determined by this method is placed in a tank with a recirculation loop, which includes: a cleaning unit nozzle, the inner surface of which is spring-loaded with a grid placed on the side of a moving air flow and a grid around the entire outlet section of the expanding nozzle. Spring-loaded mesh, placed on the side of a moving air flow, is made according to the profile of the velocity profile of the moving air flow, which is caused by the manifold speed impact on the adsorbent grains, horizontally arranged layers in order to level the absorbing capacity of silica gel KSM-5 throughout the drying device and use in the system recirculation of the air supplied by the fan leads to a probable entry of the vaporous mass of oil into the stream being cleaned, and the analysis of scientific and technical oh showed no literature data on the nature of such contaminants granular filter material, resulting in the need to study the penetration of the oil by volume adsorbent per cycle electrical testing of electronic devices in a heat chamber. Results. Based on the analysis of well-known foreign and domestic theoretical and experimental studies, there was no development related to vibration effects on the efficiency of adsorption drying of recirculated air for electrical thermal testing of electronic products. An adsorption unit has been developed with a horizontal arrangement of an adsorbing substance for treating air under conditions of vibration effects. Conclusion The installation developed by the authors passed laboratory and industrial tests at the Mayak plant of Kursk and was recommended for implementation as a resource-saving constructive solution protected by patents of the Russian Federation for invention. Keywords: special premises electrical testing of electronic products, recirculation circuit in the chamber for temperature testing - heat chamber, adsorption drying, transparent body of the drying device, oil contamination.

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Zhang, Qun Feng, Jin Li Yan, Min Wang, and Zhi Xiang Chen. "CFD Application on Ventilation System of Hydro-Generator." Advanced Materials Research 383-390 (November 2011): 3561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3561.

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Averaged 3D N-S equations and RNG k-ε equations were solved with parallel computing CFD code on the flow field of dual radial ventilation system without fan for a hydro-generator. The MRF(multiple implicit rotating frame) method was used to simulated the rotating motion of the generator and porous media model were used to simulate the pressure loss of air cooler. Rational tactics were selected to generate calculation grids to compromise with calculation CPU time and result accuracy and the grids of different parts were generated with ICEM-CFD. The flow characteristic of different parts was analyzed and flow flux of different section was obtained. The research indicated that the flow from leakage gap between poles and stators formed "air wall", which generated a recirculation zone and made the bar cooling bad. The local pressure loss of stator entrance is dominant. There are leeward and windward areas for the air flowing with circumferential velocity component. Rational design of stator ducts entrance with some diversion effect, can reduce the pressure loss of the stator ventilation and improve the cooling of leeward area in stator ducts.

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Ab Rahman, Rosdi, Masiri Kaamin, Amir Khan Suwandi, Mohd Jahaya Kesot, and Norah Mohd Zan. "Cooling System of Zinc Roofed House by Using Circulated Water." Advanced Materials Research 935 (May 2014): 84–87. http://dx.doi.org/10.4028/www.scientific.net/amr.935.84.

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Most traditional village houses uses corrugated zinc roofing due to economic reason. Thermal discomfort will result as zinc is a highly heat absorbing material. The space under the zinc covering will experience significant temperature increase proportional to the amount of supplied heat from sunlight, and this will further be aggravated if the ventilation is poor. The purpose of this study is to determine an alternative method to lower the temperature inside a zinc covered house. The proposed method is by splashing water throughout the area of the zinc roofing, where heat exchange process will occur upon contact. The process will dissipate heat from the zinc but will increase the water temperature. Heated water will then free fall by gravity into a tank through perforated tube with very fine aperture, as water droplet. By the same heat transfer process, ambient air will lower the water temperature, which will be recirculation back to the roof. To facilitate higher rate of water cooling, fan will be provided. The tests show the system was able to lower the temperature of the zinc covered house, and can reduce cost of cooling, thus suitable for low income rural population in Malaysia.

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Jiang, Qing, Chao Zhang, and Jin Jiang. "Sensitivity Analysis of a FGR Industrial Furnace for NOx Emission Using Frequency Domain Method." Journal of Energy Resources Technology 129, no. 2 (May 21, 2005): 134–43. http://dx.doi.org/10.1115/1.2141636.

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Preliminary study has shown that the flue gas recirculation (FGR) is one of the effective ways to reduce the nitric oxides (NOx) emission in industrial furnaces. The sensitivity of the NOx emission from a FGR industrial furnace to the change in three major furnace input variables—inlet combustion air mass flow rate, inlet combustion air temperature, and pressure head of the FGR fan—is investigated numerically in this study. The investigation is carried out in frequency domain by superimposing sinusoidal signals of different frequencies on to the furnace control inputs around the design operating condition, and observing the frequency responses. The results obtained in this study can be used in the design of active combustion control systems to reduce NOx emission. The numerical simulation of the turbulent non-premixed combustion process in the furnace is conducted using a moment closure method with the assumed β probability density function for the mixture fraction. The combustion model is derived based on the assumption of instantaneous full chemical equilibrium. The discrete transfer radiation model is chosen as the radiation heat transfer model, and the weighted-sum-of-gray-gases model is used to calculate the absorption coefficient.

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Kim, Yong-In, Sang-Yeol Lee, Kyoung-Yong Lee, Sang-Ho Yang, and Young-Seok Choi. "Numerical Investigation of Performance and Flow Characteristics of a Tunnel Ventilation Axial Fan with Thickness Profile Treatments of NACA Airfoil." Energies 13, no. 21 (November 8, 2020): 5831. http://dx.doi.org/10.3390/en13215831.

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An axial flow fan, which is applied for ventilation in underground spaces such as tunnels, features a medium–large size, and most of the blades go through the casting process in consideration of mass production and cost. In the casting process, post-work related to roughness treatment is essential, and this is a final operation to determine the thickness profile of an airfoil which is designed from the empirical equation. In this study, the effect of the thickness profile of an airfoil on the performance and aerodynamic characteristics of the axial fan was examined through numerical analysis with the commercial code, ANSYS CFX. In order to conduct the sensitivity analysis on the effect of the maximum thickness position for each span on the performance at the design flow rate, the design of experiments (DOE) method was applied with a full factorial design as an additional attempt. The energy loss near the shroud span was confirmed with a quantified value for the tip leakage flow (TLF) rate through the tip clearance, and the trajectory of the TLF was observed on the two-dimensional (2D) coordinates system. The trajectory of the TLF matched well with the tendency of the calculated angle and correlated with the intensity of the turbulence kinetic energy (TKE) distribution. However, a correlation between the TLF rate and TKE could not be established. Meanwhile, the Q-criterion method was applied to specifically initiate the distribution of flow separation and inlet recirculation. The location accompanying the energy loss was mutually confirmed with the axial coordinates. Additionally, the nonuniform blade loading distribution, which was more severe as the maximum thickness position moved toward the leading edge (LE), could be improved significantly as the thickness near the trailing edge (TE) became thinner. The validation for the numerical analysis results was performed through a model-sized experimental test.

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Semin, Mikhail, Evgenii Grishin, Lev Levin, and Artem Zaitsev. "Automated ventilation control in mines. Challenges, state of the art, areas for improvement." Journal of Mining Institute 246 (January 23, 2021): 623–32. http://dx.doi.org/10.31897/pmi.2020.6.4.

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The article is divided into three main parts. The first part provides an overview of the existing literature on theoretical methods for calculating the optimal air distribution in mines according to the criteria of energy efficiency and providing all sections of mines with the required amount of air. It is shown that by the current moment there are many different formulations of the problem of searching the optimal air distribution, many different approaches and methods for optimizing air distribution have been developed. The case of a single (main) fan is most fully investigated, while for many fans a number of issues still remain unresolved. The second part is devoted to the review of existing methods and examples of the automated mine ventilation control systems implementation in Russia and abroad. Two of the most well-known concepts for the development of such systems are automated ventilation control systems (AVCS) in Russia and the CIS countries and Ventilation on demand (VOD) abroad. The main strategies of ventilation management in the framework of the AVCS and VOD concepts are described and also the key differences between them are shown. One of the key differences between AVCS and VOD today is the automatic determination of the operation parameters of fan units and ventilation doors using the optimal control algorithm, which is an integral part of the AVCS. The third part of the article describes the optimal control algorithm developed by the team of the Mining Institute of the Ural Branch of the Russian Academy of Sciences with the participation of the authors of the article. In this algorithm, the search for optimal air distribution is carried out by the system in a fully automated mode in real time using algorithms programmed into the microcontrollers of fans and ventilation doors. Minimization of energy consumption is achieved due to the most efficient selection of the fan speed and the rate of ventilation doors opening and also due to the air distribution shift control and the partial air recirculation systems introduction. It is noted that currently the available literature poorly covers the issue related to emergency operation modes ventilation systems of mines and also with the adaptation of automated control systems to different mining methods. According to the authors, further development of automated ventilation control systems should be carried out, in particular, in these two areas.

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Kim, Geun-Tae, and Jin-Do Chung. "The Improvement on The Operating Characteristics of Vaporizing Gas Recirculation Fan of De-NOx facility in The NG Fired Gas Turbine Combined Cycle Power Plant." Journal of Institute of Control, Robotics and Systems 27, no. 7 (July 31, 2021): 468–72. http://dx.doi.org/10.5302/j.icros.2021.21.0056.

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Lungu, Catalin, and Florin Baltaretu. "Innovative HVAC System Using an Integrated Greenhouse for a Virtual Low Energy Office Building." E3S Web of Conferences 111 (2019): 04011. http://dx.doi.org/10.1051/e3sconf/201911104011.

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In this paper the authors describe a HVAC innovative system using an integrated greenhouse for heating and cooling an office building. The ventilation system allows natural (night) or mechanical ventilation and the passive cooling during the summer, including cold storage in the building structure and the PCM plywood and the refrigeration energy use during the day. Natural ventilation occurs when the wind or the Venturi effect, created by the « hat » that supports the photovoltaic panels, is strong enough; otherwise, a variable speed exhaust fan mounted on top of the building is used. The plants inside the greenhouse can produce O2 under certain conditions necessary for refreshing the ventilation air. The environment of the greenhouse allows air humidification naturally, without the use of humidifiers. If the greenhouse is sufficiently insulated in winter, it can be used in the ventilation process: the air intake from offices through the greenhouse, humidified and enriched in O2 (premixed, if necessary, with fresh air) reaches the general air treatment unit, and then sent back. The process is similar in the summer, but without recirculation, due to the humidity of the air extracted from offices. Stale air humidification enhances the thermal transfer process from the desiccant collector.

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Muller, Chris. "Evaluating the Effectiveness of AMC Control Strategies with Reactivity Monitoring." Journal of the IEST 45, no. 1 (September 14, 2002): 65–79. http://dx.doi.org/10.17764/jiet.45.1.f6v70v738772n6x9.

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The control of airborne molecular contaminants (AMC) is becoming a design requirement for all semiconductor manufacturing facilities. Chemical filtration in many forms is being employed in makeup air handling units, recirculation air handlers, minienvironments, fan filter units, and process tools. Suppliers of chemical filtration systems are being asked how best to determine if their systems are working and, if so, whether they are meeting design requirements. Just as there are many ways to apply chemical filtration for the control of AMC, there are many different methods being used to measure AMC and to evaluate filter system performance. Employed in either real-time or passive form, reactivity monitoring has been used in a number of fabs for several years as a way to gauge AMC levels and to evaluate the effectiveness of AMC control strategies. Whether controlling AMC directly or indirectly, reactivity monitoring can provide an overall indication of ambient air quality as well as AMC levels within the controlled spaces. This paper will focus on the use of reactivity monitoring as an air monitoring technique. Results of reactivity monitoring from semiconductor manufacturing facilities will be presented, illustrating both the validity of this air monitoring technique in general as well as its ability to gauge the effectiveness of chemical filtration when applied to the control of AMC.

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M., Sylvester, Bhandari B., and Prakash S. "3D food printing as a promising tool for food fabrication: 3D printing of chocolate." Supplementary 6 4, S6 (December 27, 2020): 42–53. http://dx.doi.org/10.26656/fr.2017.4(s6).054.

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The optimisation of printing dark chocolate was investigated, which included 3D printer modification. The modification comprises development of custom printer bed an inbuilt water recirculation system with a slow flow rate of 6.3 mL/s to avoid vibration. Additionally, a fan was attached to enhance the solidification of chocolate. It was found that 32°C was the optimal condition of chocolate melting and this temperature was applied in the printing process. The addition of the support structure on the mechanical properties of chocolate such as cross and parallel support structures printed in a hexagonal shape was also investigated. Findings indicated that the cross support increased the stability and strength (57.5±4.8 N) of chocolate more than the chocolate printed with parallel support (50.5±2.7 N) and without any support structure (12.6±6.1 N). Different infill structures (infill pattern and percentage) can contribute to the textural modification of 3D printed chocolate. The appearance of the 3DP construction was vital as this modality can influence the acceptability of the product. Sensory analysis was conducted among 30 semi -trained panellists. Most participants favoured the appearance of sample 3DP100%_IP (1.33) to those of samples 3DP25%_IP (2.00) and 3DP50%_IP (2.67). On the textural perspectives, consumers indicated their potential preferences on chocolate printed with 25% infill percentage. Similar results from consumer paired-preference test were obtained. These results suggested that consumer realised the potential of 3D printing for textural modification.

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35

Enescu, Maria Cristiana, C. Marius Vlădulescu, Aurel Gaba, Vasile Bratu, Elena Valentina Stoian, and Ivona Camelia Petre. "Cold End Corrosion Avoiding by Using a New Type of Air Combustion Pre-Heater." Materials Science Forum 907 (September 2017): 157–63. http://dx.doi.org/10.4028/www.scientific.net/msf.907.157.

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This paper analyzes the possibility of reducing the cold end corrosion in boilers and furnaces by using a new type of air combustion pre-heater. Cold end corrosion appears due to catalytic oxidation of the sulfur dioxide to sulfur trioxide and then due to the sulfuric acid condensation at dew point. Calculating dew points of various acid gases and options for reducing cold end corrosion of heat recovery exchangers are presented. For avoiding the cold end corrosion we design a new type of air combustion pre-heater for boilers and furnaces. Also, the tube skin temperature of the first row of pipes of the actual air pre-heater was simulated with this computer program, in order to determine whether this temperature is lower than acid dew point of flue gas. With the simulation for this configuration of the actual combustion air pre-heater, the skin temperature for the first row (for the combustion air flow) of tubes from the upper bundle was TS = 134 °C. A way to reduce the cold end corrosion in the combustion air pre-heaters is raising the temperature of the combustion air at the air pre-heater entrance. This solution involves taking a quantity of preheated air, recirculation and then reintroducing it in the air pre-heater. In the same time, this solution avoiding to use the steam radiator, mounted after the fan, for pre-heating the combustion air from 1°C to 45°C. Thus, the furnaces equipped with the new combustion air pre-heater and modern low NOx burners made a fuel economy about 3%.

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36

Fujikawa, T., Y. Nomura, Y. Hattori, T. Kobayashi, and M. Kanda. "Analysis of cycle-by-cycle variation in a direct injection gasoline engine using a laser-induced fluorescence technique." International Journal of Engine Research 4, no. 2 (April 1, 2003): 143–53. http://dx.doi.org/10.1243/146808703321533286.

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To analyse the cycle-by-cycle variation of combustion in a direct injection gasoline engine equipped with a fan-shape spray nozzle and operated with exhaust gas recirculation (EGR), the fuel mixture distribution was measured at a time of spark and during the combustion period by the laser-induced fluorescence (LIF) technique. It was found that in the case of advanced or retarded injection timing, the initial combustion period tends to extend and the indicated mean effective pressure (i.m.e.p.) becomes low when lean mixtures appear at the spark position and at the spark timing. This suggests that the cycle-by-cycle variation of combustion under these conditions is dominated by the fuel concentration at the spark position and spark timing. In contrast to this, for the best injection timing, which allows the lowest cycle-by-cycle variation, the i.m.e.p. fluctuation is affected not by the initial combustion period but by the main combustion period. The observation of LIF images revealed that the i.m.e.p. fluctuation at this condition is strongly correlated to the unburned mixture quantity at the side area of the piston cavity during the latter half of the combustion period. It was shown by a computational fluid dynamics (CFD) calculation that the combination of a uniform spray pattern and a compact cavity shape is effective to reduce the over-lean mixture region in the edge of the piston cavity, which is responsible for the cycle-by-cycle variation of combustion at the condition of best-tuned injection timing.

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Machida, T., H. Matsueda, Y. Sawa, Y. Nakagawa, K. Hirotani, N. Kondo, K. Goto, T. Nakazawa, K. Ishikawa, and T. Ogawa. "Worldwide Measurements of Atmospheric CO2 and Other Trace Gas Species Using Commercial Airlines." Journal of Atmospheric and Oceanic Technology 25, no. 10 (October 1, 2008): 1744–54. http://dx.doi.org/10.1175/2008jtecha1082.1.

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Abstract New automated observation systems for use in passenger aircraft to measure atmospheric carbon dioxide (CO2) and other trace species have been developed and are described in this paper. The Continuous CO2 Measuring Equipment (CME) is composed mainly of a nondispersive infrared analyzer, a datalogger, and two calibration cylinders for in situ CO2 measurements. The Automatic Air Sampling Equipment (ASE), on the other hand, is designed for flask sampling; the instrument, connected to a metal bellows pump, is made up of a specially designed control board and can accommodate 12 flasks. The CME platform can be used to conduct high-frequency measurements of CO2 for obtaining a detailed spatial observation over a wide area, while ASE, despite the limited flight frequency, can provide useful distributions not only of CO2 but also various trace gas species, as well as their isotopic ratios. ASE and CME are installed on the racks in the forward cargo compartment of the aircraft and the air bypass intake is mounted on the air-conditioning duct upstream of the recirculation fan. Both sets of sampling equipment are automatically controlled through input of relevant flight parameters from the aircraft data system. Their deployment in a Boeing 747-400 aircraft was approved by the aviation regulatory agencies in the United States and Japan through issuance of the supplemental type certificate (STC), while the approval for installation of CME in a Boeing 777-200ER was also obtained via STC. First measurement results of CO2 variations obtained by CME and ASE deployed on Japan Airlines (JAL) aircraft are reported herein.

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Xu, Wenmao, Zaixing Jiang, Ji Chen, Chao Liu, and Lingyu Dong. "Source-to-sink system in the south bank of Qinghai Lake." Interpretation 6, no. 1 (February 1, 2018): T109—T126. http://dx.doi.org/10.1190/int-2017-0005.1.

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In the south bank of Qinghai Lake, numerous alluvial fans and coastal deposits have been formed. In terms of their developmental positions and relationships, the denudation system, depositional system, and transportation system consist of source-to-sink systems. Based on the field-investigation evidence and literature survey, it was confirmed that the developmental processes of these “source-to-sink” systems can be divided into three stages: the Early-Late Pleistocene stage, from 39 to 23 ka BP; Late Pleistocene-Early Holocene stage, from 39 to 10.7 ka BP; and modern stage. At the present time, these stages can still be identified as three levels of lake shore terraces. In the Late Pleistocene, the source-to-sink system indicates that the lake level was high, supply of clasts was sufficient, fan deltas had formed, and the lakeside plain continued to develop. At the end of the Late Pleistocene, with the sudden changes in global climate, the climate was dry and cold, and the lake level fell. At this time, the source-to-sink system showed that lake level was relatively low, supply of clasts was reduced, and transportation distance was longer; ancient sediments started to recycle in this system. Until modern times, alluvial fans in the south bank of Qinghai Lake have only rarely been developed, and the supply of clasts is primarily derived from the recirculation of paleo-shore sediments. Meanwhile, a large amount of sandy gravel beaches developed along the lake shore. By studying the multistage source-to-sink systems around modern lakes, the characteristics of the system in lake basins are enriched and provide an important analogy for researches of ancient lake basins.

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Vasel, J. L., H. Jupsin, and A. P. Annachhatre. "Nitrogen removal during leachate treatment: comparison of simple and sophisticated systems." Water Science and Technology 50, no. 6 (September 1, 2004): 45–52. http://dx.doi.org/10.2166/wst.2004.0358.

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Membrane bioreactors (MBR) have become common in treating municipal wastewaters. Applied to leachates treatment MBR were also successful with pilot scale experiments and full-scale facilities as well. We succeeded previously in designing an efficient nitrificationÐdenitrification process with an ethylene glycol byproduct as carbon source for denitrification. Moreover, an unexpectedly high inert COD removal efficiency was also observed in the full-scale MBR facility thereby making it possible to increase the operating time of the final GAC (Granulated Activated Carbon) adsorber. Since MBR are very sophisticated systems. Simpler and “lower” cost systems can also be considered. For example it is possible to nitrify leachates from sanitary landfill using a simple infiltrationÐpercolation technique with a low energy cost. To validate previously published laboratory experiments, a semi industrial-scale pilot installation was installed at the Montzen landfill site (Belgium). The process is based on infiltrationÐpercolation through a granular bed. This well known process was modified to increase the load, notably by changing the support medium, adding an electric fan that is run intermittently and maintaining temperatures greater than 15°C. The new material is a type of granular calcium carbonate with a large specific surface area. These technical improvements enabled the system to nitrify up to 0.4 kg NH4+-N/m3 of reactor bed per day at a hydraulic load of 0.35 m.d-1, with an ammonia removal rate in the range of 80 to 95%. Despite the high ammonia nitrogen inlet concentrations, this system exhibits remarkable nitrification efficiency. Moreover, these performances are achieved in a batch mode system without recirculation or dilution processes. If complete nitrification is needed, it can be obtained in a second in series of bioreactors. The system can be classified as a low cost process. An international patent is pending. Possible performances of those systems were compared with the usual methods for leachates treatment.

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Ab Rahman, Rosdi, Masiri Kaamin, Mahmod Abd Hakim Mohamad, Azizul Rahman Abd Aziz, and Mohd Hadri Mohamed Nor. "Comparison of Zinc Roofed House Temperature Distribution between Open Water Exhausted with Radiator Cooling System." Applied Mechanics and Materials 773-774 (July 2015): 1178–83. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.1178.

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Thermal condition of a house is one of the comfort factors. Traditionally, village houses in Malaysia uses corrugated zinc roofing due to economic reason. Considering the thermal conductivities of the material, space under the roof coverage will intent to occur thermal discomfort due to Malaysian ambient temperature. The roof plays an important role to ensure the house is in a state insulated from the hot sun and rain where the zinc roofing will radiated by the sun in noon and yet become the heat source for in-house area. Thermal discomfort will result due to zinc highly heat absorbing material property. The space under the covering will experience significant temperature increase proportional to the amount of supplied heat from sunlight radiated to the zinc roof, and will further be aggravated if ventilation is poor. The purpose of this study is to compare the temperature distribution by two alternatives methods to reduce the temperature inside a zinc-covered house. The main concept of this cooling system is by splashing water throughout the area of the zinc roofing, where heat exchange process will occur upon contact. The process will dissipate heat from the zinc and will increase the water temperature. This research is focusing on the medium (water) re-cooling process by either open water exhausted or radiator system to state that which one will give better heat exchange. Open water exhausted system heated water will then free fall by gravity into a tank through perforated tube as water droplets. To facilitate higher rate of water-cooling, fan will be provided. Another re-cooling system is the radiator system, which use radiator device to cool down the heated water. Radiator use coolant as the medium to exchange the heat from the roof heated water. By the same heat transfer process, the circulated water temperature will be lower where, which will be recirculation back to the roof. Both systems had been compared about the differences of temperature drop distribution which result the better water re-cooling system.

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Gajjar, P., K. van der Vaart, A. R. Thornton, C. G. Johnson, C. Ancey, and J. M. N. T. Gray. "Asymmetric breaking size-segregation waves in dense granular free-surface flows." Journal of Fluid Mechanics 794 (April 4, 2016): 460–505. http://dx.doi.org/10.1017/jfm.2016.170.

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Debris and pyroclastic flows often have bouldery flow fronts, which act as a natural dam resisting further advance. Counter intuitively, these resistive fronts can lead to enhanced run-out, because they can be shouldered aside to form static levees that self-channelise the flow. At the heart of this behaviour is the inherent process of size segregation, with different sized particles readily separating into distinct vertical layers through a combination of kinetic sieving and squeeze expulsion. The result is an upward coarsening of the size distribution with the largest grains collecting at the top of the flow, where the flow velocity is greatest, allowing them to be preferentially transported to the front. Here, the large grains may be overrun, resegregated towards the surface and recirculated before being shouldered aside into lateral levees. A key element of this recirculation mechanism is the formation of a breaking size-segregation wave, which allows large particles that have been overrun to rise up into the faster moving parts of the flow as small particles are sheared over the top. Observations from experiments and discrete particle simulations in a moving-bed flume indicate that, whilst most large particles recirculate quickly at the front, a few recirculate very slowly through regions of many small particles at the rear. This behaviour is modelled in this paper using asymmetric segregation flux functions. Exact non-diffuse solutions are derived for the steady wave structure using the method of characteristics with a cubic segregation flux. Three different structures emerge, dependent on the degree of asymmetry and the non-convexity of the segregation flux function. In particular, a novel ‘lens-tail’ solution is found for segregation fluxes that have a large amount of non-convexity, with an additional expansion fan and compression wave forming a ‘tail’ upstream of the ‘lens’ region. Analysis of exact solutions for the particle motion shows that the large particle motion through the ‘lens-tail’ is fundamentally different to the classical ‘lens’ solutions. A few large particles starting near the bottom of the breaking wave pass through the ‘tail’, where they travel in a region of many small particles with a very small vertical velocity, and take significantly longer to recirculate.

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Grimes, R., M. Davies, J. Punch, T. Dalton, and R. Cole. "Modeling Electronic Cooling Axial Fan Flows." Journal of Electronic Packaging 123, no. 2 (October 2, 2000): 112–19. http://dx.doi.org/10.1115/1.1339821.

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To address the requirement for prediction and understanding of airflow in forced convection cooled electronic systems, a detailed experimental investigation of the outlet flow of typical axial cooling fans has been performed. The flow is shown to be complex over much of the fans operational range, with significant radial and tangential velocities and regions with little or no flow. The effect of partially blocking a fan and running it at elevated temperatures are both shown to be significant. The effect of attaching a fan to an electronic system is then investigated. Flow drawn through a system is shown to be simple and well predicted by a standard CFD package. Flow blown into a system is far more complex, with large areas of recirculating flow, and less accuracy in the prediction. The paper gives valuable and novel design insight into forced cooling flows in electronic systems and shows that the industry is still some way from a reliable design method.

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43

Peng, Lei, and Jae-Yoon Jo. "Performance of a Foam Fractionator in a Lab-scale Seawater Recirculating Aquaculture System." Fisheries and aquatic sciences 6, no. 4 (December 1, 2003): 187–93. http://dx.doi.org/10.5657/fas.2003.6.4.187.

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Yoon, Gil Ha, Jae-Yoon Jo, Youhee Kim, and In-Bae Kim. "Growth of Sex Reversed Nile Tilapia, Oreochromis niloticus In a Closed Recirculating Culture System." Fisheries and aquatic sciences 5, no. 1 (March 1, 2002): 59–63. http://dx.doi.org/10.5657/fas.2002.5.1.059.

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Peng, Lei, and Jae-Yoon Jo. "Performance of a Recirculating Aquarium System for the Culture and Holding of Marine Fish." Fisheries and aquatic sciences 7, no. 2 (June 1, 2004): 76–83. http://dx.doi.org/10.5657/fas.2004.7.2.076.

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Lee, Jin-Hwan. "Serial Particle Size Fractionation and Water Quality in a Recirculating Aquaculture System for Eel." Fisheries and aquatic sciences 13, no. 2 (June 30, 2010): 133–39. http://dx.doi.org/10.5657/fas.2010.13.2.133.

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Lee, Jin-Hwan. "Separation Performance of a Low-pressure Hydrocyclone for Suspended Solids in a Recirculating Aquaculture System." Fisheries and aquatic sciences 13, no. 2 (June 30, 2010): 150–56. http://dx.doi.org/10.5657/fas.2010.13.2.150.

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48

Harwanto, Dicky, Sung-Yong Oh, Heung-Sik Park, and Jae-Yoon Jo. "Performance of Three Different Biofilter Media in Laboratory-Scale Recirculating Systems for Red Seabream Pagrus major Culture." Fisheries and aquatic sciences 14, no. 4 (December 31, 2011): 371–78. http://dx.doi.org/10.5657/fas.2011.0371.

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49

Rui, Xiaocheng, Limin Lin, Junkui Wang, Xinxue Ye, Haijiang He, Wei Zhang, and Zuchao Zhu. "Experimental and Comparative RANS/URANS Investigations on the Effect of Radius of Volute Tongue on the Aerodynamics and Aeroacoustics of a Sirocco Fan." Processes 8, no. 11 (November 11, 2020): 1442. http://dx.doi.org/10.3390/pr8111442.

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The geometry of volute tongue is crucial in the design of Sirocco fans. The size of the volute tongue determines its relative position and distance from the impeller which affects the local flow characteristics and thus the aerodynamic and aeroacoustic performances of the fan. In this work, we performed experimental and numerical investigations on the effect of volute tongue radius on the aerodynamic and aeroacoustic characteristics of a Sirocco fan. The internal flow characteristics are analyzed and discussed in terms of the spatial distribution and temporal variation of pressure and streamlines, the pulsating behaviors of pressure both in the impeller and on the volute surface with emphasis in the volute tongue region, the variation of passage flow with the rotation of impeller and the aeroacoustic features of the fan. We conducted numerical simulations using both steady Reynolds-Averaged Navier-Stokes (RANS) and unsteady Reynolds-Averaged Navier-Stokes (URANS) approaches with realizable k-ε turbulence model with rotation effect correction and the results are compared against the experimental data to assess the prediction capability and accuracy in qualitative and quantitative manners. Experimental and numerical results show that as the volute tongue radius increases, the static pressure rises as well as the far-field noise of the fan and pronounced fluctuation of flow is observed within the whole impeller and volute; the reversed flow in the passage of the impeller is reduced and the high-pressure region is found to be moving towards the outlet of the volute. The decreasing radius also enlarges the size of the adverse pressure gradient (APG) region on the volute tongue which contributes to the formation of recirculating flow. The comparative RANS and URANS simulations reveal that both approaches produce generally consistent results regarding the time-averaged flow although the URANS data are much closer to those of the experimental ones. However, the fluctuating flow which is not capable to be modeled by RANS still dominates for the present configuration and thus URANS is necessary for the accurate prediction of the flow details.

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Weerakul, Sarita, Naravit Leaukosol, Derek H. Lister, Shintaro Mori, and Wolfgang Hater. "Effects on Flow-Accelerated Corrosion of Oleylpropanediamine Under Single-Phase Water Conditions Pertinent to Power Plant Feedwater." Corrosion 76, no. 2 (December 23, 2019): 217–30. http://dx.doi.org/10.5006/3225.

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Studies of the effects of the film-forming amine oleylpropanediamine (OLDA), with and without auxiliary alkalizing agents, on flow-accelerated corrosion (FAC) were performed in high-pressure, high-temperature recirculating water loops. Those loops were equipped with experimental probes to monitor FAC in situ. Experiments were performed at simulated power plant conditions in single-phase water at 140°C. The results showed that OLDA reduced FAC to a greater extent than the associated pH effect. The protective film apparently consisted of several layers and survived for several days after OLDA was removed from the bulk water. The system treated with OLDA under neutral water conditions before raising the pH had higher corrosion resistance than the system dosed with OLDA when already at high pH.

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Journal articles on the topic 'Recirculation fan'

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