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Artykuły w czasopismach na temat "Radiator airflow distribution"
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Subramaniyan, Baskar, i R. Rajaraman. "Numerical Investigation on Airflow Distribution of Automotive Radiator". International Review of Mechanical Engineering (IREME) 9, nr 4 (31.07.2015): 417. http://dx.doi.org/10.15866/ireme.v9i4.6795.
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Ng, E. Y., P. W. Johnson i S. Watkins. "An analytical study on heat transfer performance of radiators with non-uniform airflow distribution". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, nr 12 (1.12.2005): 1451–67. http://dx.doi.org/10.1243/095440705x35116.
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Heat exchangers used in modern automobiles usually have a highly non-uniform air velocity distribution because of the complexity of the engine compartment and underhood flow fields; hence ineffective use of the core area has been noted. To adequately predict the heat transfer performance in typical car radiators, a generalized analytical model accounting for airflow maldistribution was developed using a finite element approach and applying appropriate heat transfer equations including the ε-NTU (effectiveness - number of heat transfer units) method with the Davenport correlation for the air-side heat transfer coefficient. The analytical results were verified against a set of experimental data from nine radiators tested in a wind tunnel and were found to be within +24 and −10 per cent of the experimental results. By applying the analytical model, several severe non-uniform velocity distributions were also studied. It was found that the loss of radiator performance caused by airflow maldistribution, compared with uniform airflow of the same total flowrate, was relatively minor except under extreme circumstances where the non-uniformity factor was larger than 0.5. The relatively simple set of equations presented in this paper can be used independently in spreadsheets or in conjunction with computational fluid dynamics (CFD) analysis, enabling a full numerical prediction of aerodynamic as well as thermodynamic performance of radiators to be conducted prior to a prototype being built.
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Sun, He Chen, Jing Ye Zhao, Wen Hai Wang i Zhi Yong Gao. "Research on Thermal Comfort in HVAC Laboratory". Applied Mechanics and Materials 148-149 (grudzień 2011): 1122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1122.
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According to the characteristics of the laboratory, for the condition of using air conditioning that is falling to the ground pattern to assist radiator to heat, use CFD to simulate the airflow organization and thermal environment in laboratory. Meanwhile combine with the indoor relevant measured parameters, analyze distribution characteristics and finally evaluate the thermal comfort in laboratory in winter.
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Cvok, Ivan, Igor Ratković i Joško Deur. "Multi-Objective Optimisation-Based Design of an Electric Vehicle Cabin Heating Control System for Improved Thermal Comfort and Driving Range". Energies 14, nr 4 (23.02.2021): 1203. http://dx.doi.org/10.3390/en14041203.
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Modern electric vehicle heating, ventilation, and air-conditioning (HVAC) systems operate in more efficient heat pump mode, thus, improving the driving range under cold ambient conditions. Coupling those HVAC systems with novel heating technologies such as infrared heating panels (IRP) results in a complex system with multiple actuators, which needs to be optimally coordinated to maximise the efficiency and comfort. The paper presents a multi-objective genetic algorithm-based control input allocation method, which relies on a multi-physical HVAC model and a CFD-evaluated cabin airflow distribution model implemented in Dymola. The considered control inputs include the cabin inlet air temperature, blower and radiator fan air mass flows, secondary coolant loop pump speeds, and IRP control settings. The optimisation objective is to minimise total electric power consumption and thermal comfort described by predictive mean vote (PMV) index. Optimisation results indicate that HVAC and IRP controls are effectively decoupled, and that a significant reduction of power consumption (typically from 20% to 30%) can be achieved using IRPs while maintaining the same level of thermal comfort. The previously proposed hierarchical HVAC control strategy is parameterised and extended with a PMV-based controller acting via IRP control inputs. The performance is verified through simulations in a heat-up scenario, and the power consumption reduction potential is analysed for different cabin air temperature setpoints.
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Gendelis, S., i A. Jakovičs. "Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange Conditions". Latvian Journal of Physics and Technical Sciences 47, nr 4 (1.01.2010): 27–43. http://dx.doi.org/10.2478/v10047-010-0016-z.
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Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange ConditionsNumerical mathematical modelling of the indoor thermal conditions and of the energy losses for separate rooms is an important part of the analysis of the heat-exchange balance and energy efficiency in buildings. The measurements of heat transfer coefficients for bounding structures, the air-tightness tests and thermographic diagnostics done for a building allow the influence of those factors to be predicted more correctly in developed numerical models. The temperature distribution and airflows in a typical room (along with the heat losses) were calculated for different heater locations and solar radiation (modelled as a heat source) through the window, as well as various pressure differences between the openings in opposite walls. The airflow velocities and indoor temperature, including its gradient, were also analysed as parameters of thermal comfort conditions. The results obtained show that all of the listed factors have an important influence on the formation of thermal comfort conditions and on the heat balance in a room.
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Zhang, Xiaoyan, Baoyun Bu, Lang Liu, Tianrun Cao, Yaping Ke i Qiangqiang Du. "Numerical Simulation on Cooling Effect of Working Face under Radiation Cooling Mode in Deep Well". Energies 14, nr 15 (22.07.2021): 4428. http://dx.doi.org/10.3390/en14154428.
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Deep mining results in an increasingly serious hazard. Based on the principle of heat transfer and radiant cooling, a three-dimensional heat transfer model of the working face was established. The influence of the inlet airflow parameter, the surrounding wall temperature and other parameters on the temperature distribution of airflow along the working face were analyzed under the radiation cooling mode. The results show that the increment of airflow temperature in several sections along the working face decreases by 0.67 °C, 0.48 °C, 0.40 °C, 0.36 °C, 0.33 °C, 0.29 °C respectively. The farther away from the airflow inlet, the more obvious the cooling effect was. The airflow temperature of the working face is positively correlated with the airflow inlet temperature and the surrounding wall temperature, and is negatively correlated with the airflow velocity. The research provides a good solution for the working face cooling of deep mines, and also provides a theoretical reference for the research on the radiation cooling technology of the working face.
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Xie, Xu Liang, i Fu Lin Shen. "Numerical Investigation on Thermal Environment inside the Passenger Compartment of a Highway Sleeper Coach". Applied Mechanics and Materials 55-57 (maj 2011): 215–18. http://dx.doi.org/10.4028/www.scientific.net/amm.55-57.215.
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In order to verify thermal comfort of a 12-meter-long highway sleeper coach equipped with a four-ducted air-conditioning system, the thermal environment inside the passenger compartment was numerical investigated with RNG k-ε turbulence model. Also, discrete ordinates radiation model was applied to consider the effect of solar irradiation. The characteristic distribution of the airflow organization and temperature field were obtained and compared with experiment results. Results show that the air flow and temperature distribution inside the passenger compartment are not uniform and greatly influenced by solar radiation and air inlet parameters.
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Zeller, Marie-Louise, Jannis-Michael Huss, Lena Pfister, Karl E. Lapo, Daniela Littmann, Johann Schneider, Alexander Schulz i Christoph K. Thomas. "The NY-Ålesund TurbulencE Fiber Optic eXperiment (NYTEFOX): investigating the Arctic boundary layer, Svalbard". Earth System Science Data 13, nr 7 (14.07.2021): 3439–52. http://dx.doi.org/10.5194/essd-13-3439-2021.
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Abstract. The NY-Ålesund TurbulencE Fiber Optic eXperiment (NYTEFOX) was a field experiment at the Ny-Ålesund Arctic site (78.9∘ N, 11.9∘ E) and yielded a unique meteorological data set. These data describe the distribution of heat, airflows, and exchange in the Arctic boundary layer for a period of 14 d from 26 February to 10 March 2020. NYTEFOX is the first field experiment to investigate the heterogeneity of airflow and its transport of temperature, wind, and kinetic energy in the Arctic environment using the fiber-optic distributed sensing (FODS) technique for horizontal and vertical observations. FODS air temperature and wind speed were observed at a spatial resolution of 0.127 m and a temporal resolution of 9 s along a 700 m horizontal array at 1 m above ground level (a.g.l.) and along three 7 m vertical profiles. Ancillary data were collected from three sonic anemometers and an acoustic profiler (minisodar; sodar is an acronym for “sound detection and ranging”) yielding turbulent flow statistics and vertical profiles in the lowest 300 m a.g.l., respectively. The observations from this field campaign are publicly available on Zenodo (https://doi.org/10.5281/zenodo.4756836, Huss et al., 2021) and supplement the meteorological data set operationally collected by the Baseline Surface Radiation Network (BSRN) at Ny-Ålesund, Svalbard.
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Conceição, Eusébio, João Gomes, Maria Manuela Lúcio i Hazim Awbi. "Development of a Double Skin Facade System Applied in a Virtual Occupied Chamber". Inventions 6, nr 1 (4.03.2021): 17. http://dx.doi.org/10.3390/inventions6010017.
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In this study a system constituted by seven double skin facades (DSF), three equipped with venetian blinds and four not equipped with venetian blinds, applied in a virtual chamber, is developed. The project will be carried out in winter conditions, using a numerical model, in transient conditions, and based on energy and mass balance linear integral equations. The energy balance linear integral equations are used to calculate the air temperature inside the DSF and the virtual chamber, the temperature on the venetian blind, the temperature on the inner and outer glass, and the temperature distribution in the surrounding structure of the DSF and virtual chamber. These equations consider the convection, conduction, and radiation phenomena. The heat transfer by convection is calculated by natural, forced, and mixed convection, with dimensionless coefficients. In the radiative exchanges, the incident solar radiation, the absorbed solar radiation, and the transmitted solar radiation are considered. The mass balance linear integral equations are used to calculate the water mass concentration and the contaminants mass concentration. These equations consider the convection and the diffusion phenomena. In this numerical work seven cases studies and three occupation levels are simulated. In each case the influence of the ventilation airflow and the occupation level is analyzed. The total number of thermal and indoor air quality uncomfortable hours are used to evaluate the DSF performance. In accordance with the obtained results, in general, the indoor air quality is acceptable; however, when the number of occupants in the virtual chamber increases, the Predicted Mean Vote index value increases. When the airflow rate increases the total of Uncomfortable Hours decreases and, after a certain value of the airflow rate, it increases. The airflow rate associated with the minimum value of total Uncomfortable Hours increases when the number of occupants increases. The energy production decreases when the airflow increases and the production of energy is higher in DSF with venetian blinds system than in DSF without venetian blinds system.
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Tong, Zheming, i Hao Liu. "Modeling In-Vehicle VOCs Distribution from Cabin Interior Surfaces under Solar Radiation". Sustainability 12, nr 14 (8.07.2020): 5526. http://dx.doi.org/10.3390/su12145526.
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In-vehicle air pollution has become a public health priority worldwide, especially for volatile organic compounds (VOCs) emitted from the vehicle interiors. Although existing literature shows VOCs emission is temperature-dependent, the impact of solar radiation on VOCs distribution in enclosed cabin space is not well understood. Here we made an early effort to investigate the VOCs levels in vehicle microenvironments using numerical modeling. We evaluated the model performance using a number of turbulence and radiation model combinations to predict heat transfer coupled with natural convection, heat conduction and radiation with a laboratory airship. The Shear–Stress Transport (SST) k-ω model, Surface-to-surface (S2S) model and solar load model were employed to investigate the thermal environment of a closed automobile cabin under solar radiation in the summer. A VOCs emission model was employed to simulate the spatial distribution of VOCs. Our finding shows that solar radiation plays a critical role in determining the temperature distribution in the cabin, which can increase by 30 °C for directly exposed cabin surfaces and 10 °C for shaded ones, respectively. Ignoring the thermal radiation reduced the accuracy of temperature and airflow prediction. Due to the strong temperature dependence, the hotter interiors such as the dashboard and rear board released more VOCs per unit time and area. A VOC plume rose from the interior sources as a result of the thermal buoyancy flow. A total of 19 mg of VOCs was released from the interiors within two simulated hours from 10:00 am to noon. The findings, such as modeled spatial distributions of VOCs, provide a key reference to automakers, who are paying increasing attention to cabin environment and the health of drivers and passengers.
Rozprawy doktorskie na temat "Radiator airflow distribution"
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Ng, Eton Yat-Tuen, i eton_ng@hotmail com. "Vehicle engine cooling systems: assessment and improvement of wind-tunnel based evaluation methods". RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2002. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080422.100014.
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The high complexity of vehicle front-end design, arising from considerations of aerodynamics, safety and styling, causes the airflow velocity profile at the radiator face to be highly distorted, leading to potentially reduced airflow volume for heat dissipation. A flow visualisation study showed that the bumper bar significantly influenced the cooling airflow, leading to three-dimensional vortices in its wake and generating an area of relatively low velocity across at least one third of the radiator core. Since repeatability and accuracy of on-road testing are prejudiced by weather conditions, wind-tunnel testing is often preferred to solve cooling airflow problems. However, there are constraints that limit the accuracy of reproducing on-road cooling performance from wind-tunnel simulations. These constraints included inability to simulate atmospheric conditions, limited tunnel test section sizes (blockage effects) and lack of ground effect simulations. The work presented in this thesis involved use of on-road and wind-tunnel tests to investigate the effects of most common constraints present in wind tunnels on accuracy of the simulations of engine cooling performance and radiator airflow profiles. To aid this investigation, an experimental technique for quantifying radiator airflow velocity distribution and an analytical model for predicting the heat dissipation rate of a radiator were developed. A four-hole dynamic pressure probe (TFI Cobra probe) was also used to document flow fields in proximity to a section of radiator core in a wind tunnel in order to investigate the effect of airflow maldistribution on radiator heat-transfer performance. In order to cope with the inability to simulate ambient temperature, the technique of Specific Dissipation (SD) was used, which had previously been shown to overcome this problem.
Części książek na temat "Radiator airflow distribution"
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Sethuramalingam, Ramamoorthy, i Abhishek Asthana. "Design Improvement of Water-Cooled Data Centres Using Computational Fluid Dynamics". W Springer Proceedings in Energy, 105–13. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_14.
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AbstractData centres are complex energy demanding environments. The number of data centres and thereby their energy consumption around the world is growing at a rapid rate. Cooling the servers in the form of air conditioning forms a major part of the total energy consumption in data centres and thus there is an urgent need to develop alternative energy efficient cooling technologies. Liquid cooling systems are one such solution which are in their early developmental stage. In this article, the use of Computational Fluid Dynamics (CFD) to further improve the design of liquid-cooled systems is discussed by predicting temperature distribution and heat exchanger performance. A typical 40 kW rack cabinet with rear door fans and an intermediate air–liquid heat exchanger is used in the CFD simulations. Steady state Reynolds-Averaged Navier–Stokes modelling approach with the RNG K-epsilon turbulence model and the Radiator boundary conditions were used in the simulations. Results predict that heat exchanger effectiveness and uniform airflow across the cabinet are key factors to achieve efficient cooling and to avoid hot spots. The fundamental advantages and limitations of CFD modelling in liquid-cooled data centre racks were also discussed. In additional, emerging technologies for data centre cooling have also been discussed.
Streszczenia konferencji na temat "Radiator airflow distribution"
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Ruijsink, Rick, John Hoorneman i Coen Mulders. "The Measurement of the Distribution of the Airflow Through a Radiator". W Vehicle Thermal Management Systems Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1993. http://dx.doi.org/10.4271/931105.
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Raza, Hammad, Suraj Somanna Porangada, Wahidul Islam, Mohammed Naviwala i Jobaidur Rahman Khan. "Performance Enhancement in Unconventional Radiator". W ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70255.
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A number of cars are found to have an unconventional radiator. The radiator is placed at the back of the car instead of front, for which the radiator does not get the incoming airflow to cool the engine down and the engine gets overheated very easily. In order to deal with this problem, a channel has mounted at the top of the vehicle to navigate incoming air flow and direct it through the radiator to cool down the engine. The channel that is provided has three cases, which will indicate the different way of studying this problem. Both steady and transient state analysis has been performed. Each case has its own characteristics. For example, a longer channel creates little circulation but more axial flow towards the radiator, while shorter channel creates smooth but less axial flow towards the radiator. All these cases in the steady state have the same domain and will have similar inlet variables like velocity, shape, size, and position. However, the domain geometry was slightly changed for transient state scenario. At steady state simulation, most of the circulation were shown in the left-mid plane especially in longer channels. On the other hand, the transient state gives more uniform flow distribution. For longer channels in transient case, the flow is symmetric and smooth. The results were all made and developed in ANSYS for the final design where the data were simulated.
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Xie, J., i R. S. Amano. "Cooling Flow Simulation in the Enclosure of Mobile Generator". W ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60291.
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A thermal and airflow simulation model is developed for three-dimensional cooling flow study of ventilation and heat transfer inside a mobile generator’s enclosure. The purpose of this design is to achieve better sound attenuation while keeping proper cooling of the engine and generator. This paper focuses its objectives on the adjustment and improvement of cooling performances of some design factors like vent size, vent positions, fan’s flow rate and airflow route based on the CFD approach. A zero-equation HVAC turbulence model was employed and the simulation results were compared with the standard k-ε model. Numerical results show that the proper distribution in the intake vents helps in achieving uniform cooling flow distributions by avoiding the occurrence of hot spots on the engine and generator surfaces. Pressure drop through muffler and radiator are both important factors. Effective flow path arrangement is also found to be one of the most fatal factors in the thermal and noise management.
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Islam, Wahidul, i Jobaidur Rahman Khan. "Transient Analysis of Air Flow in a Channel for Unconventional Radiator". W ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88327.
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A number of cars are found to have an unconventional radiator. The radiator is placed at the back of the car instead of front, for which the radiator does not get the incoming airflow to cool the engine down and the engine gets overheated very easily. In order to deal with this problem, a channel has been mounted at the top of the vehicle to navigate incoming air flow and direct it through the radiator to cool down the engine. Three channels are tested computationally with three different lengths, which indicates the different way of studying this problem. Transient state analysis has been performed. Each length has its own characteristics. For example, a longer channel creates little circulation but more axial flow towards the radiator, while shorter channel creates smooth but less axial flow towards the radiator. All these cases in the steady state have the same domain and will have similar inlet variables like velocity, shape, size, and position. A transient state simulation, most of the circulation were shown in the left-mid plane especially in longer channels. Transient state gives more uniform flow distribution. For longer channels in transient case, the flow is symmetric and smooth, while the flow is not found symmetric for short channel. The results were all made and developed in ANSYS for the final design where the data were simulated.
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Swanson, L. W., D. K. Moyeda i B. A. Folsom. "A Thermal Model for Concentric-Tube Overfire Air Ports". W ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47025.
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A quasi-steady multi-mode heat-transfer model for boiler concentric-tube overfire air ports has been developed that predicts the effect of geometry, furnace heat source and heat sink temperatures, axial injector wall conduction, and coolant flow rate on the tube wall temperature distributions. The model imposes a radiation boundary condition at the outlet tip of the ports, which acts as a heat source. The model was validated using field data and showed that both the airflow distribution in the ports and tube diameter can be used to control the maximum tube wall temperature. This helps avoid tube overheating and thermal degradation. For nominal operating conditions, highly nonlinear axial temperature distributions were observed in both tubes near the hot outlet end of the port.
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Kruger, Sunita, i Leon Pretorius. "An Assessment of Different Boundary Conditions in a Naturally Ventilated Venlo-Type Greenhouse". W 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22849.
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This paper presents a parametric study of the indoor climate of a four span greenhouse subjected to natural ventilation. The effect of different heat fluxes through the greenhouse covering on the airflow patterns as well as temperature and velocity distributions were determined. Appropriate effective heat flux boundary conditions were introduced in the CFD model to investigate temperature and velocity distributions at plant level. Initially, three different simulations were done to represent zero wind speed conditions. Secondly, a velocity of 1m/s was specified at the domain inlet boundary. Results indicated that for all cases, the velocity distribution was heterogeneous and quite high for wind still days around midday. Temperature distributions were more homogeneous, decreased with the presence of a wind. Results indicated that a parametric value of 20% of the maximum daily solar radiation approximates previously simulated wall temperatures. It was also concluded that design changes such as additional openings including side and/or more roof ventilators be utilized to enhance ventilation on wind still days, as well as the warmer parts of the day.
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Beedie, David, Christopher Knight, Matthew Horsfield i Roy Moobola. "A Thermal-Electrochemical Model of a Fuel Cell Stack Block". W ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54829.
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RRFCS is developing SOFC fuel cell stack and system technology for a hybrid power generation system. RRFCS is also developing state of the art numerical prediction tools that will be used to support fuel cell product design. One such tool, the Block Thermal Model, is based in the FEMAP-TMG thermal model generator package. This paper describes the constituents of the block and the physics modelled, presents the initial results and states the computer resources used. Full validation could be a subject for later publication. In the RRFCS stack block, aerothermal physics in the anode and cathode gas flows is coupled with electrochemistry, distributed throughout a highly repeated three-dimensional solid geometry. The requirement was to create numerical modelling capability to accurately solve the main coupled behaviours throughout the entire domain of the block, as a function of externally applied conditions. The key distributions are thermal, electrical, chemical and hydraulic. The strength of the couplings determines the robustness of the design. The geometry, mesh density and fidelity required create considerable scope for model size to be enormous, with all the attendant issues around model setup, solution time and stability and post-processing. A finite element (FE) pre- and post-processor with a dedicated thermal solver extended by user-defined subroutines provides detailed thermal mapping and will be able to capture the coupled physics interactions. The FE mesh includes every component in the block including the end fittings and fuel pipes, as the sensible energy in the circulating fuel has significant thermal effects particularly at inlet. These components are less exposed to cooling airflow and will have significant effects in dynamic solutions. In order to capture the non-uniform distribution of fuel cell heat release, anode and cathode mass balances and electrochemical calculations are required at adequate resolution. Distributions of electrical current and fuel flow are currently user-input. Considerable attention was given to careful structuring of the mesh in order to minimise the element count. Full advantage was taken of the reasonable simplifications that can be made of the solid structure, fluid flows and fluid-solid heat exchanges. It was decided at the outset to make these simplifications as without them the model would have required orders of magnitude greater computational capability, probably without appreciably greater accuracy of the thermal distribution. Control of the radiation model setup was also both reasonable and necessary. Some validation of the tube mesh and initial steady-state results will be presented.
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Yang, Haoqi, Qingzhen Yang, Saile Zhang, Huicheng Yang i Yubo He. "Study on the Influence of Film Cooling on the Flow Field and Infrared Radiation Characteristics in the Divergent Section of a Nozzle". W ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16247.
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Abstract As the last part of the convergent divergent nozzle, the divergent section is exposed to high temperature and high-speed airflow and thus, it is more easily to be detected by the infrared detector. It is one of the main sources of the infrared radiation in the exhaust system. Film cooling is applied to protect the wall from hot flow and reduce the infrared radiation. In this paper, the study is conducted on a nozzle with spherical convergence flap in a turbofan engine exhaust system. The effect of film cooling on the internal flow and infrared radiation characteristics of the exhaust system in the divergent section was studied by numerical simulations. The k-ω SST turbulence model was used to simulate the flow field, and the Reverse Monte Carlo Method was employed to calculate the infrared radiation characteristics of the nozzle. Four different kinds of film hole arrangements are involved, they are cylindrical film holes in an in-line pattern, cylindrical film holes in a staggered pattern, converging-expanding film holes in an in-line pattern and converging-expanding film holes in a staggered pattern. The cylindrical film hole and the converging-expanding film hole have a round shape inlet, with an equivalent diameter of d = 5mm on the projection surface perpendicular to the axial direction. Angles between each film hole and the wall surface are 35°. The impact of the heat conduction on the wall was taken into account. The results show that with the given mass flow rate of the coolant, the lengths of the high temperature core zone of the four models with different film cooling structures are slightly shorter than the core zone of the model without cooling structures. However, no significant difference can be found for the length of the core zone of the four models. The average temperature of the wall in the divergent section decreases significantly by using film cooling. No significant difference can be found in the wall temperature distribution for the four models. In the 3∼5μm and 8∼14μm bands, the cooling technique barely affects the infrared radiation of the main exhaust jet flow, while it significantly reduces the infrared radiation of the solid wall in the divergent section, and the decreasing amplitude is from 45% to 51%. Different film hole arrangements result in similar effects on the infrared radiation of the nozzle. Overall, the usage of film cooling in the divergent section of the nozzle effectively reduces the averaged wall temperature and substantially suppresses the solid infrared radiation on the wall. However, the shape and arrangement of the film holes have no significant influence on the infrared radiation intensity and temperature of the wall in the divergent section.
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Hicks, R. A., i C. W. Wilson. "Comparison Between Measured and Predicted Wall Temperatures in a Gas Turbine Combustor". W ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-059.
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On of the major considerations in the development of advanced gas turbine engines are increased thrust to weight ratio and reduced development and operating costs. Improvements in engine thrust require an increase in combustion chamber heat release and inlet pressures. However, increasing the amount of heat release will also result in an increase in the radiative heat flux to the combustion chamber walls, proving detrimental to the operational life time of the combustor. To maximise combustor life, different cooling devices can be incorporated into the combustion chamber design. The effectiveness with which these devices are implemented is important and in the absence of a reliable predictive numerical tools, is difficult to quantify without undertaking expensive and timely testing. A computer analysis tool, based on a network model approach, has previously been developed to analyse airflow distributions in complex combustor geometries. A recent variant of this model has incorporated the Discrete Transfer radiation model, along with other convective and conductive sub-models, to account for heat transfer. These models have been validated against thermocouple measurements of wall temperature obtained in a sectored research combustor. The results of this comparison indicate that, whilst the model is capable of predicting the trends in wall temperature, it is currently unable to reproduce the magnitude of wall temperature with a greater accuracy than 80 K. However, the versatility of the discrete transfer model suggests that further improvements in accuracy are possible.
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Khalil, Essam E. "Holistic Approach to Green Buildings From Construction Material to Services". W ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70283.
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Attempts to adequately design an optimum HVAC airside system that furnishes comfort and air quality in the air-conditioned spaces with efficient energy consumption represent a great challenge. Air conditioning identifies the conditioning of air for maintaining specific conditions of temperature, humidity, and dust level inside an enclosed space. The conditions to be maintained are dictated by the need for which the conditioned space is intended and comfort of users. So, the air conditioning embraces more than cooling or heating. The comfort air conditioning is defined as “the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space”. Air conditioning, therefore, includes the entire heat exchange operation as well as the regulation of velocity, thermal radiation and quality of air, as well as the removal of foreign particles and vapors. Achieving occupant comfort and health is the result of a collaborative effort of environmental conditions, such as: Indoor air temperature; relative humidity; airflow velocity; pressure relationship; air movement efficiency; Contaminant concentration; Illumination and visual comfort; and sound and noise; and other factors. In the holistic approach, the totality of the effects of the heat sink and sources in the building and the technical building systems that are recoverable for space conditioning, are typically considered in the calculation of the thermal energy needs. As the technical building thermal systems losses depend on the energy input, which itself depends on the recovered system thermal sources, iteration might be required. The present paper reviews the status quo and critically analyses the appropriate approaches to sustainability.