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Wei I Chen - One of the best experts on this subject based on the ideXlab platform.
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thermal runaway in mold assisted flash sintering
Journal of the American Ceramic Society, 2016Co-Authors: Yanhao Dong, Wei I ChenAbstract:Analyzing the temperature evolution in pressureless mold-assisted flash sintering, we found the same onset condition as in standard flash sintering: When sample's DC or AC Joule Heating replaces environment's radiation Heating as the dominant power input term, thermal runaway ensues. Various serial and parallel components connected to the sample, including the mold, insulation, and punches, can affect Joule Heating and Conduction Heat Loss, thus play an important role in successful mold-assisted flash sintering.
Mark L Mckoy - One of the best experts on this subject based on the ideXlab platform.
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Heat Losses associated with the upward flow of air water co2 in geothermal production wells
International Journal of Heat and Mass Transfer, 2019Co-Authors: Tra X Phuoc, Mehrdad Massoudi, Ping Wang, Mark L MckoyAbstract:Abstract This present work reports on the Heat Losses associated with the upward flow of hot air, water, and CO2 in a production well. The Heat Losses considered here are the frictional Heat Loss, the gravitational Heat Loss, the Joule-Thomson effect, and the Conduction Heat Loss to the surrounding rock formation. These Heat Losses were characterized using the mass flow rate, the operation time as variable parameters while the surrounding formation was assumed to have constant properties with a linear geothermal gradient. The results show that, the frictional Heat Loss was small while the influences of the others depended on the flow conditions and the operation time. For water, the Joule-Thomson effect was a Heating effect and its magnitude was comparable to that due to the gravitational effect. The Conduction Heat Loss was dominant for all situations. For air as well as CO2, the Joule-Thomson effects were the cooling effects. For low mass flow rates, the Conduction Heat Loss was the dominant Heat Loss during the initial stages of the operation and the combined Heat Losses due to the gravitational and the Joule-Thomson effects became dominant during the later times. For high mass flow rates, throughout the operation life time, the gravitational and the Joule-Thomson effects were the dominant Heat Losses that control the temperature of air and CO2 in the production well.
Yanhao Dong - One of the best experts on this subject based on the ideXlab platform.
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thermal runaway in mold assisted flash sintering
Journal of the American Ceramic Society, 2016Co-Authors: Yanhao Dong, Wei I ChenAbstract:Analyzing the temperature evolution in pressureless mold-assisted flash sintering, we found the same onset condition as in standard flash sintering: When sample's DC or AC Joule Heating replaces environment's radiation Heating as the dominant power input term, thermal runaway ensues. Various serial and parallel components connected to the sample, including the mold, insulation, and punches, can affect Joule Heating and Conduction Heat Loss, thus play an important role in successful mold-assisted flash sintering.
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Thermal Runaway in Mold‐Assisted Flash Sintering
Journal of the American Ceramic Society, 2016Co-Authors: Yanhao Dong, I.‐wei ChenAbstract:Analyzing the temperature evolution in pressureless mold-assisted flash sintering, we found the same onset condition as in standard flash sintering: When sample's DC or AC Joule Heating replaces environment's radiation Heating as the dominant power input term, thermal runaway ensues. Various serial and parallel components connected to the sample, including the mold, insulation, and punches, can affect Joule Heating and Conduction Heat Loss, thus play an important role in successful mold-assisted flash sintering.
Jing Ding - One of the best experts on this subject based on the ideXlab platform.
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Heat Transfer Performances and Exergetic Optimization for Solar Heat Receiver
Evaporation Condensation and Heat transfer, 2011Co-Authors: Jian-feng Lu, Jing DingAbstract:Solar energy is one kind of important resource for clean and renewable energy, and is widely investigated in many fields. In order to increase the operating temperature and thermodynamic efficiency, concentrated solar radiation is widely used to Heat the working fluid in solar thermal power system (Trieb & Nitsch, 1998) and other industrial engineerings (Klein et al., 2007; Ali et al., 2008). Concentrated solar radiation (Kalogirou, 2004) can be collected by the parabolic trough collector, parabolic dish reflector, heliostat field, etc. The concentrated energy flux has been studied in kinds of solar energy system. Moustafa et al. (1995) measured the solar flux density distribution on a plane receiver due to a flat heliostat. Estrada et al. (2007) proposed a calorimeter to measure the concentrated solar power produced by a point focus solar concentrator. Solar thermal power system based on trough, dish or heliostat field is a very promising and challenging technology for its high operating temperature and thermodynamic efficiency. In solar thermal power plant (Odeh et al., 2003), the Heat transfer medium in solar Heat receiver is Heated by concentrated solar radiation to some high temperature, and then it can be used to operate kinds of Heat engine and generate electricity. As a result, the Heat receiver (Ortega et al., 2008) is the key problem for the photo-thermal transformation, and the Heat transfer performance of solar Heat receiver is the hotspot for solar energy research. The basic types of Heat receiver in concentrated solar thermal system mainly include Heat pipe receiver (Fujiwara et al., 1990), parabolic trough solar receiver (Gong et al., 2010), cavity receiver (Wu et al., 2010), and multistage solar receiver (Taragan, 1999), etc. The dynamical and thermal characteristics of solar Heat receiver have been investigated in much literature (Cui et al., 2008; Grena, 2010). In general, the Heat Losses from solar receiver mainly include three contributions: radiation Heat Loss, convective Heat Loss, and Conduction Heat Loss. The radiation Heat Loss (Melchior et al., 2008; Li et al., 2010) is mainly dependent upon the receiver structure, wall temperature, and emissivity/absorptivity of the receiver walls, while the convective Heat Loss (Clausing, 1981) is mainly determined by the receiver structure, wall temperature, and wind velocity. The Heat Conduction Loss (Zavoico, 2001) exists in cavity receiver through the insulation wall, and it can be ignored in many solar Heat receivers.
Araceli Lara - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Cover Glasses in Solar Cookers Box-Type Considering Conduction Heat Losses in Four Different Solar Cookers
Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Theory and Fundamentals in Heat Transfer; Nanoscale Thermal Transport; Heat Tran, 2016Co-Authors: Hilario Terres, Sandra Chavez, Raymundo Lopez, Arturo Lizardi, Araceli LaraAbstract:A evaluation of the Conduction Heat Loss over their cover for four different solar cookers box-type (1. Square solar cooker with inner reflectors placed in right angles, 2. Square solar cooker with inner reflector placed in different angles, 3. Rectangular solar cooker with inner reflectors placed in different angles and 4. Octagonal solar cooker with inner reflectors placed in right angles) is presented. In the Heating process in a solar cooker box-type, the Conduction Heat Loss in their cover is the most important in comparative with convection and radiation Losses. The cover in solar cookers is made with clear glasses, which allows the inlet solar radiation inside of it. When the Heating process happen, the temperature in the cover glasses is important and is important for this part. To evaluate the magnitude for the Heat Loss, controlled tests were planned, where a solar radiation simulator was used as energy source over the solar cookers considered. In the experiments, thermocouples to determine the gradient temperature for thickness among glasses were placed. In this activity, a Compact Field and LabView software were used. Also, in the experimental tests, thermographic imagines for some instants during the Heating process were taken. According results, the Conduction Heat Losses are bigger than 25 % of the inlet energy Flux in the cookers. The biggest values for temperature on the glasses correspond to the solar cooker 3, while minimum values are obtained for the solar cooker 1. The solar cooker 1 present the biggest Conduction Heat Losses and the cooker 4, has the minimum values for the Losses. Results of this work can be useful and important for design proposes which could impacts on save of money and cooking time.