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Aqueous suspension of phase change material (PCM) microcapsules is a new kind of function material that has a bright application prospect in many fields such as the heat dissipation of electronic and electrical equipments, and the utilization of new clean energies. It shows an improved heat transfer performance since the PCM microcapsules can absorb lots of latent heat during solid-liquid phase transition in comparison with the base fluid. In this study, a new method of particle size control was introduced for optimizing the overall performance of microcapsule suspension in heat transfer and energy consumption. The PCM microcapsules composed of octadecane and melamine formaldehyde resin was synthesized by in-situ polymerization, and showed a uniform size distribution. These microcapsules were dispersed in the deionized water by adding a surfactant, and the resultant microcapsule suspension had a good stability. Investigation on the heat transfer of the aqueous suspension of PCM microcapsules in a circular tube was conducted, focusing on the effect of microcapsule size. It was found that as the size of microcapsules decreased from 20.0 μm to 2.6 μm, a 20.3% increase in Nussell number of microcapsule suspension and a 33.0% reduction in temperature rise of circular tube could be achieved. This finding confirmed that reducing the size of PCM microcapsules is a feasible and efficient way to improve the comprehensive heat transfer performance of microcapsule suspensions. [ABSTRACT FROM AUTHOR]

The open lattice gas-cooled reactor presents a lightweight option for high-power space reactor power systems. The background of this study is a space reactor featuring a rod bundle core structure, with helium as the coolant. The typical Reynolds number at the core inlet is around 2 000. Reynolds average numerical simulation (RANS) is a commonly used computational fluid dynamics (CFD) method. The essence of the RANS method lies in turbulence models. Each turbulence model has its particular useful scenarios and needs to be chosen based on the specific working conditions. The helium-cooled rod bundle reactor is distinguished by its tight lattice structure and low flow Reynolds number. These features influence the flow and heat transfer characteristics in the reactor core. Consequently, when performing thermal-hydraulic analysis using CFD, it is essential to evaluate the applicability of turbulence models. Experiments of flow and heat transfer in 37-rod bundle structure were conducted, using electrically heated rods of the same size as the fuel rods and nitrogen as the experimental coolant. Based on these experiments, the convective heat transfer within the test section was numerically simulated using ANSYS Fluent, selecting four turbulence models: Realizable k-ε with enhanced wall treatment, SST k-ω, transition SST, and Reynolds stress model with enhanced wall treatment. The operating conditions for numerical calculations had inlet Reynolds numbers ranging from 688 to 2 986, all with uniform power distribution. By comparing the experimental measurements and calculated values of the heating rod cladding temperatures, the applicability of the four turbulence models was evaluated. Simultaneously, the differences in local flow field simulations by these models were observed, and an analysis was performed to understand the reasons behind the discrepancies in cladding temperature calculations among the different models. The results show that all four turbulence models generally underpredict the rod cladding temperatures. Among these models, the transition SST model exhibits the closest agreement with experimental data, with an overall average deviation of −2.0%. It effectively captures the crossflow characteristics between the rod bundle and is suitable for thermal-hydraulic simulations of open lattice gas-cooled reactor with Reynolds number around 2 000. This study confirms that the crossflow is an important factor affecting the flow and heat transfer in open lattice structures. Subsequent researches are needed to further investigate the factors and patterns influencing crossflow, in order to minimize its adverse effects on the heat transfer in the reactor core. The findings of this paper provide a reference for the numerical simulation and design of rod bundle gas-cooled reactors.

The topologies of 3D lattice structures were reviewed and their overall heat transfer and heat dissipation performances compared, under the fixed mass flow rate, pressure drop and pumping power conditions, respectively. In total 12 lattice structures, with 6 different materials and in 2 orientations, were compared. The conjugate heat transfer in the lattice structures was solved with validated numerical models. Numerical results indicate that, the lattice topology, the lattice material and the operating conditions significantly affect the heat transfer and cooling performances. The optimal lattice differs under different comparison conditions. Under the fixed mass flow rate condition, the shifted X-lattice in orientation A and the octet lattice in orientation A exhibit the best heat transfer performance; the shifted X-lattice in orientation A also has the best cooling performance. Under the fixed pressure drop condition, the shifted X-lattices in both orientations A and B exhibit the best heat transfer performance; while the cubic lattice in orientation B and the shifted X-lattice in orientation B show the best cooling performance. Under the fixed pumping power condition, the shifted X-lattice in orientation A and the rectangular pyramid lattice in orientation B exhibit the best heat transfer performance; the shifted X-lattice in orientation B and the rectangular pyramid lattice in orientation B show the best cooling performance. The heat transfer and cooling performance database under a given lattice porosity and A characteristic length was presented as the benchmark for performance comparison of newly developed lattice structures. In addition, the data- base can benefit various engineering designs in selecting the appropriate lattice structures. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Xi'an Jiaotong University is the property of Editorial Office of Journal of Xi'an Jiaotong University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to accurately study the temperature field distribution during the long-term sliding friction process of the limited slip clutch, Fluent software is used to solve the flow field velocity distribution of the friction pair under different working conditions to obtain the average convective heat transfer coefficient and calculate the cooling power of the lubricating oil. A dynamic heat flow distribution temperature prediction model is established with the constraint of continuous friction contact surface temperature by the heat balance method, and a long-time sliding friction test is designed to verify the analysis results. The results show that under the condition of the constant heat flow input, there is a temperature difference between the steel disc and the friction plate, which increases with time, the temperature prediction results are higher than the experimental values, and the maximum deviation is 22.2 K. The predicted deviation of the dynamic heat flow distribution temperature model is within 8.1 K. The input heat power at each position on the surface of the steel disc sheet decreases with time and tends to a fixed value. The equilibrium temperature is distributed in a parabola along the radial direction and reaches a peak at the place between the mid and the outer diameter.

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current status of research on convective heat transfer and thermal economy of hybrid Nano fluids in heat exchangers is reviewed. The influencing factors and variation mechanisms of convective heat transfer performance parameters" total heat transfer coefficient, convective heat transfer coefficient, Nu number) are introduced. The thermal economy" thermal efficiency, entropy production, fire use loos and second law efficiency) of mixed Nano fluids in heat exchanger applications is analyzed. [ABSTRACT FROM AUTHOR]

Electric heat tracing is often used for cold protection in polar ocean engineering equipment. Heat balance is the key problem of convective heat transfer. In this paper, the circular tube structure is taken as the research object. Numerical simulations using Fluent and model experiment are conducted to analyze the change of the convective heat transfer coefficient of the circular tube component under the polar environment with a wind speed range of 0—40 m/s and a temperature range of -40—0 ℃. Based on the numerical simulation data, the prediction model of the convective heat transfer coefficient of the electric heating tube is obtained. The results show that the convective heat transfer coefficient increases with the increase of wind speed and the decrease of temperature. When the temperature is below -30 ℃, or when the wind speed is greater than 25 m/s and the temperature is lower than -20 ℃, the influence of temperature on the convective heat transfer coefficient increases. The rationality of the model is verified by experimental test.

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

: The double-skin roof has been applied in the design of modern granary. The inclined upper-plate has the better thermal performance to effectively improve the situation of "hot roof" of granary, compared with the ordinary parallel double-plate. In this study, an experimental and numerical investigation was carried out to determine the thermal performance of double-skin roof with the inclined upper-plate, and the effects of physical parameters on the convective heat transfer. According to the actual size of grain warehouse in application, an experiment setup was established using the similarity theory with a scale of 1:28 to the real one. The double-skin roof consisted of two plates: the lower one was used as the original surface of the warehouse, and another was suspended above. The two flat plates were arranged parallel or inclined for comparison. Changeable parameters included the flow rate through the air gap between the double plates, the thickness of the air gap, and the reducing ratio. Other parameters were the same, such as the air temperature. A systematic investigation was made to clarify the influence of the above factors on the performance of the double-skin roof. The results showed that both the flow rate and the thickness of the air gap dominate the thermal performance of the roof. Under the optimal working condition in the parallel mode (with an air gap of 0.07 m and a flow rate of 60 m³ /h), the temperature increment at the surface of the grain bulk was 1.75 ℃, which was lower than the mode without suspended upper-plate. Moreover, the inclined design of the upper-plate increased the air velocity along the flowing direction. As such, the convection was strengthened at the outlet, and thus improved the average thermal performance of the opened roof. The inclined mode was used to control the temperature at the grain bulk surface within 24 ℃, and only dropped by 1 ℃, compared with the parallel mode under the same working conditions. In addition, a geometric model of the experiment setup was created, where the grid was divided using the software ANSYS ICEM. The convection term in the conservation equation was discretized with the QUICK scheme, and the solution for the flow field was obtained by the SIMPLE algorithm. The experimental data was used as the input profile for the model. The numerical results were compared with the experiment to verify the accuracy of the model. The average and the maximum error were within 3% and 8.9%, respectively. Simulation results demonstrated the effects of the reducing ratio on the roof thermal performance with the analysis of the Ra number and the Nu number. In the inclined mode, the smaller reducing ration was beneficial to the air convection. The outlet velocity of the roof was higher by 30.6% with a reducing ratio of about 0.500, resulting in a larger local Nu number and better thermal performance. More importantly, the Nu number was increasing, when the dimensionless length was in a range of 0.34-0.37. Furthermore, the Nu number increased with the Ra number given a dimensionless length of below 0.15 near the inlet of the double-skin roof. Therefore, the ventilated double-skin roof with an inclined upper plate was recommended for the roof reconstruction design, because of the advanced air convection. : The double-skin roof has been applied in the design of modern granary. The inclined upper-plate has the better thermal performance to effectively improve the situation of "hot roof" of granary, compared with the ordinary parallel double-plate. In this study, an experimental and numerical investigation was carried out to determine the thermal performance of double-skin roof with the inclined upper-plate, and the effects of physical parameters on the convective heat transfer. According to the actual size of grain warehouse in application, an experiment setup was established using the similarity theory with a scale of 1:28 to the real one. The double-skin roof consisted of two plates: the lower one was used as the original surface of the warehouse, and another was suspended above. The two flat plates were arranged parallel or inclined for comparison. Changeable parameters included the flow rate through the air gap between the double plates, the thickness of the air gap, and the reducing ratio. Other parameters were the same, such as the air temperature. A systematic investigation was made to clarify the influence of the above factors on the performance of the double-skin roof. The results showed that both the flow rate and the thickness of the air gap dominate the thermal performance of the roof. Under the optimal working condition in the parallel mode (with an air gap of 0.07 m and a flow rate of 60 m³ /h), the temperature increment at the surface of the grain bulk was 1.75 ℃, which was lower than the mode without suspended upper-plate. Moreover, the inclined design of the upper-plate increased the air velocity along the flowing direction. As such, the convection was strengthened at the outlet, and thus improved the average thermal performance of the opened roof. The inclined mode was used to control the temperature at the grain bulk surface within 24 ℃, and only dropped by 1 ℃, compared with the parallel mode under the same working conditions. In addition, a geometric model of the experiment setup was created, where the grid was divided using the software ANSYS ICEM. The convection term in the conservation equation was discretized with the QUICK scheme, and the solution for the flow field was obtained by the SIMPLE algorithm. The experimental data was used as the input profile for the model. The numerical results were compared with the experiment to verify the accuracy of the model. The average and the maximum error were within 3% and 8.9%, respectively. Simulation results demonstrated the effects of the reducing ratio on the roof thermal performance with the analysis of the Ra number and the Nu number. In the inclined mode, the smaller reducing ration was beneficial to the air convection. The outlet velocity of the roof was higher by 30.6% with a reducing ratio of about 0.500, resulting in a larger local Nu number and better thermal performance. More importantly, the Nu number was increasing, when the dimensionless length was in a range of 0.34-0.37. Furthermore, the Nu number increased with the Ra number given a dimensionless length of below 0.15 near the inlet of the double-skin roof. Therefore, the ventilated double-skin roof with an inclined upper plate was recommended for the roof reconstruction design, because of the advanced air convection. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Experimental investigations are performed on the single‑row jet impingement heat transfer onto a semi‑cylindrical concave surface. Two kinds of nozzle shapes are taken into consideration. They are circular nozzle and chevron nozzle. The semi‑cylindrical concave surface has a diameter ratio (D/d) of 10. The jet‑to‑jet pitch is 5d. The experiments are conducted under three Reynolds numbers (Re=5 000, 10 000, and 20 000) and four dimensionless nozzle‑to‑surface distances (H/d=2, 4, 6, and 8). The results show that both nozzles achieve their respective maximum stagnation Nusselt numbers at H/d=4. However, the longitudinally‑averaged Nusselt number in the vicinity of concave leading is monotonously reduced with the increase of nozzle‑to‑surface distance in general. The chevron nozzle is confirmed to produce higher convective heat transfer than that of circular nozzle. In comparison with the circular nozzle jet impingement, the maximum increase of longitudinally‑averaged Nusselt number at the concave leading is about 16% and the maximum increase of the locally area‑averaged Nusselt number in the vicinity of concave leading (within ±2d) is about 18%, produced by the chevron‑nozzle jet impingement. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BackgroundThe surface bubbles of the plate-type fuel assembly can cause particle blockage accident in rectangular channel.PurposeThis study aims to investigate the convective heat transfer in a partially blockage rectangular channel by experiments.MethodsIn the range of Reynolds number 470~3 300, the convective heat transfer experiments were carried out under the conditions of case 1 with no bubble, case 2 with one bubble, case 3 with transverse three bubbles and case 4 with longitudinal three bubbles respectively. The average Nusselt number of the calculated results by the Sieder-Tate formula was compared with the experimental results. On the one hand, there was little calculation error between the calculated results and the experimental results in the cases with no bubble. On the other hand, there were large errors in the cases with local blockage of bubbling. Hence the Sieder-Tate formula was modified to re-calculate the average Nusselt number in above four cases.ResultsThe maximum error of prediction on convective heat transfer of the modified formula in case 2 is reduced from 35.4% to 19.8%. The maximum error of prediction on convective heat transfer of the modified formula in case 3 is reduced from 38.5% to 21.3%. The maximum error of prediction on convective heat transfer of the modified formula in case 4 is reduced from 47.8% to 8.7%.ConclusionsThe modified formulas can more accurately calculate the convective heat transfer in rectangular channel with partial blockage.

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An experimental platform tor the convective heat transfer of low temperature sea water sweeping circular tubes is designed and constructed, and the effects of the factors such as the tube diameter, temperature difference, Re, etc., on the flow and heat transfer characteristics are studied. The application results show that the experimental platform has stable performance, convenient operation, high accuracy and good expansibility, which is conducive to training students' practical ability and innovative awareness. This experimental platform realizes the close combination of scientific research experiment projects with teaching experiment projects, and has strong practical value. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reduce the turbine blade temperature to ensure the safety, the experimental method is used to investigate the flow and heat transfer characteristic of ribbed channel with high blockage ratio, and the influence of several main factors on heat transfer characteristics is investigated for two kinds of ribbed channel with symmetric and staggered ribs. The experimental results show that:(1) The heat transfer coefficients are increased with the increase of Reynolds number, though at the cost of higher pressure losses; (2) when the rib spacing to height ratio is 10, it keeps the highest heat transfer coefficient in three kinds of rib spacing to height ratio 5, 10 and 15; (3) the heat transfer coefficient of symmetric arrangement ribs is higher than that of the staggered arrangement ribs, but the pressure losses of symmetric arrangement ribs is larger than that of the staggered arrangement ribs; (4) compared with one-side ribbed channel, the heat transfer coefficient of two-side ribbed channel is distinctly higher. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A transient model was developed to describe the heat transfer and ignition processes of coal clouds with typical sizes in a coal jet，to analyze their heating process and ignition time. The results show that the heating process greatly depends on the size of coal clouds，and the fraction of convective heat transfer decreases with the equivalent diameter of particle cloud，Dc. When Tf=2 000 K，Ts=1 400 K，for coal cloud of Dc=3 mm，the amount of convective heat transfer counts for 86% of the total heat exchanged. While Dc=10 mm，radiative heat transfer is the dominant and its amount counts for 60%.The amounts of convective and radiative heat transfer are nearly equal when Dc≈8 mm.The increase of flame temperature Tf reduces both the fraction of convective heat transfer and ignition time，and the corresponding critical Dc (D*c) at which Qconv，sc=Qrad，fp. The effect is more obvious for a larger Dc. With the increase of flue gas temperature Ts，the fraction of the convective heat transfer and D*c increase.The effect of Ts is significant only for particle clouds with a small Dc. The increase of Ccoal firstly promotes the ignition of coal clouds，leading to a minimum ignition time near Ccoal=0.6-0.8 kg/m3，while impedes the ignition when Ccoal further increases due to the increase of heat capacity. [ABSTRACT FROM AUTHOR]

Based on the fundamentals of heat transfer theory and thermal dynamics, the methods combining theoretical analysis, numerical calculation and experimental study were used to analyze the combined rock including crack and fluid. Considered heat transfer and heat convection in combined rock, calculation model of the equivalence heat conduction coefficients was deduced in fluid-thermal coupling. Stochastic simulation was used to create pore structure of rock by FEM. Unified empirical equation of equivalence heat conduction coefficients was built when air or water filling in pore. The change of the convective heat transfer coefficient with flow velocity and temperature difference was test. The effect of crack and fluid to heat thermal conductivity was analyzed. The results prove that in low-flow and small temperature difference, the convective heat transfer resistance of rock is smaller, and the effect of crack width and fluid thermal conductivity is obvious to thermal conductivity; in high-flow and small temperature difference, the convective heat transfer resistance gradually exceeded heat resistance of crack fluid, and thermal conductivity of combined rock significantly increase. [ABSTRACT FROM AUTHOR]

According to the characteristics of ventilation and heat transfer at heading face in hot mine, the correlation of heat transfer coefficient for jet flow in heading face was formulated using dimensional analysis method. The results show that the heat transfer dimensionless number Nu of jet flow in heading face has relationship with dimensionless number Re, air duct diameter d and the distance H between air duct outlet and heading face. The heat transfer conditions under 216 combinations were simulated with ANSYS software. The regression analysis of numerical simulation results shows that when D/d is 5.6, the relationship between Nu and Re, H/d could be expressed by Lorentzian model. When D/d is 4. 20 and 3. 36, the relationship between Nu and Re, H/d could be expressed by paraboloid models. The correlation coefficients R² are O. 882 2,0. 699 0 and 0. 875 4 respectively. [ABSTRACT FROM AUTHOR]

Investigation is carried out to illustrate some of the flow and heat transfer characteristics that occur when a single-air jet or mist/air jet impinges on a flat plate with a rotating disk mounted above the surface, the representative of the workpiece in a grinding process. The first objective aims to assess the detailed flow and heat transfer features in the vicinity of a rotating grinding wheel with jet impingement directed at grinding zone by numerical investigation. The second objective aims to assess the quantitative evaluation for heat transfer enhancement on a grinding workpiece surface subjected to the mist/air jet impingement by experimental investigation. The results show that the coupled action of swirl air entrainment and jet impingement is benefit for convective heat transfer enhancement near grinding region when the jet impinging direction is consistent with the rotating direction of rotating disk, especially at higher rotating speed. Furthermore, the increasing of water droplet in mist cooling can enhance the cooling effect significantly. [ABSTRACT FROM AUTHOR]