A new correlation for heat transfer in particle-fluid beds

2021 ◽  
Vol 181 ◽  
pp. 121844
Author(s):  
Z. Qi ◽  
A.B. Yu
Keyword(s):  
Heat Transfer ◽  
New Correlation

Development of a New Correlation and Post Processing of Heat Transfer Coefficient and Pressure Drop of Functionalized COOH MWCNT Nanofluid by Artificial Neural Network

2018 ◽  
Vol 14 (2) ◽  
pp. 104-112 ◽  
Author(s):  
Mohammad Hemmat Esfe ◽  
Somchai Wongwises ◽  
Saeed Esfandeh ◽  
Ali Alirezaie
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Artificial Neural Network ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Regression Coefficient ◽  
New Correlation ◽  
The Neural Network

Background: Because of nanofluids applications in improvement of heat transfer rate in heating and cooling systems, many researchers have conducted various experiments to investigate nanofluid's characteristics more accurate. Thermal conductivity, electrical conductivity, and heat transfer are examples of these characteristics. Method: This paper presents a modeling and validation method of heat transfer coefficient and pressure drop of functionalized aqueous COOH MWCNT nanofluids by artificial neural network and proposing a new correlation. In the current experiment, the ANN input data has included the volume fraction and the Reynolds number and heat transfer coefficient and pressure drop considered as ANN outputs. Results: Comparing modeling results with proposed correlation proves that the empirical correlation is not able to accurately predict the experimental output results, and this is performed with a lot more accuracy by the neural network. The regression coefficient of neural network outputs was equal to 99.94% and 99.84%, respectively, for the data of relative heat transfer coefficient and relative pressure drop. The regression coefficient for the provided equation was also equal to 97.02% and 77.90%, respectively, for these two parameters, which indicates this equation operates much less precisely than the neural network. Conclusion: So, relative heat transfer coefficient and pressure drop of nanofluids can also be modeled and estimated by the neural network, in addition to the modeling of nanofluid’s thermal conductivity and viscosity executed by different scholars via neural networks.

A New Heat Transfer Correlation for Supercritical RP-3 Flowing in Vertical Tubes

2017 ◽  
Author(s):  
Longyun Wang ◽  
Zhi Tao ◽  
Jianqin Zhu ◽  
Haiwang Li ◽  
Zeyuan Cheng
Keyword(s):  
Heat Transfer ◽  
Influence Factors ◽  
Hydrocarbon Fuel ◽  
Operating Conditions ◽  
Major Influence ◽  
Absolute Deviation ◽  
New Correlation ◽  
Vertical Tubes ◽  
Correction Terms ◽  
Good Agreement

A new empirical correlation for upward flowing supercritical aviation kerosene RP-3 in the vertical tubes is proposed. In order to obtain the database, numerical simulation with a four-component surrogate model on RP-3 and LS low Reynolds turbulence model in vertical circular tube has been performed. Tubes of diameter 2mm to 10mm are studied and operating conditions cover pressure from 3MPa to 6MPa. Heat flux is 500KW/m2, mass flow rate is 700kg/(m2·s). The numerical results on wall temperature distribution under various conditions are compared with experimental data and a good agreement is achieved. The existing correlations are summarized and classified into three categories. Three representative correlations of each category are selected out to evaluate the applicability in heat transfer of supercritical RP-3. The result shows that correlations concluded from water and carbon-dioxide do not perform well in predicting heat transfer of hydrocarbon fuel. The mean absolute deviation of them is up to 20% and predict about 80% of the entire database within 30% error bands. So a new correlation which is applicable to different working conditions for supercritical RP-3 is put forward. Gnielinski type has been adapted as the basis of the new correlation for its higher accuracy. In consideration of major influence factors of supercritical heat transfer, correction terms of density and buoyancy effect are added in. The new correlation has a MAD of 9.26%, predicting 90.6% of the entire database within ±15% error bands. The comparisons validate the applicability of the new correlation.

scholarly journals Heat transfer to a moving wire immersed in a gas fluidized bed furnace

2021 ◽  
Author(s):  
Antonio Tannas
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Steel Wire ◽  
Transfer Rates ◽  
New Correlation ◽  
Bed Temperature ◽  
Molten Lead ◽  
The Difference ◽  
Considerable Work ◽  
Work Done

In order to replace hazardous molten lead baths in the heat treatment of carbon steel wire with environmentally friendly fluidized bed furnaces a better understanding is needed of their heat transfer rates. There has been considerable work done in examining heat transfer rates to large cylinders immersed in fluidized beds, and some on wire sized ones as well, but all previous studies have been conducted on static cylinders. In order to gain a deeper understanding of heat transfer rates to a moving wire immersed in a fluidized bed furnace an apparatus has been constructed to move a wire through a fluidized bed. The heat transfer rates were calculated using the difference in inlet and outlet temperatures, wire speed and the bed temperature. As predicted, correlations for static wire were found to under-predict heat transfer rates at higher wire speeds, so a new correlation was developed by modifying an existing one.

Improved General Correlation for Heat Transfer During Gas–Liquid Flow in Horizontal Tubes

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Mirza M. Shah
Keyword(s):  
Heat Transfer ◽  
Liquid Mixtures ◽  
Mean Absolute Deviation ◽  
Absolute Deviation ◽  
Earth Gravity ◽  
Horizontal Tubes ◽  
New Correlation ◽  
Wide Range ◽  
Data Points ◽  
Gas Liquid Flow

Heat transfer to two-component gas–liquid mixtures is needed in many industries but there is lack of a well-verified predictive method. A correlation is presented for heat transfer during flow of gas–liquid nonboiling mixtures in horizontal tubes. It has been verified with a wide range of data that includes tube diameters of 4.3–57 mm, pressures from 1 to 4.1 bar, temperatures from 12 to 62 °C, gravity <0.1% to 100% earth gravity, liquid Reynolds number from 9 to 1.2 × 105, and ratio of gas and liquid velocities from 0.24 to 9298. The 946 data points from 18 sources are predicted with mean absolute deviation (MAD) of 19.2%. The same data were compared to five other correlations; they had much larger deviations. Therefore, the new correlation is likely to be helpful in more accurate designs.

Heat Flux Reduction From Film Cooling and Correlation of Heat Transfer Coefficients From Thermographic Measurements at Engine Like Conditions

2002 ◽  
Author(s):  
S. Baldauf ◽  
M. Scheurlen ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
The Heat Transfer Coefficient

Heat transfer coefficients and the resulting heat flux reduction due to film cooling on a flat plate downstream a row of cylindrical holes are investigated. Highly resolved two dimensional heat transfer coefficient distributions were measured by means of infrared thermography and carefully corrected for local internal testplate conduction and radiation effects [1]. These locally acquired data are processed to lateral average heat transfer coefficients for a quantitative assessment. A wide range variation of the flow parameters blowing rate and density ratio as well as the geometrical parameters streamwise ejection angle and hole spacing is examined. The effects of these dominating parameters on the heat transfer augmentation from film cooling are discussed and interpreted with the help of highly resolved surface results of effectiveness and heat transfer coefficients presented earlier [2]. A new method of evaluating the heat flux reduction from film cooling is presented. From a combination of the lateral average of both the adiabatic effectiveness and the heat transfer coefficient, the lateral average heat flux reduction is processed according to the new method. The discussion of the total effect of film cooling by means of the heat flux reduction reveals important characteristics and constraints of discrete hole ejection. The complete heat transfer data of all measurements are used as basis for a new correlation of lateral average heat transfer coefficients. This correlation combines the effects of all the dominating parameters. It yields a prediction of the heat transfer coefficient from the ejection position to far downstream, including effects of extreme blowing angles and hole spacing. The new correlation has a modular structure to allow for future inclusion of additional parameters. Together with the correlation of the adiabatic effectiveness it provides an immediate determination of the streamwise heat flux reduction distribution of cylindrical hole film cooling configurations.

A New Correlation for Heat Transfer Coefficient Prediction of Supercritical Pressure Water Flowing in Vertical Upward Tubes

2016 ◽  
Author(s):  
Xiangfei Kong ◽  
Huixiong Li ◽  
Changjiang Liao ◽  
Xianliang Lei ◽  
Qian Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Supercritical Pressure ◽  
Good Prediction ◽  
Empirical Correlations ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Pressure Water ◽  
Supercritical Pressure Water

Supercritical pressure water has been widely used in many industrial fields, such as fossil-fired power plants and nuclear reactors because mainly of its high thermal efficiencies. Although many empirical correlations for heat transfer coefficients of supercritical pressure water have been proposed by different authors based on different experimental data base, there exist remarkable discrepancies between the predicted heat transfer coefficients of different correlations under even the same condition. Heat transfer correlations with good prediction performance are of considerable significance for developing supercritical (ultra-supercritical) pressure boilers and SCWRs. In this paper, the experimental data (about 7389 experimental data points) and 30 existing empirical correlations for heat transfer of supercritical pressure water (SCW) flowing in vertical upward tubes are collected from the open literatures. Evaluations of the prediction performance of the existing correlations are conducted based on the collected experimental data, and a detailed multi-collinearity analysis has been made on different correction factors involved in the existing correlations, and then based on the collected experimental data, a new heat transfer correlation is developed for the supercritical pressure water flowing in vertical upward tubes under normal and enhanced heat transfer mode. Compared with the existing correlations, the new correlation exhibits good prediction accuracy, with a mean absolute deviation (MAD) of 9.63%.

scholarly journals Experimental Investigation of The Influence of Mechanical Forced Vibrations and Heat Flux on Coefficient of Heat Transfer

2018 ◽  
Vol 6 (3) ◽  
pp. 124-129
Author(s):  
Adil Bash ◽  
Aadel Alkumait ◽  
Hamza Yaseen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Forced Vibration ◽  
Vibration Amplitude ◽  
Internal Flow ◽  
Reynolds Numbers ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
New Correlation

The aim of this paper to verify the influence of vertical forced vibration on the coefficient of heat transfer of the laminar internal flow in a spiral fluted tube. With adopted the water as a working fluid, and flowing Reynolds numbers at the entrance between 228 and 1923, the tube heated under constant heat flux levels ranging from 618-3775 W/m2. The frequencies of vibration ranging from 13 to 30 Hz, and the amplitudes of vibration from 0.001 to 0.002 mm. The results appeared that the coefficient of heat transfer significantly affected by mechanical forced vibration in a flowing of the heated tube. When the vibration amplitude increases, the Nusselt number Significantly increases, with the maximum increases of 8.4% at the amplitude of vibration 0.0022 mm and the frequency 13 Hz. Generally, the coefficient of heat transfer increases with increasing Reynolds number and heat flux. At last, by using the parameters of vibration amplitude, frequency, heat flux and Reynolds number, a new correlation has been derived depends on experimental data.

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