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.

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.

A Correlation for Heat Transfer to Gas–Solid Suspensions Flowing in Pipes

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Mirza M. Shah
Keyword(s):  
Heat Transfer ◽  
Chemical Processing ◽  
Absolute Deviation ◽  
Solids Loading ◽  
New Correlation ◽  
Accurate Design ◽  
Wide Range ◽  
Data Points ◽  
Loading Ratio ◽  
Vertical Up

Abstract Heat transfer to flowing gas–solid mixtures in pipes is required in many applications including chemical processing, pneumatic transport, and nuclear reactors but no well-verified method for predicting heat transfer is available. A new correlation is presented, which has been validated with a wide range of data that includes a variety of particles (minerals, metals) in several gases. Particle diameters range from 13 to 1130 µm, pipe diameters 5.1 to 77 mm, and the solids loading ratio of 0–520. Flow orientations include horizontal, vertical up, and vertical down. The new correlation has a mean absolute deviation (MAD) of 18.9% with 630 data points from 20 studies. The same data were also compared with six published correlations. Their MAD ranged from 35% to 57%. Hence, the new correlation is likely to help in more accurate design.

General Correlation for Heat Transfer to Gas–Liquid Flow in Vertical Channels

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Mirza M. Shah
Keyword(s):  
Heat Transfer ◽  
Liquid Mixtures ◽  
Absolute Deviation ◽  
General Correlation ◽  
New Correlation ◽  
Rectangular Channels ◽  
Wide Range ◽  
Data Points ◽  
Gas Liquid Flow ◽  
Dry Out

Abstract A general correlation is presented for heat transfer during flow of gas–liquid mixtures flowing in vertical channels prior to dry out. It has been verified with a wide range of data that include upward and downward flow in heated and cooled tubes, annuli, and rectangular channels. The data are from 19 studies and include 14 gas–liquid mixtures with a wide range of properties. The parameters include pressure 1–6.9 bar, temperature 16–115 °C, liquid Reynolds number from 2 to 127,231, superficial gas and liquid velocities up to 87 and 13 m/s, respectively, and ratio of superficial gas and liquid velocities 0.03–1630. The 1022 data points are predicted by the new correlation with mean absolute deviation (MAD) of 18.1%. Several other correlations were also compared to the same data and had MAD of 28.6–45.5%.

Development of a Heat Transfer Correlation for Supercritical CO2 Based on Multiple Data Sets

2012 ◽  
Author(s):  
Tiberiu Preda ◽  
Eugene Saltanov ◽  
Igor Pioro ◽  
Kamiel S. Gabriel
Keyword(s):  
Heat Transfer ◽  
Critical Point ◽  
Supercritical Water ◽  
Wall Temperature ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Operating Conditions ◽  
Thermodynamic Efficiency ◽  
New Correlation ◽  
Multiple Data Sets

Currently, increase in thermodynamic efficiency of water-cooled Nuclear Power Plants (NPPs) can only be achieved by raising the coolant’s operating conditions above the supercritical point. The critical point of water is 22.06 MPa and 373.95°C, making supercritical water research very power-intensive and expensive. CO2 behaves in a similar manner once in the supercritical state, but at significantly lower pressure and temperature, since critical point of CO2 is 7.37 MPa and 30.98°C. The applications of supercritical CO2 research range from using it as a modelling fluid, to supercritical turbine applications in Liquid Metal Fast Breeder Reactors (LMFBRs), and use in a supercritical Brayton cycle. Therefore, it is of prime importance to model its behaviour as accurately as possible. For this purpose, experimental data of Koppel (1960), He (2005), Kim (2005) and Bae (2007) for CO2 were analyzed, and a new correlation was developed. The dataset consists of 1409 wall temperature points with pressures ranging from 7.58 to 9.58 MPa, mass fluxes from 419 to 1200 kg/m2s, and heat fluxes from 20 to 130 kW/m2. All runs take place in bare tubes of inner diameters from 0.948 to 9.00 mm in both vertical and horizontal configurations. The proposed correlation takes a wall-temperature approach to predicting the Nusselt number. This paper compares the new correlation with other work which has been done at the University of Ontario Institute of Technology by Mokry et al. (2009), as well as with correlations by Swenson et al. (1965) and Dittus-Boelter (1930). It was found that the new correlation has an overall RMS error of 13% for Heat Transfer Coefficient (HTC) values and 5% for calculated wall temperature values. The correlation can be used as a conservative approach to predict wall temperature values in Supercritical Water Reactor (SCWR) preliminary calculations, to predict heat transfer in secondary-loop turbine/ heat exchanger applications, as with the LMFBR, and to help validate scaling parameters used for water and other coolants.

scholarly journals Performance Evaluation of Wire Cloth Micro Heat Exchangers

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 715 ◽  
Author(s):  
Hannes Fugmann ◽  
Sebastian Martens ◽  
Richard Balzer ◽  
Martin Brenner ◽  
Lena Schnabel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluid Dynamic ◽  
Relative Difference ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Hydraulic Simulation ◽  
Pressure Drops ◽  
Wire Cloth ◽  
Good Agreement

The purpose of this study is to validate a thermal-hydraulic simulation model for a new type of heat exchanger for mass, volume, and coolant/refrigerant charge reduction. The new heat exchanger consists of tubes with diameters in the range of 1 m m and wires in the range of 100 m , woven together to form a 200 × 200 × 80 m m 3 wire cloth heat exchanger. Performance of the heat exchanger has been experimentally evaluated using water as inner and air as outer heat transfer medium. A computational thermal and fluid dynamic model has been implemented in OpenFOAM®. The model allows variation of geometry and operating conditions. The validation of the model is based on one single geometry with an opaque fabric and air-side velocities between 1 and 7 m / s . The simulated and measured pressure drops are found to be in good agreement with a relative difference of less than 16%. For the investigated cases, the effective heat transfer coefficients are in very good agreement (less than 5%) when adapting the contact resistance between tubes and wires. The numerical model describes the fluid flow and heat transfer of the tested heat exchanger with adequate precision and can be used for future wire cloth heat exchanger dimensioning for a variety of applications.

A New Model for Predicting Flow Boiling Heat Transfer Coefficients in Horizontal Microfin Tubes

2016 ◽  
Author(s):  
Reem Merchant ◽  
Sunil Mehendale
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Experimental Database ◽  
New Model ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Wide Range ◽  
Microfin Tubes

The objective of the current work is to present a new correlation for predicting heat transfer coefficients (HTCs) for flow boiling in horizontal microfin tubes. Correlations to predict HTCs have been proposed by numerous authors such as Yu et al., Thome et al., Cavallini et al., Yun et al., Chamra and Mago, Wu et al., and other researchers. The correlations proposed are semi-empirical due to the difficulties associated with modeling the physics of flow boiling in microfin tubes. The above correlations are based on smooth tube flow boiling correlations which are modified to capture the effect of the inner grooves in the microfin tubes on the boiling process. In a previous work, it has been demonstrated that no single correlation can reasonably predict the flow boiling HTCs over a wide range of operating conditions and tube geometric parameters (Merchant and Mehendale). A new model has been proposed and validated using an experimental database of 1576 points from published literature. For the full dataset, the new correlation has X30% of 67.3%, compared to Cavallini et al. and Wu et al. with X30% of 44.2% and 40.6% respectively. The performance of the new model for tube diameters less than and greater than 5 mm has also been discussed for halogenated refrigerants and CO2.

Heat Transfer to Supercritical Water in Gaseous State or Affected by Mixed Convection in Vertical Tubes

2006 ◽  
Author(s):  
E. N. Pis’menny ◽  
V. G. Razumovskiy ◽  
E. M. Maevskiy ◽  
A. E. Koloskov ◽  
I. L. Pioro
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Supercritical Water ◽  
Operating Conditions ◽  
Maximum Effect ◽  
Upward Flow ◽  
Downward Flow ◽  
Gaseous State ◽  
Transfer Data ◽  
Vertical Tubes

The results on heat transfer to supercritical water heated above the pseudocritical temperature or affected by mixed convection flowing upward and downward in vertical tubes of 6.28-mm and 9.50-mm inside diameter are presented. Supercritical water heat-transfer data were obtained at a pressure of 23.5 MPa, mass flux within the range from 250 to 2200 kg/(m2s), inlet temperature from 100 to 415°C and heat flux up to 3.2 MW/m2. Temperature regimes of the tubes cooled with supercritical water in a gaseous state (i.e., supercritical water at temperatures beyond the pseudocritical temperature) were stable and easily reproducible within a wide range of mass and heat fluxes. An analysis of the heat-transfer data for upward and downward flows enabled to determine a range of Gr/Re2 values corresponding to the maximum effect of free convection on the heat transfer. It was shown that: 1) the heat transfer coefficient at the downward flow of water can be higher by about 50% compared to that of the upward flow; and 2) the deteriorated heat-transfer regime is affected with the flow direction, i.e., at the same operating conditions, the deteriorated heat transfer may be delayed at the downward flow compared to that at the upward flow. These heat-transfer data are applicable as the reference dataset for future comparison with bundle data.

scholarly journals Improvement of a Nusselt-Based Simulation Model for Heat Transfer in Rotary Heat Exchangers

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 10
Author(s):  
Eloy Melian ◽  
Harald Klein ◽  
Nikolaus Thißen
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Absolute Deviation ◽  
Heat Transfer Coefficients ◽  
Proposed Model ◽  
Maximum Absolute Deviation ◽  
Empty Tube ◽  
Region Effect

In the last 50 years, the technology of rotary heat exchangers has not changed considerably. A reliable simulation can help improve the design of this technology. In this work, a simulation for rotary heat exchangers was developed and validated with multiple experimental data. This simulation takes an innovative approach based on locally calculated heat transfer coefficients and considers the entry region effect. This approach proved to be accurate since the average difference between the experimental results and the proposed model with a constant heat boundary condition is 0.1% and the maximum absolute deviation 1%. Experimental, as well as simulation results, indicate that lower empty tube gas velocity (1 m/s) and higher rotational speed (12 rpm) improve thermal efficiency compared to commonly used operating conditions. Additionally, a new model for predicting the local internal Nusselt number for sine ducts in the rotor channels is proposed, which considers the entry region effect.

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