Heat Transfer Deterioration Onset of Hydrocarbon Fuel at Supercritical Pressure

2017 ◽  
Author(s):  
Zeyuan Cheng ◽  
Zhi Tao ◽  
Jianqin Zhu ◽  
Haiwang Li ◽  
Longyun Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Safety Margin ◽  
Hydrocarbon Fuel ◽  
Supercritical Pressure ◽  
Tube Diameter ◽  
Inlet Temperature ◽  
Operating Pressure ◽  
Heat Transfer Deterioration

The present study pays attention to the pressure effect and geometric effect on heat transfer deterioration onset to supercritical hydrocarbon fuel. Numerical simulation about heat transfer deterioration of hydrocarbon fuel flowing upward in vertical round tubes with various diameter at supercritical pressure was performed. In the simulation, a four-species surrogate model of RP-3 based on the generalized corresponding states law was used and LS low-Reynolds number eddy viscosity turbulence model was selected. For the boundary conditions, inlet temperature was 623K, pressure ranged from 3 to 4MPa, tube diameter varied from 3 to 9mm, and wall heat flux to mass flux ratio changed from 0.07 to 3.18kJ/kg. Comparative analyses between the predicted results and the experimental data revealed the accuracy of thermophysical property model and numerical method. The results indicated that the operating pressure and tube diameter have significant effect to the heat transfer deterioration onset of supercritical hydrocarbon fuel: heat transfer deterioration aggravates and heat transfer deterioration onset moves upstream when the diameter increases. With the increase of operating pressure, heat transfer deterioration becomes weak and the heat transfer deterioration onset moves downstream. Based on current results, several existing correlations of the heat transfer deterioration onset were reviewed and assessed, showing different prediction performance. A new correlation of the threshold value for the ratio between heat flux and mass flux for determining the boundary for heat transfer deterioration under various tube diameter and operating pressure was obtained. The effect of length to diameter ratio on safety margin was discussed. The present study provides the optimization design of regenerative cooling on reducing heat transfer deterioration.

The Effect of Swirl, Inlet Conditions, Flow Direction, and Tube Diameter on the Heat Transfer to Fluids at Supercritical Pressure

1970 ◽  
Vol 92 (3) ◽  
pp. 465-471 ◽  
Author(s):  
B. Shiralkar ◽  
P. Griffith
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Tube Diameter ◽  
Inlet Temperature ◽  
The Heat Transfer Coefficient

An investigation has been made of the factors governing the heat transfer coefficient to supercritical pressure fluids, particularly at high heat fluxes. The deterioration in heat transfer to supercritical carbon dioxide has been experimentally studied with reference to the operating conditions of mass velocity and heat flux, tube diameter, orientation, tape induced swirl, inlet temperature, and pressure. A detailed comparison has been made with the apparently contradictory results of other investigators, and operating regions, in which the heat transfer coefficient behaves differently, have been defined. The terms used to describe these regions are the Reynolds number, a heat-flux parameter, and a free-convection parameter.

Flow Resistance Characteristics of a Specific Fuel RP-3 in Helical Tubes at Supercritical Pressure With Uniform Heat Flux

2017 ◽  
Author(s):  
Nan Zhang ◽  
Yanchen Fu ◽  
Haoran Huang ◽  
Jie Wen ◽  
Nigeer Te
Keyword(s):  
Heat Flux ◽  
Friction Factor ◽  
Mass Flux ◽  
Flow Resistance ◽  
Flow Characteristics ◽  
Supercritical Pressure ◽  
Uniform Heat Flux ◽  
Inlet Temperature ◽  
Uniform Heat ◽  
Helical Tubes

The flow resistance characteristics of aviation kerosene RP-3 in horizontal helical tubes at the supercritical pressure under heating condition are investigated. Both pressure drop and friction factor were examined under uniform heat flux of 50kW/m2−300kW/m2, mass flux from 786kg/m2s to 1375kg/m2s, and helical diameter from 20mm to 40mm. The influence of viscous factors on the resistance is analyzed to explore flow characteristics in a helical tube and provide a reference for the design of heat exchangers. Friction factor decreases with the increase of heat flux at low inlet temperatures 323K and 423K. It is explained that the viscosity changes more dramatically than the density. When the fluid inlet temperature is 523K and the fluid mean temperature Tb is close to pseudo-critical temperature, frictional flow resistance becomes significantly larger Tpc due to huge variations in thermal properties in the radical direction. The effect of centrifugal force makes the friction factor decline slowly. The friction factor goes up with the enlargement of mass flux when Tb>0.81Tpc. This phenomenon is caused by the larger radial velocity gradient under the large mass flux. Different helical diameters play the leading roles for the bending flow in the tubes.

scholarly journals Deterioration in Heat Transfer to Fluids at Supercritical Pressure and High Heat Fluxes

1969 ◽  
Vol 91 (1) ◽  
pp. 27-36 ◽  
Author(s):  
B. S. Shiralkar ◽  
Peter Griffith
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Heat ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Bulk Temperature ◽  
Operating Pressure ◽  
The Heat Transfer Coefficient

At slightly supercritical pressure and in the neighborhood of the pseudocritical temperature (which corresponds to the peak in the specific heat at the operating pressure), the heat transfer coefficient between fluid and tube wall is strongly dependent on the heat flux. For large heat fluxes, a marked deterioration takes place in the heat transfer coefficient in the region where the bulk temperature is below the pseudocritical temperature and the wall temperature above the pseudocritical temperature. Equations have been developed to predict the deterioration in heat transfer at high heat fluxes and the results compared with previously available results for steam. Experiments have been performed with carbon dioxide for additional comparison. Limits of safe operation for a supercritical pressure heat exchanger in terms of the allowable heat flux for a particular flow rate have been determined theoretically and experimentally.

Use of Algebraic Heat Flux Models to Improve Heat Transfer Predictions for Supercritical Pressure Fluids

2016 ◽  
Author(s):  
Vera Papp ◽  
Andrea Pucciarelli ◽  
Medhat Sharabi ◽  
Walter Ambrosini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbulent Heat Flux ◽  
Supercritical Pressure ◽  
Internal Diameter ◽  
Inlet Temperature ◽  
Turbulent Heat ◽  
Commercial Code ◽  
Simplifying Assumptions ◽  
Flux Model

This work proposes simulations of heat transfer under supercritical pressure conditions showing improvements with respect to previous works. This is obtained by the introduction of the Algebraic Heat Flux Model (AHFM) for evaluating the turbulent heat flux in turbulence production terms, using the in-house code THEMAT and the STAR-CCM+ code. The first code makes use of the AHFM also in the energy balance equations, while for the commercial code simplifying assumptions are considered in the implementations. Custom sets of parameters for every condition of inlet temperature and internal diameter are tuned in some cases, driven by the opinion that a single set of parameters cannot be suitable in every flow conditions, considering the complexity of the variables that concur in the heat transfer deterioration phenomenon. The AHFM model gives promising results with new sets of parameters in order to model the deterioration and the recovery phases because of its term related to the variance of temperature.

Numerical Investigation of Subcooled Boiling Heat Transfer in Helically-Coiled Tube

2020 ◽  
Vol 17 (1) ◽  
pp. 7675-7686
Author(s):  
Luthfi A. F. Haryoko ◽  
Jundika C. Kurnia ◽  
Agus P. Sasmito
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Operating Pressure ◽  
Subcooled Boiling ◽  
Coiled Tube ◽  
Helically Coiled Tube

Subcooled boiling heat transfer in helically-coiled tubes offers better heat transfer performance than any other types of boiling processes due to its ability to capture high heat flux with a relatively low wall superheat. This study investigates turbulent subcooled forced convection boiling performances of water-vapour in a helically-coiled tube with various operating conditions i.e. operating pressure, heat, and mass flux. Developed CFD model is validated against previously published experimental results using the RPI model. The model is developed based on the Eulerian-Eulerian framework coupled with k-ε RNG turbulence model and Standard Wall-Function. A good agreement is found between numerical prediction and experimental counterpart for the bulk fluid temperature and non-dimensional length. The result indicates that the subcooled boiling heat transfer in a helically-coiled tube tends to improve heat transfer coefficient and pressure drop in the domain. Subcooled boiling starts at the inner side of the helically-coiled tube (f=9900) due to the existence of secondary flow that comes from the coil curvature. Heat transfer coefficient and pressure drop increased with increasing heat flux and decreasing mass flux, and operating pressure. This is caused by the bubble movement and convective heat transfer phenomena in a helically-coiled tube. Finally, this study can provide a guideline for future research of the subcooled boiling in a helically-coiled tube.

scholarly journals Numerical Investigation of Heat Transfer Characteristics of scCO2 Flowing in a Vertically-Upward Tube with High Mass Flux

Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 79
Author(s):  
Kaigang Gong ◽  
Bingguo Zhu ◽  
Bin Peng ◽  
Jixiang He
Keyword(s):  
Heat Transfer ◽  
Mass Flux ◽  
Supercritical Pressure ◽  
High Mass ◽  
Inlet Temperature ◽  
Wall Region ◽  
Heterogeneous Structure ◽  
Heat Transfer Characteristics ◽  
Flow Acceleration ◽  
Transfer Characteristics

In this work, the heat transfer characteristics of supercritical pressure CO2 in vertical heating tube with 10 mm inner diameter under high mass flux were investigated by using an SST k-ω turbulent model. The influences of inlet temperature, heat flux, mass flux, buoyancy and flow acceleration on the heat transfer of supercritical pressure CO2 were discussed. Our results show that the buoyancy and flow acceleration effect based on single phase fluid assumption fail to explain the current simulation results. Here, supercritical pseudo-boiling theory is introduced to deal with heat transfer of scCO2. ScCO2 is treated to have a heterogeneous structure consisting of vapor-like fluid and liquid-like fluid. A physical model of scCO2 heat transfer in vertical heating tube was established containing a gas-like layer near the wall and a liquid-like fluid layer. Detailed distribution of thermophysical properties and turbulence in radial direction show that scCO2 heat transfer is greatly affected by the thickness of gas-like film, thermal properties of gas-like film and turbulent kinetic energy in the near-wall region. Buoyancy parameters Bu < 10-5, Bu* < 5.6 × 10−7 and flow acceleration parameter Kv < 3 × 10−6 in this paper, which indicate that buoyancy effect and flow acceleration effect has no influence on heat transfer of scCO2 under high mass fluxes. This work successfully explains the heat transfer mechanism of supercritical fluid under high mass flux.

scholarly journals Review of the Wall Temperature Prediction Capability of Available Correlations for Heat Transfer at Supercritical Conditions of Water

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Dhanuskodi Ramasamy ◽  
Arunagiri Appusamy ◽  
Anantharaman Narayanan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Wall Temperature ◽  
Mass Flux ◽  
Flux Ratio ◽  
Temperature Prediction ◽  
Heat Transfer Deterioration ◽  
Error Band ◽  
Wide Range ◽  
Data Points

The validity of the wall temperature predictions by 18 correlations available in the literature for supercritical heat-transfer regimes of water was verified for 12 experimental datasets consisting of 355 data points available in the literature. The correlations were ranked based on criteria like % data with <5% error, % data with <10°C error and minimum error band in temperature prediction. Details of the best fitting correlations were tabulated. The analysis indicated that for normal heat-transfer conditions, most of the correlations give close predictions. However, at deteriorated heat transfer regimes, only very few prediction points are closer to experimental value. Also, in the ranking process, the first position keeps varying, and no one correlation shall be said as the best for all experiments. Evaluation of the applicability of heat flux to mass-flux-ratio-based prediction of heat-transfer deterioration indicated 75% agreement. The empirical formulae linking mass flux for the prediction of the starting heat flux for heat-transfer deterioration indicated 58.33% of agreement. This review indicated that continued precise experimentation covering wide range of parameter conditions near pseudocritical regime and development of correlations is felt necessary for the accurate prediction of supercritical fluid heat transfer.

scholarly journals Experiments on Heat Transfer of Supercritical Pressure Kerosene in Mini Tube under Ultra-High Heat Fluxes

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1229
Author(s):  
Jianguo Yan ◽  
Shouchun Liu ◽  
Pengcheng Guo ◽  
Qincheng Bi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
High Heat ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Bulk Temperature ◽  
Rocket Engines ◽  
Maximum Heat ◽  
Regenerative Cooling

Heat transfer of supercritical-pressure kerosene is crucial for regenerative cooling systems in rocket engines. In this study, experiments were devoted to measure the heat transfer of supercritical-pressure kerosene under ultra-high heat fluxes. The kerosene flowed horizontally in a mini circular tube with a 1.0 mm inner diameter and was heated uniformly under pressures of 10–25 MPa, mass fluxes of 8600–51,600 kg/m2 s, and a maximum heat flux of up to 33.6 MW/m2. The effects of the operating parameters on the heat transfer of supercritical-pressure kerosene were discussed. It was observed that the heat transfer coefficient of kerosene increases at a higher mass flux and inlet bulk temperature, but is little affected by pressure. The heat transfer of supercritical-pressure kerosene is classified into two regions: normal heat transfer and enhanced heat transfer. When the wall temperature exceeds a certain value, heat transfer is enhanced, which could be attributed to pseudo boiling. This phenomenon is more likely to occur under higher heat flux and lower mass flux conditions. In addition, the experimental data were compared with several existing heat transfer correlations, in which one of these correlations can relatively well predict the heat transfer of supercritical-pressure kerosene. The results drawn from this study could be beneficial to the regenerative cooling technology for rocket engines.

Experimental Investigation of Jet Impingement Cooling With Carbon Dioxide at Supercritical Pressures

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Kai Chen ◽  
Rui-Na Xu ◽  
Pei-Xue Jiang
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Flux ◽  
Stagnation Point ◽  
Jet Impingement ◽  
Supercritical Pressure ◽  
Inlet Temperature ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Transfer Characteristics

Jet impingement cooling is widely used in many industrial applications due to its high heat transfer capability and is an option for advanced high power density systems. Jet impingement cooling with supercritical pressure fluids could have much larger heat transfer rates combining with the large fluid specific heat near the pseudocritical point. However, the knowledge of its flow and heat transfer characteristics is limited. In this study, the flow and the local and average heat transfer characteristics of jet impingement cooling with supercritical pressure fluids were studied experimentally with carbon dioxide first. An integrated thermal sensor chip that provided heating and temperature measurements was manufactured using micro-electro-mechanical systems (MEMS) techniques with a low thermal conductivity substrate as the impingement cooled plate. The experiment system pressure was 7.85 MPa, which is higher than the critical pressure of carbon dioxide of 7.38 MPa. The mass flow rate ranged from 8.34 to 22.36 kg/h and the Reynolds number ranged from 19,000 to 68,000. The heat flux ranged from 0.02 to 0.22 MW/m2. The nozzle inlet temperature ranged from lower to higher than the pseudocritical temperature. Dramatic variations of the density at supercritical pressures near the heating chip were observed with increasing heat flux in the strong reflection and refraction of the backlight that disappeared at inlet temperatures higher than the pseudocritical temperature. The local heat transfer coefficient near the stagnation point increased with increasing heat flux while those far from the stagnation point increased to a maximum with increasing heat flux and then decreased due to the nonuniformity of jet impingement cooling. The heat transfer is higher at inlet temperatures lower than the pseudocritical temperature and the surface temperature is slightly higher than the pseudocritical temperature due to the dramatic changes in the fluid thermo-physical properties at supercritical pressures.

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