scholarly journals Influence of heat transfer on two-phase flow behavior in onshore oil pipelines

2016 ◽  
Vol 36 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Oldrich Joel Romero ◽  
Hugo Candiá Saad ◽  
Isabela Braga Pereira ◽  
Mao Ilich Romero
Keyword(s):  
Heat Transfer ◽  
Flow Behavior ◽  
High Heat ◽  
Two Phase ◽  
River Bed ◽  
Oil Pipelines ◽  
Intermediate Section ◽  
Low Levels ◽  
Pipe Insulation

<p>Computational tools for simulation of multiphase flow in oil pipelines are of great importance for the determination of the technical feasibility of the production in oilfields. The present article presents the mathematical and numerical modeling of the oil biphasic flow in a partially submerged onshore pipeline. The biphasic behavior of the heavy oil of 13,2ºAPI is translated by the Dukler correlation. The oil’s viscosity is regarded as dependent on the temperature and on the API density of the oil by means of the Hossain correlation. The pipeline, of 3,600m and 4 inches (10.16cm) in diameter, transports the oil from a collecting station to a storage center and consists of three sections. The first and third sections are above ground and are in contact with the external environment. The intermediate section is sitting on the river bed and is the critical part of the pipeline, once high heat losses are observed. The influence on the type of pipe insulation in the pressure and temperature gradients was analyzed with the aid of commercial 1D software Pipesim®. The results, of this 1D and non-isothermal problem with prescribed outlet pressure, show that the use of isolation when appropriately designed in terms of material quality and thickness is of utmost importance to maintain the heat transfer at low levels, in order to ensure the movement of fluids in long sections without compromising the system operation.</p>

Analytical Model Quantifying the Net Coolant Flow Rate to a Microstructured Copper Surface validated with Two-Phase PIV Measurements

2021 ◽  
Author(s):  
Matt Harrison ◽  
Joshua Gess
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Flow Rate ◽  
Circular Disk ◽  
Nucleate Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Two Phase

Abstract Using Particle Image Velocimetry (PIV), the amount of fluid required to sustain nucleate boiling was quantified to a microstructured copper circular disk. Having prepared the disk with preferential nucleation sites, an analytical model of the net coolant flow rate requirements to a single site has been produced and validated against experimental data. The model assumes that there are three primary phenomena contributing to the coolant flow rate requirements at the boiling surface; radial growth of vapor throughout incipience to departure, bubble rise, and natural convection around the periphery. The total mass flowrate is the sum of these contributing portions. The model accurately predicts the quenching fluid flow rate at low and high heat fluxes with 4% and 30% error of the measured value respectively. For the microstructured surface examined in this study, coolant flow rate requirements ranged from 0.1 to 0.16 kg/sec for a range of heat fluxes from 5.5 to 11.0 W/cm2. Under subcooled conditions, the coolant flow rate requirements plummeted to a nearly negligible value due to domination of transient conduction as the primary heat transfer mechanism at the liquid/vapor/surface interface. PIV and the validated analytical model could be used as a test standard where the amount of coolant the surface needs in relation to its heat transfer coefficient or thermal resistance is a benchmark for the efficacy of a standard surface or boiling enhancement coating/surface structure.

Cavitation-Enhanced Microchannel Heat Exchanger Demonstration and Heat Transfer Correlation Development Using R-134a

2012 ◽  
Author(s):  
Joshua D. Sole ◽  
Bradley J. Shelofsky ◽  
Robert P. Scaringe ◽  
Gregory S. Cole
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
High Heat ◽  
High Heat Flux ◽  
Heat Transfer Correlation ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Military Aviation ◽  
R 134A ◽  
Two Phase Heat Transfer

Electronics of all types, particularly those in the military aviation arena, are decreasing in size while at the same time increasing in power. As a result, newer high-heat-flux electronic components are exceeding the cooling capabilities of conventional single-phase military aviation coldplates and coolants. It is for this reason that we have been investigating new methods to cool the next generation of high-heat-flux military aviation electronics. In this work, a novel method of inducing two-phase conditions within a microchannel heat exchanger has been developed and demonstrated. Micro-orifices placed upstream of each microchannel in a microchannel heat exchanger not only cause an improvement in flow distribution, but can also induce cavitation in the incoming subcooled refrigerant and result in favorable two-phase flow regimes for enhanced heat transfer. In this study, R-134a is used as the coolant in the cavitation enhanced microchannel heat exchanger (CEMC-HX) which has been integrated into a vapor compression refrigeration system. Multiple micro-orifice geometries combined with a fixed microchannel geometry (nominally 250 μm × 250 μm) were investigated over a range of applied base heat fluxes (10–100 W/cm2) and mass fluxes (500–1000 kg/m2-s). Two-phase heat transfer coefficients exceeding 100,000 W/m2-K at refrigerant qualities of less than 5% have been demonstrated due to the achievement of preferential, cavitation-induced, flow regimes such as annular flow. To the author’s knowledge, this is the highest heat transfer coefficient ever reported in the literature for R-134a. Additionally, a four term two-phase heat transfer correlation was developed that achieved a mean absolute error (MAE) of 25.5%.

A Numerical Model of a Reciprocating-Mechanism Driven Heat Loop for Two-Phase High Heat Flux Cooling

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Olubunmi Popoola ◽  
Ayobami Bamgbade ◽  
Yiding Cao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Performance Optimization ◽  
Numerical Study ◽  
High Heat ◽  
Working Fluid ◽  
High Heat Flux ◽  
Two Phase ◽  
Transfer Device

An effective design option for a cooling system is to use a two-phase pumped cooling loop to simultaneously satisfy the temperature uniformity and high heat flux requirements. A reciprocating-mechanism driven heat loop (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the two-phase working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. The objective of this paper is to develop a numerical model for the RMDHL to predict its operational performance under different working conditions. The developed numerical model has been successfully validated by the existing experimental data and will provide a powerful tool for the design and performance optimization of future RMDHLs. The study also reveals that the maximum velocity in the flow occurs near the wall rather than at the center of the pipe, as in the case of unidirectional steady flow. This higher velocity near the wall may help to explain the enhanced heat transfer of an RMDHL.

Thermoreflectance Wall Temperature Measurement in Annular Two-Phase Flow

2019 ◽  
Author(s):  
Jason Chan ◽  
Brian E. Fehring ◽  
Roman W. Morse ◽  
Kristofer M. Dressler ◽  
Gregory F. Nellis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Annular Flow ◽  
High Heat ◽  
High Heat Flux ◽  
Phase Flow ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Dry Out

Abstract A thermoreflectance method to measure wall temperature in two-phase annular flow is described. In high heat flux conditions, momentary dry-out occurs as the liquid film vaporizes, resulting in dramatic decreases in heat transfer coefficient. Simultaneous liquid and vapor thermoreflectance measurements allow calculations of instantaneous and time-averaged heat transfer coefficients. Validation, calibration and uncertainty of the technique are discussed.

Spatial and Temporal Wall Temperature Fluctuations in Two-Phase Flow in Microgap Coolers

2010 ◽  
Author(s):  
Jessica Sheehan ◽  
Avram Bar-Cohen
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Volumetric Cooling ◽  
Very High

Heat transfer to an evaporating refrigerant and/or dielectric liquid in a microgap channel can provide very high heat transfer coefficients and volumetric cooling rates. Recent studies at Maryland have established the dominance of the annular flow regime in such microgap channels and related the observed high-quality peak of an M-shaped heat transfer coefficient curve to the onset of local dryout. The present study utilizes infrared thermography to locate such nascent dryout regions and operating conditions. Data obtained with a 210 micron microgap channel, operated with a mass flux of 195.2 kg/m2-s and heat fluxes of 10.3 to 26 W/cm2 are presented and discussed.

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