scholarly journals Numerical study for removing wax deposition by thermal washing for the waxy crude oil gathering pipeline

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042095852
Author(s):  
Hui Jiang ◽  
Xiaoyan Liu ◽  
Haiqian Zhao ◽  
Yang Liu ◽  
Chuan Ma ◽  
...  
Keyword(s):  
Crude Oil ◽  
Water Temperature ◽  
Flow Rate ◽  
Numerical Study ◽  
Liquid Fraction ◽  
Melting Process ◽  
Melting Rate ◽  
Melting Time ◽  
Outlet Temperature ◽  
Waxy Crude Oil

Exploring the wax removal process by numerical simulation is beneficial for guiding field operations. In this paper, enthalpy-porosity and volume of fluid (VOF) methods were adopted to simulate the melting process of wax in the crude oil gathering pipeline. The melting patterns and liquid fraction of the wax were used to validate the mathematical model. The results show that the wax melts quickly before the liquid fraction reaches 80%, while the remaining 20% melts very slowly. Since the water with higher density sinks to the lower part of the pipeline, the wax in the lower part of the pipeline melts first, while the wax in the upper part of the pipeline melts slowly. The water temperature and flow rate disproportionately affect the melting process. Increasing the water temperature and flow rate can accelerate the melting process, but the effects on shortening the melting time of wax gradually decrease. Increasing the flow rate, the heat transfer rate and the melting rate are increasing progressively, the change of flow rate also affects the outlet temperature of the pipeline.

scholarly journals Experimental Investigation on Improvement of Wet Cooling Tower Efficiency with Diverse Packing Compaction Using ANN-PSO Algorithm

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 167
Author(s):  
Hasan Alimoradi ◽  
Madjid Soltani ◽  
Pooriya Shahali ◽  
Farshad Moradi Kashkooli ◽  
Razieh Larizadeh ◽  
...  
Keyword(s):  
Neural Network ◽  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Air Flow ◽  
Water Flow Rate ◽  
Pso Algorithm ◽  
Outlet Temperature ◽  
Air Flow Rate

In this study, a numerical and empirical scheme for increasing cooling tower performance is developed by combining the particle swarm optimization (PSO) algorithm with a neural network and considering the packing’s compaction as an effective factor for higher accuracies. An experimental setup is used to analyze the effects of packing compaction on the performance. The neural network is optimized by the PSO algorithm in order to predict the precise temperature difference, efficiency, and outlet temperature, which are functions of air flow rate, water flow rate, inlet water temperature, inlet air temperature, inlet air relative humidity, and packing compaction. The effects of water flow rate, air flow rate, inlet water temperature, and packing compaction on the performance are examined. A new empirical model for the cooling tower performance and efficiency is also developed. Finally, the optimized performance conditions of the cooling tower are obtained by the presented correlations. The results reveal that cooling tower efficiency is increased by increasing the air flow rate, water flow rate, and packing compaction.

scholarly journals Study on Optimizing Operation of Preheating Commissioning for Waxy Crude Oil Pipelines

2014 ◽  
Vol 6 ◽  
pp. 894256
Author(s):  
Jian Zhang ◽  
Yi Wang ◽  
Xinran Wang ◽  
Handu Dong ◽  
Jinping Huang ◽  
...  
Keyword(s):  
Crude Oil ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Governing Equations ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Single Station ◽  
Oil Pipelines ◽  
Volume Method

A mathematical model is established for the preheating commissioning process of waxy crude oil pipelines. The governing equations are solved by the finite volume method and the finite difference method. Accordingly, numerical computations are made for the Niger crude oil pipeline and the Daqing-Tieling 3rd pipeline. The computational results agree well with the field test data. On this basis, fluid temperature in the process of the preheating commissioning is studied for single station-to-station pipeline. By comparing different preheating modes, it is found that the effect of forward preheating is the best. Under different preheating commissioning conditions, the optimal combination of outlet temperature and flow rate is given.

scholarly journals Unavoidable Destroyed Exergy in Crude Oil Pipelines due to Wax Precipitation

Entropy ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 58
Author(s):  
Qinglin Cheng ◽  
JinWei Yang ◽  
Anbo Zheng ◽  
Lu Yang ◽  
Yifan Gan ◽  
...  
Keyword(s):  
Crude Oil ◽  
Design Parameters ◽  
Burial Depth ◽  
Outlet Temperature ◽  
Waxy Crude Oil ◽  
Wax Precipitation ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Operation Parameters

Based on the technological requirements related to waxy crude oil pipeline transportation, both unavoidable and avoidable destroyed exergy are defined. Considering the changing characteristics of flow pattern and flow regime over the course of the oil transportation process, a method of dividing station oil pipelines into transportation intervals is suggested according to characteristic temperatures, such as the wax precipitation point and abnormal point. The critical transition temperature and the specific heat capacity of waxy crude oil are calculated, and an unavoidable destroyed exergy formula is derived. Then, taking the Daqing oil pipeline as an example, unavoidable destroyed exergy in various transportation intervals are calculated during the actual processes. Furthermore, the influential rules under various design and operation parameters are further analyzed. The maximum and minimum unavoidable destroyed exergy are 381.128 kJ/s and 30.259 kJ/s. When the design parameters are simulated, and the maximum unavoidable destroyed exergy is 625 kJ/s at the diameter about 250 mm. With the increase of insulation layer thickness, the unavoidable destroyed exergy decreases continuously, and the minimum unavoidable destroyed exergy is 22 kJ/s at 30 mm. And the burial depth has little effect on the unavoidable destroyed exergy. When the operation parameters are simulated, the destroyed exergy increases, but it is less affected by the outlet pressure. The increase amplitude of unavoidable destroyed exergy will not exceed 2% after the throughput rises to 80 m3/h. When the outlet temperature increases until 65 °C, the loss increase range will not exceed 4%. Thus, this study provides a theoretical basis for the safe and economical transportation of waxy crude oil.

scholarly journals NUMERICAL STUDY OF THE GEOMETRIC INFLUENCE OF A FIN IN A CYLINDRICAL HEAT EXCHANGER FOR MELTING OF PCM

2019 ◽  
Vol 18 (1) ◽  
pp. 78
Author(s):  
F. C. Spengler ◽  
B. Oliveira ◽  
R. C. Oliveski ◽  
L. A. O. Rocha
Keyword(s):  
Heat Exchanger ◽  
Aspect Ratio ◽  
Phase Change ◽  
Latent Heat ◽  
Heat Storage ◽  
Numerical Study ◽  
Melting Process ◽  
High Energy ◽  
High Energy Density ◽  
Melting Time

The thermal heat storage it’s an effective way to suit the energy availability with the demand schedule. It can be stored in the means of sensible or latent heat, the latter applying a material denominated Phase Change Material (PCM), which is provided as organic compounds, hydrated salts, paraffins, among others. The latent heat storage systems offer several advantages, like the practically isothermal process of loading and unloading and the high energy density. However, the low thermal conductivity makes the cycle prolonged on these systems, restricting its applicability. Applying computational fluid dynamics, the behavior of the PCM melting process was studied in cylindrical cavities with horizontal and vertical fins, aiming the optimization of the fin geometry. In this way the fin area was kept constant, varying its aspect ratio. The numerical model was validated with results from the literature and it’s composed of the continuity, momentum and energy equations increased by the phase change model. Qualitative and quantitative results are presented, referring to mesh independence, contours of velocity, net fraction and temperature at different moments of the process. The results of the study indicate that the position of the fin in the heat exchanger influences the melting process, although the vertical fins have a faster total melting process, horizontal fins can reach larger partial liquid fractions in less time in the heat exchanger. Such as the position of the fin, the increase of its length propitiates the reduction of the melting time, evidencing the optimal aspect ratio.

Rheological Property of Waxy Crude Oil in Restart Process of Pipeline

2010 ◽  
Author(s):  
Yanbo Xu ◽  
Qiyu Huang
Keyword(s):  
Rheological Property ◽  
Crude Oil ◽  
Rheological Properties ◽  
Yield Stress ◽  
Outlet Temperature ◽  
Waxy Crude Oil ◽  
Time Duration ◽  
Waxy Crude

In the restart process of pipeline containing waxy crude oil after shutdown, the rheological properties of oil, including viscosity, yield stress and thixotropy is studied. The entire restart process is decided by various factors; in this paper the effects of outlet temperature, shutdown and restart temperature as well as shutdown time duration to the rheological property are taken into the consideration. The measurements are employed using a controlled shearing rheometer to investigate rheological property based on different restart conditions. In addition, this paper has also researched affection of emulsion and blended samples mixing with two types of crude oil in various ratios. Finally comprehensive rheological evaluation to restartability is obtained.

Experimental Study on the Desalination System Using Humidification-Dehumidification Technology

2020 ◽  
Vol 1008 ◽  
pp. 177-185
Author(s):  
Hamed Abbady ◽  
Mahmoud Salem Ahmed ◽  
Hamdy Hassan ◽  
A.S.A. Mohamed
Keyword(s):  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Major Objective ◽  
Cooling Water Flow Rate ◽  
Output Ratio

In this paper, an experimental work studies the principal operating parameters of a proposed desalination process using air humidification-dehumidification method. The major objective of this work is to determine the humid air behavior through the desalination system. Different operating conditions including the effect of the water temperature at the entry to the humidifier, the ratio of the mass of water to the air, the air/water flow rate, and cooling water at entry the dehumidifier on the desalination performance were studied. The results show that the freshwater increases with increasing the water temperature at the inlet of the humidifier, the ratio of the mass of water to air, and cooling water flow rate in the dehumidifier. Cooling water outlet temperature at the condenser increases with increasing the water temperature at humidifier inlet. Also, it decreases as increasing cooling water flow rate while the ratio of the mass of water to air achieves the highest productivity and gained output ratio (GOR). The achieved mass ratio (MR) is 4.5 and the mass flow rate of air is 0.8 kg/min.

scholarly journals Role of honeycomb structure in improving the melting process of a phase change material inside a latent heat storage unit

2021 ◽  
Vol 19 ◽  
pp. 589-592
Author(s):  
M. Hariss ◽  
◽  
M. El Alami ◽  
A. Gounni
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Numerical Study ◽  
Melting Process ◽  
Honeycomb Structure ◽  
Melting Time ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
The Impact

In this work, a numerical study is performed to analyze the impact of honeycomb structure on heat transfer within the PCM. The modeling is based on a transient calculation making it possible to analyze the phase change of the paraffin using the commercial software "Fluent" based on the enthalpy-porosity model. The results showed that the impregnation of a metal matrix in a rectangular enclosure helps to decrease the melting time and thus improve the heat transfer within the PCM.

scholarly journals Electric Field Interaction with Hydrocarbon Flames

2018 ◽  
Vol 63 (5) ◽  
pp. 402
Author(s):  
S. G. Orlovskaya ◽  
M. S. Skoropado ◽  
F. F. Karimova ◽  
V. Ya. Chernyak ◽  
L. Yu. Vergun
Keyword(s):  
Melting Point ◽  
Field Strength ◽  
Electric Field ◽  
Fossil Fuels ◽  
Melting Process ◽  
Melting Rate ◽  
Melting Time ◽  
Field Interaction ◽  
Hydrocarbon Flames ◽  
Dc Electric Field

The problem of electric-field-assisted combustion for low-melting point hydrocarbons (paraffin wax, n-alkanes) attracts the attention of scientists in relation to the development of paraffin-based propellants. Our study is aimed at the detailed investigation of the dc electric field interaction with the flame of octadecane droplet. We have studied the melting and combustion of alkane particles in the electric field ranging from 33 kV/m to 117 kV/m. It is found that the melting rate decreases distinctly starting with the electric field strength E ∼ 80 kV/m. This effect is more pronounced at high gas temperatures (Ste >1), when the melting time is about a few seconds. So, the melting process slows down in the dc electric field. At the same time, the burning rate constant rises by more than 10 percents. The obtained results can be used to develop efficient and clean technologies of fossil fuels combustion.

Numerical Simulation of a Composite Metal Foam-PCM Air Heat Exchanger Using Rod PTC Heating Elements

2019 ◽  
Author(s):  
Pouyan Talebizadeh Sardari ◽  
Donald Giddings ◽  
Gavin S. Walker ◽  
Mark Gillott ◽  
David Grant
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Metal Foam ◽  
Liquid Fraction ◽  
High Capacity ◽  
Melting Process ◽  
Positive Temperature Coefficient ◽  
Space Heating ◽  
Outlet Temperature ◽  
Positive Temperature

Abstract The aim of this paper is to study the charging/discharging process in a Latent heat exchanger for the purpose of space heating by using a composite metal foam/PCM. The composite PCM-air system is modelled in a 3-D CFD approach for the purpose of 8h charging during the night and 16h discharging during the daytime using the non-equilibrium thermal model to simulate the presence of a porous medium in the domain. For the charging process, rod Positive Temperature Coefficient (PTC) heating elements with constant temperature are selected to heat the PCM based on the maximum operating temperature of the PCM. For the discharging process, a blower is assumed to pass the air from the middle of the PCM container and so the air can gain heat and its temperature rises which is used then for space heating. RT70HC is also selected as the PCM material due to the high capacity of latent heat and suitable melting point for domestic usage. The system is studied according to the average liquid fraction and temperature of the PCM during both charging and discharging as well as the outlet temperature of the air during discharging. The results show that by using two rod heating elements with the diameter of 1cm, length of 25cm and temperature of 95°C, the melting process is performed in less than 8h. Furthermore, a uniform output temperature of almost 29.5°C is also achieved in the next 16h during the discharging process with the air mass flow rate of 0.04 kg/s.

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