scholarly journals Analysis of the main parameters of crude oil pipeline transport

2020 ◽  
Vol 74 (2) ◽  
pp. 79-90
Author(s):  
Jasna Tolmac ◽  
Slavica Prvulovic ◽  
Marija Nedic ◽  
Dragisa Tolmac
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Crude Oil ◽  
Transfer Coefficient ◽  
Cooling Rate ◽  
Pour Point ◽  
Operating Conditions ◽  
Pipeline Transport ◽  
Oil Pipeline ◽  
The Heat Transfer Coefficient

The paper presents results of experimental research and simulation of the main parameters of crude oil pipeline transport. In Serbia, 70 % of the produced oil belongs to a paraffin type, of which over 25 % has a high content of paraffin. High-content paraffin oil usually has a high pour point. The paraffin content in crude oil from Vojvodina, Serbia, is in the range 7.5 to 26 %, and the oil pour temperature varies from 18 to 36?C. The imported crude oil has a flow point max. 8?C. Homogenization, i.e. mixing of domestic and imported crude oil, improves the transport properties and decreases the pour point. After homogenization, the crude oil is pre-heated, and then transported by a pipeline to the refinery for further processing. Heating induces modification of crude oil physical properties, especially flow properties so to prevent wax formation within the oil pipeline. The aim of this paper was to determine operating parameters and flow characteristics for a particular oil pipeline (428 mm inner diameter, 91,000 m length) under real operating conditions. By heating in the range of 20 - 50?C, the viscosity of crude oil was reduced, approaching the viscosity of water. The pipeline is isolated (100 mm thick isolation) and buried into in the ground (1 m depth). It is found that the heat transfer coefficient has a dominant influence on the cooling rate of the oil in the pipeline. The heat transfer coefficient is mainly determined by the isolation thickness so that it was determined as 0.60 W m-2 K-1 for + 100 mm thickness, while it was 2.20 W m-2 K-1 for the non-isolated pipeline. Heat losses through the main pipeline ranged from 36 - 110 kJ m-1 h-1 (10 - 30 W m-1). The difference between the starting and the ending temperature of crude oil ranged from 10 to 12?C. Such a decrease of ?t = 10 oC and, consequently, the increase in viscosity induced a noti-ceable increase in the pressure drop and pump power by 3 to 4 %, at the maximum flowrate of 0.194 m3 s-1 (700 m3 h-1). The cooling rate during transportation under stationary thermal and hydraulic conditions is in the range 0.52 ? 0.5 oC h-1. In the case of domestic oil (Vojvodina, Serbia) transport, the downtime should not exceed 24 h, since stopping and cooling of the oil would result in formation of solid paraffin particles followed by oil gelation.

Novel Arrangement of Rough Tubes for Heat Flux Improvement

2012 ◽  
Vol 326-328 ◽  
pp. 81-86
Author(s):  
Farshad Farahbod ◽  
Sara Farahmand ◽  
Farzaneh Farahbod
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Crude Oil ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Set Up ◽  
The Heat Transfer Coefficient

The objective of the research is to represent a novel arrangement of conical three dimensional rough tubes (FS3D) for heat transfer coefficient enhancement. Experiments were performed with 316 stainless steel tubes of FS3D roughness and hot crude oil was circulated in constant heat flux condition in the related set up. The pressure drop is measured in this set up and compared with the pressure drop in a smooth tube with the same operating conditions. The heat transfer coefficient is one of essential parameters for design of heat transfer equipments and in this experimental work this is investigated for an Iranian crude oil in the FS3D rough tube. The heat transfer coefficient in FS3D rough tubes is higher than in other commercial enhanced tubes. FS3D rough tubes improve the performance of heat transfer equipments and also optimize the size of the mentioned devices. Consequently this type, the FS3D rough tube, is advantageous in energy and cost saving.

Predicting Heat Transfer From Unsteady Synthetic Jets

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Mehmet Arik ◽  
Tunc Icoz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Small Scale ◽  
Wide Range ◽  
The Heat Transfer Coefficient

Synthetic jets are piezo-driven, small-scale, pulsating devices capable of producing highly turbulent jets formed by periodic entrainment and expulsion of the fluid in which they are embedded. The compactness of these devices accompanied by high air velocities provides an exciting opportunity to significantly reduce the size of thermal management systems in electronic packages. A number of researchers have shown the implementations of synthetic jets on heat transfer applications; however, there exists no correlation to analytically predict the heat transfer coefficient for such applications. A closed form correlation was developed to predict the heat transfer coefficient as a function of jet geometry, position, and operating conditions for impinging flow based on experimental data. The proposed correlation was shown to predict the synthetic jet impingement heat transfer within 25% accuracy for a wide range of operating conditions and geometrical variables.

scholarly journals The Effect of Density Ratio on the Heat Transfer Coefficient From a Film Cooled Flat Plate

1989 ◽  
Author(s):  
H. D. Ammari ◽  
N. Hay ◽  
D. Lampard
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Strong Dependence ◽  
Density Ratio ◽  
Polymer Surface ◽  
Operating Conditions ◽  
Density Ratios ◽  
The Heat Transfer Coefficient

The effect of density ratio of cooling films on the heat transfer coefficient on a flat plate is investigated using a heat-mass transfer analogy. The experimental technique employed uses a swollen polymer surface and laser holographic interferometry. A density ratio of 1.0 was achieved using air as the injectant. Density ratios of 1.38 and 1.52, representative of turbine operating conditions, were obtained by using foreign gases. The coolant fluids were injected at various blowing rates through a single normal hole or through a row of holes spaced at three-diameter intervals, and inclined at 35° or 90° to the mainstream direction. The experiments were conducted under isothermal conditions in a subsonic, zero mainstream pressure gradient turbulent boundary layer. The results indicated large differences in behaviour between the two injection angles. For normal injection, the heat transfer coefficient at a fixed blowing parameter was insensitive to the variation of density ratio, whereas for 35° injection strong dependence was observed. Scaling parameters for the heat transfer data have been proposed so that use can be made of data obtained at density ratios not representative of gas turbine practice. In addition, a correlation for normal injection data has been formulated.

Prediction of the Heat Transfer Coefficient in a Bubble Column Using an Artificial Neural Network

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Adel A. Al-Hemiri ◽  
Nada S. Ahmedzeki
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Artificial Neural Network ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Operating Conditions ◽  
Liquid Viscosity ◽  
Input Parameters ◽  
Artificial Neural ◽  
The Heat Transfer Coefficient

An artificial neural network (ANN) was applied for the prediction of the heat transfer coefficient in bubble columns, in order to obtain a general model and to facilitate the scale up of these multiphase contactors, covering a wide range of operating conditions, physical properties, and column dimensions, obtained from literature. A large number of data was collected (more than 1000) via a comprehensive literature survey. Selected parameters affecting the heat transfer coefficient were organized in six groups to serve as the input parameters. These were: gas superficial velocity, gas density, liquid density, diameter of the column, liquid viscosity, and gas hold-up. Four Back-Propagation Networks (BPNNS) were built. Two were trained using a different number of input parameters. The first ANN was trained with six inputs, which were the aforementioned parameters. The second was trained with three inputs only. These were gas velocity, liquid viscosity and gas hold-up. Each ANN was examined for two structures i.e., one hidden layer and two hidden layers. Comparison between these networks was made to find the optimal ANN structure with minimum %AARE and the maximum correlation coefficient (%R). It was found that the ANN structure of [6-13-1] with a %AARE of 16.2 and a %R of 94 was the best.

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.

scholarly journals Comparison between R134a and R1234ze(E) during Flow Boiling in Microfin Tubes

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 417
Author(s):  
Andrea Lucchini ◽  
Igor M. Carraretto ◽  
Thanh N. Phan ◽  
Paola G. Pittoni ◽  
Luigi P. M. Colombo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Fluid Dynamic ◽  
Saturation Temperature ◽  
Operating Conditions ◽  
Two Fluids ◽  
The Heat Transfer Coefficient

Environmental concerns are forcing the replacement of commonly used refrigerants, and finding new fluids is a top priority. Soon the R134a will be banned, and the hydro-fluoro-olefin (HFO) R1234ze(E) has been indicated as an alternative due to its smaller global warming potential (GWP) and shorter atmospheric lifetime. Nevertheless, for an optimal replacement, its thermo-fluid-dynamic characteristics have to be assessed. Flow boiling experiments (saturation temperature Tsat = 5 °C, mass flux G = 65 ÷ 222 kg·m−2·s−1, mean quality xm = 0.15 ÷ 0.95, quality changes ∆x = 0.06 ÷ 0.6) inside a microfin tube were performed to compare the pressure drop per unit length and the heat transfer coefficient provided by the two fluids. The results were benchmarked for some correlations. In commonly adopted operating conditions, the two fluids show a very similar behavior, while benchmark showed that some correlations are available to properly predict the pressure drop for both fluids. However, only one is satisfactory for the heat transfer coefficient. In conclusion, R1234ze(E) proved to be a suitable drop-in replacement for the R134a, whereas further efforts are recommended to refine and adapt the available predictive models.

Forced Convective Heat Transfer From Helicoidal Pipes

2001 ◽  
Author(s):  
Ahmad Fakheri ◽  
Abdelrahman H. A. Alnaeim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Characteristic Length ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Operating Conditions ◽  
Straight Pipe ◽  
Wide Range ◽  
The Heat Transfer Coefficient

Abstract Forced convection heat transfer from helicoidal pipes is experimentally investigated over a wide range of operating conditions. Based on the experimental results, a characteristic length incorporating the tube diameter, the coil diameter, and the coil spacing, is proposed as the relevant scale for defining Nusselt and Reynolds numbers. Based on this characteristic length, Nusselt number for helicoidal pipes can be predicated from the correlations available for cylinders in the range of available experimental data. It is shown that the performance of the coils depends on the Reynolds number. At high Reynolds numbers, the heat transfer coefficient is essentially equal to that of the straight pipe and the coil pitch has little influence on the heat transfer rate. On the other hand, at low Reynolds numbers, the heat transfer coefficient is lower than that of a straight pipe and its value is a strong function of the coil spacing.

Local Heat Transfer Coefficient During Condensation in a 0.8 mm Diameter Pipe

2006 ◽  
Author(s):  
Alberto Cavallini ◽  
Davide Del Col ◽  
Marko Matkovic ◽  
Luisa Rossetto
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Operating Conditions ◽  
Local Heat Transfer Coefficient ◽  
Wide Range ◽  
The Heat Transfer Coefficient

The first preliminary tests carried on a new experimental rig for measurement of the local heat transfer coefficient inside a circular 0.8 mm diameter minichannel are presented in this paper. The heat transfer coefficient is measured during condensation of R134a and is obtained from the measurement of the heat flux and the direct gauge of the saturation and wall temperatures. The heat flux is derived from the water temperature profile along the channel, in order to get local values for the heat transfer coefficient. The test section has been designed so as to reduce thermal disturbances and experimental uncertainty. A brief insight into the design and the construction of the test rig is reported in the paper. The apparatus has been designed for experimental tests both in condensation and vaporization, in a wide range of operating conditions and for a wide selection of refrigerants.

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