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Przemysław Kosewski - One of the best experts on this subject based on the ideXlab platform.
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Existence and regularity result for Stokes system with special inlet/Outlet Condition
arXiv: Analysis of PDEs, 2019Co-Authors: Kamil Wołos, Przemysław KosewskiAbstract:Our aim is to analyse special type of boundary Conditions created to simulate flows like in cardiovascular and respiratory systems. Firstly we will describe model of viscous incompressible fluid in a domain consisting many inlets and Outlets with open dissipative boundary Conditions. The Conditions are augmented by the inertia terms and we are posing additional constrains on a fluid motion by a volumetric flow rates or inlet/Outlet pressure. Afterwards we will define weak formulation of the problem and it's motivation. Then we will prove mathematical correctness of proposed Conditions by properly modified Galerkin method. We will prove also existence of a solution.
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existence and regularity result for stokes system with special inlet Outlet Condition
arXiv: Analysis of PDEs, 2019Co-Authors: Kamil Wolos, Przemysław KosewskiAbstract:Our aim is to analyse special type of boundary Conditions created to simulate flows like in cardiovascular and respiratory systems. Firstly we will describe model of viscous incompressible fluid in a domain consisting many inlets and Outlets with open dissipative boundary Conditions. The Conditions are augmented by the inertia terms and we are posing additional constrains on a fluid motion by a volumetric flow rates or inlet/Outlet pressure. Afterwards we will define weak formulation of the problem and it's motivation. Then we will prove mathematical correctness of proposed Conditions by properly modified Galerkin method. We will prove also existence of a solution.
Bo Yang - One of the best experts on this subject based on the ideXlab platform.
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How Are the Subsurface Drainage Outlets in Iowa Roadways with Recycled Concrete Aggregate Base Performing
Geotechnical and Structural Engineering Congress 2016, 2016Co-Authors: Sunghwan Kim, Halil Ceylan, Kasthurirangan Gopalakrishnan, Bo YangAbstract:This paper discusses subdrain Outlet Condition and performance in Iowa roadways. A forensic test plan was developed and executed during wet summer Conditions covering over 230 and 120 drain Outlet locations of the newly constructed jointed plain concrete pavement (JPCP) and the hot mix asphalt (HMA) over JPCP sites, respectively. The tufa formation (i.e., calcium carbonate deposits) is the primary cause of drainage Outlet blockage in newly constructed JPCP sites using recycled portland cement concrete (RPCC) as a subbase material. Lesser tufa formation from the use of RPCC base in JPCP was observed with the: (a) use of plastic Outlet pipe without the gate screen type rodent guard, (b) use of blended RPCC and virgin aggregate materials. The observations of moisture-related surface distresses nearby blocked drainage Outlet locations in HMA over JPCP indicates that compromised drainage Outlet performance could accelerate the development of moisture-related distresses in HMA over JPCP.
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Evaluating Roadway Subsurface Drainage Practices - Phase II
2015Co-Authors: Halil Ceylan, Robert F. Steffes, Kasthurirangan Gopalakrishnan, Sunghwan Kim, Bo YangAbstract:Well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). The recently completed Iowa Highway Research Board (IHRB) project TR-643 provided extensive insights into Iowa subsurface drainage practices and pavement subdrain Outlet performance. However, the project TR-643 (Phase I) forensic testing and evaluation were carried out in a drought year and during the fall season in 2012. Based on the findings of IHRB Project TR-643, the Iowa DOT requested an expanded Phase II study to address several additional research needs: evaluate the seasonal variation effects (dry fall 2012 versus wet spring/summer 2013, etc.) on subdrain Outlet Condition and performance; investigate the characteristics of tufa formation in Iowa subdrain Outlets; investigate the Condition of composite pavement subdrain Outlets; examine the effect of resurfacing/widening/rehabilitation on subdrain Outlets (e.g., the effects of patching on subdrain Outlet performance); and identify a suitable drain Outlet protection mechanism (like a headwall) and design for Iowa subdrain Outlets based on a review of practices adopted by nearby states. A detailed forensic test plan was developed and executed for inspecting the Iowa pavement subdrains in pursuit of fulfilling the Phase II study objectives. The observed Outlets with blockage and the associated surface distresses in newly constructed jointed plain concrete pavements (JPCPs) were slightly higher during summer 2013 compared to fall 2012. However, these differences are not significant. Less tufa formation due to the recycled portland cement concrete (RPCC) base was observed with (a) the use of plastic Outlet pipe without the gate screen–type rodent guard and (b) the use of blended RPCC and virgin aggregate materials. In hot-mix asphalt (HMA) over JPCP, moisture-related distress types (e.g., reflection cracking) were observed more near blocked drainage Outlet locations than near “no blockage” Outlet locations. This finding indicates that compromised drainage Outlet performance could accelerate the development of moisture-related distresses in Iowa composite pavement systems.
O̸yvind Hundseid - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Performance Models for Wet Gas Compressors
2008Co-Authors: O̸yvind HundseidAbstract:The Norwegian petroleum industry has played an important role in the country’s industrial development since the early 1970s. At present, however, the largest oil and gas fields on the Norwegian continental shelf have been developed. To maintain its position and production rates in the future, the petroleum industry rely on improved recovery from existing fields and the development of smaller, remoter and more technically complicated discoveries. A major contribution to accomplishing this will be made by the development of new and cost-efficient technology. One consequence of technological progress in recent years is that a greater proportion of the processing equipment is being installed subsea. Ormen Lange and Snohvit are gas fields developed on the basis of subsea solutions, where wellstream processing is located on land. These discoveries are characterised by high gas fractions with relative small amounts of liquid. Gas containing less that 5% liquid on a volume basis is denoted wet gas. To maintain production rates as well pressure decreases, boosting the wellstream is essential. This has therefore created a big incentive in recent years to develop subsea boosting technology. Subsea compression is also applicable for boosting existing gas fields to increase tail production and in development of marginal fields where subsea boosting can be utilised in transportation of wellstream to nearby processing facility. Technology development for subsea compression is currently based on two alternatives: compressing the unprocessed wellstream and subsea separation with compression based on traditional gas compressors and pumps. This thesis evaluates performance prediction models for wet gas compression. No commercial available wet gas compressors exist at present, but several concepts for such equipment have been tested. No performance and test standards currently exist for wet gas compressors. To ensure nominated flow under varying fluid flow Conditions, a complete understanding of compressor performance is essential. Present evaluation methods for compressor performance fail when evaluating the compression of wet gas. The development of a wet gas compressor performance model has been based on the polytropic approach given in ASME and ISO standards, and a full review of this method is given. Assuming a polytropic compression path, the method is based on averaged gas properties of inlet and Outlet Condition. Depending on how this polytropic compression analysis is implemented, the review has revealed up to 4% deviation in polytropic head and efficiency for some specific compressors. This adds an extra uncertainty in compressor performance verification. Even though the API 617 allows up to 4% deviation, some compressors have to meet a more stringent demand, such as 2% at the Snohvit gas liquefaction plant. Existing computer technology permits a direct integration of the compression path where the variation in actual gas properties along the path is included. This method eliminates the averaging of gas properties which the Schultz procedure includes. Direct integration is of special interest when evaluating wet gas compression. Phase changes along the compression path are included, enabling a detailed prediction to be made of the actual volumetric flow rate for the various compressor stages. This thesis reports the implementation of the direct integration procedure for wet gas performance prediction. The procedure enables generic wet gas compression to be studied, which forms the foundation for performance analysis with variations in operation Conditions and fluid properties. The polytropic procedure in its current form does not permit a direct comparison of wet and dry gas Conditions owing to the influence of a high-density liquid phase in wet Conditions. Correction methods to account for these changes are presented. These correction parameters are verified against the results from a wet gas compressor test. The compressor was tested on fluid Conditions typically encountered in a North Sea gas and condensate field. The main contributions of this work are presented in four international papers contained in the appendix.
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Wet Gas Performance Analysis
Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics Parts A and B, 2006Co-Authors: O̸yvind Hundseid, Lars E. BakkenAbstract:The growing interest in wet gas compressors calls for accurate methods for performance prediction. Present evaluation methods for compressor and pump performance fail when evaluating the compression of gases containing liquid. Gas compression performance predictions given in ASME PTC-10-97 and ISO 5318 are based on the method John M. Schultz proposed in 1962. This method assumes a polytropic compression path and is based on averaged gas properties of inlet and Outlet Condition. The polytropic compression path is defined by keeping pvn constant, where n is constant along the compression path. When employing the Schultz method there is a challenge in defining the polytropic constant. This is seen in cases where dry gas compressors are exposed to wet components and compressor efficiency estimates exceed 100%. Today’s computer technology makes a direct integration of the polytropic head (∫vdp) possible where actual fluid properties along the compression path are included. Phase changes along the compression path are included with this method. This enables a detailed prediction to be made of the actual volumetric flow rate for the various compressor stages. This paper reports the implementation of the direct integration procedure for wet gas performance prediction. The procedure enables generic wet gas compression to be studied which forms the foundation for performance analysis with variations in operation at Conditions and fluid components and properties.Copyright © 2006 by ASME
G.a. Longo - One of the best experts on this subject based on the ideXlab platform.
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HFO1234ze(E) vaporisation inside a Brazed Plate Heat Exchanger (BPHE): comparison with HFC134a and HFO1234yf.
International Journal of Refrigeration, 2016Co-Authors: G.a. Longo, Simone Mancin, Giulia Righetti, Claudio ZilioAbstract:Abstract This paper investigates the effects of heat flux, saturation temperature, and Outlet Conditions on HFO1234ze(E) boiling inside a Brazed Plate Heat Exchanger (BPHE). The effect of the heat flux on the heat transfer coefficients was remarkable. Similar consideration applies for Outlet Condition effects whereas the impact of saturation temperature was found to be lower. The frictional pressure drop shows a linear dependence on the refrigerant kinetic energy per unit volume. The two-phase flow boiling heat transfer coefficients were compared with a new model for refrigerant boiling inside BPHE (Longo et al., 2015): the mean absolute percentage deviation between calculated and experimental data is 7.2%. The present data points were compared with those of HFC134a and HFO1234yf previously measured inside the same BPHE under the same operating Conditions: HFO1234ze(E) exhibits heat transfer coefficients very similar to HFC134a and HFO1234yf and frictional pressure drops slightly higher than HFC134a and HFO1234yf.
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Hydrocarbon Refrigerant Vaporization Inside a Brazed Plate Heat Exchanger
Journal of Heat Transfer, 2012Co-Authors: G.a. LongoAbstract:This paper presents the experimental heat transfer coefficients and pressure drop measured during HC-600a (isobutane), HC-290 (propane), and HC-1270 (propylene) vaporization inside a brazed plate heat exchanger (BPHE): the effects of heat flux, refrigerant mass flux, saturation temperature (pressure), evaporator Outlet Condition, and fluid properties are investigated. The experimental tests include 172 vaporization runs carried out at three different saturation temperatures (10, 15, and 20 °C) and four different evaporator Outlet Conditions (Outlet vapor quality around 0.80 and 1.00, Outlet vapor super-heating around 5 and 10 °C). The refrigerant mass flux ranges from 6.6 to 23.9 kg m−2 s−1 and the heat flux from 4.3 to 19.6 kW m−2. The heat transfer and pressure drop measurements have been complemented with IR thermography analysis in order to quantify the portion of the heat transfer surface affected by vapor super-heating. The heat transfer coefficients show great sensitivity to heat flux, evaporator Outlet Condition and fluid properties and weak sensitivity to saturation temperature (pressure). The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on refrigerant mass flux. HC-1270 exhibits heat transfer coefficients 6–12% higher than HC-290 and 35–50% higher than HC-600a and frictional pressure drops 5–10% lower than HC-290 and 60% lower than HC-600a. The experimental heat transfer coefficients are compared with two well-known correlations for nucleate boiling and a linear equation for frictional pressure drop is proposed.
Halil Ceylan - One of the best experts on this subject based on the ideXlab platform.
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How Are the Subsurface Drainage Outlets in Iowa Roadways with Recycled Concrete Aggregate Base Performing
Geotechnical and Structural Engineering Congress 2016, 2016Co-Authors: Sunghwan Kim, Halil Ceylan, Kasthurirangan Gopalakrishnan, Bo YangAbstract:This paper discusses subdrain Outlet Condition and performance in Iowa roadways. A forensic test plan was developed and executed during wet summer Conditions covering over 230 and 120 drain Outlet locations of the newly constructed jointed plain concrete pavement (JPCP) and the hot mix asphalt (HMA) over JPCP sites, respectively. The tufa formation (i.e., calcium carbonate deposits) is the primary cause of drainage Outlet blockage in newly constructed JPCP sites using recycled portland cement concrete (RPCC) as a subbase material. Lesser tufa formation from the use of RPCC base in JPCP was observed with the: (a) use of plastic Outlet pipe without the gate screen type rodent guard, (b) use of blended RPCC and virgin aggregate materials. The observations of moisture-related surface distresses nearby blocked drainage Outlet locations in HMA over JPCP indicates that compromised drainage Outlet performance could accelerate the development of moisture-related distresses in HMA over JPCP.
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Evaluating Roadway Subsurface Drainage Practices - Phase II
2015Co-Authors: Halil Ceylan, Robert F. Steffes, Kasthurirangan Gopalakrishnan, Sunghwan Kim, Bo YangAbstract:Well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). The recently completed Iowa Highway Research Board (IHRB) project TR-643 provided extensive insights into Iowa subsurface drainage practices and pavement subdrain Outlet performance. However, the project TR-643 (Phase I) forensic testing and evaluation were carried out in a drought year and during the fall season in 2012. Based on the findings of IHRB Project TR-643, the Iowa DOT requested an expanded Phase II study to address several additional research needs: evaluate the seasonal variation effects (dry fall 2012 versus wet spring/summer 2013, etc.) on subdrain Outlet Condition and performance; investigate the characteristics of tufa formation in Iowa subdrain Outlets; investigate the Condition of composite pavement subdrain Outlets; examine the effect of resurfacing/widening/rehabilitation on subdrain Outlets (e.g., the effects of patching on subdrain Outlet performance); and identify a suitable drain Outlet protection mechanism (like a headwall) and design for Iowa subdrain Outlets based on a review of practices adopted by nearby states. A detailed forensic test plan was developed and executed for inspecting the Iowa pavement subdrains in pursuit of fulfilling the Phase II study objectives. The observed Outlets with blockage and the associated surface distresses in newly constructed jointed plain concrete pavements (JPCPs) were slightly higher during summer 2013 compared to fall 2012. However, these differences are not significant. Less tufa formation due to the recycled portland cement concrete (RPCC) base was observed with (a) the use of plastic Outlet pipe without the gate screen–type rodent guard and (b) the use of blended RPCC and virgin aggregate materials. In hot-mix asphalt (HMA) over JPCP, moisture-related distress types (e.g., reflection cracking) were observed more near blocked drainage Outlet locations than near “no blockage” Outlet locations. This finding indicates that compromised drainage Outlet performance could accelerate the development of moisture-related distresses in Iowa composite pavement systems.
