Pressure Loss Ratio Research Articles

Multi-objective optimization of supersonic separator for gas removal and carbon capture using three-field two-phase flow model and non-dominated sorting Genetic Algorithm-II (NSGA-II)

Supersonic separator (SS) is an efficient technology used for gas removal and carbon capture. To enhance its performance, many researchers have studied its structure; however, existing studies have primarily used traditional CFD models for single-objective structural optimization of the separator’s separation performance. However, in the SS, separation efficiency and pressure-loss ratio are the most important and conflicting performance parameters, and evaluating separation performance in isolation from either one is incomplete. Therefore, in this paper, a gas–liquid two-phase three-field CFD model considering a liquid film is firstly established, and then this model is combined with the non-dominated Sorting Genetic Algorithm-II (NSGA-II) for multi-objective optimization of the coupled multiple structural parameters with the objective of the separation efficiency and pressure-loss ratio. The results indicated that the maximum relative errors between simulated and predicted values for the four Pareto optimal solutions in computing pressure loss ratio and separation efficiency are 5.4% and 5.3%, respectively, with these solutions achieving the maximum reduction in pressure loss ratio of 28.3% at the same 90% separation efficiency compared to the original structure.

Y-ring’s mechanical behavior during sealing cap’s assembly process based on the pressure core sampling for seafloor drill

In order to expand the application of seafloor drill in the field of natural gas hydrate exploration, a pressure core sampling technical scheme suitable for seafloor drill operating conditions is proposed. The assembly action principle of sealing cap in the scheme is introduced. The factors affecting the sealing reliability during the assembly of the sealing cap are analyzed. A geometric model of the sealing structure is established. The variation regular of the max von Mises stress is discussed during the assembly process. The relationship between the assembly parameters and the maximum von Mises stress is clarified. The parameters optimization scheme is proposed and verified by experiments. The results show that: the Y-ring’s maximum von Mises stress variation trend has five stages and the maximum von Mises stress produces peak stress in the rising stage, excessive interference and friction factor make the peak appear in the fluctuation stage in advance, the lead angle within 10°–30° has little effect on the maximum von Mises stress peak value, the axial displacement speed affect the growth rate and amplitude of the maximum von Mises stress curve, the drilling tool’s pressure loss ratio is within 8% under the 10–40 MPa after 6 h.

Numerical Analysis of Temperature Separation and Exergy Analysis of a Dual-Inlet Section Convergent Vortex Tube

Abstract The present study deals with the optimization of a counter flow vortex tube with a straight single intake section, straight dual intake section, and convergent dual intake section vortex tube model for different physical and flow parameters. The effect of variation of convergent angles (θ), intake pressures, and a number of inlet sections on the flow separation has been analyzed in the present study. ANSYS FLUENT software has been used to simulate flow considering air as a working fluid. Moreover, some physical and flow parameters such as intake pressure, cold temperature gradient (ΔTc), pressure loss ratio, cold mass fraction, and hot temperature gradient (ΔTh) have been studied to optimize the vortex tube. The coefficient of performance has been compared for various convergent angles from 1 deg to 5 deg. The result has been validated by the experimental and numerical studies performed previously. Moreover, the exergy analysis has also been conducted for the convergent dual intake vortex tube for various convergent angles, cold mass fraction, and intake pressure. The study concludes that the convergent vortex tube having a dual inlet section, 5-deg angle shows the optimized result for all the mass fraction and intake pressure, compared to a straight single intake section and straight dual intake vortex tube.

Effect of diffuser on condensing flow in nozzles for carbon capture

Previous work investigated the possibility of using Laval nozzles for carbon capture. However, the rapid expansion in nozzles changes the pressure energy to kinetic energy, which resulted in low pressure at the nozzle exit. To reuse this energy, a diffuser is installed at the end of the nozzle. Therefore, a model is established to describe the CO2 condensing flow in flue gas, and the influence of diffuser and flue gas saturation on the carbon capture is analyzed by CFD. The results show that Wilson point moves upstream by increasing the saturation degree of flue gas. When the saturation increases from 0.19 to 0.24, the limit saturation required for condensation decreases by 0.21, and the liquid CO2 content and droplet size increase by 36.4% and 81.5%, respectively. If a diffuser with a smaller expansion angle or length wants to achieve the same carbon capture effect as a diffuser with a larger expansion angle or length, the pressure energy should be paid. On the contrary, under the premise of the same pressure loss ratio, the diffuser with smaller expansion angle or length has poor carbon capture effect.

Investigation of novel passive methods of generation of swirl flow in supersonic separators by the computational fluid dynamics modeling

In this paper, three passive methods for the generation of swirl flow in the supersonic separator (3S) were investigated, and their structures were optimized by computational fluid dynamics (CFD) modeling. The influence of the structural and operational parameters on the dew point depression, phase envelope diagram, rate of natural gas liquid (NGL) recovery, and separation efficiency have also been evaluated. The collection efficiency was significantly improved for the nozzle equipped with the passive swirler compared with the simple nozzle. The selection of passive swirler type played a crucial role in the natural gas liquefaction and separation. The side injected swirler, and serpentine swirler showed the most significant improvement in separation efficiency than the U-turn swirler. For the side injected swirler at the optimum injection angle, the maximum collection efficiency was about 89% at the pressure loss ratio (PLR) of 0.2. Besides, the simulation results demonstrated that for the serpentine 3S, with the increase in serpentine twist number, the highest improvement on the collection efficiency of the investigated nozzle was obtained. In addition, it was observed that, when the convergent section profile was designed according to the Witoszynski line-type, a larger refrigeration zone was obtained than other considered profiles.

Experimental Research on the Effects of Suction Ports on Twin Screw Expander Performance

An organic Rankine cycle (ORC) system is an efficient technology for generating power from low-grade thermal sources. Twin screw expanders are widely used in ORC systems. Pressure loss caused by a suction port influences the suction process and the system performance. In this paper, the effects of suction ports on twin screw expander performance are experimentally investigated. The pressure loss value of R245fa is measured under different working conditions, and its effects on the suction coefficient are discussed. Results show that a lower rotation speed results in a lower pressure loss value and a higher suction coefficient under certain working conditions. Increasing the suction pressure leads to a higher pressure loss value but a lower pressure loss ratio. Discharge pressure has little effect on the suction process.

Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

The aim of this work is to numerically analyse fluid flow and heat transfer characteristics in a crossflow air-to-water fin-and-tube heat exchanger (FTHEX) by implementing two configurations of delta-winglet type vortex generators at the air side: delta-winglet upstream (DWU) and delta-winglet downstream (DWD). The vortex generators are mounted on a fin surface and deployed in a “common flow up” orientation. The effects of attack angles of 15°, 30° and 45° on air-side heat transfer and pressure drop were examined. Since the implementation of the full-size model would involve large numerical resources, the computational domain is simplified by considering a small segment in the direction of water flow. The fully developed temperature and velocity boundary conditions were set at the water inlets. To validate the defined mathematical model and numerical procedure, measurements have been performed on a plain FTHEX. The air side Reynolds number, based on hydraulic diameter, was in the range of 176 ≤ ReDh ≤ 400 and water side Reynolds number, based on inner tube diameter, was constant Redi = 17,065. The results have shown that the highest increase in the Colburn factor j (by 11–27%) and reduction in the air-side thermal resistance fraction (from 78.2–76.9% for ReDh = 176 to 76–72.4% for ReDh = 400) is achieved by using the DWD configuration with attack angle 45°. In addition, the overall heat transfer coefficient is improved by up to 15.7%. The DWD configuration with the attack angle 30° provides the greatest improvement in the heat transfer to pressure loss ratio, 5.2–15.4% over the range of ReDhstudied.

Evaluation of influential parameters for supersonic dehydration of natural gas: Machine learning approach

The supersonic dehydration of natural gas is gaining more attention due to its numerous advantages over the conventional natural gas dehydration technologies. However, supersonic separators have seen minimal field applications despite the multiple benefits over other gas dehydration techniques. This has been mostly attributed to the uncertainty in ascertaining the design and operating parameters that should be monitored to ensure optimum dehydration of the supersonic separation device. In this study, the decision tree machine learning model is employed in investigating the effects of design and operating parameters (inlet and outlet pressures, nozzle length, throat diameter, and pressure loss ratio) on the supersonic separator performance during dehydration of natural gas. The model results show that the significant parameters influencing the shock wave location are the pressure loss ratio and nozzle length. The former was found to have the most significant effect on the dew point depression. The dehydration efficiency is mainly dependent on the pressure loss ratio, nozzle throat diameter, and the nozzle length. Comparing the machine learning model-accuracy with a 1-D iterative model, the machine learning model outperformed the 1-D iterative model with a lower mean average percentage error (MAPE) of 5.98 relative to 15.44 as obtained for the 1-D model.

Structural optimization and characteristics of a novel single-ended pressure vessel with inside and outside tubes

A new type of inside and outside tubes differential pressure flowmeter was designed. The throat structure and single-end pressure tapping method is proposed. Three-dimensional numerical simulation is used for structural optimization. The experimental prototype is processed and calibrated in real-time. It was found that the differential pressure values of the new flowmeter was 3.4 times higher and pressure loss ratio only 20% of the original flowmeter in forward flow, while 2.6 times higher and pressure loss ratio only 25% in reverse flow. The sensitivity and energy efficiency of the novel flowmeter is shown to be significantly improved.

Investigation of the Effects of Different Working Fluids on Compressor Cascade Performance

The compressor of closed Brayton cycle (CBC) plant operating with working fluid other than air is a vital element of the energy conversion unit. However, due to insufficient understanding of the influence of the physical properties of working fluids on the performance of the compressor, the actual working conditions and design conditions of the compressor’s performance deviate greatly. In this paper, the objective is to analyze the influence mechanism of the physical properties on the performance of the cascade of compressor (static pressure ratio and total pressure loss coefficient). Therefore, the impact of a specific heat ratio on the performance of the compressor cascade is studied utilizing carbon dioxide (γ = 1.29), air and carbon monoxide (γ = 1.4), argon and helium (γ = 1.667). Moreover, the relationships of static pressure ratio and total pressure loss coefficient with physical properties of the working fluids are analyzed in the compressor cascade. It is established that a higher specific heat ratio fluid gives a higher coefficient of total pressure loss and static pressure ratio in contrast to smaller specific heat ratio at matching inlet Reynolds number and Mach number.

Using spiral channels for intensification of cooling process in an innovative liquid block operated with a biologically produced nanofluid: First and second law analyses

The hydrothermal and irreversibility characteristics of an eco-friendly graphene-based nanofluid within a novel spiral heat sink are numerically investigated. The effects of heat sink material, nanoparticle weight fraction (φ), and Reynolds number (Re) are studied. Some comparisons are made between the spiral heat sink and two ordinary heat sinks, namely serpentine and base-plate heat sinks. The results indicate that the serpentine heat sink shows a somewhat better heat transfer ratio, but the corresponding pressure loss ratio is exceptionally high. The spiral heat sink is able to improve the heat transfer with reasonable pressure drop intensification and smaller irreversibility than the serpentine one. It is found that the main irreversibility occurs because of the temperature gradients, while the irreversibility caused by the friction is inconsequential. Higher particle concentration diminishes the temperature gradients and leads to smaller thermal irreversibility. For instance, at Re = 1000 and spiral heat sink made of copper, the thermal entropy generation of the nanofluid diminishes by 12.6 % when φ rises by 0.1 %. Furthermore, employing the copper heat sink yields a flatter temperature profile and declines the thermal entropy production, such that using the nickel leads to 41.4 % higher thermal entropy production than the copper at Re = 1000 and φ = 0.1 %.

Experimental investigation of optimal location of flow straightener from the aspects of power output and pressure drop characteristics of a thermoelectric generator

This study addresses the combined effects of the location and porosity of a flow straightener on the waste heat recovery performance of a thermoelectric generator (TEG). An exhaust gas channel was built for the flexible placement of a flow straightener with varying porosity in the range of 0.121–0.516 at five different locations. Customized thermoelectric modules were placed between the exhaust gas channel and two coolant channels for waste heat recovery. A diesel engine releases the exhaust gas flow into the exhaust gas channel of the TEG placed in the middle of the tail pipe. Experimental results showed that a TEG design in which a flow straightener is positioned near the inlet of the TEG needs to be avoided because of a low power output to pressure loss ratio. The net power output, energy conversion efficiency, and pressure drop characteristics were enhanced as the location of flow straightener moved rearward of the TEG. A friction factor correlation was also proposed for predicting pressure drop characteristics of TEGs equipped with a flow straightener to improve their practicality in industry and engineering fields.

A modified model for wet gas flowrate measurement considering entrainment downstream of a cone meter

To develop a reliable wet gas flowrate measurement model, the relationships between pressure drop characteristics and entrainment downstream of the cone are investigated experimentally. The equivalent diameter ratio of the cone is 0.45. The experimental fluids are air and tap water with XLM in the range of 0–0.3. The two-phase mass flow coefficient and pressure loss ratio are employed to establish the measurement model. The piecewise characteristics of pressure loss ratio are disclosed innovatively, which is explained by the different intensity of entrainment downstream of cone caused by gas-liquid jetting. A simplified method for evaluating the degree of entrainment is proposed to facilitate the establishment of the modified measurement model. Under the present experimental conditions, the relative error of liquid fluctuates within ±20% when XLM is larger than 0.02, and the relative error of gas flowrate is within ±5%. Compared with the model without piecewise consideration, the relative error of the liquid flowrate of the modified model reduces obviously under low wetness conditions (0.02<XLM<0.1). The modified measurement model provides a reliable and cost-effective technology for wet gas flowrate measurement.

Comparison of throttle devices to measure two-phase flowrates of wet gas with extremely-low liquid loading

The online measurement of wet gas with extremely-low liquid loading (Lockhart-Martinelli parameter lower than 0.02) remains a challenge. In this study, three types of throttle devices, Venturi, orifice plate and cone, are compared experimentally with air-water two-phase flow in a horizontal pipe of inner diameter of 50 mm. High-precision correlations are established to measure the gas and liquid flowrates via a single throttle device. Results show that the two-phase mass flow coefficient (K) of the three throttle devices all increase linearly with the liquid densiometric Froude number and the K correlations are established respectively to correct the gas mass flowrate deviation. The pressure loss ratio (δ) for Venturi is sensitive and monotonous to the liquid loading, which contributes to the high accuracy of liquid flowrate measurement. By incorporating the K correlations, both the gas and liquid mass flowrates can be predicted precisely. The relative error of the gas mass flowrate predicted by the Venturi is within ±2.0% at 95% confidence level, and that of the liquid mass flowrate is within ±15% at 90% confidence level.

Novel fluid diode plate for use within ventilation system based on Tesla structure

For building ventilation, it is often necessary to create airflow in a particular direction and prevent the backflow of pollutants and unnecessary expenditure of energy. At present, most check devices can only be used in small areas, such as pipelines, which cannot fully meet the needs of building ventilation systems. Based on the principle of a Tesla structure, this paper proposes a new type of fluid diode plate (FDP) without moving parts, which can be infinitely extended in terms of area and is suitable for various ventilation environments. A series of experiments and numerical simulations were performed to test the check effect of this FDP under different influencing factors. Two evaluation indices, the pressure loss ratio (FFDP) and minor loss coefficient (ζ), were used to evaluate the flow pressure losses in both forward and reverse directions for the FDP. The results showed that the flow pressure loss in both directions for the FDP were very different. For the fluid diode plate with 4 flow loops, the pressure loss of reverse flow could be more than 6 times that of a forward flow. The pressure loss of a forward flow showed a little increase compared with an orifice plate with the same porosity. Moreover, the check effect of the FDP increased with the inflow velocity and reached a stable value when the flow in the FDP channel became fully turbulent. In future research, the check effect of the FDP will be further improved by further optimizing the structure.

Numerical Investigation of Mixing Characteristic for CH4/Air in Rotating Detonation Combustor

The mixing process of fuel and oxidizer is a very critical factor affecting the real operating performance of non-premixed rotating detonation combustor. In this paper, a two-dimensional numerical study is carried out to investigate the flow and mixing characteristics of CH4/air in combustor with different injection structures. On this basis, the effect of CH4/air mixing on the critical ignition energy for forming detonation is theoretically analyzed in detail. The numerical results indicate that injection strategies of CH4 and air can obviously affect the flow filed characteristic, pressure loss, mixing uniformity and local equivalence ratio in combustor, which further affect the critical ignition energy for forming detonation. In the study for three different mass flow rates (the mass flow rates of air are 12.01 kg/s,8.58 kg/s and 1.72 kg/s, respectively), when air is radially injected into combustor (fuel/air are injected perpendicular to each other), although the mixing quality of CH4 and air is improved, the total pressure loss is also increased. In addition, the comparative analysis also shows that the increase of mass flow rate of CH4/air can decrease the difference of the critical ignition energy for forming detonation at a constant total equivalence ratio. The ignition energy decreases with the decrease of the total flow rate and then increases gradually.

Flow Characteristics of a Solid-Liquid Non-Newtonian Fluid for Directional Drilling.

As petroleum technology has developed, both slim-hold and directional drillings have developed as well. Although these techniques are currently being utilized in industry, the literature on them is still insufficient. In the present study, the friction coefficient, pressure loss, and particle transport ratio pertaining to these methods are measured. It is determined that these quantities are influenced by the particle size and concentration within the flow, the pipe rotation, the flow volume, and the inclination of the annulus. The study is performed on a concentric annulus with a variable inclination; the ratio of the inner to outer pipe radius is 0.7, homogeneous, 2-mm sand is used, and both experimental and numerical results are presented for fully developed solid-liquid two-phase flows of non-Newtonian fluid with different CMC solutions. It is determined that the transport ratio and pressure loss are both directly related to the drilling efficiency in directional drilling.

Non-Newtonian fluid flow dynamics in rotating annular media: Physics-based and data-driven modeling

A thorough understanding and accurate prediction of non-Newtonian fluid flow dynamics in rotating annular media are of paramount importance to numerous engineering applications. This is in particular relevant to oil and gas industry where this type of flow could occur during, e.g., drilling, well completion, and enhanced oil recovery scenarios. Here, mathematically we report on physical-based (numerical) and data-driven (intelligent) modeling of three-dimensional laminar flow of non-Newtonian fluids driven by axial pressure gradient in annular media that consist of a coaxially rotating inner cylinder. We focus on the dynamics of pressure loss ratio (PLR)—the ratio of total pressure loss in presence of rotation to that in stationary condition. We develop a novel and computationally efficient machine-learning based predictive model based on a Least Square Support Vector Machine (LSSVM) optimized with a Coupled Simulated Annealing (CSA) algorithm, which is trained and tested by 730 experimental data collected for this study. We then perform numerous CFD simulations governed by Navier-Stokes set of equations, which correspond to each of the experimental cases. Comparing the results with those obtained from a widely used empirical correlation for PLR, we find that the both of our numerical and machine-learning based models are more accurate and present a larger applicability domain. The predictive LSSVM model enjoys a supervised learning paradigm and leads to the highest accuracy, while the physically originated CFD approach captures more consistently the nonlinear behavior of PLR versus key system features. Following the validation of our models, we study the less understood effects of fluid viscosity, axial velocity and rotational velocity on PLR dynamics. We employ a dimensionless parameter analogous to Strouhal number and identify specific regimes where PLR shows a distinct behavior. Our study elucidates the role of shear-thinning effect and its interplay with inertial forces on the dynamical behavior of pressure loss (ratio) in rotating yield-power-law fluids.

Pressure drop of wet gas flow with ultra-low liquid loading through DP meters

The most common method to predict the gas and liquid flow rates in a wet gas flow simultaneously is to use dual pressure drops (dual-DPs) from two or even one single DP meter. In this paper, the metering mechanism of applying dual-DPs were overviewed. To fully understand the response of DP meters to wet gas flows, the pressure drops of wet gas flow with ultra-low liquid loading through three typical DP meters were experimentally investigated, including an orifice plate meter, a cone meter and a Venturi meter. The equivalent diameter ratio is 0.45. The experimental fluids are air and tap water. The pressure is in the range of 0.1–0.3 MPa and the Lockhart-Martinelli parameter (XLM) is less than approximately 0.02. The results show that the upstream-throat pressure drop, the downstream-throat pressure drop and the permanent pressure loss of individual DP meters have unique response to liquid loading. The upstream-throat pressure drop of the orifice plate meter decreases at first and then increases as the liquid loading increases, while that of the cone meter and the Venturi meter increase monotonically. The non-monotonicity of the pressure drop for the orifice plate meter can be attributed to the flow modulation of trace liquid. The downstream-throat pressure drops of all the three test sections decrease at first and then increase. The reason is that the liquid presence in a gas flow increases the downstream friction and vortex dissipation. The permanent pressure loss of the orifice plate meter also shows non-monotonicity. To avoid non-monotonicity, the pressure loss ratio is introduced, which is defined as the ratio of the permanent pressure loss to the upstream-throat pressure drop. Results show that the pressure loss ratio of the Venturi meter has the highest sensitivity to the liquid loading.

Research on the measuring characteristics of a new design butterfly valve flowmeter

Flowmeters and control valves are important components of flow measurement and control in heating, ventilating, and air conditioning (HVAC) system, which directly or indirectly impact building room comfort and energy costs. Valves as resistance components produce differential pressure which in turn can be used for flow measurement. This paper studies the function among valve opening position, pressure difference and flowrate of a new designed butterfly valve. The flow model of the butterfly valve is established based on the Bernoulli equation, the discharge coefficient C under different valve opening conditions are studied by CFD simulations and verified by experiments. The simulation results show that the discharge coefficient C reached a stable value of 0.67–0.70 as Reynolds number exceeded 5000, and the permanent pressure loss ratio is range from 0.95 to 0.37 corresponding to opening range from 10° to 70°. The correctness of the simulation results of C is verified by experiments, in which C is about 0.60. With the corrected values obtained from experiments, the simulation results are instructive to practice. The new designed butterfly valve flowmeter can be used efficiently in HVAC system, especially in variable air volume (VAV) air conditioning system. And the work of this paper offers a reference for other types of valve flowmeters in fluid control processes.