Port Diameter Research Articles

Geometric correlation of discharge coefficients for discharge valve system in rolling piston rotary compressor

In this study, a geometric correlation for discharge coefficient of the discharge valve system of a rolling piston compressor was proposed to predict the discharge mass flow rate. A computational fluid dynamics simulation was conducted and verified with experimental data to derive the correlation of the discharge coefficient with variations in the valve lift, valve diameter, discharge port diameter, and upstream and downstream pressure ratio of a discharge port. The discharge coefficient was dominantly affected by the geometric parameters, whereas the pressure ratio was not a dominant factor. The derived correlation, which could be applied to a wide operational range for a discharge valve system, was adopted in a compressor simulation for a rolling piston rotary compressor. The simulation results showed good agreement with experimental data. The cooling capacity, input power, and energy efficiency ratio (EER) were predicted within 10 %, and the trends agreed well over wide operating ranges for the compression ratio and compressor speed.

Heat transfer investigations on impinging flame jets of a multi-port convex burner

Multi-port curved surface burners are used in industrial boilers, preheating of large diameter pipes, textile industries, preheating of cylindrical metal billets and other industrial applications. The present work reports the heat transfer characteristics of convex shaped burner with 49 inline ports arranged in an array of 7 each. The methane-air premixed flame jets are impinged on the concave surface of a curved plate placed with radial spacing of 12 mm. Two different burners with port diameters of 2 mm and 3 mm with pitch to diameter ratio of 2.33 are used. The flame jet is studied for Reynolds number (Re) ranging from 75 to 200 and equivalence ratio of 0.9–1.5. The characterisation is done by impinging the pre-characterised air jets of various flow rates on the rear surface and capturing the wall temperature. The wall temperature is analysed to get the distributions of Nusselt number and effectiveness. The variation of coefficient of variance of Nusselt number, average Nusselt number and thermal efficiency is reported in the present work. The Nusselt number and effectiveness distributions increase with the increase in mixture Reynolds number. For a fixed mixture Reynolds number, the optimum heat transfer is obtained for stoichiometric flame. The thermal efficiency and average heat transfer of 2 mm port diameter is observed to be 18–25% higher as compared with burner with port diameter of 3 mm. Correlations are developed to predict the average Nusselt number, average effectiveness, coefficient of variance (COV) of Nusselt number distribution and thermal efficiency.

Effect of R Ratio on Performance of Injection-Pressure-Operated Gas-Lift Valves

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 186110, “Effect of R Ratio on Performance of Injection-Pressure-Operated Gas-Lift Valves,” by K.L. Decker, SPE, Decker Technology. The paper has been peer reviewed and published in the February 2018 SPE Production & Operations journal. An injection-pressure-operated gas-lift valve’s closing force comes from a nitrogen charge acting on the effective area of the bellows (Ab) or a spring force. The opening force is the production pressure acting on the area of the port (AP) plus the injection pressure acting on the bellows effective area minus the area of the port. The ratio AP / Ab is referred to as the R ratio, which traditionally has been considered constant for every valve of the same type. The actual R ratio, however, is not a constant. This paper describes the consequences of using an assumed R ratio in a gas-lift design that is not the same as the actual R ratio of the valve. Introduction The force from a spring or a nitrogen-charged dome acting on the effective area of the bellows creates a contact area be-tween the ball and port. When using a square-edge seat, this contact area is de-fined by an outer seal diameter and the port diameter. The contact area is an annular ring on the surface of the port where neither production nor annulus pressure is acting. The width of this area changes with the valve-dome pressure, strength of port material, port size, and lap band. Fig. 1 shows a typical nitrogen-charged gas-lift valve. For chamfered ports, the ball makes contact on the chamfered surface. In this case, an outer sealing area and an inner sealing area exist because of the lap band. The outer diameter of the lap band defines the annulus-pressure sealing area. The inner diameter of the lap band defines the production-pressure sealing area. The R ratio can be obtained by an equation that uses properties of the valve (please see the complete paper for the equation). It generally is not possible to measure the seal area or the lap-band width directly; therefore, the R ratio determined by means of the equation should be considered an estimate. The most reliable and accurate method of determining the R ratio is by means of pressure testing. Both opening- and closing-pressure tests must be performed. Please see the complete paper for the equation to calculate R ratio using the opening and closing pressures. Discussion The opening pressure is commonly used as the basis for preparing a valve for service in a well. The reason is the ease with which it can be tested and the idea that the valve acts as a backpressure regulator. The gas-lift technician strives to keep the opening pressure within ±5 psi of what is requested. The dome pressure is normally charged to a pressure slightly higher than intended. The opening pressure is adjusted by lightly tapping the core valve of the nitrogen dome, releasing a small amount of nitrogen until the desired pressure is achieved. The practical ability of adjusting a very high pressure to an accuracy of ±5 psi by the tap of a hammer on the core valve is generally not within the skill set of gas-lift technicians.

Design of Multiport Grain with Hydrogen Peroxide Hybrid Rocket

A high length-to-diameter ratio of a rocket leads to unstable flight performance, affects structural loads, and makes a high dry mass of the rocket with a diameter constraint. To improve the volumetric efficiency of the fuel, a multiport design with optimum ratio was considered by adjusting the number of ports and diameter while decreasing the length. To optimize the ratio, the final port diameter was predicted, and the arrangement of the ports to prevent the merging of the ports was considered. The length of the fuel content was reduced to 30% when the number of ports was 14, compared with the single-port fuel. The experimental result showed a slight decrease in the ratio with the increased number of ports and reduced length of fuel at the same oxidizer mass flow rate, and the characteristic velocity efficiency increased. Peak-to-peak pressure amplitude in the prechamber was calculated to compare the effect on the amplitude of the multiport fuels. The application of the simple cylindrical multiport design reduces the length-to-diameter ratio of the hybrid thruster and improves rocket combustion performance.

Experimental investigation on the effect of swirling flow on combustion characteristics and performance of solid fuel ramjet

Solid-fuel ramjet converts thermal energy of combustion products to a forward thrust without using any moving parts. Normally, it uses air intake system to compress the incoming air without swirler. A new design of swirler has been proposed and used in the current work. In this paper, a series of firing tests have been carried out to investigate the impact of using swirl flow on regression rate, combustion characteristics, and performance of solid-fuel ramjet engines. The influences of swirl intensity, solid fuel port diameter, and combustor length were studied and varied independently. A new technique for determining the time and space averaged regression rate of high-density polyethylene solid fuel surface after experiments has been proposed based on the laser scan technique. A code has been developed to reconstruct the data from the scanner and then used to obtain the three-dimensional distribution of the regression rate. It is shown that increasing swirl number increases regression rate, thrust, and characteristic velocity, and, decreases air-fuel ratio, corner recirculation zone length, and specific impulse. Using swirl flow enhances the flame stability meanwhile negatively affected on ignition process and specific impulse. Although a significant reduction of combustion chamber length can be achieved when swirl flow is used. Power fitting correlation for average regression rate was developed taking into account the influence of swirl number. Furthermore, varying port diameter and combustor length were found to have influences on regression rate, combustion characteristics and performance of solid-fuel ramjet.

Analysis and comparison of dynamic behavior of heat exchangers for direct evaporation in ORC waste heat recovery applications from fluctuating sources

Organic Rankine Cycle (ORC) is one of the most prominent technologies for power generation from waste heat sources. Due to their nature, as residual energy from an upstream process, waste heat sources typically present a fluctuating behavior that makes the recovery of the waste heat a challenging task.Direct evaporation from the waste heat carrier has gained substantial interest, especially on volume and weight sensitive applications where the introduction of an additional intermediary thermal oil heat exchanger can hinder the feasibility of the system. Because of the highly dynamic operation of direct evaporators under fluctuating waste heat sources, it is important to consider the thermal response time of the evaporator already at the design stage.In this paper, a systematic analysis and comparison of the dynamic response of two types of ORC evaporators for direct heat transfer between an exhaust gas and the organic working fluid is performed. Based on detailed dynamic models and simulations, maps are built to highlight in a generalized, compact and systematic way the dependence of the thermal response time of the evaporators on the geometric design and boundary conditions and its implications on the weight, volume and pressure drops. The analysis and application of the methodology to diesel engines long haul duty trucks, shows that fin and tube evaporators with large tube diameters and small cross-sectional areas of the exhaust side are the preferred option for high thermal inertia design, while louver fin multi-port flat tubes evaporators with large port diameters are better for fast response, despite the high pressure drops.

A closed-form analytical model for predicting 3D boundary layer displacement thickness for the validation of viscous flow solvers

A closed-form analytical model is developed for estimating the 3D boundary-layer-displacement thickness of an internal flow system at the Sanal flow choking condition for adiabatic flows obeying the physics of compressible viscous fluids. At this unique condition the boundary-layer blockage induced fluid-throat choking and the adiabatic wall-friction persuaded flow choking occur at a single sonic-fluid-throat location. The beauty and novelty of this model is that without missing the flow physics we could predict the exact boundary-layer blockage of both 2D and 3D cases at the sonic-fluid-throat from the known values of the inlet Mach number, the adiabatic index of the gas and the inlet port diameter of the internal flow system. We found that the 3D blockage factor is 47.33 % lower than the 2D blockage factor with air as the working fluid. We concluded that the exact prediction of the boundary-layer-displacement thickness at the sonic-fluid-throat provides a means to correctly pinpoint the causes of errors of the viscous flow solvers. The methodology presented herein with state-of-the-art will play pivotal roles in future physical and biological sciences for a credible verification, calibration and validation of various viscous flow solvers for high-fidelity 2D/3D numerical simulations of real-world flows. Furthermore, our closed-form analytical model will be useful for the solid and hybrid rocket designers for the grain-port-geometry optimization of new generation single-stage-to-orbit dual-thrust-motors with the highest promising propellant loading density within the given envelope without manifestation of the Sanal flow choking leading to possible shock waves causing catastrophic failures.

The impact of inflow velocity on thermal stratification in a water storage tank

The paper presents the analysis of thermal processes occurring in thermal energy storage tanks used for heating hot water systems. Three-dimensional Computational Fluid Dynamics (CFD) methods were used. The standard buffer charging stage was modelled for three tank inlets’ diameters DN20, DN40 and DN80. With a constant charging water flow and temperature the port diameter affects inlet velocity, heat storage dynamics, thermal stratification and thermocline thickness in storage tank. The smallest diameter causes unfavourable thermal mixing of accumulated water, and the largest diameter supports thermal stratification

Thermal-hydraulic optimization of plate heat exchanger: A multi-objective approach

In the present work, thermal-hydraulic optimization of plate heat exchanger is investigated. Maximization of overall heat transfer coefficient and minimization of total pressure drop considered simultaneously as objective functions during multi-objective optimization. Multi-objective heat transfer search algorithm is applied to obtain a set of Pareto-optimal points for conflicting objectives. An application example of plate heat exchanger is presented to identify conflicting thermal-hydraulic behaviour. Eight geometric design variables which include port diameter, a horizontal distance of ports, a vertical distance of ports, length of compact plates, plate thickness, chevron angle, enlargement factor and number of plates are investigated for optimization. Decision-making method is adopted to select the final optimal solution from Pareto points. Distribution of each design variables corresponding to Pareto optimal points is presented to identify its effect on conflict behaviour of the thermal-hydraulic function. The sensitivity of design variables to the optimized value of the thermal-hydraulic function is also presented and discussed. Finally, the validation of the present work is carried out by experimentation on plate heat exchanger. The comparative results revels that 8.87% deviation in overall heat transfer coefficient and 9.96% deviation in total pressure drop are observed between optimization and experimental results.

Evaluation of impacts of cooling tower design properties on the near-field environment

In a nuclear power plant, ultimate heat sink (UHS) and circulating water system (CWS) cooling towers both ultimately remove heat from the essential service water system, main condenser, and non-essential service water system during all operation modes including accident conditions. Since the visible plume from the cooling tower has an adverse effect on the environment, however, an environmental impact assessment of the cooling tower is required for the construction of a new nuclear power plant. In this study, the environmental impact of UHS and CWS cooling towers of an APR1400 standard design plant was assessed for the purpose of testing and demonstrating the recently-updated SACTI2 model. Because the site for the APR1400 standard design plant had not been decided, one-year meteorological data from the Spokane International Airport weather station, WA, USA, were used as hypothetical input data for the environmental impact assessment. The quantitative effect of cooling tower design changes on the environment was analyzed in terms of index-value dispersion area (AD) and dispersion ratio (δ) for nine environmental assessment indexes. Scenario test conditions were varied by changing cooling tower arrangement, distance between cooling towers, length of cooling tower, exit port height, exit port diameter, the number of exit ports, heat load per tower, and air flow rate per tower.

Numerical investigation of spray characteristics of an air-blast atomizer with dynamic mesh

In this paper, a numerical simulation of an air-blast atomizer using OpenFOAM software is performed to evaluate the effects of geometrical parameters and flow conditions on spray characteristics. The method used in this numerical simulation is discrete droplets tracking-based Eulerian–Lagrangian approach. In the primary breakup of liquid jet modeling, the Rosin–Rammler distribution function and in modeling the secondary breakup phase, the Kelvin–Helmholtz, Rayleigh–Taylor (KHRT), and the TAB models are used and compared. The simulation results show that the KHRT model has reasonable prediction of atomization characteristics and, at a specific Weber number, SMD increases with raising liquid port diameter. However, in high Weber number, this parameter has little effect on SMD. In addition, gas–liquid injection angle has an insignificant effect on the penetration depth of spray, while increasing the liquid port diameter decreases it considerably.

Vortex Formation during Draining from Cylindrical Tanks: Effect of Drain Port Eccentricity

AbstractThis paper reports an experimental study on the combined effect of drain port eccentricity and port diameter on air core vortex formation in a cylindrical tank with a rotating liquid column...

Transient Computational Thermofluid-Dynamic Simulation of Hybrid Rocket Internal Ballistics

A computational thermofluid-dynamic model of hybrid rocket internal ballistics is developed. Numerical simulations of the flowfield in a laboratory small-scale hybrid rocket motor, operated with gaseous oxygen and high-density polyethylene propellants, are carried out with the aim of predicting the solid fuel regression rate experimentally achieved with two different oxidizer injectors. The fuel regression rate is the main parameter for the hybrid rocket design. Here, it is calculated with a detailed gas/surface interface characterization based on local mass and energy balances. The combustion of oxygen and gaseous ethylene injected from the fuel wall is modeled by means of the probability-density-function approach coupled to chemical equilibrium. Two oxidizer-injection configurations, which generate either a two-dimensional axially symmetric or three-dimensional flowfield, are analyzed. The local regression rate is evaluated along both the fuel grain axis and inner circumference in the three-dimensional case, as well as at several stages in the firing, by updating the local port diameter, which is thus not assumed constant. Data retrieved from three firing tests are compared with the numerical results, revealing good agreement between both the average regression rates (maximum deviation less than 5%) and the fuel consumption axial profiles (with maximum deviation of 14%).

CFD simulations of compressed air two stage rotary Wankel expander – Parametric analysis

A small scale volumetric Wankel expander is a powerful device for small-scale power generation in compressed air energy storage (CAES) systems and Organic Rankine cycles powered by different heat sources such as, biomass, low temperature geothermal, solar and waste heat leading to significant reduction in CO2 emissions. Wankel expanders outperform other types of expander due to their ability to produce two power pulses per revolution per chamber additional to higher compactness, lower noise and vibration and lower cost. In this paper, a computational fluid dynamics (CFD) model was developed using ANSYS 16.2 to simulate the flow dynamics for a single and two stage Wankel expanders and to investigate the effect of port configurations, including size and spacing, on the expander’s power output and isentropic efficiency. Also, single-stage and two-stage expanders were analysed with different operating conditions. Single-stage 3D CFD results were compared to published work showing close agreement.The CFD modelling was used to investigate the performance of the rotary device using air as an ideal gas with various port diameters ranging from 15mm to 50mm; port spacing varying from 28mm to 66mm; different Wankel expander sizes (r=48, e=6.6, b=32)mm and (r=58, e=8, b=40)mm both as single-stage and as two-stage expanders with different configurations and various operating conditions. Results showed that the best Wankel expander design for a single-stage was (r=48, e=6.6, b=32)mm, with the port diameters 20mm and port spacing equal to 50mm. Moreover, combining two Wankel expanders horizontally, with a larger one at front, produced 8.52kW compared with single-stage which gave 4.75kW power output at the same operating conditions. Also, a maximum isentropic efficiency of 91% was calculated with inlet pressure of 6bar and inlet temperature of 400K at 7500rpm for the two-stage compared to the 87.25% for the single-stage.

Parameters affecting the localized fluidization in a particle medium

The current study presents experiments for the initial stages of fluidization induced by a localized fluid injection. The process was studied by recording high‐speed videos in a 2‐D‐region far from the boundaries using Planar Laser Induced Fluorescence and Refractive Index Matching. The experimental setup allowed for several parameters to be systematically studied including particle sizes, initial bed heights, and injection port diameters. The results show that the critical flow rate required for fluidization is primarily dependent on the initial height of the granular bed. However, this dependence is not a linear relation but progressively plateaus for larger heights. Conversely, the diameter of the chimney relates only slightly to the injection port diameter and significantly more to the diameter of the particles. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1529–1542, 2017

Enhanced Gas Lift Valve Performance for Sharp Edged Seat using Larger Ball Sizes

Theoretically, each Sharp Edged Seat has fully open stem travel based on the port and ball diameters. Gas lift valve 1.5” has 6 different port diameters (3/16”, ¼”, 5/16”, 3/8”, 7/16” and ½”). For each port the ball diameter is usually larger than the port diameter by 1/16”. Laboratory testing for sharp edged seats showed that the actual flow area is less than theoretically calculated area resulting from the bellows stacking before the stem reaches the fully open. Consequently, the valve stem restricts the flow and the flow rate through the valve declines. The purpose of this work is to examine the possibility of improving the efficiency of the gas lift valve by using larger ball size than conventionally used. For each port, different ball sizes were tested at different stem positions for the same condition (Injection pressure & Temperature). Results obtained from benchmark test displayed increasing in the flow rate as the ball size increases at the same stem travel.

An experimental study of the transient regime to fluidized chimney in a granular medium

Localized fluidization within a granular packing along an almost cylindrical chimney is observed when an upward fluid-flow, injected through a small port diameter, exceeds a critical flow-rate. Once this threshold reached, a fluidized area is first initiated in the close vicinity of the injection hole before gradually growing upward to the top surface of the granular layer. In this work, we present an experimental investigation specifically dedicated to the kinetics of chimney fluidization in an immersed granular bed. Two different transient regimes are identified depending on whether the expansion of the fluidized area is rather fast and regular, reaching the final chimney state typically in less than 10 seconds, or, on the contrary, slow and very progressively accelerated, giving rise to transient duration up to 1 hour or even more. Some systematic investigations allow to propose several empirical scaling relations for the kinetics of chimney fluidization in the fast regular regime.

Performance and Regression Rate Characteristics of 5-kN Swirling-Oxidizer-Flow-Type Hybrid Rocket Engine

Burning tests were carried out for the 5-kN-thrust swirling-oxidizer-flow-type hybrid rocket engine to establish the engine technology and to obtain the fuel regression characteristics. The engine attained stable burning without any combustion oscillation and efficiencies of more than 98% under the 5-kN-thrust conditions. The maximum time-averaged thrust realized was 4.4 kN, which was lower than 5 kN. This was attributed to the regression rate being lower than the value estimated by regression rate correlation. The fuel regression behavior of this engine was characterized as the flow-development region near the grain leading edge and the fully developed turbulent flow region. The axial length of the flow-development region varied from that observed in the laboratory-scale engine, and it depended on the oxidizer mass flow rate, grain initial port diameter, and swirl strength. The controlling parameter of the regression rate in the fully developed flow region was modified to correlate with the grain port diameter. By effecting these modifications, the accuracy of the regression rate prediction was improved. The range of the applicable controlling parameter of the modified regression rate correlations was extended for use for larger-scale engines.

A simplified computational fluid-dynamic approach to the oxidizer injector design in hybrid rockets

Fuel regression rate in hybrid rockets is non-negligibly affected by the oxidizer injection pattern. In this paper a simplified computational approach developed in an attempt to optimize the oxidizer injector design is discussed. Numerical simulations of the thermo-fluid-dynamic field in a hybrid rocket are carried out, with a commercial solver, to investigate into several injection configurations with the aim of increasing the fuel regression rate and minimizing the consumption unevenness, but still favoring the establishment of flow recirculation at the motor head end, which is generated with an axial nozzle injector and has been demonstrated to promote combustion stability, and both larger efficiency and regression rate. All the computations have been performed on the configuration of a lab-scale hybrid rocket motor available at the propulsion laboratory of the University of Naples with typical operating conditions.After a preliminary comparison between the two baseline limiting cases of an axial subsonic nozzle injector and a uniform injection through the prechamber, a parametric analysis has been carried out by varying the oxidizer jet flow divergence angle, as well as the grain port diameter and the oxidizer mass flux to study the effect of the flow divergence on heat transfer distribution over the fuel surface. Some experimental firing test data are presented, and, under the hypothesis that fuel regression rate and surface heat flux are proportional, the measured fuel consumption axial profiles are compared with the predicted surface heat flux showing fairly good agreement, which allowed validating the employed design approach. Finally an optimized injector design is proposed.

Comparison of drill- and needle-based tree injection technologies in healing of trunk injection ports on apple trees

Excessive tree wounding is a common concern regarding the use of trunk injection technology for tree protection purposes in landscapes and urban greening. We investigated the rate of healing of injection ports (points) in apple trees by monitoring parameters such as port diameters, the size of bark cracking, and port depths. We compared drilled injection ports from 4.4 and 9.5mm drill bits, with latter being sealed with plastic-silicone plug (Arborplug®) or not, and the lenticular port from a double-edged blade. Depending on port size and type, port closure ranged from one to more than two years. Bark cracking around injection ports was more pronounced longitudinally. On the sealed 9.5mm port, bark cracking was largely similar to all drilled ports. The depth of port wounds decreased faster on the port from the 4.4mm drill bit and on lenticular injection port versus the unsealed port from the 9.5mm drill bit. Plastic-silicone plugs, which simulate removed bark, slowed the healing of 9.5mm drill port with callus and increased the port depths over time due to callus formation over the top of the plug. From fastest-healing to slowest-healing, on average the injection ports were: lenticular port from blade (70.8%), the unsealed 9.5mm drill port (44.4%), 4.4mm drill port (43.9%), and 9.5mm drill port sealed with plastic-silicone plug (20.4%).