Outlet Valve Research Articles

Optimization of Cyclic Adsorption Processes and Gas Mixture Separation Plants

The analysis of the cyclic adsorption process and the installation of separation of gas mixtures by the method of pressure swing adsorption as an object of optimization have been carried out. The study found operating (control) variables (the duration of the adsorption stage, the pressure at the compressor outlet, the coefficient of reverse flow for the regeneration of the adsorbent, the program of changes in the opening time of the inlet and outlet valves of the installation); undefined parameters (composition, temperature and pressure of the initial gas-air mixture); output variables of the installation (concentration of oxygen, nitrogen in the product gas flow, the productivity of the installation, the degree of extraction and reduced costs for the production of oxygen with a given purity of 40 - 90 and higher vol.%). A one-stage problem of optimization of the regimes of a stationary periodic process of adsorption separation of atmospheric air and oxygen concentration was formulated and solved by the method of short-cycle adsorption under conditions of partial uncertainty of the initial information in the presence of restrictions on the purity of the product gas, the productivity of the installation and the rate of gas flow in the “frontal layer” of the adsorbent. An iterative algorithm for its solution is proposed.

Face Coverings, Aerosol Dispersion and Mitigation of Virus Transmission Risk.

The SARS-CoV-2 virus is primarily transmitted through virus-laden fluid particles ejected from the mouth of infected people. Face covers can mitigate the risk of virus transmission but their outward effectiveness is not fully ascertained. Objective: by using a background oriented schlieren technique, we aim to investigate the air flow ejected by a person while quietly and heavily breathing, while coughing, and with different face covers. Results: we found that all face covers without an outlet valve reduce the front flow through by at least 63% and perhaps as high as 86% if the unfiltered cough jet distance was resolved to the anticipated maximum distance of 2-3 m. However, surgical and handmade masks, and face shields, generate significant leakage jets that may present major hazards. Conclusions: the effectiveness of the masks should mostly be considered based on the generation of secondary jets rather than on the ability to mitigate the front throughflow.

Simulation tests of selected gas flow parameters through combustion engine valves

The article presents the numerical analysis of a single-cylinder gasoline engine with indirect injection and spark ignition. The goal is to recognize and analyze gas flow through inlet and outlet valves and channels. These data were obtained from the simulation of a four-cycle engine cycle without combustion of the fuel-air mixture. The simulation was carried out in ANSYS, using a dedicated IC Engine module. After the simulation, the result was analyzed on the cross-sectional plane of both the valves and the combustion chamber. This method provided the necessary and concise representation of the flow characteristics. Five separate stages are presented - two describing the different displacement of the valve for each inlet and exhaust stroke and one representing the phenomenon of overlapping. The type of flow, its speed and tendency to create turbulence are described

Design, Manufacturing Technology and In-Vitro Evaluation of Original, Polyurethane, Petal Valves for Application in Pulsating Ventricular Assist Devices.

Minimizing of the life-threatening thrombo-emboli formation in pulsatile heart assist devices by a new biomimetic heart valve design is presently one of the most important problems in medicine. As part of this work, an original valve structure was proposed intended for pneumatic, extracorporeal ventricular assist devices. The valve design allows for direct integration with other parts of the pulsating blood pump. Strengthening in the form of the titanium or steel frame has been introduced into the polyurethane lagging, which allows for maintaining material continuity and eliminating the risk of blood clotting. The prototype of the valve was made by the injection molding method assisted by numerical simulation of this process. The prototype was introduced into a modified pulsating, extracorporeal heart assist pump ReligaHeart EXT (developed for tilting disc valves) and examined in-vitro using the “artificial patient” model in order to determine hydrodynamic properties of the valve in the environment similar to physiological conditions. Fundamental blood tests, like hemolysis and thrombogenicity have been carried out. Very low backflow through the closed valve was observed despite their slight distortion due to pressure. On the basis of immunofluorescence tests, only slight activation of platelets was found on the inlet valve and slight increased risk of clotting of the outlet valve commissures as a result of poor valve leaflets assembling in the prototype device. No blood hemolysis was observed. Few of the clots formed only in places where the valve surfaces were not smooth enough.

Biogas Fuel Utilization as Efforts to Overcome Household Economic Budget Problems in Rural Areas

Biogas is an important renewable energy as a superior substitute and is able to contribute to meeting the needs of household fuel stairs. The energy produced is used as a substitute for kerosene or LPG gas to meet daily needs such as cooking and others. Plant waste and livestock manure contain methane gas which has very good combustibility. Manure wastes such as cattle, horses, and others, are also found throughout Indonesia with different qualities. In general, the use of agricultural waste as a base for biogas is more difficult than livestock manure, because it takes longer to process the hydrolysis of cellulosic materials from agricultural waste and nutrients. One kilogram of manure releases about 208-268 liters of methane gas into the atmosphere. High nutritious livestock rations, resulting in low methane levels of manure. To describe comprehensively the usefulness of biogas utilization as a source of bioenergy fuel in an effort to overcome household economic budget problems in rural areas. Anearobic digestion process which is the basis and biogas reactor processed by the breakdown of organic matter by the activity of methanogenic bacteria in airless conditions. The materials required are a minimum of 3 culverts, a septi tank for the digester tank, and a large oil drum that can contain approximately 200 liters of material intended as methane gas. Another material, in the form of a metal pipe with a diameter of 2 cm, is useful as a gas discharge pipe and a biogas outlet valve. The pipe is used as a pipe for gas distribution from the digestive tank to the stove for cooking, lamps and others. The final result is a solid which functions as a plant organic fertilizer. There are also several compounds / materials that must be prevented because they can inhibit the breakdown process, such as Antibiotics and Disinfectants, and Heavy Metals. Please note that do not burn the gas that first formed, as it contains air in it and can explode. A few days after the biogas catcher drum is lifted upwards, it is advisable to open the tap and remove all the gas that has formed. To handle it with care and avoid fire around the biogas production unit. There is no need to release the gas formed and the gas is safe to use to meet household fuel needs. The best use of the biogas that has been collected from the biogas production unit is for cooking. Biogas technology is the right choice to convert agricultural and livestock waste to produce energy and fertilizer in order to obtain social benefits both in terms of economic, especially for households, especially in rural.

Aqueous outflow regulation - 21st century concepts.

We propose an integrated model of aqueous outflow control that employs a pump-conduit system in this article. Our model exploits accepted physiologic regulatory mechanisms such as those of the arterial, venous, and lymphatic systems. Here, we also provide a framework for developing novel diagnostic and therapeutic strategies to improve glaucoma patient care. In the model, the trabecular meshwork distends and recoils in response to continuous physiologic IOP transients like the ocular pulse, blinking, and eye movement. The elasticity of the trabecular meshwork determines cyclic volume changes in Schlemm’s canal (SC). Tube-like SC inlet valves provide aqueous entry into the canal, and outlet valve leaflets at collector channels control aqueous exit from SC. Connections between the pressure-sensing trabecular meshwork and the outlet valve leaflets dynamically control flow from SC. Normal function requires regulation of the trabecular meshwork properties that determine distention and recoil. The aqueous pump-conduit provides short-term pressure control by varying stroke volume in response to pressure changes. Modulating TM constituents that regulate stroke volume provides long-term control. The aqueous outflow pump fails in glaucoma due to the loss of trabecular tissue elastance, as well as alterations in ciliary body tension. These processes lead to SC wall apposition and loss of motion. Visible evidence of pump failure includes a lack of pulsatile aqueous discharge into aqueous veins and reduced ability to reflux blood into SC. These alterations in the functional properties are challenging to monitor clinically. Phase-sensitive OCT now permits noninvasive, quantitative measurement of pulse-dependent TM motion in humans. This proposed conceptual model and related techniques offer a novel framework for understanding mechanisms, improving management, and development of therapeutic options for glaucoma.

Investigation of ventriculoperitoneal shunt disconnection for hydrocephalus treatment.

This investigation is aimed at gaining a better understanding of the factors that lead to mechanical failure of shunts used for the treatment of hydrocephalus, including shunt catheter-valve disconnection and shunt catheter fracture. To determine the root cause of mechanical failure, the authors created a benchtop mechanical model to mimic mechanical stressors on a shunt system. To test shunt fracture, cyclical loading on the catheter-valve connection site was tested with the shunt catheter held perpendicular to the valve. Standard methods were used to secure the catheter and valves with Nurolon. These commercial systems were compared to integrated catheters and valves (manufactured as one unit). To test complete separation/disconnection of the shunt catheter and valve, a parallel displacement test was conducted using both Nurolon and silk sutures. Finally, the stiffness of the catheters was assessed. All mechanical investigations were conducted on shunts from two major shunt companies, assigned as either company A or company B. Cyclical loading experiments found that shunts from company B fractured after a mean of 4936 ± 1725 cycles (95% CI 2990-6890 cycles), while those of company A had not failed after 8000 cycles. The study of parallel displacement indicated complete disconnection of company B's shunt catheter-valve combination using Nurolon sutures after being stretched an average 32 ± 5.68 mm (95% CI 25.6-38.4 mm), whereas company A's did not separate using either silk or Nurolon sutures. During the stiffness experiments, the catheters of company B had statistically significantly higher stiffness of 13.23 ± 0.15 N compared to those of company A, with 6.16 ± 0.29 N (p < 0.001). Mechanical shunt failure from shunt catheter-valve disconnection or fracture is a significant cause of shunt failure. This study demonstrates, for the first time, a correlation between shunt catheters that are less mechanically stiff and those that are less likely to disconnect from the valve when outstretched and are also less likely to tear when held at an angle from the valve outlet. The authors propose an intervention to the standard of care wherein less stiff catheters are trialed to reduce disconnection.

Modeling and Validation of a Two-Phase Flow Valve for Expanders in Waste Heat Recovery

Abstract Waste heat recovery is a promising method to reduce fuel consumption and CO2 emissions in heavy-duty vehicles. An organic Rankine cycle (ORC) is used to convert the thermal energy of the exhaust gases into useable energy to support the power train. A key component of the ORC is the expansion machine where the conversion of thermal into mechanical energy takes place. In the case of volumetric expansion machines such as axial piston expanders, lubrication oil is mixed in with the working fluid to reduce friction and increase the component durability. However, the presence of oil also affects both the efficiency and the fluid dynamical behavior inside the expander. To implement a one-dimensional simulation model that considers the oil influence, a continuous flow approach is selected. Particular attention is dedicated to the inlet and outlet valve modeling, as these have to account for two-phase flow and multicomponent fluid mixtures. A valve model is built up in the simulation environment dymola based on the homogeneous nonequilibrium (HNE) approach. A virtual one-cylinder test bench is set up to calibrate and validate the model. The simulation results show good correspondence with the measurement data.

An Advanced TiAl Alloy for High-Performance Racing Applications.

Requirements and strict regulations for high-performance racing applications involve the use of new and innovative lightweight structural materials. Therefore, intermetallic γ-TiAl-based alloys enable new opportunities in the field due to their lower density compared to commonly used Ni-base superalloys. In this study, a β-solidifying TiAl alloy was examined toward its use as structural material for inlet and outlet valves. The nominal composition of the investigated TNM alloy is Ti–43.5Al–4Nb–1Mo–0.1B (in at%), which enables an excellent formability at elevated temperatures due to the presence of bcc β-phase. Different hot-extrusion tests on an industrial scale were conducted on the cast and hot isostatic pressed material to determine the ideal microstructure for the respective racing application. To simulate these operation conditions, hot tensile tests, as well as rotational bending tests, at room temperature were conducted. With a higher degree of deformation, an increasing strength and fatigue limit was obtained, as well as a significant increment of ductility. The fracture surfaces of the rotational bending test specimens were analyzed using scanning electron microscopy, revealing the relationship between crack initiation and microstructural constituents. The results of this study show that the mechanical performance of extruded TiAl material can be tailored via optimizing the degree of hot-extrusion.

Reducing Defects on Cam Shaft by Six Sigma Methodology

The efficiency of an IC engine is mainly depends on opening and closing of inlet and outlet valves. The valves are operated by cam shaft. So cam shaft must be free from defects to maintain proper combustion of a internal combustion engine. Thus we are focusing to reduce the defects and improving quality in the manufacturing process and operations of a cam shaft in manufacturing industry for different automotives. In camshaft manufacturing the considerable defects are material selection, changing their mechanical properties while machining, temperature defects, casting defects, tolerances and surface roughness. So manufactured cam shaft has to overcome above defects for safe operating of valves. Six Sigma is a business technique and a methodical philosophy utilization of which prompts achievement in benefit through quantum gain in item quality, consumer loyalty and efficiency. The goal was to diminish the quantity of deformities to as low as 3.4 parts per million chances. Methodology used: DMAIC is one of the tool of six sigma used to improve the process and also to find root causes for any problem to reduce the defects occuring in any industry. we are using DMAIC tool to reduce defects and improve quality. DMAIC stands for define, measure, analyze, improve, control.

Analysis of Stiffness Effect on Valve Behavior of a Reciprocating Pump Operated by Piezoelectric Elements.

This study analyzed the characteristics of a small reciprocating pump with a cantilever valve driven by a piezo actuator. Three types of valves were fabricated to investigate the effect of the valve stiffness on the pump performance and to measure the variation in the flow rate according to the frequency. The flow rate increased with the driving frequency until a certain frequency was reached, and then it started to decrease. The rise in the pressure of the pump was found to increase as the stiffness decreased. The pump performance could be clearly distinguished according to the stiffness of the valve. The observation of the valve movements revealed that the valve opening time did not change regardless of the operating frequency, but it changed with the valve stiffness. The delay in time for the outlet valve increased significantly with an increase in the frequency. It seems that the overlap of the opening time of the inlet valve and the outlet valve plays an important role in pump performance. Therefore, it is advisable to use different designs for the inlet and outlet valves, where the shape and stiffness of the valve are adjusted.

Evaluation and Optimization of O2 Used Ranque-Hilsch Vortex Tube Performance

ABSTRACT Ranque-Hilsch Vortex Tube (RHVT) is a mechanic system which can make heating and cooling by using basic heat transfer laws with a compressed fluid. Environmental friendly RHVT is widely used in cooling systems in medicine, electronics, and computer sectors, particularly in the food sector. In this study, the performances of parallel RHVTs in which oxygen (O2) gas is used were reviewed considering different inlet pressures, nozzle materials and orifice numbers. Test results were modeled by multiple linear regression method and regression equation was derived. Besides, Signal/Noise (S/N) ratios of the designed test results were calculated using Taguchi L16 mix type (4 × 2 2 × 1) orthogonal sequence, and optimum conditions were determined. Throughout the test, hot fluid outlet valve of the counter flow RHVTs having Ø10 mm inner diameter and 100 mm body length was completely left open. As control factors and levels, four different inlet pressures (200, 350, 500, and 650 kPa), four different number of orifices (three, four, five, and six), and two different nozzle materials (brass and polyamide) were selected. For quality characteristics, maximum temperature gradient (∆T) was determined. In order to determine the effect rates of the control factors on quality characteristics (∆T), variance analysis (ANOVA) was applied to test results at 95% confidence level. According to statistical results, it was determined that the response rates of ΔT values from the control factors were determined as inlet pressure, the number of orifices and nozzle material, respectively. Validity of the optimization was checked with confirmation tests, and the optimization proved to be used in evaluation of RHVT performances.

The ability of detainment bunds to decrease surface runoff leaving pastoral catchments: Investigating a novel approach to agricultural stormwater management

Storm generated surface runoff is responsible for significant portions of the contaminants exported from grazed pastures that contribute to water quality impairment in inland and coastal waters. Detainment bunds (DBs) were investigated as a novel strategy to mitigate the losses of nutrients and sediment in surface runoff from pastures in the Lake Rotorua catchment, in New Zealand. A DB is a ∼1.5-2 m high earthen stormwater retention structure constructed on productive pastures in the flow path of targeted ephemeral streams. The current DB design protocol recommends a minimum pond volume of 120 m3 per hectare of contributing catchment. Bunds are capable of temporarily ponding up to 10,000 m3 of surface runoff, which can be rapidly drained by opening an outlet valve. This 12-month study of 2 DB sites with 55 ha and 20 ha subcatchments in the Lake Rotorua catchment, found that DBs effectively decreased annual discharge volumes by 31% and 43%. Decreased runoff discharges were the result of increased soil infiltration facilitated by increased stormwater residence times on well-drained soils in the ponding area. Furthermore, discharges from the DBs occurring after runoff generation in the catchment had ceased were likely to infiltrate the soils downstream of the DBs. Combining the in-pond and downstream infiltration, the DBs prevented 43% and 63% of the annual runoff generated in the targeted catchments from reaching downstream surface waters. The results of this study demonstrate that DBs constructed on sufficiently permeable soils reduce surface runoff volumes from pastures, and are thereby capable of decreasing contaminant loads delivered to receiving surface waters. As such, DBs are likely to be an effective strategy to add to the nutrient mitigation toolbox in the Lake Rotorua catchment, and in other pastoral locations where contaminants mobilised by surface runoff contribute to water quality degradation.

Numerical Investigation of Methodologies for Cavitation Suppression Inside Globe Valves

Cavitation inside globe valves, which is a common phenomenon if there is a high-pressure drop, is numerically investigated in this study. Firstly, the cavitation phenomenon in globe valves with a different number of cages is compared. When there is no valve cage, cavitation mainly appears at the valve seat, the bottom of the valve core, and the downstream pipelines. By installing a valve cage, cavitation bubbles can be restricted around the valve cage protecting the valve body from being damaged. Secondly, the effects of the outlet pressure, the working temperature, and the installation angle of two valve cages in a two-cage globe valve are studied to find out the best method to suppress cavitation, and cavitation number is utilized to evaluate cavitation intensity. Results show that cavitation intensity inside globe valves can be reduced by increasing the valve outlet pressure, decreasing the working temperature, or increasing the installation angle. Results suggest that increasing the outlet pressure is the most efficient way to suppress cavitation intensity in a globe valve, and the working temperature has a minimal effect on cavitation intensity.

Research on Power Matching and Energy Optimal Control of Active Load-Sensitive Electro-Hydrostatic Actuator

Electro-hydrostatic actuator (EHA) is an important type of power-by-wire (PBW) which is a highly integrated closed volume control system with the advantages of high reliability, high efficiency and easy maintenance. However, under heavy load conditions, a large amount of heat the EHA motor produces affects the system’s working time and even the system life, which restricts the widespread application of EHA systems. In order to solve the problem of motor heating and the contradiction between high dynamics and high efficiency of the EHA system, a novel active load-sensitive principle and structure of EHA system is proposed based on the load-sensitive principle. The active load-sensitive EHA (ALS-EHA) is a dual control variable system consisting of a motor pump main loop and a load-sensitive loop. As for the latter, the system load pressure is introduced into a special designed and optimized pressure fellow valve (PFV). The valve outlet is connected to the plunger pump swash plate variable mechanism. The EHA pump displacement is actively adjusted by controlling the current input to PFV. The two-degree-of-freedom cooperative control for the output flow of the pump can be implemented by adjusting the motor speed and the pump displacement. An energy optimal robust control law based on fuzzy and disturbance compensation is presented for the control architecture. The simulation results show that the ALS-EHA system based on the control law proposed in this paper can effectively reduce the motor heat while ensuring the dynamic performance of the system.

Use of experimental and numerical simulation methods for rational design of the air cooling apparatus for lubrication systems of compressors

The objective of the present work was to study heat and hydraulic parameters of an air cooling apparatus of oil (ACAO), whose geometry of its flow-through part is changed to decrease hydraulic losses in its air conduit and to increase the cooling efficiency of oil. Using numerical simulation methods of heat transfer, we have developed and tested the computational techniques applied in a wide class of heat exchange apparatuses, including those consisting of the sections of finned flat tubes manufactured by extrusion with subsequent deforming cutting. We have proposed to make a finned part of a heat-exchange surface in the form of porous inserts. This has allowed us to reduce numerical simulation equipment requirements and to decrease computational time. Predicted results well agree with experimental data; their analysis shows that the calculated value of thermal performance of the oil cooler due to the revealed construction drawbacks of the air conduit is by 19 % less than that of the designed one. Based on the results of the numerical simulation studies, a number of recommendations have been made how to improve the layout inside the air cooling apparatus for oil in order to enhance its thermal performance and aerodynamic quality. In particular, we have proposed to mount new fan blades to enhance its performance; to change the construction of the air outlet valve by taking away a baffle that partially overshadows the exit area of the bottom fan; to modify the shape of the bottom collector of the oil cooler in order to make a uniform velocity profile at the entrance of cooling sections. Connecting in series heat exchange sections may be a perspective engineering decision. The outcomes of all proposed engineering decisions can be assessed by numerical simulation methods that will allow us not to design expensive equipment.

Development of a novel rotary flow control valve with an electronic actuator and a pressure compensator valve for a gas turbine engine fuel control system

This paper presents a new rotary proportional flow control valve with Cam-Nozzle configuration. The rotating cam against the fixed nozzle changes the flow area and then can meter the fuel flow. This valve equipped with a pressure compensator plunger type valve to retaining constant pressure difference across the flow control or metering valve. The cam shaft directly coupled to an electronic servomotor type rotary actuator and then it is possible to apply digital control techniques such as pulse width modulation (PWM) in this control system. This new valve configuration is developed for an electro hydro mechanical fuel control system in a gas turbine engine. In addition to aero engine application, this type of flow metering valve can widely be used in industrial hydraulic systems. In this unit, the output flow is proportional to the cam's angular position (or throttle command) and it is not sensitive to pressure fluctuations at nozzle inlet and outlet. The aim of this new design is to modify a manual single adjusted hydro-pneumatic fuel control unit to obtain a new electro-hydraulic fuel control system for a gas turbine engine. The main innovations in the presented fuel metering unit include new design of the rotary valve opening shape (Cam-Nozzle) without metal to metal contact, use of a rotary electronic actuating mechanism and also direct coupling between the actuator and the rotating cam. The increased fuel metering precision in the new flow control valve has improved the ultimate control accuracy of system. A computer simulation software based on the proposed model, is performed to predict the steady state and transient performance and to analyze effect of important design parameters on valve outlet fuel flow and obtain the final design parameters. The validity of the proposed valve configuration is assessed experimentally in the steady state and transient modes of operation. The results show good agreement between simulation and experimental in both modes (max. 4% deviation).

Effects of Fiber and Copper Particles on Conductivity and Breakdown Characteristics of Natural Ester and Mineral Oil under DC Voltage

The converter transformer is a key equipment in high voltage direct current (HVDC) transmission system. Its oil-paper insulation system in the valve winding and outlet bushing experiences AC, DC, AC/DC, and transient impulse voltages simultaneously. The oil contamination problem is more serious under DC electric field. Therefore, it is significant to investigate the characteristic of particles motion and accumulation under DC electric field. In this paper, first, the movement and accumulation behavior of fiber particles and copper particles in mineral oil and natural ester were recorded and simulated. Then, the influence of fiber and copper particles on the oil conductivity was analyzed. Finally, the DC breakdown strength of mineral oil and natural ester with different particles concentration was compared. Results show that the movement speed of copper particles was larger than that of fiber particles. Fiber impurities were easy to form bridges in mineral oil, while there was no impurity bridge in natural ester. The current density of mineral oil containing particles is larger than that of the natural ester at the same testing time. The DC 50% probability breakdown voltages of oil samples containing fiber and copper particles decreased linearly with the increase of particle concentration, and the decrease rate of DC 50% probability breakdown voltages of oil containing copper particles were faster than that of oil containing fiber particles. Compared to pure mineral oil, the DC breakdown voltages corresponding to 50% probability of contaminated mineral oil showed a decrease from 11.9% to 22.5% when the fiber particle concentration increased from 0.001% to 0.012%. The DC 50% probability breakdown voltages of contaminated mineral oil with copper particles decreased from 23.8% to 45.0% when the particle concentration increased from 0.1 g/L to 1.5g/L. However, the decline range of the figures for natural ester contaminated by fiber or copper particles showed a smaller drop.

Design and Efficiency Analysis of Small Displacement Pump

To address the common issues of low-production oil wells like unbalanced supply and output, low pump efficiency and system efficiency and high energy consumption, a small-displacement oil pump has been developed. The pump has an enhanced structural strength with solid plunger and the mobility of the pumping oil with offset outlet valve. The outlet valve is located at the highest point of pump chamber when the plunger is at the bottom dead center, which is preferable for the discharge of gas and high gas-liquid and pump efficiency improvement. Combined with the distribution law of oil and gas in vertical pipe flow, it is assumed that the dissolved gas is linearly distributed from the oil inlet valve to the bottom end of the plunger after the pump is introduced. According to the position of the oil pumping valve of the oil pump, the efficiency calculation formula is derived. Then through reasonable matching of working conditions, the influence of various factors on pump efficiency is analyzed. The pump’s pump efficiency is about 10% higher than the API minimum pump diameter (32 mm), which is important for energy saving in oil fields.

Construction and Evaluation of a Bio-Engineered Pump to Enable Subpulmonary Support of the Fontan Circulation: A Proof-of-Concept Study

Create a bio-engineered pump (BEP) intended for subpulmonary Fontan circulation support consisting of a biological blood reservoir flanked by valves that can be externally compressed and produce a 2-6 mmHg pressure gradient across the device without flow obstruction. Decellularlized urinary bladder matrix (UBM), previously shown to be a suitable substrate for endothelial cells, underwent a lamination process to created bilayer UBM sheets which were then used to create biological reservoirs. Reservoir testing included compliance and pressure evaluation. BEPs were constructed by securing the biological reservoir between inlet (Vi) and outlet (Vo) valves and compressed with a polyurethane balloon (A). The BEP function was evaluated in a simple flow loop representative of a modified subpulmonary Fontan circulation with representative vena cava (IVC) and pulmonary artery (PA) with a baseline "filling pressure" of 6 mmHg at a flow rate of 4.0 liters per minute (LPM). BEPs were successfully constructed (B). The devices demonstrated high compliance with small pressure increases at low volumes (4.25 mmHg/mL) and were able to withstand internal pressure increases >70 mmHg. Placement of a non-active BEP into the flow loop caused a flow rate change from ∼4.0 LPM to ∼3.9 LPM with < 1 mmHg pressure change between the IVC and PA (C). A BEP with biological reservoir fill volume of 92 mL operating at 60 cycles per minute produced pulsatile downstream flows at an average of 4.0 LPM and generated a pressure gradient across the device maintaining upstream pressure of 6 mmHg and producing downstream pressure of 13 mmHg (D). Urinary bladder matrix can be formed into a biological reservoir and used to construct a bio-engineered pump. In a simple flow loop representative of a subpulmonary Fontan circulation, the BEP can produce pulsatile downstream flow and create a favorable pressure gradient across the device while maintaining a low upstream pressure.