Introduction
Literature Review of Hydraulic Fluid Bubble Elimination
Various methods for removing air bubbles from fluids have been explored in existing literature However, the topic remains under-researched, particularly because traditional hydraulic systems can naturally deaerate in large open tanks with sufficient settling time This approach is impractical for hydraulic hybrid vehicles, which require a more compact design.
(packaging concerns) and be lightweight.
Cyclone bubble elimination devices are an effective deaeration system that utilizes rotation to separate air from oil-air mixtures Research by Suzuki et al has explored the theoretical foundations of these systems, highlighting their non-quantitative performance While cyclone bubble eliminators are noted for their challenges in removing small bubbles from viscous fluids, a lack of quantitative data on their bubble removal efficiency remains.
Gas permeable oil impermeable membranes offer a viable solution for deaeration by creating a pressure difference that allows gas to be extracted from fluids These membrane systems have been specifically developed for micro-gravity environments, where buoyancy prevents bubbles from settling naturally While membrane devices are effectively utilized in water and chemical purification to eliminate dissolved gases, their application in degassing hydraulic oil is less common Additionally, the requirement for a large membrane surface area can lead to bulky devices, making them less suitable for hydraulic hybrid vehicles.
Zeolite is a crystalline substance known for its ability to trap and redirect unwanted molecules, with extensive research conducted on its various applications in industry However, its potential use in the degassing of hydraulic oil remains unexplored, leaving its feasibility uncertain To assess the effectiveness of this concept, comprehensive research by chemical engineering experts is essential.
A comprehensive survey on bubble elimination methods was conducted, with results summarized in Appendix A The survey indicated that cyclone technology was the most favorable choice due to its compact design and promising theoretical research However, after discussions with key EPA collaborators, it was concluded that designing a cyclone bubble elimination device was too complex an engineering task to pursue Consequently, the GE-Totten BM-6 cyclone bubble eliminator was selected for the evaluation of hydraulic fluid deaeration.
Efficiency Testing of Deaeration Devices Literature Review
Determining the bubble elimination efficiency of deaeration devices is crucial for assessing their suitability in dry sump pump systems To evaluate this efficiency, it is essential to measure the gas content in the hydraulic fluid that exits the device This requires a highly accurate measurement device capable of detecting small quantities of gas in the fluid Various methods for achieving this measurement have been documented in the literature.
A void meter is an instrument used to measure the quantity of gas in a fluid, as demonstrated in experiments by Suzuki et al and Morgan et al It operates by integrating a Coriolis mass flow meter with a volumetric flow meter, enabling the calculation of the density flow rate and the percentage of air in the fluid However, it has limitations in accurately measuring small bubble percentages and dissolved gases, making it unsuitable for applications that demand high precision in bubble elimination efficiency.
An optical probe is utilized to measure gas quantities in liquids by emitting light from within the fluid and assessing the intensity of the reflected light However, this method lacks accuracy due to interference from air bubbles that can directly impact the probe, leading to fluctuating readings based on bubble velocity and the probe's moisture level after contact with the bubbles.
Indirect measurement using two air mass flow meters can effectively quantify the air content in hydraulic oil This method involves one meter measuring incoming air and another measuring outgoing air from the bubble elimination device, with the airflow difference indicating the air volume in the oil, based on the conservation of mass principle While air mass flow meters are commonly utilized in testing, there is limited literature on this specific application The system's accuracy hinges on the precision of the mass flow meters, which typically exhibit low accuracy at low flow rates, making it unsuitable for assessing bubble elimination efficiency.
Volume measurements taken with a graduated cylinder before and after allowing air to settle in the fluid can effectively determine the gas percentage in the fluid This widely recognized technique yields a volumetric percentage of hydraulic fluid ranging from 97.93% to 99.99%, as detailed in Appendix B.
The graduated cylinder method was selected for its high accuracy and capability to measure significant volumetric percentages of hydraulic fluid This method was employed to assess the efficiency of bubble removal in the cyclone bubble elimination system.
Goals and Objectives
The goals of this research are:
• Develop a system to measure bubble elimination
• Determine bubble removal efficiency in a cyclone device
• Understand forces that act on bubbles and dissolving process
• Model how bubble size, pressure, and temperature effect bubble removal
All of these goals lead to the overall objective of designing and developing a dry sump pump deaeration system for use in a hydraulic vehicle.
Overview of Thesis
This thesis contains five chapters which describe the work that has been completed on the dry sump pump bubble elimination for hydraulic hybrid vehicle systems project.
Chapter 2 Bubble Elimination Efficiency Testing Apparatus: BEETA was constructed and allows for experimental testing and optimization of any style of in-line bubble eliminator This versatility makes it a great asset to the project.
Chapter 3 Performance Efficiency and Testing Results: The efficiency of a cyclone bubble elimination device was tested under varying conditions The device failed to remove an adequate amount of small bubbles and dissolved gas.
Chapter 4 Theory of Dissolving Gas and Forces on Bubbles: The process of dissolving gas into fluid is researched Also the forces on bubbles in fluid are examined along with the effects that bubble radius, pressure, and temperature have on bubbles settling out of fluid.
Chapter 5 Conclusions and Recommendations: From testing it is concluded that the cyclone device cannot be used in a dry sump pump Based on this conclusion and theory studied it is recommended that settling methods that involve pressure and temperature be further researched along with the use of alternative gases in the dry sump pump.
Bubble Elimination Efficiency Testing Apparatus .8
Overview
The BEETA system enables efficient testing and optimization of pressure and flow in various bubble elimination devices It operates by creating a controlled mixture of hydraulic fluid and air, which is then directed through the chosen bubble eliminator By measuring the air content in the exiting mixture, the system calculates the efficiency of the bubble eliminator Additionally, optimization controls are available to adjust the inlet flow rate, inlet pressure, air vent flow rate, and outgoing pressure, providing a comprehensive overview of the BEETA design.
Figure 2.1 Overview of bubble elimination efficiency testing apparatus (BEETA)
2.1.1 Description of fluid flow diagram
The fluid flow diagram for the BEETA system, illustrated in Figure 2.2, features valves numbered V1 to V9 for easy reference, which will be consistently referred to throughout this paper.
V1 With relief valve regulates oil flow and pressure
V3 Controls bubble eliminator vent pressure
V4 Controls back pressure on the outlet flow of the bubble eliminator V5, V6, V7 Allows oil to dump back into fluid tank
V8 Fine tune adjustment of air vent flow rate
V9 Three way valve: Sends hydraulic fluid to graduated cylinder or dump tank
Figure 2.2 Fluid diagram for the BEETA system
Hydraulic oil lines Air lines
Mixture of air and hydraulic oil
Hydraulic fluid is initially stored in the fluid tank and is pumped through valve V1 at the start of testing The oil's pressure and flow rate are regulated by a relief valve in conjunction with V1, which can be adjusted using pressure gauges A flow meter measures the hydraulic fluid's flow rate before it passes through a check valve, where it encounters incoming air.
Air from a compressed internal source flows through a pressure regulator and V2, enabling precise control over both pressure and flow rate Pressure gauges provide operators with the necessary feedback to adjust these control devices effectively The mass flow rate of the air is measured before it passes through a check valve, where it subsequently mixes with oil.
The oil line and air line converge, mixing through a static mixer and screen mixer before entering clear piping and the bubble eliminator The bubble eliminator's vent port directs fluid into a small drip tank, where pressure is regulated by valves V3 and V8, with V8 serving as a needle valve for precise adjustments V7 manages the vent fluid flow, monitored by a flow meter, while ball valve V4, aided by a pressure gauge, controls the outlet flow and back pressure on the bubble eliminator The hydraulic fluid then proceeds to valve V9, directing it to either the dump tank or the graduated cylinder.
At the conclusion of the testing process, the hydraulic fluid is drained back into the fluid tank through valves V5, V6, and V7, utilizing gravity to facilitate the flow To ensure proper functionality of the system, it is essential that the fluid tank is positioned lower than both the graduated cylinder and the dump tank.
The BEETA system cannot function as a closed loop flow system, as established in previous research by Suzuki et al It is essential to know both the incoming and outgoing oil-air mixture ratios to accurately calculate the bubble eliminator efficiency.
2.1.3 Necessity of second dump tank
To ensure accurate measurements with the BEETA system, air must be purged from the lines before adjustments can be made to the valves, a process that requires time To facilitate this, a secondary dump tank is incorporated into the design, allowing operators a window of 4 minutes to configure all pressure and flow rates prior to the hydraulic fluid entering the graduated cylinder for air percentage measurement.
The two check valves are essential for preventing the reverse flow of oil and air, which safeguards the air mass flow meter from potential damage While they may complicate system drainage, these valves enhance operational efficiency by eliminating concerns about backflow, making the system easier for the operator to manage.
The clear tubes of the bubble eliminator provide a visual gauge of its effectiveness, with the bottom tube filled with bubbles and the top tube nearly bubble-free when functioning correctly Additionally, the transparent tube at the inlet offers insight into the mixing efficiency of air and hydraulic fluid.
The drip tank serves as a reservoir for oil while the operator adjusts the vent pressure using valve 8, allowing for precise control until only air escapes Its transparent design enables easy monitoring, and it also facilitates testing of a semi-closed loop system by keeping valve V7 open, permitting both air and hydraulic fluid to flow into the tank A dedicated flow meter is installed to accurately measure the amount of hydraulic fluid exiting the drip tank in this semi-closed loop configuration.
BEETA Component Design and Selection
Appendix C, D, and E provide a comprehensive bill of materials for the BEETA system, which was assembled using numerous components sourced from various suppliers This section will outline the key items utilized in the construction of the BEETA system.
2.2.1 Mixing air and hydraulic fluid
A 3/8” diameter, 11” long stratos tube mixer was acquired from Koflo, featuring 21 mixing elements within its stainless steel body This static mixer is designed to effectively combine air and hydraulic fluid at elevated flow rates, resulting in a well-aerated mixture.
A screen mixer enhances the blending of air and hydraulic fluid, and it was built using two washers, a screen, and J.B Weld This assembly was then positioned inside a clear tube, as illustrated in Figure 2.4.
Figure 2.4 Screen mixer inside clear tube
The BEETA system utilizes a custom-fabricated graduated cylinder by Polyfab to accurately measure the air content in the outgoing hydraulic oil and air mixture The cylinder's dimensions were specifically designed based on the analysis detailed in Appendix B, ensuring precise measurements This setup enables the BEETA system to achieve a volumetric percentage of hydraulic fluid ranging from 99.99% to 97.93%.
Figure 2.5 Graduated cylinder full of hydraulic fluid
The transparent tank design enables easy visibility of air bubbles escaping from the hydraulic fluid Its conical shape facilitates the effective separation of air from the fluid in the graduated cylinder Additionally, the top fitting is designed for overflow, while the bottom fitting allows for the entry and exit of hydraulic fluid.
Two hydraulic fluid tanks were acquired from McMaster Carr to store hydraulic oil: a large tank with a capacity of 30.2 liters and a smaller dump tank of 11.4 liters The larger tank is designed to ensure that the system maintains an adequate supply of hydraulic fluid during operation Meanwhile, the smaller dump tank is configured to provide the operator with at least four minutes to adjust all valves and pressures in a closed-loop setup before hydraulic fluid is required to enter the graduated cylinder.
Pressure gauges are essential for operators to effectively adjust valves during testing Six gauges were acquired from McMaster-Carr, including low-pressure gauges that measure between 0 and 414 kPa and high-pressure gauges that range from 0 to 690 kPa Corrosion-resistant models were selected for use with hydraulic oil Additionally, a gauge for monitoring the hydraulic fluid pressure exiting the bubble eliminator was specifically chosen for its built-in flange, facilitating easy installation The incoming air pressure regulator also includes an integrated pressure gauge.
The Omega FMA-A23-10 mass flow meter is essential for accurately measuring the air entering the deaeration device, featuring an impressive accuracy of ±1% of full scale Although its response time is 1 second, this is acceptable since tests will be conducted under steady state conditions The meter is capable of handling pressures up to 1700 kPa, which exceeds the current capabilities of the BEETA system but allows for future high-pressure testing if needed Additionally, it offers a 0 to 5 volt output, facilitating electronic data acquisition and storage during testing.
The flow meter is designed to measure volumetric air concentrations between 2% and 30%, with a specific capability to read flow rates from 0 to 15 SLM (liters per minute at atmospheric pressure) This enables the BEETA system to effectively achieve a diverse range of volumetric air concentrations based on varying hydraulic fluid flow rates and pressures, as illustrated in Figure 2.6 Consequently, the maximum and minimum values depicted in Figure 2.6 fall within the target region, making them ideal for the system's requirements.
Figure 2.6 Minimum and maximum flow meter range
2.2.6 Borrowed items and petty cash items
The construction of the BEETA system involved utilizing various items sourced from the EPA, detailed in Appendix E Additionally, Appendix D outlines the petty cash items acquired from several hardware stores and Radio Shack.
Fabrication
The BEETA system was constructed at WuMRC utilizing previously mentioned components, which included the fabrication of brackets for secure assembly and the careful routing of hydraulic lines.
M in im um A ch ie va bl e A ir C on ce nt ra tio n M ax im um A ch ie va bl e A ir C on ce nt ra ti on
Bracketry items were designed to securely support essential components, including a hydraulic pump and a 30.2 L fluid tank Additionally, the lower shelf provides a mounting location for check valves This shelf is constructed using two 6-foot long 2”x4” boards and a 6-foot long ¾” x 1’ board, as illustrated in Figure 2.7.
To ensure proper fluid drainage from the system, the clear piping, drip tank, outflow pressure gauge, and valves 3 and 4, along with the bubble eliminator, should be installed at an elevated position above the table This setup is achieved using sturdy steel towers sourced from the WuMRC and a custom-fabricated polycarbonate mounting bracket created with a band saw and drill press.
To secure valves 1, 2, 5, 6, and 7, custom aluminum brackets were created, as illustrated in Figure 2.8 These brackets, measuring four inches in length, were fabricated using a drill press and band saw Each bracket features three small mounting holes on one side and a large 7/8” hole on the opposite side for valve installation.
The BEETA system maximizes the operator's workspace by keeping the table top surface as clear as possible, routing most fluid lines underneath the table Clear plastic lines are used for low-pressure fluid, while green rubber lines handle high-pressure fluid, all of which are essential for completing the fluid diagram previously illustrated.
Figure 2.9 Fluid lines routed underneath BEETA system table
Electrical Setup and Data Acquisition
During testing, it is essential to record flow information using two fluid flow meters and an air mass flow meter, which are connected to a computer for real-time data logging This recorded data can be analyzed once the testing process is complete, allowing for comprehensive evaluation and insights.
The wiring configuration ensures that all meters receive the required input voltage, allowing the generated signals to effectively reach the data acquisition equipment As illustrated in Figure 2.10, all three meters are interconnected with soldered and heat-shrunk connections, enhancing the system's durability.
Data acquisition computer equipment is necessary to read and store data during testing
A computer equipped with a data acquisition card was borrowed from WuMRC and positioned alongside the BEETA system to collect data from the meters Several Labview programs were adapted to develop a custom program for acquiring and saving data from all three meters, with the user interface illustrated in Figure 2.11 When executed, this program stores the data in a text file, which is subsequently analyzed using the Matlab program detailed in Appendix F.
Figure 2.11 User interface for data acquisition
Procedure for Use
To operate the BEETA system a series of steps must be performed These steps are listed below.
Step 1: Presetting all the valves
To properly configure the hydraulic system, close valves V5, V6, and V7, and position valve V9 to direct hydraulic fluid into the dump tank Ensure valve 1 is closed while valve 2 remains open, allowing only air to flow through the BEETA system upon startup Close valve 3 to limit fluid tank filling at the onset, and keep valve 4 open to prevent pressure buildup in the line Additionally, close valve V8 for easier adjustments later This initial valve configuration is detailed in Table 3.
To ensure accurate readings from the air mass flow meter, all meters must be activated The operator can then utilize the pressure regulator and V2 to adjust the air pressure and flow rate to the specified values This process can be conducted at the operator's convenience, as there will be no hydraulic fluid in operation during this time.
Step 3: Start hydraulic fluid flow
When the hydraulic pump is activated, the operator has about four minutes to complete step five before the dump tank overflows It is crucial for the operator to monitor the fluid level in the dump tank and to turn off the pump to prevent any overflow.
To prevent excessive pressure buildup, V1 should remain fully open while the hydraulic pump is activated, initiating fluid flow By utilizing V1 and the relief valve, the system's oil flow rate and pressure can be precisely adjusted to match the air pressure necessary for bubble production It is essential to make system adjustments to maintain the correct airflow rate and air pressure.
To maintain a constant hydraulic fluid level in the drip tank and ensure desired pressures and flow rates, it is essential to adjust valves V7, V3, and V8 Additionally, V4 plays a crucial role in regulating backpressure Together, these valves effectively manage the system's backpressure and the drainage fluid flow rate.
After adjusting the pressures and flow rates, the V9 is rotated to initiate the filling of the graduated cylinder Simultaneously, the data acquisition program is activated to capture data from the three meters at the outset.
Step 6: Stopping the hydraulic fluid flow
To control the flow of hydraulic fluid, V9 is activated to halt the fluid once it reaches the top of the graduated cylinder Simultaneously, V6 is opened and V2 is closed, while the hydraulic pump is turned off Finally, V5 is utilized to drain the fluid from the graduated cylinder until it reaches the 200 ml mark.
Step 7: Final measurements and draining the system
After allowing 24 hours for the air to settle, the new fluid height is recorded This measurement, combined with the initial fluid height, provides the volumetric concentration of air present in the hydraulic fluid that passed through the bubble eliminator.
To drain the system V2 through V7 must be opened Blowing air through the system helps oil move into the fluid tank on the lower shelve
Chapter 3 Performance Efficiency and Testing Results
Performance efficiency testing of cyclone bubble elimination is essential to determine the suitability of this system for dry sump pump applications This section outlines the calculation of bubble removal efficiency, details the experimental procedure, presents the test results, discusses the findings of Suzuki et al on dissolved gas studies, and concludes with insights drawn from the testing.
The bubble removal efficiency, denoted as B rem , is the value of most interest and was determined from data analysis using:
_ in bubble out bubble rem in bubble
_ _ in bubble rem in bubble
V in_bubble and V out_bubble denote the volumetric concentration of air, at standard temperature and pressure, entering and exiting the cyclone bubble elimination device, respectively
H final denotes the final fluid height (ml) as read by the graduated cylinder and 200
S w70 (maximum V out_bubble value that can be read using the graduated cylinder)
The volumetric flow rate of incoming air (V In_air) and the incoming oil flow rate (V In_oil) are essential for calculating V in_bubble using Eq (3) V In_air is measured with an air mass flow meter, while V In_oil is determined using an incoming fluid flow meter, with both measurements expressed in liters per minute (L/min) at standard temperature and pressure.
_ _ in air in bubble in air in oil
V out_bubble is found using:
When H final is less than 0, it is impossible to ascertain an exact V out_bubble; however, a maximum value for B rem can be established, indicated by a pink symbol in all tables, using Equation (2) The Matlab program detailed in Appendix F was utilized to analyze the extensive data collected from testing, allowing for the calculation of the average flow rate for each test conducted.
A series of 20 experiments were performed to evaluate the B rem across diverse operating conditions, incorporating varying V in_oil values and differences in vent and back pressure (P delta), as detailed in Tables 2 and 3 Throughout all tests, the back pressure was maintained at a constant 138 kPa, which GE-Totten identified as optimal, although no specific optimum vent pressure was suggested.
Table 2: Low Flow Rate Testing
Table 3: High Flow Rate Testing
The interrelationship between P delta, V in_oil, and V in_air in the BEETA system complicates the control of testing values, as changes in one parameter affect the others Lower flow rate tests showed V in_oil values ranging from 1.45 to 2.06 L/min, with P delta varying between 0 and 48.3 kPa, as detailed in Table 2 In contrast, higher flow rate tests focused on three different P delta values while examining corresponding ranges of V in_oil, as illustrated in Table 3 The data analysis exclusively considers B rem, incorporating varying V in_bubble values in the performance evaluation of the device.
3.3 Results Effect of Flow Rate
Increasing the flow rate to 6 L/min negatively impacts B rem, contrary to GE-Totten's assertion that this is the optimal flow rate This inconsistency in the BEETA system arises from variations in bubble size and dissolved gas concentration based on V in_oil At elevated flow rates, bubbles become significantly smaller, and higher dissolved gas concentrations result from increased pressure and enhanced mixing capabilities of the BEETA system The static and screen mixers in the system improve their mixing efficiency at these higher flow rates, leading to greater solubility and an increased amount of dissolved gas in the oil Consequently, as the flow rate rises, the bubble size decreases while the cyclone bubble eliminator faces a greater challenge from the increased dissolved gas.
The BEETA system effectively generates smaller bubbles (less than 0.75 mm radius) and dissolved gas at high flow rates, which leads to a significant reduction in B rem as the flow rate approaches 6 L/min This trend is depicted in Figure 3.1, which presents test results across various V in_oil and P delta values It is important to note that the pink data points indicate values that are unknown but fall below the depicted points The figure reveals that air removal levels for the small bubble and dissolved gas mixture are unacceptably low The maximum flow rate achieved by the BEETA system was 5.6 L/min, constrained by system pressure limitations that prevented higher flow rates.
Figure 3.1 Cyclone bubble elimination performance
Performance Efficiency and Testing Results
Bubble Removal Efficiency
The bubble removal efficiency, denoted as B rem , is the value of most interest and was determined from data analysis using:
_ in bubble out bubble rem in bubble
_ _ in bubble rem in bubble
V in_bubble and V out_bubble denote the volumetric concentration of air, at standard temperature and pressure, entering and exiting the cyclone bubble elimination device, respectively
H final denotes the final fluid height (ml) as read by the graduated cylinder and 200
S w70 (maximum V out_bubble value that can be read using the graduated cylinder)
V in_bubble is calculated using Equation (3), which incorporates the volumetric flow rate of incoming air at atmospheric pressure (V In_air) and the incoming oil flow rate (V In_oil) The air mass flow meter determines V In_air, while the incoming fluid flow meter measures V In_oil, with both values expressed in liters per minute (L/min) at standard temperature and pressure.
_ _ in air in bubble in air in oil
V out_bubble is found using:
If H final is less than 0, an exact value for V out_bubble cannot be established; however, a maximum value for B rem can be calculated, indicated by a pink symbol in all tables using Eq (2) The Matlab program detailed in Appendix F was utilized to analyze extensive data collected from testing, enabling the determination of the average flow rate for each test conducted.
Experimental Procedure
Twenty experiments were conducted to assess the B rem across various operating conditions, incorporating different V in_oil values and variations in vent and back pressure (P delta) values, as detailed in Tables 2 and 3 Throughout all tests, the back pressure was maintained at a constant 138 kPa, which GE-Totten identified as optimal, although no specific optimum vent pressure was recommended.
Table 2: Low Flow Rate Testing
Table 3: High Flow Rate Testing
In the BEETA system, P delta, V in_oil, and V in_air are interconnected, making it challenging to control testing values since a change in one affects the others Lower flow rate tests resulted in V in_oil values ranging from 1.45 to 2.06 L/min, with P delta varying between 0 and 48.3 kPa, as detailed in Table 2 Conversely, higher flow rate tests examined three distinct P delta values within specific ranges of V in_oil, as indicated in Table 3 The data analysis focuses solely on B rem, ensuring that variations in V in_bubble values are considered in the device's performance evaluation.
Results Effect of Flow Rate
Increasing the flow rate to approximately 6 L/min results in a negative correlation to B rem, contrary to GE-Totten's assertion that this is the optimal flow rate This discrepancy in the BEETA system arises from variations in bubble size and dissolved gas concentration, which are influenced by V in_oil At elevated flow rates, bubbles become extremely small, and the concentration of dissolved gas increases due to heightened pressure and enhanced mixing capabilities of the BEETA system The static and screen mixers in the system improve their mixing efficiency at higher flow rates, leading to increased pressure and solubility, which further contributes to a greater amount of dissolved gas in the oil Consequently, as the flow rate rises, bubble size decreases, and the cyclone bubble eliminator must manage a higher concentration of dissolved gas.
The BEETA system produces smaller bubbles (less than 0.75 mm radius) and dissolved gas at high flow rates, which affects efficiency; as the flow rate approaches 6 L/min, the B rem decreases significantly Figure 3.1 displays the results of various tests with different V in_oil and P delta values, highlighting that some data points (marked in pink) indicate unknown exact values but are below the specified point The figure also reveals unacceptably low air removal levels for the small bubble and dissolved gas mixture, with the maximum achievable flow rate being 5.6 L/min, constrained by system pressure limitations.
Figure 3.1 Cyclone bubble elimination performance
The error in the experiment was determined by considering the precision of the graduated cylinder and the variations observed in the flow meter readings during testing Due to the inability to maintain exact stable conditions for the flow rates, fluctuations occurred as pressure increased while the graduated cylinder filled To mitigate this issue, data was collected at three distinct intervals: the beginning, middle, and end of each test, allowing for a more accurate assessment of error.
The presence of small bubbles or dissolved gas mixtures leads to significantly reduced performance levels In contrast, large bubbles can be easily eliminated, resulting in standard deviations that vary among the tests Consequently, error bars were incorporated into Figure 3.1 to reflect this variability.
Results Effect of Vent Pressure
At lower flow rates, a higher P delta value significantly improves cyclone bubble elimination performance However, at higher flow rates, determining the optimal P delta visually is challenging, and experimental results indicate no correlation between B rem and P delta.
For low oil flow rates (