Theoretical and experimental investigation of a Solar Free-Piston Stirling Engine (FPSE) using a flexible bellow for water pumping/power generation

Fossil fuels are the primary energy source globally and currently represent more than 80% of the overall energy consumption. Fossil fuels such as natural gas, oil and coal remain the principal fuels for supply and off-grid power generation in remote areas. Concerns over the negative environmental impact of greenhouse gases emission have shifted toward deploying and developing renewable and low carbon energy technologies. In the last decades, many sustainable and clean energy alternatives have been exploited to make energy and power generation clean and affordable to mitigate the negative impact of fossil fuels on the environment. The Stirling engine is considered one of the most promising solutions of sustainable power technologies to generate electricity from external heat sources. This research develops the computer model of a free-piston Stirling engine (FPSE) prototype operated by a solar simulator for small-scale power generation. The mathematical model was based on solving the working fluid's mass, energy and momentum conservation equations in different engine components. The engine's performance was evaluated based on the other three models: Schmidt, Adiabatic and Simple analysis. It is found that Simple analysis gave the most accurate result because the model considers the heat losses of the Stirling cycle. This research also investigated a novel design of a solar Free-piston Stirling engine for power generation and water pumping, which can be used in remote world regions. The design incorporates flexible bellows or diaphragm working as a power piston and two pre-compressed springs to support the displacer. This mechanical arrangement of the moving components in the engine reduces mechanical friction and air leakage. The experimentally testable FPSE was carried out, including a linear electric generator to develop and validate the theoretical simulation model. It was demonstrated the engine could operate successfully at an input heat temperature of 300C°, at 1 bar pressure and a frequency of 10 Hz. Moreover, a novel design is added to the engine to convert the linear motion to rotary motion. Overall, the engine's measured power and efficiency are low, and more tests of increasing the pressure of the engine for more than 1 bar are required to obtain better performance

Theoretical and experimental investigation of a Solar Free-Piston Stirling Engine (FPSE) using a flexible bellow for water pumping/power generation

Fossil fuels are the primary energy source globally and currently represent more than 80% of the overall energy consumption. Fossil fuels such as natural gas, oil and coal remain the principal fuels for supply and off-grid power generation in remote areas. Concerns over the negative environmental impact of greenhouse gases emission have shifted toward deploying and developing renewable and low carbon energy technologies. In the last decades, many sustainable and clean energy alternatives have been exploited to make energy and power generation clean and affordable to mitigate the negative impact of fossil fuels on the environment. The Stirling engine is considered one of the most promising solutions of sustainable power technologies to generate electricity from external heat sources. This research develops the computer model of a free-piston Stirling engine (FPSE) prototype operated by a solar simulator for small-scale power generation. The mathematical model was based on solving the working fluid's mass, energy and momentum conservation equations in different engine components. The engine's performance was evaluated based on the other three models: Schmidt, Adiabatic and Simple analysis. It is found that Simple analysis gave the most accurate result because the model considers the heat losses of the Stirling cycle. This research also investigated a novel design of a solar Free-piston Stirling engine for power generation and water pumping, which can be used in remote world regions. The design incorporates flexible bellows or diaphragm working as a power piston and two pre-compressed springs to support the displacer. This mechanical arrangement of the moving components in the engine reduces mechanical friction and air leakage. The experimentally testable FPSE was carried out, including a linear electric generator to develop and validate the theoretical simulation model. It was demonstrated the engine could operate successfully at an input heat temperature of 300C°, at 1 bar pressure and a frequency of 10 Hz. Moreover, a novel design is added to the engine to convert the linear motion to rotary motion. Overall, the engine's measured power and efficiency are low, and more tests of increasing the pressure of the engine for more than 1 bar are required to obtain better performance

Maternal Race, Demography, and Health Care Disparities Impact Risk for Intraventricular Hemorrhage in Preterm Neonates

OBJECTIVE: To determine whether risk factors associated with Grade (Gr) 2–4 intraventricular hemorrhage (IVH) differs between African ancestry and white subjects. STUDY DESIGN: Inborn, appropriate for gestational age (GA) infants with birth weights (BW) 500–1250 grams and exposed to >1 dose of antenatal steroids were enrolled in 24 neonatal intensive care units. Cases had Gr 2–4 IVH and controls matched for site, race and BW range had 2 normal ultrasounds read centrally. Multivariate logistic regression modeling identified factors associated with IVH across African ancestry and white race. RESULTS: Subjects included 579 African ancestry or white race infants with Gr 2–4 IVH and 532 controls. Mothers of African ancestry children were less educated, and white case mothers were more likely to have > 1 prenatal visit and have a multiple gestation (P ≤.01 for all). Increasing GA (P =.01), preeclampsia (P < .001), complete antenatal steroid exposure (P = .02), cesarean delivery (P < .001) and white race (P = .01) were associated with decreased risk for IVH. Chorioamnionitis (P = .01), Apgar< 3 at 5 min (P < .004), surfactant (P < .001) and high frequency ventilation (P < .001) were associated with increased risk for IVH. Among African ancestry infants, having >1 prenatal visit was associated with decreased risk (P = .02). Among white infants, multiple gestation was associated with increased risk (P < .001) and higher maternal education with decreased IVH risk (P < .05). CONCLUSION: Risk for IVH differs between African ancestry and white infants and may be attributable to both race and health care disparities