Effect of Organic Compounds Additives for Biodiesel Fuel blends on Diesel Engine Vibrations and Noise Characteristics

The extensive consumption of petroleum fuel directly correlates with both hazardous exhaust emissions affecting human health and contributing to global warming. Initially, biodiesel fuels were proposed as a viable alternative to address these issues. This perspective finds support in numerous published studies that highlight how the significant catalytic effect of nanoparticles allows for their integration into biodiesel blends, resulting in improved combustion characteristics, reduced exhaust emissions, and enhanced performance. This study investigates the impact of additives on biodiesel fuel properties and its effects on engine performance metrics such as brake power, brake thermal efficiency, exhaust gas concentration, engine vibration, and noise levels. In this work, we extracted the majority of previous research findings from specific studies. The inclusion of additives leads to increased concentrations of carbon dioxide (CO2) and NOx, as well as enhanced brake power and brake thermal efficiency. It also reduces the amount of gasoline consumed during braking, exhaust gas temperature, vibration, noise, hydrocarbons, carbon monoxide (CO), and smoke emissions. The comprehensive review concludes definitively that the compromised engine performance, combustion, and emission characteristics of biodiesel-diesel blends can be effectively restored through the addition of nanoparticles

A Technical Survey on the Impact of Exhaust Gas Recirculation and Multifuel Blends on Diesel Engine Performance and Emission Characteristics

The increasing demand for fossil fuels poses significant challenges as their reserves gradually deplete over time. Biodiesel is considered one of the most effective alternative fuels to mitigate these issues. Current research focuses on comparing engine performance parameters when blending biodiesel with fossil fuels in Compression Ignition (C.I.) engines. The study demonstrates a comparison of the exhaust emissions produced by biodiesel fuel. In comparison to diesel, biodiesel generally exhibits lower heating value, higher density, increased fuel consumption, and elevated nitrogen oxide levels. To address these challenges, various additives are mixed and blended with biodiesel to meet international fuel standards. These additives include oxygen additives, cetane improvers, growth enhancers, and antioxidants, which contribute to producing high-quality biodiesel fuel. By incorporating these additives, engine performance can be enhanced in terms of thermal efficiency, brake-specific fuel consumption, and exhaust gas temperatures. Furthermore, biodiesel usage leads to lower emissions of greenhouse gases such as hydrocarbons and carbon dioxide compared to conventional fuels. Notably, blending additives with biodiesel and diesel fuel has been shown to reduce nitrogen oxide (NOx) emissions. Additionally, this research highlights aspects related to engine vibrations and the efficiency coefficient

Analyzing the Influence of Design and Operating Conditions on Combustion and Emissions in Premixed Turbulent Flames: A Comprehensive Review

Recently, premixed combustion has dominated the field of combustion research worldwide. The current work is a review that addresses the effects of design and operating regimes on the combustion and emission characteristics of premixed turbulent flames. The study accounts for recent developments aimed at overcoming combustor operability issues that influence emissions and flame stability. Various experimental setups have been utilized in investigations, with results pertaining to performance and emissions concerning premixed turbulent flames. Thus, the objective of this paper is to provide a comprehensive review of the effects of swirl vane angles and equivalence fuel-air ratios for tests conducted both with and without secondary air, aiming to improve combustion performance and reduce emissions. This review extensively analyzes published studies to provide and discuss different strategies for controlling premixed turbulent combustion techniques within a wide range of swirl vane angles and equivalence air-fuel ratios

Experimental Study on the Impact of Secondary Air Injection and different swirl van angles on Premixed Turbulent Flame Propagation and Emission Behaviors

The objective of the present paper is to investigate experimentally the flame characteristics utilizing different secondary air inlet direction for different primary air swirl numbers and equivalence fuel-air ratios. In this study, an experimental test rig was carried out to investigate the flame temperature and emission behavior with flame length at the equivalence fuel-air ratios taken0.96, 0.80, 0.70, and 0.60, and swirl vane angles were varied as 20, 30, 45, and 60° to generate different swirl numbers of 0.26, 0.416, 0.71 and 1.23, respectively. In addition to the introduction of secondary air in test combustor, whereas the primary air and fuel mass flow rates were kept constant at 12.5. Also, the secondary air flow rate was changed to give different secondary over primary air and fuel ratios of 0.19, 0.32, 0.41, and 0.48. The study showed that the flame temperature distribution with flame length at the equivalence fuel-air ratios is increased at 20.0 mm of radial flame distance and decreases gradually with radial flame distance. Also, the experimental investigation illustrated the emission characteristics at different equivalence fuel-air ratios accounting for nitrogen oxide and unburned hydrocarbon were decreased gradually with radial flame distance at different swirl vane angles. Moreover, the emission characteristics at different equivalence fuel-air ratios accounting for the concentration percent of carbon dioxide and carbon monoxide were decreased gradually with radial flame distance at different swirl vane angle

Effects of Fuel Equivalence Ratio and Swirl Vane Angles on Premixed Burner Turbulent Flame Combustion Characteristics

A turbulent flow field has a major effect on the premixed flame structure and temperature distribution that specifically determines the effectiveness of the burned fuel and the amounts of produced emissions. However, the premixed flame tangential and axial velocity distribution through the flame length help to predict the combustion and emissions attributes of the burned fuel. In this regard, an experimental and analytical investigation on premixed turbulent burners at different equivalence fuel-air ratios with different swirl vane angles has been achieved in the present work to assess the combustion performance and emissions characteristics. A theoretical methodology was carried out to predict the flame temperature distribution with flame length at the equivalence fuel-air ratio of 0.6 and 0.8and swirl vane angle 20°. Also, the emission characteristics such as NOx, CO2, CO, and UHC have accounted experimentally and analytically to accounting gas temperature, and axial and tangential velocities distribution along the flame length. However, a statistical analysis was performed to verify and validate the proposed model. The prediction and experimental observations illustrated the acceptable agreement whereas the overall error in the experimental testes verification is about 3.66 %

Obstetric history and mammographic density: a population-based cross-sectional study in Spain (DDM-Spain)

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45–68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd’s semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [>9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02–1.72] and weight of first child (>3,500 g: OR = 1.32; 95% CI = 1.12–1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17–2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18–3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland

An assessment of existing models for individualized breast cancer risk estimation in a screening program in Spain

Background: The aim of this study was to evaluate the calibration and discriminatory power of three predictive models of breast cancer risk. Methods: We included 13,760 women who were first-time participants in the Sabadell-Cerdanyola Breast Cancer Screening Program, in Catalonia, Spain. Projections of risk were obtained at three and five years for invasive cancer using the Gail, Chen and Barlow models. Incidence and mortality data were obtained from the Catalan registries. The calibration and discrimination of the models were assessed using the Hosmer-Lemeshow C statistic, the area under the receiver operating characteristic curve (AUC) and the Harrell’s C statistic. Results: The Gail and Chen models showed good calibration while the Barlow model overestimated the number of cases: the ratio between estimated and observed values at 5 years ranged from 0.86 to 1.55 for the first two models and from 1.82 to 3.44 for the Barlow model. The 5-year projection for the Chen and Barlow models had the highest discrimination, with an AUC around 0.58. The Harrell’s C statistic showed very similar values in the 5-year projection for each of the models. Although they passed the calibration test, the Gail and Chen models overestimated the number of cases in some breast density categories. Conclusions: These models cannot be used as a measure of individual risk in early detection programs to customize screening strategies. The inclusion of longitudinal measures of breast density or other risk factors in joint models of survival and longitudinal data may be a step towards personalized early detection of BC.This study was funded by grant PS09/01340 and The Spanish Network on Chronic Diseases REDISSEC (RD12/0001/0007) from the Health Research Fund (Fondo de Investigación Sanitaria) of the Spanish Ministry of Health

Breast cancer risk factors in relation to breast density (United States)

OBJECTIVES: Evaluate known breast cancer risk factors in relation to breast density. METHODS: We examined factors in relation to breast density in 144,018 New Hampshire (NH) women with at least one mammogram recorded in a statewide mammography registry. Mammographic breast density was measured by radiologists using the BI-RADS classification; risk factors of interest were obtained from patient intake forms and questionnaires. RESULTS: Initial analyses showed a strong inverse influence of age and body mass index (BMI) on breast density. In addition, women with late age at menarche, late age at first birth, premenopausal women, and those currently using hormone therapy (HT) tended to have higher breast density, while those with greater parity tended to have less dense breasts. Analyses stratified on age and BMI suggested interactions, which were formally assessed in a multivariable model. The impact of current HT use, relative to nonuse, differed across age groups, with an inverse association in younger women, and a positive association in older women (p < 0.0001 for the interaction). The positive effects of age at menarche and age at first birth, and the inverse influence of parity were less apparent in women with low BMI than in those with high BMI (p = 0.04, p < 0.0001 and p = 0.01, respectively, for the interactions). We also noted stronger positive effects for age at first birth in postmenopausal women (p = 0.004 for the interaction). The multivariable model indicated a slight positive influence of family history of breast cancer. CONCLUSIONS: The influence of age at menarche and reproductive factors on breast density is less evident in women with high BMI. Density is reduced in young women using HT, but increased in HT users of age 50 or more