A piston bowl's design and spray angle improve air–fuel mixing, resulting in more complete combustion and higher efficiency. Ansys Forte 2023 R1 a CFD software was used to analyze the effects of five combustion chamber geometries of cylinder, modified re‐entrant, re‐entrant, double‐stepped, and stepped on engine performance, combustion, and emission characteristics at spray angles of 1000°, 1050°, 1100°, 1150°, and 1200°, respectively. This study looks into the effects of piston bowl shape and spray angle on engine performance and emission characteristics. The numerical investigation is carried out with a load of 0.44 MPa and a start of injection at 7° bTDC. The double stepped piston bowl with spray angles of 110°–115° has the maximum thermal efficiency and the lowest ISFC, while reducing VOC, UHC, soot, and CO emissions. The combustion and performance parameters for piston bowl geometries are optimized at spray angles of 110° and 115°. At these spray angles, improved fuel–air interaction leads to higher peak cylinder pressure, peak cylinder temperature, thermal efficiency, and ISFC consumption while producing reduced emissions. The results show that spray angle optimization is crucial, with 110°–115° emerging as the optimal spray angle range for piston bowl selection and combustion optimization. Among the bowl geometries, the double stepped demonstrate the most balanced performance‐emission trade‐off at spray angles of 110° and 115° compared to stepped, modified re‐entrant, re‐entrant, and cylindrical shapes.
Md. Nazmul Haque, Abdullah Al Rifat, Tafsirul Hassan et al.· Energy Science & Enginee...· 0 citations
Background: Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of chronic morbidity and mortality, with frequent exacerbations that can lead to acute respiratory failure. Non-invasive ventilation (NIV) is a key treatment for acute respiratory failure in COPD exacerbations. The Blood Urea Nitrogen (BUN) to serum albumin ratio has been proposed as a prognostic marker in various diseases, reflecting metabolic stress and systemic inflammation. Still, its association with the need for NIV in COPD exacerbations has not been widely studied.
Objective: This study aims to evaluate the association between the BUN/Albumin ratio and the need for NIV in patients with exacerbations of COPD.
Methods: This cross-sectional study was conducted in the inpatient Department of Respiratory Medicine at the National Institute of Diseases of the Chest and Hospital (NIDCH), Dhaka, Bangladesh, from June 2023 to December 2024. A total of 116 patients diagnosed with exacerbations of COPD were enrolled. The BUN/Albumin ratio was measured for each patient, and the need for NIV was assessed. Data were analysed to determine if there was a significant association between the BUN/Albumin ratio and the requirement for NIV.
Results: The mean BUN/Albumin ratio was significantly higher in patients who required NIV (9.1±2.8) compared to those who did not (5.3±1.8, p = 0.001). A progressive increase in the BUN/Albumin ratio was observed with worsening severity of COPD exacerbations, with severe cases showing the highest ratios (9.5±2.9). Multivariate regression analysis showed that the BUN/Albumin ratio was significantly associated with the need for NIV (adjusted OR 19.629, 95% CI 13.976-27.561, p = 0.001).
Conclusion: The BUN/Albumin ratio is significantly associated with the need for NIV in patients with exacerbations of COPD. Elevated BUN/Albumin ratios may serve as a useful biomarker for identifying patients at higher risk for respiratory failure and may help guide early intervention in clinical practice.
Chest Heart J. 2025; 49(1) : 3-9
Md Shahjahan Ali, Mahmud Rahim, Rezaul Haque et al.· Chest & Heart Journal· 0 citations
