Government Engineering College, Aurangabad

Abstract A third-order displacement-based formulation is utilized to model transverse shear and normal deformation phenomena in the bending analysis of simply supported square and rectangular sandwich plate structures. The plate is subjected to transverse loading in five forms: sinusoidal, uniformly distributed, linearly varying, concentrated, and parabolic. The kinematics adopt a displacement field in which both in-plane and transverse components vary nonlinearly across the plate thickness. By enforcing zero transverse shear traction on the top and bottom surfaces, the formulation obviates the shear correction factors typically invoked in first-order shear deformation models. The governing equations and boundary conditions are obtained via the virtual work principle, and closed-form solutions are provided for simply supported sandwich plates. Flexural analysis encompasses square and rectangular sandwich plates with different aspect ratios. The complete numerical solution framework is developed using MATLAB software. Validation is performed by cross-checking the present formulation against benchmarks from classical plate theory, first-order shear deformation theory, multiple higher-order shear deformation models, and exact solutions from three-dimensional elasticity wherever available.

Abstract Access to freshwater remains a critical global challenge, particularly in arid and off-grid regions where conventional desalination technologies are energy-intensive. Solar stills offer a sustainable alternative; however, the effect of still geometry on thermal behavior and freshwater productivity remains insufficiently understood. Existing studies focus mainly on single geometries or hybrid configurations, leaving a clear knowledge gap in the direct comparative evaluation of different pyramid architectures under identical operating conditions. This study addresses this gap by conducting a combined mathematical and experimental comparison of two newly fabricated solar stills, a Pentagonal Pyramid Solar Still (PPS) and a Square Pyramid Solar Still (SPS), each constructed with an identical basin area of 0.25 m2. Experiments were performed under outdoor tropical climatic conditions (solar intensity 600–950 W/m2), and hourly data for temperature, humidity, and distillate yield were recorded. A Python-based transient heat and mass transfer model was developed and validated using statistical indicators (R2 = 0.96, MAPE ≈ 3–5%). The findings show that PPS consistently outperformed SPS, producing 18.3% higher daily distillate output, 15.1% greater thermal efficiency, and 17.6% higher exergy efficiency. The performance enhancement is primarily attributed to the additional inclined glass face in the pentagonal geometry, which increases optical exposure, internal radiation trapping, and the effective condensation surface. Economic analysis further demonstrates that PPS reduces the cost per liter of freshwater by nearly 12% compared with SPS. Overall, the study establishes that geometric optimization plays a decisive role in solar desalination performance, and the validated mathematical model provides a practical framework for future solar still design and scaling in decentralized water-scarce regions.

Pyramid solar stills have gained attention for their larger condensation area and improved solar exposure, yet the influence of geometry on internal heat and mass transfer mechanisms remains insufficiently understood. Most existing studies focus mainly on productivity, leaving the underlying transport physics unexplored. In this work, a three-dimensional transient Computational Fluid Dynamics (CFD) model is used to compare square, pentagonal, and hexagonal pyramid geometries under identical operating conditions and to examine how they shape natural convection, vapor transport, and phase change behavior. The simulations reveal that geometry fundamentally alters circulation strength, vapor residence time, and condensation distribution. The square pyramid forms a single weak loop with strong stagnation zones, whereas the pentagonal geometry reduces stagnation by similar to 50%, and the hexagonal design strengthens overall circulation by similar to 29%. Condensation uniformity also improves markedly, with the global CUI increasing from 0.42 (square) to 0.81 (hexagonal), while vapor residence time decreases from 14.8 s in the square pyramid to 7.6 s in a hexagonal shape. A key finding is the decoupling between evaporation and condensation performance, demonstrating that similar basin temperatures do not guarantee effective condensation unless vapor is uniformly redistributed. Two transport-based performance indicators-the circulation strength factor and the condensation uniformity index-are introduced to enable systematic geometric comparison. By translating classical cavity convection principles into the context of solar desalination, this study demonstrates the decoupling of evaporation and condensation performance. The work introduces practical, transport-based indicators, the circulation strength factor and the condensation uniformity index, to provide a systematic framework for engineers to evaluate geometry-induced transport efficiency beyond standard empirical yield measurements.

Solar distillation offers a sustainable solution for potable water production, yet the influence of geometric alignment on multi-face systems remains a critical but often overlooked design parameter. This work experimentally isolates the influence of azimuth orientation on the thermal and distillation performance of a fixed pentagonal pyramid solar still under the tropical summer climate of Nagpur, India. Four identical units, constructed with galvanized iron basins, internal matte black coating, thirty millimeters of polyurethane insulation, and four-millimeter-thick clear float glass, were tested simultaneously with a constant basin water depth of two centimeters. The systems were oriented toward the East (90°), West (270°), South-East (135°), and South (180°) to examine azimuth-dependent solar interception over a campaign of at least three clear sky days per configuration. The experimental results, analyzed using a validated energy balance model, determined that the south-facing orientation achieved the highest daily freshwater production of 3.6 to 3.7 L/m²·day−1 and a thermal efficiency of 38 to 40%. The South-East orientation followed with a yield of 3.3 to 3.4 L/m²·day−1, representing a performance decrease of approximately 8 to 9% compared to the optimal south orientation. Conversely, the east-facing unit produced 2.7 to 2.9 L/m²·day−1, while the west-facing unit yielded 2.6 to 2.7 L/m²·day−1, both showing time-shifted productivity peaks and lower cumulative output relative to the south-aligned configuration. These findings validate azimuth alignment as a zero-cost optimization parameter, establishing south orientation as the superior strategy and South-East as a viable alternative for fixed desalination installations.

Abstract Rotameters are reliable primary sensors for measuring the flow rate of fluids in pipelines. However, they have the limitation of being local, indicative sensors that rely on vertically mounted, breakable, transparent, or semi-transparent tapered tubes, suitable only for transparent liquids. To enable remote indication of flow rates or for control purposes, a non-contact secondary sensor is necessary. This paper investigates a modified non-contact rotameter transducer using a magneto-resistive (MR) element as the secondary sensor. A signal conditioner circuit is designed to transmit the rotameter reading and transducer output to a remote location for monitoring and control. The theoretical equations explaining the sensor, transducer, and transmitter’s performance are derived and discussed. Experimental studies on the prototype transmitter have been conducted, with results showing good linearity and repeatability, validating the theoretical model. Furthermore, artificial neural networks (ANN) have been applied to optimize the flow rate measurement by enhancing accuracy and reducing any environmental impacts on sensor performance. ANN-based models provide better calibration and fault tolerance, ensuring improved precision in flow rate detection even under varying environmental conditions. The experimental results and their correlation with the theoretical equations are presented, confirming the effectiveness of the proposed system.