This paper aims to improve the mechanical properties and fatigue life of AISI/SAE 4140 alloy steel connecting rods (CRs). Conventional CRs are typically manufactured through open die forging/hammering, blocking, and hot forging processes. In the present work, a modification to the process route has been proposed such that the open die forging/hammering was completely replaced with a multistep asymmetrical reducer rolling technique. Four rolling passes were introduced to achieve the desired preform shape and size. The effect of each rolling pass on grain size, mechanical properties, and fatigue life was investigated. Samples from each multistep rolling, blocking, and forging stage were subjected to impact, hardness, tensile, and fatigue testing. Metallography using optical and scanning electron microscopes was also conducted to reveal metallurgical changes. Fatigue testing and fractography were performed using the R.R. Moore Rotating-Beam Fatigue testing machine and scanning electron microscope, respectively, to evaluate the fatigue life and the fracture behavior of both the conventional and multistep rolled forged CRs. It was observed that, unlike the conventional forging process, multistep asymmetrical rolling gradually reduces grain size as the rolling progresses and improves yield, tensile, and impact strengths, hardness, and ductility. In comparison to conventional forging, multistep rolling led to an almost 33% and 29% increase in yield and tensile strengths, respectively. Moreover, the fatigue life of multistep rolled CR increased by more than five times compared to conventional CR.

Industrial facilities worldwide reject between 20% and 50% of their primary energy input as low- and medium-grade exhaust heat, however, deployment of recovery systems in GCC (Gulf Cooperation Council) remains well below OECD (Organization of Economic Cooperation and Development) average. The Kingdom of Bahrain has some heavy manufacturing industries such as aluminium smelting, petrochemicals, and steel, however, the lack of widespread exhaust-heat recovery is evident. This research presents a reproduceable design, thermo-fluid modeling, and techno-economic assessment of a gas-to-water shell-and-tube exhaust heat recovery system (EHRS) that is contextualized with Bahrain industry for representative exhaust stream (320°C, 3.2 kg/s, 6 000 h/yr). A reproducible MATLAB/Simulink digital twin was developed, integrating steady-state thermodynamic sizing, dynamic plant response, fault injection (fouling, sensor bias, flow loss), and an anomaly-detection layer based on moving statistics. Results show a nominal recovery of 537.6 kW with an exchanger area of 72.7 m², yielding 3226 MWh of useful energy annually, displacing 3795 MWh of natural-gas fuel, and avoiding of ≈ 686 t CO₂/yr. Techno-Economic screening using 2025-26 Bahrain industrial tariff yield a payback of 2.3–3.5 years and a positive 10-year NPV across all sensitivity scenarios. A Heat-as-a-Service (HaaS) Energy-Service-Company (ESCO) business model is proposed as the most viable route to market in Bahrain, to eliminate host factory CAPEX exposure and aligning with national sustainability targets.

Bahrain relies heavily on centralized seawater desalination, driven by minimal rainfall (70–80mm/year), high evaporation (>2,000 mm/year), and depleted groundwater, while conventional reverse osmosis and multi-stage-flash systems demand 3–22kWh/m³ and grid scale infrastructure. This paper presents the thermal design, analytical modeling, experimental validation and performance evaluation of a passive single slope solar still adapted to Bahrain's climate. Using energy balance equations and Dunkle's correlation for internal heat and mass transfer, hourly simulation under representative summer conditions (G=850W/m², Ta = 40°C, Vw=3m/s) predicts a baseline productivity of 2.05L/m²/day at 34% thermal efficiency. Experimental measurements obtained from a fabricated prototype showed good agreement with the model. Sensitivity analyses across water depth (0.02–0.15m) and glass tilt (15°–35°) identify design tradeoffs, and three enhancement strategies; latent heat recovery, basin fins, and an external air cooled condenser raise productivity to 2.93L/m²/day (+43%) in combination. The design projects 720L/m²/year at a fabrication cost of ~68BHD, supporting a viable commercial deployment pathway aligned with Bahrain Vision 2030 and the United Nations Sustainable Development Goals (SDGs) 6 (Clean Water and Sanitation), 7 (Affordable and Clean Energy), 9 (Industry, Innovation and Infrastructure), and 13 (Climate Action).

Bahrain faces increasing pressure on freshwater resources and relies heavily on energy-intensive desalination. This study investigates the performance of a passive single-slope solar still designed for Bahrain climatic conditions through analytical modelling and prototype testing. An energy-balance model based on Dunkle's heat and mass transfer correlations was developed to predict water production under representative summer conditions. The model predicted a freshwater yield of 2.05 L/m²/day with a thermal efficiency of 34%. Experimental testing of a fabricated prototype showed good agreement with the model, with a mean absolute percentage error of approximately 4%. The influence of key design and environmental parameters, including water depth, glass-cover inclination, humidity, wind speed, solar irradiance, optical properties, and feedwater salinity, was also examined. In addition, three enhancement options, namely latent heat recovery, basin fins, and an external air-cooled condenser, were evaluated analytically. When combined, these measures were analytically predicted (not yet experimentally verified) to increase productivity to 2.93 L/m²/day, an improvement of about 43% over the baseline design. The results indicate that passive solar desalination can provide a practical small-scale water-production solution under Bahrain conditions. However, annual productivity estimates and performance enhancements remain model-based predictions requiring further experimental validation.