Research Article
Numerical Modeling of Heat Transfer and Aerodynamic Characteristics in a Semi-cylindrical Solar Air Heater
Sardorali Mirzayev*
,
Bekzod Abdukarimov,
Mukhammadrafik Tokhirov
Issue:
Volume 12, Issue 2, April 2026
Pages:
25-34
Received:
14 May 2026
Accepted:
25 May 2026
Published:
10 June 2026
Abstract: This study presents a transient numerical investigation of heat transfer and airflow characteristics in a semi-cylindrical solar air heater using COMSOL Multiphysics. A three-dimensional conjugate heat transfer model was developed to evaluate the effect of daily solar-radiation variation on air temperature, local convective heat transfer, Reynolds number, and useful heat gain. The model includes transient solar heat flux on the absorber surface, heat loss from the outer collector surface by natural convection, no-slip wall conditions, and a free outlet boundary condition. The calculation was performed for a low inlet-air velocity of 0.01 m/s during the period from 08: 00 to 18: 00. For the adopted geometry, the hydraulic diameter was 0.611 m, and the Reynolds number was approximately (3.7–4.0) × 102, indicating a laminar low-velocity regime. The maximum absorber-region temperature reached about 371–374 K during peak solar irradiation, while the maximum air temperature at the control points was about 338–340 K. The maximum local convective heat transfer coefficient and useful heat gain were approximately 0.176 W/(m2·K) and 2.3–2.4 W, respectively. The results show that the semi-cylindrical geometry forms a stable temperature field under low-velocity conditions. However, the useful heat output remains limited because of the small air mass flow rate. Therefore, the developed model should be considered as a baseline numerical tool for further optimization at higher airflow rates and for future experimental validation.
Abstract: This study presents a transient numerical investigation of heat transfer and airflow characteristics in a semi-cylindrical solar air heater using COMSOL Multiphysics. A three-dimensional conjugate heat transfer model was developed to evaluate the effect of daily solar-radiation variation on air temperature, local convective heat transfer, Reynolds ...
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Research Article
Analysis of the State of Production Costs in the Oil and Gas Industry
Shamshod Nosirjonovich Gofurov*
Issue:
Volume 12, Issue 2, April 2026
Pages:
35-41
Received:
1 March 2026
Accepted:
10 March 2026
Published:
22 July 2026
DOI:
10.11648/j.ajme.20261202.12
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Abstract: The oil and gas industry is the primary catalyst for Uzbekistan`s industrial stability, contributing significantly to the national GDP and energy security. However, the sector is currently grappling with a critical paradox: while domestic demand for energy is surging due to rapid urbanization, the cost of production is escalating at an unsustainable rate. This study aims to conduct a rigorous analysis of the production cost structure within the national oil and gas framework, specifically focusing on the transition from easily accessible reserves to complex, high-depth extraction. The study identifies a sharp 22% increase in average production costs over the last four years. The actual problem lies in the inefficient distribution of resources: currently, approximately 35% of the budget is consumed by “legacy costs” - the maintenance of obsolete infrastructure and inefficient geological exploration methods. Furthermore, operational costs have been inflated by a 12-15% rise in the cost of imported technical equipment and chemical reagents. Statistics indicate that while geological exploration is vital, the lack of modern seismic technology leads to a high “dry hole” ratio, meaning millions are spent on ineffective drilling. In the current Uzbek landscape, energy-intensive secondary recovery methods (such as water flooding or gas injection) now account for nearly 40% of the cost of a single barrel of oil equivalent. The research is necessary for Uzbekistan`s economy as it provides a roadmap for fiscal optimization in an era of energy transition. By identifying the specific points of resource leakage-particularly in geological surveying and inefficient operational labor-this study contributes a “Digital Optimization Model”. This model suggests that a 10% shift in investment from legacy maintenance toward automated monitoring systems could reduce overall production costs by 8.5% annually. The findings offer a strategic framework for policymakers to enhance the competitiveness of the national energy sector on the global stage.
Abstract: The oil and gas industry is the primary catalyst for Uzbekistan`s industrial stability, contributing significantly to the national GDP and energy security. However, the sector is currently grappling with a critical paradox: while domestic demand for energy is surging due to rapid urbanization, the cost of production is escalating at an unsustainabl...
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