ـJournal of Engineering Research and Applied Science

PERFORMANCE ANALYSIS OF A SHELL AND TUBE HEAT EXCHANGER AT DIFFERENT OPERATIONAL AND DESIGN PARAMETERS

Mohammad A. M. Sead Sead — 2026-12-15

Abstract

Shell and tube heat exchangers are widely used in the industrial chemical processes, especially in refineries, due to their main advantages over other types of heat exchangers. The concerned shell and tube heat exchanger that studied in the paper is used at ZWETINA OIL COMPANY. Extensive simulations of steady state thermal analysis were carried out by using MATLAB R2013a software in an attempt to determine quantitative combined and overlapping relationships among the heat exchanger performance and its associated design and operating parameters such as heat transfer coefficient, friction coefficient, length, and pressure drop. Different tube wall materials and fluid streams were also simulated in order to investigate their effect on the heat exchanger effectiveness. The results show the total heat transfer increases with the increase of tube length and decreasing the input temperature. The pressure drop on the shell side increases with increasing both the flow velocity and number of baffles. The pressure drop on the pipe side increases with increasing both the flow velocity and number of passages. The pressure drop increases with increasing the fluid density. The Nusselt number increases when the increase of internal heat transfer coefficient and decreasing the thermal conductivity.

Keywords: Shell and Tube Heat Exchanger, Thermal Conductivity, MATLAB

Risk Management in Libyan Engineering Projects: Challenges, Strategies, and the Tripoli West Ring Road Case Study"

Hamza Ali Abdel Salam Abdel Salam — 2026-12-15

Abstract

The aspect of risk management is a core element in the successful implementation of engineering projects especially in a place where there is a politically unstable situation and weak institutions like in Libya. The engineering and construction industries in Libya have experienced an extreme strain in the last ten years since the country has been affected by unremitting conflict, inadequate governance, unstable oil revenues and lack of coordinating institutions. Such circumstances have resulted in a complicated risk environment which spans across the conventional technical and financial aspects into political, social and environmental aspects. This paper examines issues, approaches and uses of risk management in Libyan Engineering projects using qualitative research methodology of literature review, documents analysis and case study of a leading infrastructure project in Tripoli. The analysis reveals the most essential risk types, such as political, financial, technical, environmental and social, and assesses how each of these risks affects the performance of the project, i.e., costs, schedule, and quality. The results indicate that the most common and the most severe risks are political and financial ones, which explain the most frequent project failures and cost increase. In addition, lack of standardized risk frameworks and the paucity of institutional capacity also leads to the inconsistent results of projects. The paper also considers how global standards including the ISO 31000 and the PMBOK Guide can be adapted to the fragile Libyan environment. It finds that risk management in Libya will necessitate not only technical equipment but also governance change, involvement of stakeholders, and capacity building of institutions. The study suggests that a national risk management framework that is specific to Libya challenges should be developed, with the focus on proactive planning, online risk management, and cross-sectoral cooperation. These can contribute to resilience and better implementation of projects and provide the foundation to sustainable development of infrastructure in vulnerable settings.

Keywords: Risk Management, Engineering Projects, Libya, Fragile States, Project Governance, Infrastructure Resilience.

Piston Bowl Geometry Optimization for Enhanced Internal Combustion Engine Performance and Emission Reduction: A Comprehensive Review

Mohammed.A.M.Haweel Haweel — 2026-08-08

Abstract

The design of the piston bowl is one of the key factors influencing flow characteristics, combustion, performance, and emissions in modern diesel engines. With the increasing stringency of environmental emission standards and the need to enhance thermal efficiency, the design of combustion chambers has become one of the most important areas of research in internal combustion engine engineering. The objective of this paper is to provide a review of previous studies conducted from 2018 to 2026, which investigated the effect of piston bowl shapes on internal flow, combustion characteristics, emissions, and the thermal and mechanical effects on the piston. The review focused on analyzing engineering variables such as bowl depth, diameter, and cavity design concerning heat release rates, combustion efficiency, and emissions of nitrogen oxides and soot. Additionally, the review included the most significant numerical models used in combustion simulation, as well as the gaps and future trends affecting the design of combustion chambers.

Keywords: piston bowl, combustion efficiency, (CFD,FEA), Alternative Fuels, Thermo Structural

Second-Law Analysis of Transient Heat Transfer Enhancement in Tubes Equipped with Elliptical-Cut Twisted Tape Using Hybrid Nanofluids under Mixed Convection

Amir Mohamed Khfagi Khfagi — 2026-09-19

Abstract

This study numerically investigates entropy generation during transient heat transfer in a vertical receiver tube fitted with elliptical-cut twisted tape inserts, with particular emphasis on the thermodynamic impact of forced and mixed convection conditions. Simulations are performed using STAR-CCM+, employing an Al₂O₃–Cu/water hybrid nanofluid as the working medium to enhance thermal transport and capture realistic solar receiver behavior. The analysis focuses on the distribution of entropy production arising from both heat transfer and viscous dissipation under unsteady flow conditions influenced by buoyancy effects. Results indicate that entropy generation is strongly dependent on the convection regime, where the inclusion of buoyancy in mixed convection reduces thermal irreversibility by improving temperature uniformity and weakening local gradients along the tube surface. In contrast, forced convection exhibits higher entropy levels due to stronger thermal non-uniformity. Although the twisted tape induces localized increases in frictional entropy generation due to intensified velocity gradients, its overall contribution remains secondary compared with thermal effects. A comparison between the two regimes shows that mixed convection achieves a notable reduction in total entropy generation, reaching approximately 58.2%, highlighting its superior thermodynamic performance. The findings demonstrate that coupling hybrid nanofluids with swirl-inducing inserts under buoyancy-assisted conditions is an effective strategy for reducing irreversibility and improving the efficiency of solar thermal receiver systems.

Keywords: Hybrid nanosuspension; Entropy generation (local/global); Bejan parameter; Time-dependent heat transfer; Elliptical-cut swirl tape; Thermodynamic irreversibility