Donglin's Photo

Dr Donglin Zhao


Lecturer in Chemical Engineering
PhD

Academic and research departments

School of Chemistry and Chemical Engineering.

About

Research

Research interests

Teaching

Publications

Nura Makwashi, Donglin Zhao, Bingxing Wang, Mukhtar Abdulkadir, Muhammad Umar Garba (2025)New insights into wax deposition challenges: Experimental investigation across varied pipeline curvatures, In: Experimental thermal and fluid science163111400 Elsevier Inc

•Novel experimental investigation of wax deposition behaviour in pipelines with varying curvature.•Demonstration of higher deposition rates in curved pipes compared to straight pipes.•Integration of bend parameters into a new correlation model for wax deposition prediction.•Highlighting the underestimated effects of Brownian diffusion and gravity settling on wax deposition.•Contribution to advancing the understanding of wax deposition phenomena. This study investigates the intricate phenomenon of wax deposition in oil pipelines, with a primary focus on enhancing the understanding of wax deposition mechanisms. Special attention is given to the role of pipe curvature in influencing these deposition processes, exploring how bends in pipeline structures may alter the behaviour of wax deposition, potentially leading to operational challenges. A novel flow rig was designed and commissioned to simulate wax deposition in straight pipes and pipes with 45° and 90° bends at both horizontal and inclined positions. The objective of the work is to quantify the impact of flow parameters, such as the temperature and flow rate, on wax buildup under different pipe configurations. The results demonstrate that the temperature and flow rate are critical factors influencing wax deposition processes. Specifically, lower temperatures (ranging from 10 °C to 30 °C) and laminar flow conditions (Re 

Ishaka Muhammad, Nura Makwashi, Tariq Galadanchi Ahmed, George Manos, Donglin Zhao (2023)A Mechanistic Model on Catalyst Deactivation by Coke Formation in a CSTR Reactor, In: Processes11(3)944 Mdpi

A mechanistic model on catalyst deactivation by coke formation in a continuous stirred tank reactor (CSTR) has been developed in the paper. Catalyst deactivation by coke formation was treated as a surface reaction. Four reaction mechanisms representing coke formation through different routes were proposed. The evolved system of ordinary differential equations (ODEs) was solved numerically using MATLAB. This approach was validated by applying it to the skeletal isomerization of 1-pentene over ferrierite. Simulation results were compared qualitatively to those obtained from the literature. Simulation results indicated that coke formation is an extremely rapid process with fast formation of coke components on the strongest acid sites leading to final coke. The coke deposition is slower at higher residence times resulting in more stable product formation and weaker deactivation. The results obtained from this work revealed that the developed model is indeed able to successfully demonstrate the most essential features of catalyst deactivation by coke formation and are in agreement with the findings in the literature. Future work is aimed to extend the study to different reactors such as a plug flow reactor, in addition to analysis of the reaction system's sensitivity to variables such as temperature and pressure.