A Compact CNN-Transformer Model for Robust Fault Diagnosis in Large-Scale Chemical Processes Pratyush Kumar Pal, Sumona Ray, Narottam Behera, Somnath Chowdhury, Abhiram Hens, Sandip Kumar Lahiri International Journal of Prognostics and Health Management, 2026 Ensuring the safe and stable operation of large-scale chemical processes requires accurate fault detection and diagnosis under nonlinear dynamics and strong variable interactions. This study investigates deep learning-based fault diagnosis for the Tennessee Eastman Process (TEP), focusing on whether performance improvements beyond near-saturation Long Short-Term Memory (LSTM) baselines can be achieved. A standardised TEP dataset with 52 measured and manipulated variables is used, excluding the non-detectable fault cases (IDV 3, 9, and 15), resulting in a 19-class classification problem. A hybrid Convolutional Neural Network–Transformer (CNN-Transformer) architecture is proposed in which one-dimensional convolutional layers capture local cross-variable correlations, while a Transformer encoder models long-range temporal dependencies through self-attention. To ensure fair comparison, both the proposed model and a strong LSTM baseline are trained and evaluated under identical preprocessing, optimization, and evaluation protocols. The CNN-Transformer achieves an overall classification accuracy of 99.92%, marginally outperforming the LSTM baseline (99.86%). Although the numerical improvement is slight, the proposed model consistently yields higher macro-averaged F1-scores and reduced fault-wise misclassification, indicating enhanced robustness in challenging fault scenarios. The key contribution of this work is demonstrating that combining convolutional feature extraction with attention-based temporal modelling provides consistent class-level robustness beyond near-saturated recurrent architectures, while maintaining a compact structure suitable for practical deployment.
Heat transfer analysis of liquid nitrogen film boiling in the presence of reduced gravity and electric field Indradev Kumar, Sandip Kumar Lahiri, Abhiram Hens Numerical Heat Transfer Part A Applications, 2026 The cryogens generally exhibit different nature of boiling from the conventional liquids. The boiling process in cryogens sometimes don’t exhibit the appropriate heat transfer due to transition into film boiling regime. In the present work, film boiling characteristics of liquid nitrogen (a widely used cryogen) were examined at different gravity conditions and under the influence of an electric field. Employing continuum-based numerical simulations and utilizing the coupled level set and volume of fluid (CLSVOF) method for interface tracking, the effects of wall superheat and reduced gravity on bubble dynamics during film boiling near the critical pressure were investigated. The heat flux values obtained from the simulations were compared with the experimental results. It was observed that under lower gravity levels, the number of bubble formation sites decreases, and the apex height of the bubble increases, resulting in slower detachment frequency and reduced average heat transfer rate. An external electric field was found to be effective in controlling the heat transfer rate in such cases. The effect of the electric field was found to be more prominent in lower gravity levels.
Digital twins: Transforming the chemical process industry—A review Pratyush Kumar Pal, Abhiram Hens, Narottam Behera, Sandip Kumar Lahiri Canadian Journal of Chemical Engineering, 2025 Digital twin (DT) technology represents a significant advancement in the digital transformation of the chemical process industry (CPI), offering innovative capabilities for real‐time monitoring, predictive maintenance, and process optimization. This review investigates the current deployment status, frameworks, architectures, and applications of DTs within CPI, highlighting their transformative potential in improving operational efficiency, enhancing safety, and promoting sustainability. By examining case studies from industry leaders and analyzing recent advancements, this study elucidates the critical roles of DTs in asset health monitoring, process optimization, and environmental performance. The review identifies key components of DT frameworks, including data integration, hybrid modelling, and real‐time analytics, which are essential for effective implementation. It further explores challenges such as high computational requirements, integration with legacy systems, cybersecurity risks, and the lack of standardization, which impede widespread adoption. Despite these challenges, the paper emphasizes opportunities for leveraging advanced technologies such as artificial intelligence, edge computing, and 5G connectivity to enhance DT capabilities and scalability. In addition, this review underscores the importance of DTs in addressing global sustainability goals, mainly through their ability to optimize energy consumption, reduce emissions, and facilitate circular economy practices. By synthesizing insights from academia and industry, this study provides a comprehensive understanding of DTs' current state and future potential in CPI, offering strategic directions for research and development. The findings contribute to advancing the deployment of DTs as a cornerstone technology in achieving operational excellence, safety, and sustainability in the chemical process industry.
CFD-based investigation of NOx removal from industrial waste gas by selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) process using NH3 Debanik Bose, Kartik C. Ghanta, Abhiram Hens International Journal of Chemical Reactor Engineering, 2025 The present study conducts a comparative analysis between selective catalytic reduction (SCR) using a Cu-zeolite catalyst and selective non-catalytic reduction (SNCR) for the removal of NO x from industrial waste gas. The primary objective of this investigation is to computationally explore the removal of NO x using NH3 at various reactor conditions, along with the study of different hydrodynamic aspects. The study revealed the impact of different porosity of the catalyst (in SCR) and the number of baffles (in SNCR) on the reaction and fluid flow profile. Distinct geometries were employed to model each process, incorporating a turbulent model and kinetic parameters with an eddy-dissipation model (EDM) for simulations. Analyzing the effect of the NH3/NO ratio on NO conversion efficiency is a crucial component of the study. With diminishing efficiency at higher ratios, the SCR process demonstrated nearly complete NO conversion at a certain NH3/NO ratio, and this value changes with the inlet gas temperature. In contrast, SNCR produced less favorable conversion rates than SCR, indicating that the amount of NH3 supply affects conversion efficiency. At the SCR system’s optimum NH3/NO ratio, SNCR achieved an 83 % conversion, and the conversion rate remained relatively constant as the ratio was increased. The results highlight the various possibilities for optimization of the reactor systems in terms of efficiency and economic feasibility.
Interfacial hydrodynamics of electrosprays using leaky dielectric fluids Probir Biswas, Raj M. Agarwal, Braj Bhushan, Abhiram Hens, Gautam Biswas Physics of Fluids, 2025 Electrohydrodynamics (EHD) deals with the motion of a liquid under the influence of an external electric field, and a leaky dielectric fluid has low but non-zero conductivity. Many earlier studies on EHD have considered the flow of perfect dielectric fluids. This study has established a computational framework to investigate the droplet evolution pattern of leaky dielectric fluids under an externally applied electric field. The Navier–Stokes equations and charge conservation equations are solved using the coupled level set and volume of fluid method. It was observed that the dynamics of the leaky dielectric liquid emanating from the orifice of an ejector depends on several factors such as flow rate, electric field intensity, surface tension, Coulombic forces, and electrophoretic forces. Different jetting regimes, such as choked jets, pulsating jets, steady cone jets, and multi jets, were observed based on these conditions. Variations in the drop diameters and jet breakup length at different flow rates were studied, and the results were compared with the available experimental results. It was also observed that the breakup time and detached drop volume can be suitably tuned by varying the strength of the applied electric field.
Heat transfer analysis of liquid nitrogen film boiling in the presence of reduced gravity and electric field I Kumar, SK Lahiri, A Hens Numerical Heat Transfer, Part A: Applications 87 (1), 2541811 , 2026 2026
A Compact CNN-Transformer Model for Robust Fault Diagnosis in Large-Scale Chemical Processes PK Pal, S Ray, N Behera, S Chowdhury, A Hens, SK Lahiri International Journal of Prognostics and Health Management 17 (1) , 2026 2026
Application of waste polypropylene pyrolytic oil in CI engines: Performance and emission assessment R Kumar, AK Sadhukhan, N Upadhyay, B Ruj, A Roy, A Hens Journal of the Indian Chemical Society, 102586 , 2026 2026
Advancing fault diagnosis for ethyl benzene production plant: A machine learning and explainable AI approach S Chowdhury, S Roy, B Modak, F Ahmed, A Mahto, A Hens, SK Lahiri Journal of the Indian Chemical Society 102 (11), 102157 , 2025 2025 Citations: 1
Advanced Studies in Film Boiling: Interfacial Instability, Multimode Bubble Formation, and Nanoscale Heat Transfer A Hens, G Biswas Recent Developments in Power and Propulsion Applications, 887-907 , 2025 2025
Digital twins: Transforming the chemical process industry—A review PK Pal, A Hens, N Behera, SK Lahiri The Canadian Journal of Chemical Engineering 103 (8), 3611-3636 , 2025 2025 Citations: 35
CFD-based investigation of NO x removal from industrial waste gas by selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) process using NH3 D Bose, KC Ghanta, A Hens International Journal of Chemical Reactor Engineering 23 (6), 701-713 , 2025 2025 Citations: 6
Influence of surface morphology and temperature on nanoscale boiling of liquid nitrogen on a platinum substrate I Kumar, SK Lahiri, A Hens, G Biswas International Journal of Thermal Sciences 210, 109655 , 2025 2025 Citations: 5
Interfacial hydrodynamics of electrosprays using leaky dielectric fluids P Biswas, RM Agarwal, B Bhushan, A Hens, G Biswas Physics of Fluids 37 (2) , 2025 2025 Citations: 1
Design and optimization of reactive distillation for enhancing supercritical transesterification process to produce biodiesel D Bose, A Bangal, A Hens, S Barma Chemical Engineering and Processing-Process Intensification 203, 109877 , 2024 2024 Citations: 9
Enhancing fuel-air mixing in COG-BOG non-premixed combustion: A CFD analysis with different turbulent models D Bose, I Kumar, A Hens Journal of the Indian Chemical Society 101 (9), 101222 , 2024 2024 Citations: 9
Effect of patterned condensation surface on the performance of a newly designed basin-type solar desalination unit R Anand, MK Mandal, RG Chaudhuri, A Hens Applied Thermal Engineering 249, 123399 , 2024 2024 Citations: 10
Optimisation of geometry and surface wettability for enhanced efficiency of the solar still-based desalination unit R Anand, MK Mandal, RG Chaudhuri, A Hens International Journal of Ambient Energy 44 (1), 1549-1556 , 2023 2023 Citations: 4
Effect of pressure variations on film boiling characteristics of liquid nitrogen I Kumar, AK Roy, A Hens Physics of Fluids 35 (10) , 2023 2023 Citations: 3
Mitigation of oil spills from synthetic seawater using human hair – Experimentation, modeling and optimization NK Jilagam, A Sau, SV Addepalli, A Hens, S Dutta Chemometrics and Intelligent Laboratory Systems 242, 104998 , 2023 2023 Citations: 13
Performance analysis of methanol steam micro-reformers for enhanced hydrogen production using CFD D Bose, I Kumar, A Hens Chemical Engineering Research and Design 196, 297-308 , 2023 2023 Citations: 14
A Continuum and Molecular Dynamics-based Simulation Study of Boiling in Liquid Nitrogen I Kumar, A Hens Chemical Engineering Transactions 100, 343-348 , 2023 2023
Dynamics of Taylor bubbles in non-Newtonian shear thinning continuous phase S Chatterjee, A Hens, KC Ghanta, G Biswas Progress in Computational Fluid Dynamics, an International Journal 23 (5 … , 2023 2023
Study of cryogenic film boiling in the presence of external electric field using a variant of volume of fluid-based interface tracking algorithm I Kumar, A Hens, SK Lahiri, G Biswas Industrial & Engineering Chemistry Research 61 (49), 18176-18186 , 2022 2022 Citations: 9
Modeling and multi-objective optimization of commercial ethylene oxide reactor to strike a delicate balance between profit and negative environmental impact SK Lahiri, S Chowdhury, A Hens, KC Ghanta Environmental Science and Pollution Research 29 (14), 20035-20047 , 2022 2022 Citations: 7
MOST CITED SCHOLAR PUBLICATIONS
Density functional theory and molecular dynamics simulation study on corrosion inhibition performance of mild steel by mercapto-quinoline Schiff base corrosion inhibitor SK Saha, P Ghosh, A Hens, NC Murmu, P Banerjee Physica E: Low-dimensional systems and nanostructures 66, 332-341 , 2015 2015 Citations: 529
Nanoscale study of boiling and evaporation in a liquid Ar film on a Pt heater using molecular dynamics simulation A Hens, R Agarwal, G Biswas International Journal of Heat and Mass Transfer 71, 303-312 , 2014 2014 Citations: 200
Molecular dynamics and density functional theory study on corrosion inhibitory action of three substituted pyrazine derivatives on steel surface SK Saha, A Hens, A RoyChowdhury, AK Lohar, NC Murmu, P Banerjee Can Chem Trans 2 (4), 489-503 , 2014 2014 Citations: 131
A comparative density functional theory and molecular dynamics simulation studies of the corrosion inhibitory action of two novel N-heterocyclic organic compounds along with a … SK Saha, A Hens, NC Murmu, P Banerjee Journal of Molecular Liquids 215, 486-495 , 2016 2016 Citations: 130
A paper based microfluidic device for easy detection of uric acid using positively charged gold nanoparticles A Kumar, A Hens, RK Arun, M Chatterjee, K Mahato, K Layek, N Chanda Analyst 140 (6), 1817-1821 , 2015 2015 Citations: 102
Calculation of diffusion coefficient of long chain molecules using molecular dynamics T Chakraborty, A Hens, S Kulashrestha, NC Murmu, P Banerjee Physica E: Low-dimensional Systems and Nanostructures 69, 371-377 , 2015 2015 Citations: 82
Evaporation of water droplets on Pt-surface in presence of external electric field—A molecular dynamics study A Hens, G Biswas, sudipta De Journal of Chemical Physics 143, 094702 , 2015 2015 Citations: 48
Development of 6-Thioguanine conjugated PLGA nanoparticles through thioester bond formation: Benefits of electrospray mediated drug encapsulation and sustained release in … M Chatterjee, N Jaiswal, A Hens, N Mahata, N Chanda Materials Science and Engineering: C 114, 111029 , 2020 2020 Citations: 42
Analysis of interfacial instability and multimode bubble formation in saturated boiling using coupled level set and volume-of-fluid approach A Hens, G Biswas, S De Physics of Fluids 26 (012105), 012105-1 to 012105-14 , 2014 2014 Citations: 38
Digital twins: Transforming the chemical process industry—A review PK Pal, A Hens, N Behera, SK Lahiri The Canadian Journal of Chemical Engineering 103 (8), 3611-3636 , 2025 2025 Citations: 35
Molecular dynamics study of vapor-liquid equilibria and transport properties of Sodium and Lithium based on EAM potentials AK Metya, A Hens, JK Singh Fluid Phase Equilibria , 2011 2011 Citations: 34
Molecular dynamics study of sessile ionic nanodroplet under external electric field S Chatterjee, A Hens, KC Ghanta, G Biswas Chemical Engineering Science 229, 116143 , 2021 2021 Citations: 25
Study of multiphase flow inside straight and spiral microchannel and effect of two phase flow on Dean’s vortices S Chatterjee, KC Ghanta, A Hens Chemical Engineering Research and Design 165, 398-408 , 2021 2021 Citations: 19
Performance enhancement of commercial ethylene oxide reactor by artificial intelligence approach S Chowdhury, SK Lahiri, A Hens, S Katiyar International Journal of Chemical Reactor Engineering 20 (2), 237-250 , 2022 2022 Citations: 16
A novel approach to fabricate dye-encapsulated polymeric micro-and nanoparticles by thin film dewetting technique M Chatterjee, A Hens, K Mahato, N Jaiswal, N Mahato, N Chanda Journal of colloid and interface science 506, 126-134 , 2017 2017 Citations: 16
Performance analysis of methanol steam micro-reformers for enhanced hydrogen production using CFD D Bose, I Kumar, A Hens Chemical Engineering Research and Design 196, 297-308 , 2023 2023 Citations: 14
Vapor-liquid phase coexistence and transport properties of two-dimensional oligomers TK Patra, A Hens, JK Singh The Journal of Chemical Physics 137 (8), 084701-084701-10 , 2012 2012 Citations: 14
Mitigation of oil spills from synthetic seawater using human hair – Experimentation, modeling and optimization NK Jilagam, A Sau, SV Addepalli, A Hens, S Dutta Chemometrics and Intelligent Laboratory Systems 242, 104998 , 2023 2023 Citations: 13
Insight into molecular rearrangement of a sessile ionic nanodroplet with applied electric field S Chatterjee, I Kumar, KC Ghanta, A Hens, G Biswas Chemical Engineering Science 247, 117083 , 2022 2022 Citations: 13
Ethylenediamine assisted functionalization of self-organized poly (d, l-lactide-co-glycolide) patterned surface to enhance cancer cell isolation N Jaiswal, A Hens, M Chatterjee, N Mahata, N Chanda Journal of colloid and interface science 534, 122-130 , 2019 2019 Citations: 11