Department of Chemical Engineering

This work contributes to the estimation of new and complementary density data for carbon dioxide (CO2) confined in carbon slit pores at different conditions. Grand canonical Monte Carlo (GCMC) simulations were employed to predict the CO2 adsorption capacities in carbon slit pores of height 20, 31.6, 63.2, 94.85 and 126.5 Å at 673.15 and 873.15 K over a pressure range of 500–4000 kPa, which corresponds to steam reforming of methane process. The bulk densities of CO2 at these temperature and pressure conditions have been estimated via isothermal–isobaric ensemble MC simulations using the Elementary Physical Model. The predicted density shows an excellent agreement with the experimental data. The adsorption capacities of CO2 in all the aforementioned pores at 673.15 and 873.15 K over the pressure range of 500–4000 kPa have also been estimated in the presence of wall–fluid interactions, in addition to the fluid–fluid interactions. The study on the thermodynamic phase behaviour of confined CO2 in the presence of wall–fluid interactions showed the existence of vapour–liquid equilibria at high temperature and pressure conditions.

This current experimental study aims to resolve the demerits of pure PCM by introducing the hybrid nanomaterial-induced composite PCM (HNIPCM) with practical feasibility on solar water heater performance using an indigenously developed setup. To settle out these performance characteristics, expanded graphite (EG) and nickel ferrite nanoparticles (NiFe2O4) with different weight concentrations (ɸ = 1–5 %) were used for the first time as a thermophysical property-enhancing filler material inside a eutectic organic-organic PCM (polyethylene glycol 6000/paraffin wax) by two-step method. A detailed study on the physical and chemical stability, surface morphology, and thermal feasibility of the HNIPCM was conducted to provide the optimized characteristics for the target applications. The energy storage capacity, melting and crystallization temperature, thermal stability, thermal reliability, thermal behaviour, and thermal conductivity were also examined by DSC, TGA, thermal cycling, and charging-discharging, respectively. The HNIPCM with 3 wt% filler concentration revealed comparatively well-balanced thermophysical properties among the prepared samples. The results also showed that the melting point, crystallization point, melting enthalpy, and crystallization enthalpy were changed to 54.55 °C, 48.83 °C, 128.52 J/g, and 129.02 J/g, respectively, for HNIPCM with 3 wt% of filler material in comparison with eutectic PCM of 59.14 °C, 41.23 °C, 154.37 J/g, and 155.21 J/g. An increase in thermal conductivity up to 253.72 %, enhancement in the charging and discharging rate, and good stability up to 500 working cycles with a 12.19 °C decrease in the supercooling were also observed with no physical and chemical alteration. The real-time performance of the prepared HNIPCM was also investigated using a novel indigenously developed solar water heater at different inclination angles (40°, 45°, and 50°), flow rates (1.2 LPM, 2.2 LPM, and 5.2 LPM), and charging periods (90mins, 120mins, and 180mins). Comparatively higher performance at a 45° inclination angle, 2.2LPM water low rate with 68.99 % efficiency (day) and 50.45 % (night) was observed. The enhanced thermophysical properties of the HNIPCM made it suitable for a viable candidate for solar thermal energy, air conditioners, TES, and electronic cooling units.

Date palm (Phoenix dactylifera L.) is the most commonly cultivated fruit tree in the Middle East and North Africa. Date fruits are an excellent source of nutrition due to their high sugar content and high levels of phenols, minerals, and antioxidants. This work aimed to prepare a soluble natural sweetener from date fruit extract using colloidal gas aprons (CGAs) generated with a food-grade non-ionic surfactant (Tween 20). Various process parameters, such as the flow rate of the CGAs, the volume of the feed, the temperature of the CGAs, and the feed solution, were varied to obtain the optimal parameters. In the foam phase, the maximum soluble sugar enrichment of 92% was obtained at a flow rate of 50 mL/min of CGA and a solution temperature of 23 °C. The formation of intermolecular hydrogen bonding between the glucose molecules and the surfactant Tween 20 was confirmed by molecular modeling studies.

Tanker-based water distribution systems are amongst one of the most prevalent methods to supply water in many developing countries facing water crisis and intermittent piped water supply. These tanker water supply systems need tighter coordination between the water sources, treatment facilities, consumers and tanker suppliers to efficiently manage timely delivery and quality water. Furthermore, accounting for the uncertain nature of customer demands while making the planning decisions would not only aid in achieving minimum operational cost but is also important in reducing the water wastage. This paper proposes a two-stage stochastic recourse programming model for an optimal planning and scheduling of tanker water supply system under daily demand uncertainty. The main objective is to supply water to maximum number of consumers with minimum total operating costs. A solution strategy combining Sample Average Approximation (SAA) and Monte-Carlo Simulation (MCS) methods, to generate an equivalent deterministic MILP (mixed integer programming problem) model with multiple scenarios of demand uncertainty realization, is adopted for problem solving. The proposed model is applied to an example tanker water supply system and the benefits of two-stage stochastic modelling in making agile decisions incorporating the effect of uncertainties are illustrated. The results also demonstrate the efficacy of adopting stochastic programming models and methods in such real-world application cases.

The primary goal of Sustainable Development Goal 7 (SDG 7) is to increase renewable energy use to reduce reliance on fossil fuels and mitigate climate change. Energy-intensive industries can benefit from in-house renewable power generation, reducing their reliance on fossil fuel-based grid power and making processes greener. However, integration among power generation/purchase, energy storage systems (ESS), and power consumption is crucial to overcome the intermittent nature of renewable power sources. ESS plays a vital role in increasing resilience and optimizing material production based on power availability and pricing. The efficacy of ESS needs critical evaluation considering cost, efficiency, and uncertainties related to renewable power generation and material product demand. The paper proposes two scenario-based optimization approaches to assess the impact of uncertainties on the integrated supply and demand side management (ISDM) system, focusing on lithium-ion batteries and cryogenic energy storage (CES). Compared to the conservative approach of the scenario-based robust optimization (SRO) method, the proposed stochastic simulation optimization (SSO) method provides a ‘risk-neutral’ solution, which is 6.45% less than the minimum expected cost solution. The analysis also suggests that lithium-ion batteries are more economically effective for the proposed integrated framework than CES, resulting in almost a 29% reduction in operating costs compared to no battery option. The proposed framework could contribute to sustainable and economically viable energy management practices in energy-intensive industries. Further research and implementation of such frameworks could accelerate the adoption of renewable energy and energy storage technologies in industrial processes.

Batch reactors with polymerisation reaction and ineffective cooling arrangements are prone to thermal runaway. In the present case study, we have investigated such a thermal runaway scenario in case of thermally initiated free radical styrene polymerisation reaction inside adiabatic and non-adiabatic batch reactors. We found that our developed process model for the well-mixed batch reactor along with the reported kinetic model in the literature; aptly describes the thermal runaway polystyrene formation reaction conditions (critical temperature for runaway, Tcr and the critical time for runaway, tcr). We have also deployed the well-studied Extended Kalman Observer (EKO) to provide online estimates of the runaway reaction process parameters, by using reaction temperature as the only measurement to the observer. It is noted that the non-linear EKO with this one temperature measurement provides accurate estimates of all runaway process parameters from an early time interval. We have also shown that an accurate online estimate of the critical process variables of the polystyrene formation reaction by using the EKO algorithm helps in effective manipulation of initiator concentration that increases the operational safety of the non-adiabatic batch reactors by delaying the attainment of Tcr at a higher monomer conversion.

In wastewater treatment (WWT), advanced computational fluid dynamics (ACFD) is a rapidly expanding discipline applicable to practically all unit processes. This chapter introduces ACFD to several WWT unit procedures. Removing suspended growth nutrients and anaerobic digestion are two of these unit processes. Other examples include hydraulic aspects, such as flow splitting and physical, chemical, and biological procedures. The purpose of this study is to articulate the current state of practice as well as the need for research and development. The amount of capability that can be achieved using ACFD varies throughout the different process units, with such a high prevalence of use in the domains of subsequent sedimentation, activated sludge basin modeling and disinfection, and increased demands in primary sedimentation and anaerobic digestion. Although the techniques are comprehensive, in the sense that even though they may often contain non-Newtonian fluids, multiphase systems, and biokinetics, these models still need to be completed. As a result, further work must be done to meet the variety of process designs. Various other demands have been discovered, but the most prominent needs include enhanced particle aggregation, breakdown (flocculation), and enhanced coupling of biology and hydraulics.

Hydrogen is considered as one of the promising green energy alternatives to non-renewable fuels to accommodate the ever-increasing demand for energy resources. The growing application of hydrogen at its ‘technical grade, i.e., 99.999% pure’ in the fuel cell and as blending with natural gas in the gas grid has enormously increased the demand to produce extremely pure hydrogen for all practical purposes. Ammonia, being easy to liquefy, and store, and with high hydrogen content (17.6% w/w) chemicals, is considered as one the important carbon-free sources of hydrogen. Among different existing technologies, membrane reactors have been extensively explored mainly because of the feasibility of simultaneously decomposing ammonia using a catalyst and in-situ separate hydrogen using a membrane. Conventionally, packed bed membrane reactors (PBMR) are extensively explored for the process of ammonia decomposition. However, catalytic membrane reactors (CMR) are considered as advanced membrane reactors mainly because of the constraint of diffusional mass transfer resistance and temperature non-uniformity in PBMR. The application of materials such as Ruthenium (Ru) based catalysts and Palladium (Pd) based inorganic membranes are extensively explored owing to their high performance. However, their industrial application is constrained due to the high price, limited availability, and the brittle nature of the Pd-membrane. In this chapter, the recent developments in the technologies for catalytic membrane reactor-based hydrogen production from ammonia are discussed. A comprehensive insight on the material selection for catalyst and membrane preparation, reactor design, and its coupling with sustainable processes of solar energy will be elaborated.

Increasing demand for wearable sensors for multipurpose applications have made it an essential part of our everyday life. In such a scenario; reusability, flexibility, cost effectiveness, and integrability of such sensors are among the top desirable features. Using our casual clothing as sensors can be one of the most effective ways for various therapeutic, diagnostic, and continuous monitoring functionalities. Conducting yarns, possibly, have the capability to deeply influence the 4th industrial revolution and rule the e-textile based smart wearables for wide range applications. Herein, we present a comparative experimental study of three different capacitive sensor structures for humidity sensing applications. These structures have been explored using conducting yarns having tungsten metal as core conducting materials.

In the petroleum industry, dehydration and desalting of a crude oil-brine emulsion are critical to further processing and refining of crude. The process of dehydration and desalting is typically done in large units called electrocoalescers. Enhancing the performance of an electrocoalescer includes the ability to dehydrate the emulsion in a shorter time, that is to increase the rate of separation of water while keeping the operation safe. The work proposes the enhancement of separation based on AC electric field modulation. The modulated waveform is composed of a high amplitude electric field step, followed by a low amplitude electric field step, and the process is repeated. The work demonstrates the efficacy of the technique through several experiments and their analysis. The work includes designing and optimizing the electrical waveform and then demonstrating the faster kinetics of electrocoalescence achieved in comparison with the conventional practice. The main advantage of modulation is facilitation of chaining of drops during the high voltage period, followed by their effective coalescence in the low voltage period. The effect of the modulation field and period has been investigated, and optimization of the time periods of the high field and the low field steps is carried out. Our analysis indicates that an increase in the fraction of the total period spanned by the high field improves the water separation, while a relatively weaker dependence is found on the total period. The electric field was applied both in directions parallel and perpendicular to the gravity, and performances were compared. It was found that the parallel configuration was better than the perpendicular configuration.