Band 19, Heft 1

This research examines the removal efficiency of organic chloride (OC) compounds from the naphtha fraction of polluted crude oil (CO) using sintered micro and nano γ-Al 2 O 3 at a consistent temperature of 30 °C. The adsorbents were characterized through BET, SEM-EDS, and XRD analyses. When utilizing micro-adsorbents to eliminate OC components from naphtha fraction samples containing initial contaminant concentrations of 105 and 8.5 mg/L, the maximum removal efficiency reached only 28 % and 56 %, respectively. In contrast, the use of nano-based adsorbents resulted in significantly higher adsorption percentages, exceeding 45 % and 96 % for the same two samples, respectively. Equilibrium investigations revealed that the Freundlich isotherm model yielded a superior match for the adsorption equilibrium data for the nano-adsorbents case, while the Langmuir model accurately characterized the data for the micro-adsorbents. Kinetic data analysis indicated that the adsorption kinetics for nano-adsorbents followed the pseudo-second-order model, while the micro-adsorbents obeyed the intra-particle diffusion mechanism. Overall, these findings suggest that sintered γ-Al 2 O 3 nanoparticles (NPs) are more effective than microparticles (MPs) for the adsorptive removal of organic chlorides (OCs) from crude oil’s naphtha distillate.

The distillation tower’s reboiler is one of the largest energy consumers in petrochemical facilities, and reducing its energy consumption is a crucial issue. This study proposes two optimal methods, namely Direct Vapor Recompression (DVR) and External Vapor Recompression (EVR), to reduce the consumption of cold and hot utilities in a petrochemical deethanizer tower. The Pars petrochemical in Iran is taken as a case study, and the proposed methods are compared with the base case using energy, exergy, and economic approaches, simulated through Aspen HYSYS software in the steady-state design conditions. Exergy analysis reveals that the EVR and DVR methods reduce the exergy destruction of the deethanizer tower by about 70.06 % and 67.29 %, respectively, compared to the base case. Moreover, the EVR method allows for complete recycling of low-pressure vapor, reducing the total exergy destruction rate from 0.871 to 0.261 GJ/t ethane . The feed separation cost for the base case, DVR, and EVR are estimated to be around 28 $/kg feed , 21.57 $/kg feed , and 21.14 $/kg feed , respectively. The EVR method results in reduced utility and ethane separation cost rates from 5.153 to 3.274 $/t ethane and 17.64 to 15.78 $/year. Overall, the findings suggest that both DVR and EVR methods are effective in reducing the energy consumption and costs associated with deethanizer tower operations. Moreover, real-time optimization techniques can be developed to monitor and adjust the deethanizer tower’s operating parameters, such as feed flow rate, reboiler duty, and reflux ratio.

In this paper, a thermodynamic study of the combination of Concentrated Photovoltaic Thermal (CPVT) and Multi Effect Desalination (MED) system was conducted. CPVT produces electricity, and the heat produced in CPVT is used for the MED system. Engineering Equation Software (EES) was utilized to simulate this system. The effect of CPVT parameters (area, concentration ratio, and average solar radiation) and MED parameters (effect number and temperature of heating steam) were investigated on the produced heat, produced power, exergy destruction, total mass flow rate (FR) of desalinated water, total FR of feed water, heating steam FR and total brine FR. The range of changes for CPVT surface, concentration ratio, and average solar radiation was considered from 2000 m 2 to 20000 m 2 , from 5 to 15 and from 400 W/m 2 to 1100 W/m 2 , respectively. Based on obtained results, as the surface area of the solar panel, the ratio of concentration, and average solar radiation increase, the heat produced increases. Transferring this heat to the MED unit increases the total FR of desalinated water. But it has no significant effect on the Gain ratio (GOR). As the surface area of the solar panel increases from 10000 m 2 to 12000 m 2 , the average radiation intensity increases from 800 W/m 2 to 1000 W/m 2 , and the concentration ratio increases from 10 to 12 in effect the number of 4 and steam temperature of 70 °C, the total mass FR of desalinated water increases by 29 %, 23 %, and 20 %, respectively.

The generator energy consumption in the renewable refrigeration cycles is supplied by solar energy, geothermal energy and waste heat. The thermal energy of low grade can be utilized to superheat the vapour in a generator of the refrigeration cycle. The effect of primary flow superheating was examined on the renewable refrigeration cycle performance using the wet steam model in the ejector. The vapour’s degree of superheating was selected in the 0–100 K range. The superheating level effects were investigated on parameters (wet steam, entrainment ratio, energy consumption, COP, second law efficiency and exergy destruction). The aim of this study is a comprehensive evaluation of the effect of superheat on the ejector refrigeration cycle and the flow behavior in the steam ejector simultaneously. The results represented that superheating the inlet steam in the primary nozzle weakens the spontaneous condensation intensity and delays the condensation shock, the combining process between the secondary flow and the primary flow is improved, and the entrainment ratio is increased, the generator energy consumption and the efficiency of the second law are decreased, the exergy destruction in the ejector is reduced, and the total exergy destruction of the refrigeration cycle is increased. Considering the second law efficiency, COP, the entrainment ratio and the energy consumption, a temperature of 40° of the superheat was achieved as the best degree of the superheat in this cycle that in comparison to the state without superheating, the entrainment ratio and COP are increased by 4.4 % and 1 %, the second law efficiency and the generator energy consumption are reduced by 19.5 % and 1.6 %, respectively.

Nowadays, the use of equipment with little pollution is essential due to the increase in the planet’s temperature. Ejectors are considered one of the equipment with no pollution, and their failure rate is low due to the lack of moving parts. Also, scholars have recently focused on improving the efficiency of industrial equipment. The use of accurate modeling is required to improve steam ejector performance. In a steam ejector, non-equilibrium condensation creates a two-phase flow situation. The wet steam model, used in this study, characterizes this two-phase flow. The study’s objective was to compare this wet steam model with the dry gas model. In the wet steam model, the liquid mass fraction is 0.25, and its calculated entrainment ratio is lower than the dry gas model, closely matching experimental observations. The dry gas model reaches a maximum Mach number of about 5, while the wet steam model approximates 4. A significant temperature difference exists between the two models, with the dry gas model indicating lower temperatures compared to the wet steam model. Diagonal shocks and expansion waves are evident in the mixing chamber, fixed cross-section, and diffuser. These phenomena occur with greater intensity and a slight delay in the wet steam model compared to the dry gas model.

Extensive research has been done to provide energy from renewable sources due to climate change, global warming and limited fossil resources. Due to its low energy density, biomass is one of the renewable energy sources that is not used directly. Biomass is a clean, renewable energy source with a zero carbon dioxide release rate. Gasification is a chemical process that converts carbonaceous materials like biomass into gaseous fuels or useful chemical raw materials for gasification to occur in an oxygen-deficient environment with a requirement for heat which needs mediators for the reaction, like air, oxygen, superheated steam, or a combination of these. This study has been conducted to investigate the impact of the type of biomass feed on the production of syngas using the steam gasification method. Therefore, rice husk, wood chip, wood residue, coffee bean and green waste are considered, and the impact of gasification temperature and steam to biomass ratio (S/B) is investigated. According to the results, wood residue produces the most hydrogen compared to other feeds. With the increase of gasification temperature, an increase-decrease trend in the mass flow rate of hydrogen and an increase trend in the mass flow rate of carbon monoxide can be seen. The hydrogen produced in wood residue is 855 kg/h at S/B of 0.2 as well as a gasification temperature of 1200 °C. The lowest mass flow rate of hydrogen and carbon monoxide is related to green waste feed.

Microfluidic technology has garnered growing interest in diverse domains. The efficacy and precision of microfluidic devices are significantly influenced by micromixing processes. Micromixers, comprising microchannels designed to blend fluids within a confined space and limited flow pathway, constitute indispensable components of microfluidic systems. Among these components, the micromixer stands out as a critical element, tasked with achieving maximal mixing efficiency while imposing minimal pressure drop. This paper focusses on the numerical and experimental study the baffle-based split and recombine chamber (B-SARC) micromixers. The models of a curved wavy micromixer (without baffle) and the baffle-based split and recombine chamber (B-SARC) micromixers with three baffles such as square, triangular and teardrop shaped baffles been developed using COMSOL Multiphysics software. The mixing performance analysis has been carried out by studying the mixing index and pressure drop. The influence of baffle shapes i.e. square, triangular and teardrop shaped baffles of aspect ratio 1, 1.5 and 2 on mixing performance analysis has been investigated numerically, for widespread assortment of Reynolds numbers (Re) lies between 0.1 and 90. The polydimethylsiloxane (PDMS) baffle-based split and recombine chamber (B-SARC) micromixers have been fabricated. Further, the experimental analysis has been carried out. The experimental analysis for pressure drop as well as mixing index has been performed. A good agreement has been observed between experimental and computational results which leads to validation of the computational results. The results revel the role of diffusion at lower Reynolds numbers and the production of derivative flows owing to advection at higher Reynolds numbers within the considered range of Re.

Unstable processes are challenging to control because they have one or more positive poles that produce unrestrained dynamic activity. Controlling such unstable plants becomes more challenging with the occurrence of the delay. This article presents a novel direct synthesis based sliding mode controller design for unstable second order plus dead-time processes. A sliding surface with three parameters has been considered. The continuous control law, which is responsible for maintaining the system mode to the desired sliding surface mode, has been obtained using the direct synthesis approach. The discontinuous control law parameters have been obtained using the differential evolution optimization technique. A desired reference model is considered for the direct synthesis method, and an objective function is constituted in terms of performance measure (integral absolute error) and control effort measure (total variation of controller output) for the optimization approach. Illustrative examples show the superiority of the proposed controller design method over recently reported literature, especially in terms of load rejection. The proposed controller approach is further extended to control the temperature of a nonlinear chemical reactor. Furthermore, the robustness of the proposed controller is also investigated for plant parametric uncertainty.

Partial Least Squares (PLS) is a supervised multivariate statistical/machine learning technique, which is used for classification and identification/authentication of a variety of operating conditions in tomato juice concentrator/evaporator, yeast fermentation bioreactor and fluid catalytic cracking process plants. Data for the three processes were generated pertaining to different operating conditions (for each of them) including faulty ones by simulating their mechanistic models over 25 h. The simulated data at transient conditions were chosen for further processing. They were divided into training and testing data pools. After training, the developed PLS model could classify various process operating conditions 100 % accurately and identify unknown process operating conditions (simulated using training pool with certain degree of variations in them) pertaining to the processes.

The present paper presents a numerical investigation of heat transfer in an exchanger fitted with a modified conical-shaped turbulator containing water/Fe 2 O 3 nanofluid. The study aims to address the critical need for improved heat exchanger efficiency, a vital component in various industries, including the chemical, power generation, and food industries. The work focuses on achieving enhanced heat transfer performance within a smaller volume, a primary goal of modern technology and industrial processes. The innovation in this study lies in the design and analysis of a novel conical turbulator, which has not been explored extensively in the context of heat exchangers fitted with nanofluids. Unlike traditional methods, which often rely on active or semi-active means to enhance heat transfer, this research introduces a passive approach through the incorporation of turbulators. Specifically, the study investigates the use of perforated cone-shaped turbulators in conjunction with nanofluids to boost heat transfer performance. The research employs state-of-the-art computational fluid dynamics (CFD) models, allowing for a comprehensive evaluation of the turbulator’s performance across a wide range of Reynolds numbers (Re = 4000–20,000). It further examines the influence of various turbulator parameters, nanoparticle content, and geometry on heat transfer efficiency. Key findings indicate that the modified turbulator exhibits exceptional performance, increasing Nusselt numbers by 3.4–5.4 times and friction coefficients by 2.3–1.8 times compared to smooth pipes. Particularly noteworthy is the 92 % increase in the Nusselt number achieved with a mere 2 % increase in the Fe 2 O 3 nanoparticle content. The present study introduces a novel passive heat transfer enhancement method using perforated cone-shaped turbulators and nanofluids, filling a significant gap in existing research. The innovative turbulator design and its substantial performance improvements offer promising prospects for achieving higher heat exchanger efficiency, making it a valuable contribution to thermal systems and heat transfer engineering.