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A slit-less gas-solid vortex reactor (SL-RFBSG) has high heat and mass transfer capability, applicable in pharmaceutical and food processing industries, especially in food grain drying and preservation. Validating the numerical outcomes with experimental results of the SL-GSVR vortex chamber with a capacity of 500 g, the scale-up of this reactor is performed numerically to a solid capacity of 3000 g. In the present investigation, a three-dimensional computational fluid dynamics analysis of gas-solid hydrodynamics and heat transfer characteristics in SL-GSVR has been performed using the commercial software ANSYS FLUENT 14.5, applying an Eulerian-Eulerian approach for the gas-solid phase. As the SL-GSVR vortex chamber is developed without slits, it improves bed-uniformity and fluidization, along with the reduction in system cost and complexity. Comparing numerical outcomes with experimental results, the measured temperature difference, inventory, heat transfer coefficient in the radial direction and transverse directions are 0.24%, 7.72%, 14.8%, and 17.8%, respectively. The requirement of drying air in the SL-GSVR dryer is decreased by 18.6%, with an improvement in the product quality compared to the RFB reactor. Further, the solid loading capacity of the scaled-up SL-GSVR drying chamber has been increased to 3000 g.

In the present research, a parametric study of a pilot-scale gas–solid vortex reactor (GSVR) with static geometry dryer has been carried out. It is an intense and clean energy technology of the gra...

The demand for energy has been increasing all over the world, necessitating the introduction of novel devices to work with lower energy consumption. Modern technologies used for paddy drying are on...

Paddy drying is an important task which is vital to the quality and storability of rice. Hence, evaluation of the drying process has to be performed for achieving a good quality of dried paddy in shorter duration. In this present work, performance evaluation of the drying process of paddy was experimentally investigated in two conical bubbling fluidized bed dryers with cone angles of 5° and 10° and results were compared with a conventional fluidized bed dryer having cone angle 0°. The experiments were conducted at three different superficial air velocities of 1.1, 1.6 and 2.1 m/s with bed inventories between 1 and 3 kg. Three different inlet air temperatures of 55, 60 and 65 °C were maintained for the evaluation of the drying process. Both hydrodynamic behaviour and drying characteristics have been investigated at these operating conditions. It has been evident from the experimental investigations that the conical fluidized bed dryer with 10° cone angle shows better performance than the other two dryers. The quality of the dried product has been tested for three different drying times and results were found to be in good agreement with the previously published literature. The milling quality was also tested for conical dryer and the use of a conical dryer recovered 77% of the milling rice.

An enormous amount of heat energy is available in the cyclone and downcomer of a circulating fluidized bed (CFB). The downcomer section can thus be a major source of heat recovery. There is scope for investigation on prospects of recovering heat along the downcomer. In the present work, an attempt is made to utilize the heat from the downcomer of a laboratory-scale Pressurized circulating fluidized bed (PCFB) set up by incorporating a spiral type of heat exchanger inside it. Transient behaviour of the heat recovery for various transient operating conditions such as superficial air velocity and power input which are operated under either step and ramp increase or decrease are reported. The PCFB unit in the present study consists of a riser of 2000 mm height and 54 mm inner diameter. The length of the downcomer is 1465 mm with an inner diameter of 54 mm. The results indicated that a maximum amount of around 350 W of heat could be recovered in the downcomer. It is also observed in some cases that this heat recovery fluctuates in phase with the transients in various operating conditions while it fluctuates with delays and phase shifts in others.

The present work is to study the effect of pressure on the gasification of sugarcane bagasse in a pressurized circulating fluidized bed reactor. The range of operating pressure is maintained at 1–4 bar, and thereby the composition of generated syngas is measured with the help of gas chromatography. The gasification parameters like dry gas yield, lower heating value (LHV), cold gas efficiency (CGE), and carbon conversion efficiency (CCE) have been calculated from the syngas composition. The output yields some interesting results, i.e., with the increase in pressure from 1 to 4 bar, and there is an increment of concentration value by 26% for CH4 as well as CO2. However, a decreasing trend of H2 concentration (7.62–6.75% by volume) is observed for the same pressure rise. In addition, it has been observed a little deviation in the trend for CO (16.39–16.86%), which bears an increasing trend from a pressure of 1–2 bar and a decreasing trend thereafter. Following a similar trend for CO, the LHV first increases from 4013 to 4200 kJ Nm−3 with an increase in pressure from 1 to 2 bar and thereafter decreases gradually to 4081 kJ Nm−3 at a pressure of 4 bar. Apart from these parameters, gas yield, CCE, and CGE values imparted positive effects with pressure rise, and the magnitudes increased from 0.93 to 1.27 Nm3 kg−1, 38.3–57.5 and 23.3–32.3%, respectively, with an increase in pressure from 1 to 4 bar. The exergy destruction and exergy efficiency are observed to be 140 MW and 76% at 4 bar operating pressure.

A rotating fluidized bed in static geometry (RFB-SG) without slits is presented in this paper as a research objective. The concept of RFB-SG is highly beneficial in numerous industrial operations such as granular drying, particle coating, mixing, agglomeration, and combustion. In this study, a three-dimensional CFD model is developed using the commercial software ANSYS FLUENT 14.5, to investigate hydrodynamics and heat transfer characteristics of gas–solid in the vortex chamber. The analysis of the flow pattern of gas–solid and the prediction of fluidization capacity have been made, using appropriate parameters. The findings showed that the significant factors, such as inlet air velocity, solid-bed thickness, the volume fraction of solids, solids pressure, and heat transfer coefficient, influenced the reactor capacity. It is observed that the solid inventories of 300 and 500 g have been fluidized perfectly at inlet air velocities of 30 m s−1 and 44 m s−1, respectively. The overall operating and drying costs are found to be decreased due to the reduction in fluidization air requirements.

The present research is focused on the gasification study of a lab-scale pressurized circulating fluidized bed (PCFB) gasifier considering low-grade Indian coal and biomass such as sawdust and rice husk with a mean particle size of 600 μ m as feed materials. Syngas composition, lower heating value (LHV), dry gas yield (Y), carbon conversion efficiency (CCE), and cold gas efficiency (CGE) are evaluated based on the experiments in the range of pressure 1–4 bar. It is observed that the concentration of CH4 increases with pressure for all the three feed materials. The concentration of CH4 is found to be increasing from (3.65–4.86 vol%) and (2.98–3.46 vol%) for sawdust and rice husk, respectively. Similarly, the LHV is found to be increasing with pressure for coal and sawdust. There is a significant increase of 12% in LHV with an increase in pressure from 1 to 4 bar for both coal and sawdust. The CGE is found to increase by 34, 51, and 61% for rice husk, coal and sawdust, respectively with the increase in pressure from 1 to 4 bar.

This paper reports gasification of coal/biomass blends in a pilot scale (50 kWe) air-blown circulating fluidized bed gasifier. Yardsticks for gasification performance are net yield, LHV and composition and tar content of producer gas, cold gas efficiency (CGE) and carbon conversion efficiency (CCE). Net LHV decreased with increasing equivalence ratio (ER) whereas CCE and CGE increased. Max gas yield (1.91 Nm3/kg) and least tar yield (5.61 g/kg of dry fuel) was obtained for coal biomass composition of 60:40 wt% at 800 °C. Catalytic effect of alkali and alkaline earth metals in biomass enhanced char and tar conversion for coal/biomass blend of 60:40 wt% at ER = 0.29, with CGE and CCE of 44% and 84%, respectively. Gasification of 60:40 wt% coal/biomass blend with dolomite (10 wt%, in-bed) gave higher gas yield (2.11 Nm3/kg) and H2 content (12.63 vol%) of producer gas with reduced tar content (4.3 g/kg dry fuel).

Biogas produced from anaerobic digestion of organic waste is composed of methane (CH4) and carbon dioxide (CO2) as the major constituents with trace amounts of other components like water vapor, hydrogen sulfide, ammonia, and nitrogen. Scrubbing of CO2 is essential for upgradation of biogas, which increases the calorific value of the treated gas and enhances its efficiency for power production and cooking. This study was conducted to investigate and compare the effects of different concentrations of KOH (0.1, 0.3, 0.5, 0.7, and 1.0 M) and natural base ash solutions prepared from different parts of banana plant, viz. banana pseudostem (BPS), Musa balbisiana Peel (MBP), and Musa acuminata Peel (MAP) for scrubbing of CO2 from biogas. The methane content of the untreated biogas analyzed in a gas chromatograph was found to be 56.9%. The scrubber with natural base solution from MBP could enrich the methane content in biogas from 56.9% to 86.3% followed by MAP (78.4%) and BPS (76.8%). The experiments revealed that banana peel ash base solutions have nearly equivalent potential as KOH for CO2 absorption from biogas. The highest CO2 absorption of ~ 68% was achieved with MBP with saturation time of 19 min approximately at a flow rate of 200 ml/min. The study also indicated that CO2 absorption by different natural as well as chemical base solvents is transient and has to be replenished after saturation. Natural bases have the added advantage of being easily available, cheap production method, environment friendly and require no treatment for disposal.

This study presents a thermal performance comparative study of three shell-and-tube latent heat storage (LHS) models. With the help of the optimization technique, 19 tubes are chosen with an internal and external diameter of 17 mm and 20 mm, respectively. In the first case, the LHS model is considered without fins. In the second case, the LHS model is also modeled without fins, but the phase changing materials (PCM) are mixed with 5% volume fraction of Cu nanoparticles. In the third case, every HTF tube is supported by four fins. In order to maintain the same volume of PCM in all the models, shell diameter of the first LHS model is 235 mm and for the second and third cases, the diameter is set to be 240 mm. Commercial sugar alcohol known as Erythritol (C4H10O4) is considered as PCM. ANSYS Fluent environment is employed for the numerical modeling and solution of the governing equations representing PCM. The performance study of LHS units is evaluated using parameters, such as transient temperature and liquid fraction. In order to account buoyancy impact of liquid PCM, Boussinesq approximation method is applied to the model. The inner walls of the HTF tubes are maintained at 138 °C as inlet temperature. The numerical estimations are validated against experimental results. LHS model in the third case, which is supported by fins, becomes fully charged after 80 min, whereas, LHS models in the first and second cases take 120 and 136 min, respectively, for complete melting.

The escalated energy demand in conjunction with the global warming and environmental degradation has paved the path of transportation electrification. Electric Vehicles (EVs) need to recharge their batteries after travelling certain distance. Thus, large scale deployment of EVs calls for development of sustainable charging infrastructure. The placement of charging stations is a complex optimization problem involving a number of decision variables, objective functions, and constraints. Placement of charging station mimics a non-convex and non- combinatorial problem involving both transport and distribution network. The complex and non-linear nature of the charging station placement problem has compelled researchers to apply Nature Inspired Optimization (NIO) algorithms for solving the problem. This study aims to review the NIO algorithms applied for solving the charging station placement problem. This work will endow the research community with a systematic review of NIO algorithms for solving charging station placement problem thereby revealing the key features, advantages, and disadvantages of each of these algorithms. Thus, this work will help the researchers in selecting suitable algorithm for solving the charging station placement problem and will serve as a guide for developing efficient algorithms to solve the charging station placement problem.

Biogas is made up of methane, carbon dioxide, and traces of numerous trace of elements. It is created through the anaerobic digestion of organic materials, such as cattle manure, and is dependent on a number of parameters impacting the population and activity of the bacteria that make biogas. Temperature is one of the many variables that affect biogas production from cattle manure. The effect of temperature on biogas production from cattle dung was investigated at temperatures ranging from 35°C to 55°C, with each step of 5°C. The effect of temperature on the rate of biogas production from cattle dung is evaluated using a mathematical model developed in this study. The temperature impact is added to the modified Gompertz model to create the new mathematical model. The new model was found to be capable of predicting biogas production from cattle dung at temperatures ranging from 35°C to 55°C. The results of the new model are found to be highly correlated with the experimental data of the current study.

Effective thermodynamic analysis is quite necessary for proper system design performance and optimization of system processes. Energy is concerned with the quantitative evaluation of system processes. Nonetheless, exergy gives a qualitative analysis of the system processes. The present investigation deals with the study of exergy and energy analysis of the paddy drying processes in two tapered fluidized bed dryers having the tapered angle 5 deg and 10 deg, respectively, and one cylindrical bubbling fluidized bed dryer. The energy utilization (EU) and energy utilization ratio (EUR) for various operating parameters such as inlet air velocity, mass of paddy, temperature, a spiral, and cone angle are investigated. Similarly, the exergetic efficiency and the rate of exergy destruction are also studied for the same operating parameters. The EU and EUR are found to have an increasing order when the inlet air velocity, temperature, and mass of paddy increase. The trend of EU and EUR also increases with an addition of a spiral inside a dryer. The increasing cone angle of the dryer has a similar impact on EU and EUR as that of other operating parameters. Similarly, exergy utilization and exergetic efficiency also show an increment with the rise in inlet air velocity, mass of paddy, cone angle of dryer, and temperature. The incorporation of a spiral inside a dryer improves exergy utilization and exergetic efficiency. Hence, the conical dryer with a higher cone angle is found to be the best option for drying.

Tea has become an important crop in a many regions of the world. India is one of the best quality tea producers in the world. Despite of being an important cash crop, much research has not been made on tea, due to which modern drying technologies have not been employed in this regard. This work reflects the drying characteristics for tea in a bubbling conical bed dryer. Fresh Assam tea leaves have been processed into crush, tear, and curl (CTC) tea initially, followed by fermentation and drying in a conical bubbling fluidized bed dryer. The effect of various parameters, such as drying air temperature, superficial air velocity, inventory, and cone angle, on moisture removal rate from CTC tea in the conical bed dryer has been experimentally investigated and analyzed in this present work. Drying temperature and superficial air velocity are found to be the major parameter that affects the moisture removal rate from tea. The moisture removal rate from tea varies proportionally with the increase in drying temperature, but the quality deteriorates after a certain limit of temperature. Different cone angles of 0°, 5°, and 10° for the conical bubbling fluidized bed dryer are also inquired into for a static inventory bed height of 15 cm. It is found that moisture removal rate is highest for the case 10° cone angle of the dryer.

Hydrodynamics plays an essential role in the flow of gas-solid characteristics in the fluidized bed (FB) unit. The present paper deals with the hydrodynamic study of biomass (sawdust, mean diameter dp = 400 µm and particle density Pp = 410 kg/m3) in a pressurized fluidized bed (PFB) having an internal diameter 100 mm and height 3000 mm. The Experiment has been carried out, at four different inventory of sawdust 500, 750, 1000, and 1250 g and each inventory at four different working pressure 1, 2, 3, and 4 bar. The effect of the operating condition has been analyzed for voidage profile, suspension density, and drop of pressure in the riser. The results show that at the lower part of the riser section, bed voidage reduces with an enhancement in operating pressure whereas at the upper part of the riser section bed voidage increases with a rise in operating pressure. It also can be observed that the bed voidage along the peak of riser decreases with a rise in solid inventory. The bed voidage is found minimum (e = 0.51 at a distance 720 mm from distributor plate) at 1250 g of inventory having operating pressure 4 bar. Solid inventory and operating pressure having a positive effect on suspension density and suspension density found an increasing trend with an enhancement of pressure and bed inventory. At the inlet of riser minimum suspension density was found 59.3 kg/m3 at a pressure of 1 bar having 500 g inventory whereas maximum suspension density was found 124.7 kg/m3 at a pressure of 4 bar having 1250 g inventory.

Pressurized Circulating Fluidized Bed (PCFB) has earned appreciation in using low-grade coal for gasification and combustion applications because of its built-in capacity to capture sulphur and NOx. It becomes more attractive due to its compactness and elevated heat release rate. Whether the fluidized bed is used to separate or react, the key objective is to operate the bed at a flow rate that optimizes the application. Accurate models would help a great deal but modelling continues to challenge engineers and researchers even at a qualitative level. In this present investigation, numerical simulation is carried out in two conical risers and one columnar riser by considering coal as a bed inventory. The simulation is performed at a superficial velocity of 4 m/s for an inventory of 1 kg. The model k–e is used as a turbulence model. The simulation is performed to investigate the optimum parameters for the efficient use of the pressurized circulating fluidized bed. From the simulation, the variation of bed voidage, suspension density and pressure over the riser height are calculated at the operating pressure of 1, 2, 5 and 10 bar and results have been compared among the three risers. It is observed that pressure drop decreases up to a certain height and then increases with the height of the riser. Suspension density is also found to be decreasing with height. The pressure drop in the conical bed is found to be lower than that of columnar bed.

Biogas is mainly composed of methane (CH4) and carbon dioxide (CO2) with trace amounts of hydrogen sulfide (H2S), of which CO2 and H2S are impurities. Scrubbing of these two impurities are crucial for purification and upgradation of biogas, which would simultaneously also increase the calorific value of the treated biogas and address the issue of corrosion. Several studies have used expensive and environmentally harmful chemicals for the purification of biogas. This study reports a simple biogas purification system that utilizes biomass biochar and biochar–clay composites to remove CO2 and H2S from biogas by the process of adsorption. The biomass biochar could enrich the methane content of raw biogas from 59.7 to 84.6%, which shows the potentiality and applicability of biomass biochar for the removal of CO2 and H2S from biogas. This simultaneously enhanced the calorific value of the biogas and retarded the corrosiveness due to H2S. The study also indicated that CO2 adsorption by biomass biochar and biochar–clay composite is transient and has to be reloaded after saturation. Biochar and clay have the added advantage of being environment friendly and require no treatment for disposal. Observed results indicated that similar degree of enrichment, compared to commonly used chemical, could be achieved by application of biomass biochar and biochar–clay at a much lesser cost.

A rotating fluidized bed with static geometry (RFB-SG) drying is a promising technique that is useful for various operations, such as agglomeration, food grain drying, particle coating, separation, and combustion. The advantage of this technique is that a large volume of hot air is circulated across the particles in a very small geometry, which results in higher heat and mass transfer. The higher heat and mass transfer through the RFB-SG dryer makes the drying process faster. Initially, the high-velocity air is injected into the vortex chamber through multi-air inlets, and then the solid particles are inserted into the vortex chamber. The high-velocity air injected into the reactor forces the solid particle to rotate in the form of a solid bed. The air entering into the vortex chamber carries away the moisture of food grains via a centrally located chimney outlet. In the present work, performance of scaled-up RFB-SG dryer has been evaluated considering parameters, such as temperature (55–65 °C), airflow rate (600–800 m3/h), inventory (400–1000 g), and drying time. The RFB-SG dryer is found to be more efficient than the conventional fluidized bed (CFB) dryers as this dryer works on a higher airflow rate. Drying efficiency is improved by better utilization of the drying air at a temperature of 65 °C.

Growing concern about the rapid depletion of fossil fuels, current environmental conditions, energy challenges and new environmental regulations has encouraged the researchers worldwide for new environmentally compatible alternatives from natural resources. In this context, biogas produced from anaerobic digestion of organic resources may be considered as a significant bioenergy with the potential to address these concerns. Biogas is a mixture of methane and carbon dioxide as the major constituents with other trace components like water vapor, hydrogen sulfide, ammonia, carbon monoxide and nitrogen. Uses of biogas can be seen in heating, cooking, lighting and power production. However, cleaning of biogas from its impurities, mainly CO2 and H2S, can extend its scope of applications. There are numerous physico-chemical (viz. cryogenic, adsorption, membrane separations and absorption) and biological (in situ and ex situ) technologies for biogas upgradation. These operations are aimed at enriching the methane content of biogas above 90% and thereby enhancing the calorific value up to 35.3 MJ/m3. The purpose behind such upgrading is generally focused to meet the fuel standards to be used in vehicles, for injection in the natural gas grid, and to be used as substrate for the production of chemicals or for fuel cell applications. Enriched biogas is compressed and stocked in gas cylinder and transported to the desired location for utilization. Additionally, use of enriched biogas reduces greenhouse gas emissions. This chapter aims at meticulously evaluating the existing and emerging biogas production and upgradation technologies and confers the outlook for overcoming the challenges associated with them.

The velocity distribution in the axial direction of a conical fluidized bed is not uniform due to the expansion of cross-sectional area along the height. As such, the hydrodynamic and heat transfer characteristics of a tapered fluidized bed differ from that of the columnar fluidized bed. Various operating parameters have a significant effect on these characteristics. In this paper, the effect of bed inventory and airflow rate on the hydrodynamic and heat transfer characteristics in a columnar and conical are investigated and compared both experimentally and numerically. A Eulerian-Eulerian model is employed to investigate the hydrodynamics and heat transfer behaviour for both the types of bed. The Syamlal-O’Brien model is used as a drag model. The pressure drop across the bed is found to higher for the columnar bed. The heat transfer is also found to be better for the conical bed. Results obtained by experiments are seen to be excellent agreement with the numerical results.

The concept of rotating fluidized bed with static geometry (RFB-SG) is highly beneficial in drying operations. The present work is focused on the drying of granular particles (paddy) in the developed RFB-SG dryer. In this RFB-SG, the tangential injection of fluidizing gas via several inlets induces rotary motion to the solid particles and forms a solid-bed. In the entire process of fluidization, the solid particles experience a radially outward centrifugal force, whereas the gas is forced to move inward towards the chimney. The RFB-SG is expected to operate more efficiently at higher gas flow rates as compared to the conventional fluidized bed reactor. Experiments were carried to dry paddy of initial moisture ranging 23–37% (wb) to 14% (wb) with drying air inlet temperature of 55 and 60 °C and mass flow 250 m3/h. A better air utilization decreased the drying time by 20% on increasing the air inlet temperature by 9%. Air inlet temperature of 60°C is better for drying paddy as compared to 55°C.

The purpose of this investigation is to study the effect of welding variables on bead geometry, fusion zone profile and tensile properties of double-sided submerged arc welding on SS 304 austenitic stainless steel. The individual effect of welding parameters, i.e., welding current, voltage and traverse speed, on bead geometry and tensile properties was investigated. Both microstructural and mechanical characterizations of the weldment were carried out in the present study. It was observed that the operating parameters have significant effect on bead geometry and tensile properties. The double-sided welding effectively enhanced the weld seam ductility. The percentage of elongation is improved by 19.48% to 50.2% for double-sided samples as compared to base material. A comparative study between single and double-sided butt welding was also carried out. For single-sided sample the percentage of elongation is lower than the base material. The percentage reduction in angular distortion of 55.17% is observed with double-sided weld sample as compared to single-sided weld sample.

Submerged arc welding is a high productivity process for joining thick sections of steels, used particularly in ship building, pipe welding, construction applications and surfacing. In the present work double sided submerged arc welded was performed on 12 mm thick austenitic stainless steel plates to determine the effect of welding current on bead profile and mechanical properties. As the welding current increases, reinforcement height, reinforcement area, penetration depth and area, bead overlap area are found to show improvement in almost linear fashion. The welding current doesn’t much influence the weld bead width. The average bead contact angle decreased with increase in welding current. The tensile properties were found to increase steeply with increase in welding current. Two different morphologies of δ ferrite namely, skeletal and lathy structures were observed in the fusion zone.

This review presents an overview of the existing state-of-the-art practices of improved performance in buildings required for the algorithmic logic and/or hardware. The main focus is on sensor-actuator-based applications in intelligent buildings like air quality, lighting, heating/cooling, ventilation, power management, water management, cooking gas management, and building health monitoring. The following are some of the major factors that usually rule in the development of intelligent buildings, such as good accuracy of the system, energy efficiency, response time of the sensor module, cost of the overall system, radio frequency interference, adequate signal-to-noise ratio, open interface capability, and intricacy of computation. The importance of the concerned issues and factors are discussed in detail for future research directions.

The performance of all latent heat storage system depends on the quality of phase change material used. In the present study, paraffin-based nanofluid dispersed with 5% of Cu, 5% of CuO and 5% of Al2O3 nanoparticles are used to investigate its effect on the storage characteristics. A 3-D numerical model of a shell and tube regenerative type latent heat storage is developed using®COMSOL Multiphysics 4.3a to predict the average temperature and melt fraction of paraffin-based nanofluid. The validation with the established pieces of literature and experiments indicated a sound agreement. The effect of adding nanoparticles on melting/solidification rate and energy storing/releasing rate are also studied. The result revealed that addition of 5% of Cu, 5% of Al2O3 and 5% of CuO nanoparticles improved the melting rate by 10 times, 3.46 times and 2.25 times and the discharged rate by 8 times, 3 times and 1.7 times, respectively compared to the pure paraffin filled latent heat storage system. However, it decreased the specific heat and heat of fusion which reduced the sensible and latent heat storing capacity. Additionally, orientations of cylinder and tube arrangement are also studied numerically using paraffin as phase change material.