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The current critical global concerns regarding fossil fuel exhaustion and environmental pollution have been driving advancements in transportation electrification and related battery technologies. In turn, the resultant growing popularity of electric vehicles (EVs) calls for the development of a well-designed charging infrastructure. However, an inappropriate placement of charging stations might hamper smooth operation of the power grid and be inconvenient to EV drivers. Thus, the present work proposes a novel two-stage planning model for charging station placement. The candidate locations for the placement of charging stations are first determined by fuzzy inference considering distance, road traffic, and grid stability. The randomness in road traffic is modelled by applying a Bayesian network (BN). Then, the charging station placement problem is represented in a multi-objective framework with cost, voltage stability reliability power loss (VRP) index, accessibility index, and waiting time as objective functions. A hybrid algorithm combining chicken swarm optimization and the teaching-learning-based optimization (CSO TLBO) algorithm is used to obtain the Pareto front. Further, fuzzy decision making is used to compare the Pareto optimal solutions. The proposed planning model is validated on a superimposed IEEE 33-bus and 25-node test network and on a practical network in Tianjin, China. Simulation results validate the efficacy of the proposed model.

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.

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.

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).

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.

The rise in mean atmospheric temperature resulting from the emissions of greenhouse gases, especially CO 2 , has become a widespread concern in the recent years. This awareness of increase in greenhouse gas emissions has resulted in the development of new technologies which would lower emissions of CO 2 from flue gases. The purpose of this study is to investigate the performance of bubbling fluidized bed for CO 2 adsorption to mitigate CO 2 from flue gas. Adsorption of CO 2 had been carried out onto zeolite 4A, zeolite 5A, zeolite 13X and activated carbon at a pressure up to 4 bars. The effects of adsorbent mass on breakthrough time, gas velocity, adsorption isotherm, thermodynamics and heat transfer characteristics were also investigated during the continuous operation of the bubbling fluidized bed. As flow rate increased, the breakthrough curves become steeper and reached the breakthrough quickly due to the residence time of the adsorbate in the column, which was long enough for adsorption equilibrium to be reached at high flow rate. The experimental data were fitted with isotherm models like Langmuir and Freundlich isotherm model. It was found that the Langmuir model fit well with the zeolites based adsorbent and Freundlich model fit well with activated carbon. The experimental results permitted the determination of adsorption capacities of the adsorbents and showed that there is an improvement in the adsorption capacity using fluidized bed due to a better gas solid contact as compared to conventional fixed bed.

A critical review and analysis of co-gasification of coal/biomass blends is presented. Initially, the chemistry of gasification of coal and biomass has been described along with different models for pyrolysis of cellulose/biomass. The mechanistic issues of catalytic effect of alkali metals on coal char gasification have been reviewed. This is followed by literature review on gasification of coal/biomass blends in two parts, viz. thermogravimetric and fluidized bed gasification. First part deals with effects of operational parameters on char reactivity. Second part analyzes influence of these parameters on gasification chemistry and producer gas. Factors governing tar content in producer gas have been discussed. Finally, the literature on kinetic modeling of coal/biomass blends has been analyzed. Some new approaches in kinetic modeling of solid-state reactions have been discussed.

The absorber plate and outlet water temperature of a solar flat plate collector with straight riser and header arrangement is investigated. The effect of different operating parameters, viz., inlet water temperature, solar insolation, ambient temperature, and mass flow rate on the outlet water temperature and thermal efficiency were studied. Both the closed as well as open loop solar water heating system is considered for the present investigation. It is observed that the thermal efficiency of the solar water heating system increases with ambient temperature, solar insolation, and mass flow rate of water. However, thermal efficiency decreases as inlet water temperature increases. Numerical simulations were carried out using a 3-dimensional computational fluid dynamics (CFD) to predict the outlet water and absorber plate temperatures using the experimental values of solar insolation, ambient temperature and inlet water temperature within one hour interval. The CFD results were validated with the experimental results. It was found that the developed model could predict the outlet water and absorber plate temperature of the heating system with reasonable accuracy.

We report here the characterization of five biomass samples ( Impereta cylindrica, Eragrostis airoides, Typha angustifolia L., Arundinella khasiana Nees ex Steud, and Echinochloa stagnina (Retz.) P. Beauv) based on the proximate, ultimate and compositional analysis. The biomasses were examined physico-chemically and characterized to understand their compositional and structural properties. The moisture content was found to be highest in Typha angustifolia (13.951%) and lowest in Eragrostis airoides (8.275%). Ash content was seen to be maximum in Arundinella khasiana (8.12%) and minimum in Eragrostis airoides (3.660%). Derivative Thermogravimetric (DTG) peak was observed below 120 °C indicating the loss of water molecules from the biomass. Cellulose degradation occured between 350 °C to 500 °C. The maximum carbon content was visible in Typha angustifolia (52.895%) and minimum in Eragrostis airoides (41.024%). The FTIR spectra showed a range of peaks such as 3450 cm −1 , 2860 cm −1 , 1668 cm −1 , 1175 cm −1 , 1097 cm −1 , 7872 cm −1 , 625 cm −1 , 554 cm −1 etc. The cellulose content was found maximum in Eragrostis airoides (43.17%) and minimum in Echinochloa stagnina (24.90%). The results demonstrate that the collected lignocellulosic biomass could be potential candidate for bioethanol production.

Due to the complicated structure of lignocellulosic plant cell wall, their utilization for biogas production via anaerobic digestion has not been widely adopted. Alternative to this is to use aquatic plant materials as feedstock for biogas production. In this context, duckweed, an aquatic plant may prove to be a promising new energy source for bioenergy as well efficient CO 2 sequestration. This study entails a detailed characterization of duckweed to evaluate their potential as an alternate feedstock to cattle dung for biogas production. The duckweed was characterized for volatile matter, moisture content, ash content and carbon, hydrogen, and nitrogen (CHN) content. Property analysis of duckweed was also done by Fourier transform spectroscopy and thermogravimetric analysis. The volatile matter of duckweed was found to be 84.24± 0.2% with a lignin content of 12.2%, which is very encouraging for biogas production. Co-digestion of duckweed (DW) with cattle dung (CD) in varying ratios (DW:CD = 90:10, 75:25, and 50:50 respectively) in batch type anaerobic digesters was performed at 37 °C temperature for 55 days. The cumulative biogas production for CD (100%), DW/CD (90:10), (75:25) and (50:50) was found to be 11,620, 305, 11,695, and 12,070 mL, respectively, which indicated that duckweed can be a potential lignocellulosic feedstock when co-digested with cattle dung at an optimum ratio of 1:1. Methane content of the biogas from co-digested feedstock is comparable to the biogas from cattle dung alone.

The use of porous burner in combustion appliances finds widespread attention due to its inherent nature of low emission and high efficiency. This paper presents a finding on the effects of the porous medium (PM) configuration and operating parameters on the performance of a kerosene pressure stove equipped with Silicon Carbide (SiC) and Alumina (Al2O3) operating in the submerged combustion mode. The study covers three different diameter burners: 60 mm, 70 mm and 80 mm, and their thermal performances are assessed through thermal efficiency, emissions and radial temperatures at different air and fuel flow rates. The best performance is observed in the case of 70 mm diameter burner with a minimum of 44 ppm CO (carbon monoxide) and NOx (oxides of nitrogen) ∼1.5 ppm. An air flow rate range of 120–130 lpm is found optimum.

The intensification of interfacial mass, heat, and momentum transfer makes vortex chambers potentially interesting for the efficient drying of paddy, allowing shorter drying times and/or more compact equipment. The presence of a shell introduces particular challenges. Intraparticle diffusion limitations are strong and may reduce the advantage from intensified interfacial mass and heat transfer and the efficiency of air usage. Furthermore, high shear and normal stresses in the fast rotating particle bed may cause damage to the paddy shell, posing problems for transport and storage. With these specific aspects in mind, the use of vortex chambers for paddy drying is experimentally evaluated.

Porous media combustion (PMC) is relatively a new concept, and due to its inherent characteristics of high efficiency and low emissions, it has found wide applications in many practical systems like internal combustion engine (IC engine), water heater, LPG (Liquefied Petroleum Gas) stoves, etc. In this study, the concept of PMC has been employed in a kerosene pressure stove, and the usefulness of the media consisting of alumina (Al2O3) and silicon carbide (SiC) in terms of efficiency and emissions is investigated. Further, the conditions for optimum efficiency and emission are brought out through a systematic analysis with different burner geometry and exergy calculation. The major highlight of this study is that the highest efficiency of the stove with porous media is found to be ∼10% higher than the average thermal efficiencies of the stoves available in the Indian market.

The present study's main objective is to develop a best-performing gas-solid vortex reactor (GSVR) dryer observing at the effect of spiral versus conical chimney outlet in capacity enhancement. Three-dimensional computational fluid dynamics study of the GSVR model with spiral and the conical chimney has been conducted using a commercial software ANSYS FLUENT 14.5, applying an Eulerian-Eulerian approach for gas-solid. The fluidization capacity of the SL-GSVR drying chamber with a spiral chimney is enhanced by increasing chamber-length. In contrast, in the case of SL-GSVR with a conical chimney outlet, the fluidization capacity is increased by improving the diameter of the reactor, considering various operating parameters, such as air velocity, pressure, bed-thickness, temperature, and heat transfer coefficient. For the same input parameters, the solid loading capacity of the SL-GSVR with a spiral drying chamber is found to be 27% higher than the SL-GSVR with a conical-chimney outlet. Also, the capacity enhancement seems simpler and easy by using a spiral-chimney outlet due to its symmetric nature of construction.

Recent strategies on fuel-development to reduce oil dependency to mitigate greenhouse gas emissions and to utilize domestic resources have generated interest in the search for alternative sources of fuel supplies. In this context, the industrial waste may be regarded as potential alternatives for biogas production. This study entails a detailed characterization of tea waste and food waste to evaluate their potential as an alternate feedstock to cattle dung for biogas production. The samples were characterized for volatile matter, moisture content, ash content and carbon hydrogen nitrogen (CHN). Property analysis of the biomass was also done by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The volatile matter content in tea and food waste was found to be 64.17% and 36.05% respectively, which is quite encouraging. The carbon-to-nitrogen (C:N) ratio, chemical oxygen demand and total solids of the sample also attributed its suitability for biogas production. The thermal behavior and heating values interpreted higher lignin content in tea waste. The lab scale study was conducted with combination of food waste/cattle dung and tea waste/cattle dung that showed higher biogas production in comparison to cattle dung alone implying their potential as biogas feedstock. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1247–1253, 2016

Removal of $$\hbox {CO}_{2}$$ from flue gases has become an effective way to mitigate the greenhouse gases, and adsorption is considered to be one of the methods. Adsorption of $$\hbox {CO}_{2}$$ on locally available coconut fibre-based activated carbon has been investigated and compared with adsorbents like zeolite 13X, zeolite 5A, and zeolite 4A at a temperature ranging from 298 to 333 K and pressure up to 100 kPa. The adsorption process was simulated by considering a linear driving force for the overall mass transfer and diffusivity factor. It was observed that the simulated curves acceptably reproduce the experimental data for the different temperatures studied. The adsorption isotherms for the three adsorbents were obtained and equilibrium characters about both adsorbate and adsorbent were analysed based on Toth isotherm model.

In the present work, quality drying characteristics of sliced ginger were studied utilizing the concept of waste heat recovery in a biomass operated natural convection dryer with sensible heat storage material (SHSM) and phase change material (PCM). Ginger slices (2 and 4 mm thick) were dried from initial moisture content (MC) 88-90% (w.b.) to final moisture content 11-12% (w.b.) with hot air maintained at temperature 60 0 C, air velocity 0.2 m/sec, atmospheric average relative humidity 74% and ambient temperature 25 0 C. It was observed that the biomass consumption and melting time of PCM were significantly reduced due to the use of waste heat. The optimum drying time was found to be 5.5 h for 2 mm thick ginger slices. Color, texture and aroma were found better in treated sample.

Gasification is the thermochemical conversion of solid fuel into the gas which contains mainly hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. In gasification, fluidized bed technology is widely used due to its various advantageous features which include high heat transfer, uniform and controllable temperature and favorable gas–solid contacting. Modeling and simulation of fluidized bed gasification is useful for optimizing the gasifier design and operation with minimal temporal and financial cost. The present work investigates the different modeling approaches applied to the fluidized bed gasification systems. These models are broadly classified as the equilibrium model and the rate based or kinetic model. On the other hand, depending on the description of the hydrodynamic of the bed, fluidized bed models may also be classified as the two-phase flow model, the Euler–Euler model and the Euler–Lagrange model. Mathematical formulation of each of the model mentioned above and their merits and demerits are discussed. Detail reviews of different model used by different researchers with major results obtained by them are presented while the special focus is given on Euler–Euler and Euler–Lagrange CFD models.

In the present investigation, bed-to-wall heat transfer coefficient was studied at the upper splash region of a pressurized circulating fluidized bed (PCFB) riser of internal diameter 54 mm and height of 2000 mm. The experiments were carried out at three different temperatures. At each temperature, experiments were performed at three different operating pressures viz. 1, 3 and 5 bar to investigate the influence of operating pressure. At each pressure condition, bed temperature distributions along the height of the riser were investigated. The superficial velocity was maintained constant throughout the experiment at 7 m/s. The effect of twisted tape inserts on heat transfer at the upper splash region of the riser was studied at three different solid inventories of 400, 600 and 800 g and the results obtained are compared without twisted tape inserts. The average particle size of sand used in the experiment was of 307 μm. The overall uncertainty in calculating the heat transfer coefficient was found to be ±12.3%.

The desulfurization process to a two-dimensional (2-D) and three-dimensional (3-D) Eulerian–Eulerian computational fluid dynamic (CFD) model of a coal bubbling fluidized gasifier is introduced. The desulfurization process is important for the reduction of harmful SOx emissions; therefore, the development of a CFD model capable of predicting chemical reactions involving desulfurization is key to the optimization of reactor designs and operating conditions. To model the process, one gaseous phase and five particulate phases are included. Devolatilization, heterogeneous, and homogeneous chemical reactions as well as calcination and desulfurization reactions are incorporated. A calcination-only model and a calcination plus desulfurization model are simulated in 2-D and 3-D and the concentrations of SO2 leaving the reactors are compared. The simulated results are assessed against available published experimental data. The influence of the fluidized bed on the desulfurization is also considered. © 2013 American Institute of Chemical Engineers AIChE J, 59: 1952–1963, 2013

In the present investigation, the effects of particle size, solid inventory and operating pressure on bed hydrodynamics and heat transfer in a pressurized circulating fluidized bed has been studied. Three different particle sizes of mean diameter of 278, 307 and 469 μm are considered. Experiments have been conducted at five different solid inventories such as 400, 500, 600, 800, and 1000 g, and at three different operating pressures such as 1, 3 and 5 bar. All the above studies have been made at three different superficial velocities of 5, 6 and 7 m/s. The axial variation of heat transfer coefficient with various percentage blending of sawdust in sand has also been studied. Results show that, with the increase in operating pressure and solid inventory, the bed voidage decreases. The solid circulation rate is found to increase with an increase in superficial velocity as well as with an increase in solid inventory. The heat transfer coefficient decreases with an increase in particle size, while it increases with operating pressure from the bottom to the top of heat transfer probe. The heat transfer coefficient is also found to increase with the increase in % blending of sawdust in sand and the operating pressures. The overall uncertainties in calculating solid circulation rate and heat transfer coefficient are estimated to be ±5.32% and ±3.90%, respectively.

In the present work, a pressurized circulating fluidized bed (PCFB) unit of 54 mm inner diameter and riser height of 2000 mm has been fabricated to investigate the effect of pressure on suspension density and heat transfer. The effects of blending of biomass in sand, and superficial velocity on bed hydrodynamics and heat transfer has also been studied. Experiments have been conducted at four different percentage blending of biomass such as 2.5%, 7.5%, 15% and 20% in sand with two different weight composition ratios and at a superficial velocity of 5 m/s. Operating pressure is varied from 1 to 5 bar in a step of 2 bar. Results show that, the axial heat transfer coefficient increases from the bottom to the top of heat transfer probe with the increase in operating pressure. The radial variation of heat transfer coefficient decreases from the wall to the core of the heat transfer probe. The heat transfer coefficient is also found to be higher in between the 7.5 to 15% biomass blending in sand. The overall uncertainty in calculating heat transfer coefficient is found to be 3.90%.

In the present work a comparative study of steady state wall-to-bed heat transfer was conducted along the risers of height 2.85 m of three different circulating fluidized beds (CFBs) with bed cross sections of 0.15 m × 0.15 m, 0.20 m × 0.20 m, and 0.25 m × 0.25 m, respectively. Experiments were conducted on each CFB unit for five superficial air velocities ( U = 2.5 m/s, 2.75 m/s, 3 m/s, 3.3 m/s, and 4 m/s) and two different weights of sand inventory per unit area of the distributor plate ( P = 1750 N/m 2 and P = 3050 N/m 2 ) with average sand particle size of 460 μm. Bed temperature distributions across the three risers were measured and compared at different heights (1.04 m, 1.64 m, and 2.24 m above the distributor plate). Axial distribution of heat transfer coefficient along the height of riser was evaluated and compared for the three bed cross sections. Effect of superficial velocity of air, sand inventory, and bed cross section on bed temperature and heat transfer coefficient was investigated. An empirical correlation was developed for the bed Nusselt number as a function of various non-dimensional parameters based on the parametric study. The correlation was compared with available literatures.

In the present work, a comparative study of steady-state wall-to-bed heat transfer was conducted along the lower and middle splash region located in the riser of height 2.85 m of three different circulating fluidized beds (CFBs) with bed cross-sections of 0.15 m×0.15 m, 0.20 m×0.20 m, and 0.25 m×0.25 m. Experiments were conducted under similar operating conditions on above-mentioned three CFB set-ups using the same weight of sand per unit area of the distributor plate, non-dimensional superficial velocity ( U∗), heat flux, and sand particle size. Further, experiments were conducted on all the three CFB set-ups for five different non-dimensional air velocities ( U∗ = 5, 5.5, 6, 6.6, and 8) and two different weights of sand inventory per unit area of the distributor plate with average particle size of 460 μm. Bed temperature distributions across the lower and middle splash regions were measured and compared for the three bed cross-sections. Axial distributions of heat transfer coefficient along the height of lower and middle splash region of risers were evaluated and compared for the three bed cross-sections. The effect of superficial velocity, sand inventory, and bed cross-section on temperature and heat transfer coefficient was investigated. Based on the present study, correlations were developed for the bed Nusselt number as a function of various non-dimensional numbers for lower and middle splash regions of the riser. The non-dimensional area parameter ( A∗) was found to be a significant number. Predictions of these correlations are in agreement (±16 per cent) with experimental data.

Present work deals with the development of butanol−diesel−biodiesel blends to substitute for petrodiesel. These blends were tested for physical stability and various fuel properties conforming to ASTM standards. Subsequently engine performance and emission tests were conducted with each blend. Observations revealed the blends to be thermally and physically stable, and they showed good resemblance to the properties of diesel, with the exception of flash point only. Brake power showed marginal decrease and fuel consumption an increase in the range of 4.9%−10.7% as compared to diesel for identical performance. Exhaust gas temperature showed a drop in the range of 3.3%−9.4% due to quenching effect of butanol, whereas brake thermal efficiency showed a reduction of 6.3%−10% to that over petrodiesel. Exhaust gas emissions showed a significant decrease in CO (42%) at medium and higher loads, whereas NO showed an average increase of 2.4%−11% as compared to diesel.

In recent years, biomass gasification has emerged as a viable option for decentralized power generation, especially in developing countries. Another potential use of producer gas from biomass gasification is in terms of feedstock for Fischer–Tropsch (FT) synthesis – a process for manufacture of synthetic gasoline and diesel. This paper reports optimization of biomass gasification process for these two applications. Using the non–stoichometric equilibrium model (SOLGASMIX), we have assessed the outcome of gasification process for different combinations of operating conditions. Four key parameters have been used for optimization, viz. biomass type (saw dust, rice husk, bamboo dust), air or equivalence ratio (AR = 0, 0.2, 0.4, 0.6, 0.8 and 1), temperature of gasification (T = 400, 500, 600, 700, 800, 900 and 1000 °C), and gasification medium (air, air–steam 10% mole/mole mixture, air–steam 30%mole/mole mixture). Performance of the gasification process has been assessed with four measures, viz. molar content of H2 and CO in the producer gas, H2/CO molar ratio, LHV of producer gas and overall efficiency of gasifier. The optimum sets of operating conditions for gasifier for FT synthesis are: AR = 0.2–0.4, Temp = 800–1000 °C, and gasification medium as air. The optimum sets of operating conditions for decentralized power generation are: AR = 0.3–0.4, Temp = 700–800 °C with gasification medium being air. The thermodynamic model and methodology presented in this work also presents a general framework, which could be extended for optimization of biomass gasification for any other application.

This article attempts to highlight the technical and economical issues related to decentralized power generation in India using biomass gasification. Biomass-based energy has several distinct advantages such as wide availability and uniform distribution that puts it ahead among the renewable energy options for India. The estimated potential of power generation through renewable sources in India is 85 GW with biomass power contributing approximately 20 GW. Especially, in the remote areas and hilly terrains of India, biomass gasification-based power generation offers a highly viable solution for meeting energy demands of small villages and hamlets, which would not only make them independent but will also reduce burden on state electricity boards. This paper reviews various technical options for biomass gasification-based low-, medium- and large-scale power generation. We essentially discuss the merits and demerits (operational and other problems) of different systems. Further, we also deal with economics of these systems and discuss principal factors influencing the viability of the biomass-based power generation. Finally, we review some case studies of biomass-based power generation for meeting energy needs, both thermal and electrical.

Fluoride contaminated drinking water is a severe problem in many parts of the world because of fluoride-related health hazards, which are considered to be a major environmental problem today. The present work is aimed at utilizing solar energy for removal of fluoride from drinking water by using a “solar still”. Also tests have been conducted with the “solar still” to find out hourly output rate and “still efficiencies” with various test matrixes. It is observed that the distillate from “solar still” showed a fluoride reduction of 92–96%. Further, the efficiency of “solar still” got increased by 11% when capacity of water in the solar basin was raised from 10 to 20 L. Upon suitable modification of the solar basin with appropriate base liner and insulation, this efficiency of the “solar still” is found to be further increased by 6% with a 20 L basin capacity.

The present work investigates the suitability of mesua ferrea (nahar) oil seed as a source of alternative fuel in CI engines. Non-edible straight vegetable oil obtained from mesua ferrea seeds was extracted using a solvent extraction technique. A significant amount of unsaturated fatty acids was found from a gas chromatography test, which was further ascertained by measuring the acid value. The thermo-physical and chemical properties of straight mesua ferrea oil were determined. The flash point, kinematic viscosity, and density of the straight mesua ferrea oil were found to be much higher than diesel, though the calorific value was found to be lower. The variation in thermo-physical and chemical properties of various blends of straight mesua ferrea oil and diesel were studied. The straight mesua ferrea oil blend up to 15% with the diesel met the standard specification. Based on the present study, it was concluded that due to higher viscosity and density and low volatility of straight mesua ferrea oil, it ...

Present work deals with testing a performance of a compression ignition (CI) engine with different blends of non-edible oil as well as their methylesters with petrodiesel. Various blends of a non-edible vegetable oil, commonly known as honge ( Pongamia pinnata L.) in India, were prepared and tested over a wide range of engine load. Results obtained from the study showed that 15–20 per cent pongamia methylester-diesel blend (B15 and B20) could be a better fuel in terms of fuel efficiency and power developed. Further, the blend can be used in any existing CI engine without modification and preheating. The pongamia oil is transesterified by using base catalysed transesterification process in a batch type transesterification reactor. Transesterification shows improvement in fuel properties of pongamia oil. Results obtained with B15 and B20 show improvement in brake thermal efficiency and reduction in brake specific fuel consumption, especially at higher load. Emission results show significant reduction in percentage of CO and HC for B15 and B20 at medium and higher power output.

Application of the discrete transfer method is extended to solve transient radiative transport problems with participating medium. A one-dimensional gray planar absorbing and anisotropically scattering medium is considered. Both boundaries of the medium are black. The incident boundary of the medium is subjected to pulse-laser irradiation, while the other boundary is cold. For radiative parameters such as optical thickness, scattering albedo, anisotropy factor, transmittance, and reflectance at the boundaries are found. Results obtained from the present work are compared with those available in the literature. The discrete transfer method has been found to give an excellent agreement.

In the present study, a new method is proposed for temperature controlling by combustion staging. Two combustion stages can be used with two stages of fuel feeding. A high stoichiometric ratio (SR) gimel > 1 is used at the first stage to mitigate adiabatic flame temperature (AFT) in case of high O2% in the oxidant. For validation, a series of experiments are conducted using mini-CFB (circulating fluidized bed), and an oxidant of 100% O-2 concentration is used with three SR ratios, i.e. gimel = 1.25, 2.0 and 3.0. The resulting average temperatures along the riser for biomass are 1031 degrees C, 950 degrees C and 798 degrees C; and for coal 1129 degrees C, 1051 degrees C and 961 degrees C respectively. The controlling of AFT with pure oxy-fuel combustion eliminates the recycled flue gas in oxy-fuel CFB combustion and flue gas recirculation section; this simplifies design, fabrication and installing-operating costs of the power plants. Familiarizing this concept can accelerate adapting oxy-fuel combustion in CFB power plants for carbon capturing and sequestration. This study can help commercialize the third generation of oxy-fuel CFB combustion with zero RFG. Finally, the concept of controlling AFT by SR is validated experimentally.

Present study involves characterisation and thermal analysis of rice husk as a potential source for gasification. Both the thermogravimetric (TG) analysis and differential scanning calorimetry were used to study the influence of heating rate on the degradation of rice husk. Experiments were carried out at three different heating rates of 10, 30, and 80 K min−1. The kinetic parameters, viz. pre-exponential factor, activation energy, and order of reaction were evaluated for both first and second reaction zones, which are categorized based on the degradation of cellulose, hemicelluloses, and lignin content present in the biomass. The degradation of mass with temperature obtained from TG curve was validated numerically. The thermal response of rice husk undergoing decomposition has also been modelled by using a one dimensional (1-D) transient thermal model with an nth order approximation for the rate of decomposition. Kinetic parameters, heat of decomposition, and thermal properties are taken as input to the model. The model was validated by measuring the transient temperature profiles during decomposition using Heisler chart at heat transfer coefficient of 20 W/m2 K. The data for specific heat and thermal conductivity of the biomass were taken from the literature and the values of heat of decomposition and kinetic parameters were taken from the experiments. Model results were compared well with the result obtained by using Heisler chart.

Biomass has great potential as a clean, renewable feedstock for producing modern energy carriers. Low density biomass, such as rice husk, sawdust, bamboo dust, etc., can provide a continuous supply of liquid and gaseous fuels through thermochemical conversion processes. In the present study, kinetics of the thermal decomposition of three biomasses such as rice husk, sawdust, and bamboo dust were evaluated under air atmosphere from ambient temperature to 1000 °C at a heating rate of 10 °C min−1. Two distinct reaction zones were observed for all the three biomasses. From the thermogravimetric (TG) and differential TG curves, the activation energies, pre-exponential factors, and order of reaction were determined for both the reaction zones. Experimental results were validated numerically and these results are found to be very close to the numerical results. As observed, thermal decomposition rates in the first reaction zone were found to be significantly higher than those in the second reaction zone.

Combustion of fossil fuels is one of the major sources of greenhouse gas (GHG) CO2, it is therefore necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of GHG. Removal of CO2 from flue gasses has become an effective way to mitigate the GHG and adsorption is considered to be one of the methods. Adsorption of CO2 on zeolite 13X, zeolite 4A and activated carbon (AC) have been investigated at a temperature ranging from 25 to 60 °C and pressure up to 1 bar. The experimental data were fitted with isotherm models like Langmuir and Freunlich isotherm model. The Langmuir model fit well with the two zeolites and Freunlich model fit well with AC. The thermodynamics parameters were calculated and found to be exothermic in natures for all three adsorbents. Moreover, regeneration studies have been conducted in order to verify the possibility of activated carbon reutilization, to determine its CO2 adsorption capacity within consecutive cycles of adsorption–desorption. Temperature swing adsorption was employed as the regeneration method through heating up to a temperature of approximately 100 °C. There is no full reversibility for zeolites while AC can achieve complete regenerations.

The Indian Government's National Biogas and Manure Management Programme (NBMMP) seeks to deliver renewable energy services to households across the country by facilitating the deployment of family-sized ( 3 ) anaerobic (biogas) digesters. NBMMP policy is implemented at three levels, from government and state nodal agency, via private contractors to households, creating multiple institutional arrangements. We analysed the scheme in Assam, north-east India, focusing on how policy was implemented across two districts and interviewing stakeholders in rural households, state and non-state institutions. The top-down, supply-side approach to policy enables government to set targets and require individual states to deploy the scheme, which benefits households who can afford to participate. NBMMP delivered improved energy service outcomes to a majority of households, although the level of knowledge and understanding of the technology amongst users was limited. Training and education of householders, and particularly women, is needed in relation to the maintenance of digesters, feedstock suitability and the environmental and potential livelihood benefits of digestate. A revised bottom-up approach to policy, which highlights the contextual and demand-side issues around adopting the technology, may deliver monetary benefits from market competition and enable development of community-focused microfinance schemes to improve the affordability of biogas systems.