Pali Rosha

Bio: Pali Rosha is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Biodiesel & Biogas. The author has an hindex of 9, co-authored 18 publications receiving 266 citations. Previous affiliations of Pali Rosha include Thapar University.

Waste materials as potential catalysts for biodiesel production: Current state and future scope

Abstract: Recent studies on the exploration of eco-friendly approach by utilizing large-scale waste materials as potential catalyst in biodiesel production have attracted much attention. The development of heterogeneous catalysts especially from calcium has gained much awareness due to the large availability of calcium-rich waste materials and their corresponding high catalytic activity in the transesterification of oil. Most of the waste materials employed as heterogeneous catalysts have an abundance of natural Ca content and they have high catalyst activity and selectivity despite being environment-friendly and cost-effective. Heterogeneous catalysts with high activity can be produced from Ca based waste materials when calcined at high temperatures. This review gives a brief overview of the developments of various Ca based catalysts derived from waste materials as an efficient catalyst for biodiesel production with significant yield. Industrial wastes (red mud, slag, ash) and biological catalysts (chicken eggshells, mollusk shells, animal bones) possess enormous potential towards developing an economical catalyst and subsequently, low-cost biodiesel generation. However, future challenges await a better utilization of useless wastes into a useful resource to satisfy human needs.

Effect of compression ratio on combustion, performance, and emission characteristics of compression ignition engine fueled with palm (B20) biodiesel blend

Abstract: Limited fossil fuel reserves led to focus on alternatives fuels for combustion engines. Several studies reported optimal (20%) biodiesel blend for utility in compression ignition engine at constant compression ratio. Literature lacks on the study of palm-based biodiesel in blended form at varying engine compression ratios. In this study, an initiative was undertaken to study the effect of variable compression ratio (16:1, 17:1 and 18:1) on various engine characteristics by fuelling 20% palm biodiesel blending compression ignition engine. The ignition delay period decreased, whereas the peak cylinder pressure and brake thermal efficiency increased with increase in the engine compression ratio from 16:1 to 18:1. At 3.5 bar bmep, brake thermal efficiency values were observed to be 28.9, 30.8 and 33.8% at 16:1, 17:1 and 18:1 CRs, respectively in B20 fuel. Moreover, increasing compression ratio from 16:1 to 18:1, the average reduction in emissions of hydrocarbon, carbon monoxide and smoke opacity were observed to be 47.8, 41.0 and 35.7%, respectively whereas, oxides of nitrogen emissions increased by 41.1%. Thus, it is inferred that B20 fuel performed well at high engine compression ratio.

Influence of gaseous fuel induction on the various engine characteristics of a dual fuel compression ignition engine: A review

Abstract: Currently, the unsustainable fossil fuels have been chiefly used for power generation in CI engines. From the standpoint of fossil fuels depletions and environmental concerns, it is imperative to hunt out alternative energy resources that could replace hydrocarbon fossil fuels in the existing engines. In this regards, enormous studies have focused on the utilization of renewable fuels along with conventional petroleum fuel in existing compression ignition (CI) engine. The induction of gaseous fuels under dual fuel mode have emanated as a potential energy carrier to address the environmental aspects related to CI engines. This review focussed to analyze the influence of gaseous fuels (like H2, biogas, syngas) addition to CI diesel engine under dual fuel mode with diesel/biodiesel as a pilot fuel. Various engine characteristics such as combustion, performance, and emission of the dual fuel CI engine using gaseous fuels as a secondary fuel were analyzed and compared with CI engine working under single fuel mode. Findings of some experimental studies have been presented in the form of graphs for selective important parameters as case studies. The overall impression from the review suggests that the performance of the dual fuel CI engine slightly deteriorates while enriching the gaseous fuel, but the improvement in environmental emissions have been reported. Furthermore, various approaches are discussed comprehensively in order to evaluate the performance of dual fuel CI engine along with a check on harmful emissions.

The role of hydropower energy in the level of CO2 emissions: An application of continuous wavelet transform

Abstract: The purpose of this paper is to investigate the association between hydroelectric energy consumption and CO2 emissions in the USA from 1980:1 to 2019:8 by using the wavelet transform model. This research revealed that (a) in the short runs (at higher frequencies), hydro energy uses intensified CO2 emissions for the periods 1990:01–1992:12, 1994:01–1994:12, and 2002:07–2007:11, and (b) during the longer periods (at lower frequencies), however, hydro energy consumption diminished CO2 emissions for the periods 1983:01–2001:12 and 2011:01–2017:03. The paper explained as well why hydro energy can yield adverse and affirmative contributions to Greenhouse gas emissions by emphasizing the role of energy generation from hydro plants in shorter runs and longer runs in the USA considering all sub-samples of the sample period 1980:1–2019:8. This research eventually suggests some energy policies to enhance the positive environmental influences of hydropower energy production in the USA.

Recent advances in biogas upgrading to value added products: A review

Abstract: It is undeniable that oil and gas explorations are going on at a frantic pace due to excessive fossil fuel usage across the world. This has compelled us to explore isolated or even uninhabited places to meet the surging demand for oil and gas. There is no doubt that scientists and researchers worldwide are exploring more renewable energy sources to produce value-added products. In the last few years, biogas' usage as a reactant gas in the catalytic reforming process has emanated as an energy carrier to produce energy-efficient products, i.e., syngas and methanol. This review aimed to analyze the research works focusing on the biogas DR reactions and methanol production from biogas. The findings of some experimental studies have been presented in the form of graphs for important selective parameters as case studies. The overall impression from the review suggests that the performance of the reforming catalysts deteriorates regarding different operating conditions. Still, the improvement in syngas production has been reported by neglecting the effect of H2S impurity. Furthermore, various parameters have been discussed paragraphically to evaluate the catalytic performance in biogas dry reforming reactions and a check on catalyst synthesis methods. After that, a few scattered studies have been discussed on methanol synthesis using biogas as a feedstock.

Review on transesterification of non-edible sources for biodiesel production with a focus on economic aspects, fuel properties and by-product applications

Abstract: Biodiesel has privileges than conventional diesel fuel because of its low toxicity, renewability, and eco-friendly properties. Biodiesel is produced from various edible and non-edible sources via transesterification process. Non-edible sources such as waste cooking oil (WCO), algal oil, non-edible vegetable oil, and waste animal oil are commonly used to produce biodiesel due to their low cost and no dependency on the food chain. The production process is influenced by several factors such as reaction temperature and time, alcohol to oil molar ratio, and catalyst type and concentration. The analyses of economic aspects of biodiesel production are crucial to reduce the cost of biodiesel production by finding alternatives to available technologies, catalyst, and feedstock. Moreover, the biodiesel production cost is affected by factors such as the type of raw material, by-product selling price, operation and labor cost, the catalyst, and the reaction type. Besides, crude glycerol is a major by-product of biodiesel production with yields ranging between 8% and 10%. Crude glycerol could be used as a beneficial material to produce biopolymers, hydrogen, ethanol, and fuel additive through pyrolysis and gasification processes. Therefore, this review focuses on the recent finding in transesterification of non-edible sources for biodiesel production as well as its economic aspects, fuel properties, and by-products applications. Finally, the economic aspects and process optimization of biodiesel production should be considered as important factors in order to enhance the economic sustainability of biodiesel production.

State of the Art of Catalysts for Biodiesel Production

Abstract: Biodiesel is one of the potential alternative energy sources that can be derived from renewable and low-grade origin through different processes. One of the processes is alcoholysis or transesterification in the presence of a suitable catalyst. The catalyst can be either homogeneous or heterogeneous. This article reviews various catalysts used for biodiesel production to date, presents the state of the art of types of catalysts and compares their suitability and associated challenges in the transesterification process. Biodiesel production using homogeneous and heterogeneous catalysis has been studied extensively and novel heterogeneous catalysts are being continuously investigated. Homogeneous catalysts are generally efficient in converting biodiesel with low free fatty acid (FFA) and water containing single-origin feedstock. Heterogeneous catalysts, on the other hand, provide superior activity, range of selectivity, good FFA and water adaptability. The quantity and strengths of active acid or basic sites control these properties. Some of the heterogeneous catalysts such as zirconia and zeolite-based catalysts can be used as both basic and acidic catalyst by suitable alteration. Heterogeneous catalysts from waste and biocatalysts play an essential role in attaining a sustainable alternative to traditional homogeneous catalysts for biodiesel production. Recently, high catalytic efficiency at mild operating conditions has drawn attention to nanocatalysts. This review evaluates the state of the art and perspectives for catalytic biodiesel production and assesses the critical operational variables that influence biodiesel production along with the technological solutions for sustainable implementation of the process.

A CFD model for biomass fast pyrolysis in fluidized-bed reactors

Abstract: In this work, an Euler–Euler multiphase CFD model is proposed for continuous fast pyrolysis of biomass in a fluidized-bed reactor. In the model, a lumped, multi-component, multi-stage kinetic model is applied to describe the pyrolysis of a biomass particle. Variable particle porosity is used to account for the evolution of the particle's physical properties. Biomass is modeled as a composite of three reference components: cellulose, hemicellulose, and lignin. Pyrolysis products are categorized into three groups: gas, tar vapor (bio-oil), and solid char. The particle kinetic processes and their interactions with the reactive gas phase are modeled with a multi-fluid description derived from the kinetic theory of granular flows. A time-splitting approach is applied to decouple the convection and reaction calculations using a synchronized time step. The CFD model is employed to study the fast pyrolysis of both cellulose and bagasse in a lab-scale fluidized-bed reactor. The dynamics, particle heating, reaction of the biomass phase, char formation, elutriation, and spatial distribution of tar and gas inside the reactor are investigated. The yields of tar, gas, and char are also discussed.

A review on low temperature combustion engines: Performance, combustion and emission characteristics

Abstract: Low temperature combustion (LTC) is a recent engine technology that can reduce the oxides of nitrogen (NOx) and soot emissions simultaneously while maintaining higher thermal efficiency. The present review work investigates the performance, emission and combustion characteristics of LTC mode engines. Partially premixed LTC (PPLTC), homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI) and reactivity controlled compression ignition (RCCI) modes are researched under LTC mode. In recent decades, different engine strategies have been employed to reduce exhaust emissions and to enhance thermal efficiency. Exhaust gas recirculation, variable valve timing (VVT), advanced fuel injection technologies are adapted to achieve LTC mode in internal combustion (IC) engines to get improved outcomes. This review highlights the properties of fuels, fuel supply systems, valve actuation mechanisms, engine operating conditions and its effects on the engine characteristics. This review provides a perspective plan to the researchers for enhancing the performance, emission and combustion behavior of an engine by using LTC mode with lower NOx and soot emissions. Among LTC mode engines, RCCI mode engine operates well in 60% load, 60% premixed ratio, 35:1 air-fuel ratio and 56% brake thermal efficiency within the combustion phasing control.

Performance and emission characteristics of diesel engine fueled with rice bran biodiesel and n-butanol

Abstract: Due to the depletion of petroleum products and fatal emissions from the tailpipe of diesel engines it has become a need to seek for the alternative of petroleum products for long-term use. Currently, researchers and experts have come to the conclusion that biodiesel along with higher alcohols can be an appropriate substitute for this situation. Former investigations have presented that biodiesel and higher alcohol can help in improving the performance and depreciating harmful exhaust gases in a diesel engine. In the current investigation blends of diesel, rice bran biodiesel and n-butanol were prepared to check its effect on performance and emission characteristics of a diesel engine. Biodiesel was prepared by single stage alkaline transesterification process in this study and after that blends of diesel–biodiesel and diesel–biodiesel-n butanol were prepared as B10, B20, B10 nb10 and B20 nb20. Then these blends were tested in a single cylinder, small utility diesel engine with a rated power output of 3.73 kW to compare them with baseline diesel. Experimental investigation demonstrates that blends of rice bran biodiesel and n-butanol can be used as a fuel in a diesel engine without any change in the engine.