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Publications 1

A review on utilisation of biomass from rice industry as a source of renewable energy

Volatile oil price and growing emphasis on environmental conservation have stimulated the development and utilisation of biomass as a vital source of renewable energy. In reducing the global dependency on fossil fuels, rice husk and rice straw which are the widely abundant agricultural wastes from the rice industry have a vital role to play. This paper reviews the key aspects of the utilisation of rice husk and rice straw as important sources of renewable energy. The paper provides some essential background information that includes the physical and chemical characteristics that dictates the quality of these rice biomasses. This paper also describes the various chemical and physical pretreatment techniques that can facilitate handling and transportation of rice straw and husk. Finally, the paper presents the state-of-the-art on thermo-chemical and bio-chemical technologies to convert rice husk and rice straw into energy.

Keywords: Rice straw, Rice straw, Biomass, Pretreatment, Thermo-chemical, Bio-chemical, Energy conversion

Publications 2

A comprehensive review of solid particle erosion modeling for oil and gas wells and pipelines applications

Sand is commonly produced along with production fluids (oil and gas), and this is a major problem for the oil and gas industry. Amid them, three problems stand out above all: pressure drop, pipe blockage, and erosion. The latter is a complex mechanical process in which material is removed from the pipeline due to repeated sand particle impacts. As a result, the pipeline can be eroded. Eroded pipelines may cause pipe failures which can result in financial losses and environmental issues. Therefore, it is important to know what parameters govern the erosion phenomenon and how it can be modeled. The present work describes key factors influencing erosion and reviews available erosion equations. Computational fluid dynamics (CFD) based erosion modeling as a comprehensive method for erosion studying is explained as well.

Keywords: Erosion equation, Sand particle erosion, Multiphase flow, Single-phase flow, CFD-based erosion modeling

Publications 3

Targeting the minimum water flow rate using water cascade analysis technique

This work presents the water cascade analysis (WCA) as a new technique to establish the minimum water and wastewater targets for continuous water‐using processes. The WCA is a numerical alternative to the graphical water targeting technique known as the water surplus diagram. The WCA is to the water surplus diagram in water pinch analysis (WPA) as problem table analysis (PTA) is to the grand composite curves in heat pinch analysis. By eliminating the tedious iterative steps of the water surplus diagram, the WCA can quickly yield accurate minimum water targets, pinch point locations, and water allocation targets for a maximum water recovery (MWR) network, thereby offering a key complementary role to the water surplus diagram in the synthesis of water network. As in the case of the water surplus diagram, the WCA is not limited to mass‐transfer–based operations and is applicable to a wide range of water‐using operations. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3169–3183, 2004

Publications 1

A review on utilisation of biomass from rice industry as a source of renewable energy

Volatile oil price and growing emphasis on environmental conservation have stimulated the development and utilisation of biomass as a vital source of renewable energy. In reducing the global dependency on fossil fuels, rice husk and rice straw which are the widely abundant agricultural wastes from the rice industry have a vital role to play. This paper reviews the key aspects of the utilisation of rice husk and rice straw as important sources of renewable energy. The paper provides some essential background information that includes the physical and chemical characteristics that dictates the quality of these rice biomasses. This paper also describes the various chemical and physical pretreatment techniques that can facilitate handling and transportation of rice straw and husk. Finally, the paper presents the state-of-the-art on thermo-chemical and bio-chemical technologies to convert rice husk and rice straw into energy.

Keywords: Rice straw, Rice straw, Biomass, Pretreatment, Thermo-chemical, Bio-chemical, Energy conversion

Publications 5

Synthesis of maximum water recovery network for batch process systems

Development of maximum water recovery (MWR) networks for continuous processes based on Pinch Analysis has been rather well established. In contrast, less work has been done on the water minimisation problem for batch process systems. This work presents a two-stage procedure for the synthesis of an MWR network for a batch process system, covering both mass transfer-based and non-mass transfer-based water-using processes. The first stage of the synthesis task is to locate the various network targets, which include the overall and interval-based minimum utility targets (fresh water and wastewater flows) as well as storage capacity target using the newly developed time-dependent water cascade analysis (WCA) technique.

Keywords: Water minimisation, Pinch analysis, Batch process systems, Utility targeting, Network design

Publications 6

Surplus diagram and cascade analysis technique for targeting property-based material reuse network

Recycle of process and waste streams are among the most effective resource conservation and waste reduction strategies. In many cases, recycle/reuse is dictated by sink constraints on properties of the recycled streams. In this work, we introduce an algebraic technique to establish rigorous targets on the minimum usage of fresh resources, maximum direct reuse, and minimum waste discharge for property-based material reuse network. Two new tools have been developed. A new graphical tool called the property surplus diagram is firstly introduced to provide a basic framework for determining rigorous targets for minimum fresh usage, maximum recycle, and minimum waste discharge. The tools also determine the property-based material recycle pinch location.

Keywords: Property integration, Process integration, Pinch analysis, Resource recovery, Material surplus, Cascade analysis

Publications 7

A process integration targeting method for hybrid power systems

Pinch Analysis is a well-established methodology of Process Integration for designing optimal networks for recovery and conservation of resources such as heat, mass, water, carbon, gas, properties and solid materials for more than four decades. However its application to power systems analysis still needs development. This paper extends the Pinch Analysis concept used in Process Integration to determine the minimum electricity targets for systems comprising hybrid renewable energy sources. PoPA (Power Pinch Analysis) tools described in this paper include graphical techniques to determine the minimum target for outsourced electricity and the amount of excess electricity for storage during start up and normal operations. The PoPA tools can be used by energy managers, electrical and power engineers and decision makers involved in the design of hybrid power systems.

Keywords: PoPA (Power pinch analysis), Process integration, Hybrid systems, Renewable energy, Minimum outsourced electricity supply, Minimum electricity targets

Publications 8

Optimal planning of renewable energy-integrated electricity generation schemes with CO2 reduction target

This paper presents a Mixed Integer Linear Programming (MILP) model that was developed for the optimal planning of electricity generation schemes for a nation to meet a specified CO2 emission target. The model was developed and implemented in General Algebraic Modeling System (GAMS) for the fleet of electricity generation in Peninsular Malaysia. In order to reduce the CO2 emissions by 50% from current CO2 emission level, the optimizer selected a scheme which includes Integrated Gasification Combined Cycle (IGCC), Natural Gas Combined Cycle (NGCC), nuclear and biomass from landfill gas and palm oil residues. It was predicted that Malaysia has potential to generate up to nine percent of electricity from renewable energy (RE) based on the available sources of RE in Malaysia.

Keywords: GAMS, Solar PV, Nuclear, Renewable energy ,Electricity generation, MILP

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Publications 9

Industrial implementation issues of Total Site Heat Integration

Heat Integration has been a well-established energy conservation strategy in the industry. Total Site Heat Integration (TSHI) has received growing interest since its inception in the 90s. The methodology has been used with certain simplifications to solve TSHI problems. This paper investigates the main issues that can influence the practical implementation of TSHI in the industry. The main aim is to provide an assessment and possible guidance for future development and extension of the TSHI methodology from the industrial perspective. Several key issues have been identified as being of vital importance for the industries: design, operation, reliability/ availability/ maintenance, regulatory/policy and economics. Design issues to consider include plant layout, pressure drop, etc. For operation, issues such as startup and shutdown need to be considered. Reliability, availability and maintenance (RAM) are important as they directly affect the production. Relevant government policy and incentives are also important when considering the options for TSHI. Finally, a TSHI system needs to be economically viable. This paper highlights the key issues to be considered for a successful implementation of TSHI.

Keywords: Total Site Heat Integration, Key issues, Industrial implementation, Minimum energy targets, Design

Publications 10

CO2 capture with potassium carbonate solutions: A state-of-the-art review

The potassium carbonate (PC) solution is an important chemical solvent to reduce CO2 emissions due to its advantages of low cost, little toxicity, ease of regeneration, slow corrosiveness, low degradation, and its high stability as well as CO2 absorption capacity. As a result, the PC process has been applied in more than 700 plants worldwide for CO2 and hydrogen sulphide removal from streams like ammonia synthesis gas, crude hydrogen, natural gas, and town gas. This paper provides a state-of-the-art review on the research works on CO2 capture using the PC solution. The studies related to the PC solution comprise three main areas: process, thermodynamics, and kinetics. Important experimental studies as well as modeling and simulation studies are reviewed. Future research directions on CO2 absorption by aqueous PC solution are highlighted and discussed.

Keywords: CO2 capture, Chemical absorption, Experimental studies, Modeling and simulation studies, Potassium carbonate solution, Pilot plantReview

Publications 11

Experimental study of Al2O3/water nanofluid turbulent heat transfer enhancement in the horizontal double pipes fitted with modified twisted tapes

In this study, fluid flow of the Al2O3 nanofluid in a horizontal double pipe heat exchanger fitted with modified twisted tapes were experimentally studied under turbulent flow conditions. The experiments with different geometrical progression ratio (GPR) of twists as the new modified twisted tapes and different nanofluid concentration were performed under similar operation condition. Pitch length of the proposed twisted tapes and consequently the twist ratios changed along the twists with respect to the geometrical progression ratio (GPR) whether reducer (RGPR < 1) or increaser (IGPR > 1). Regarding the experimental data, utilization of RGPR twists together with nanofluids tends to increase heat transfer and friction factor by 12% to 52% and 5% to 28% as compared with the tube with typical twisted tapes (GPR = 1) and nanofluid. Contrarily, performances were weakened by using for IGPR twists 0.6 to 0.92 and 0.75 to 0.95. The thermal performances of the heat exchanger with nanofluid and modified twisted tapes were evaluated for the assessment of overall improvement in thermal behavior.

Keywords: Nanofluid, Heat exchanger, Twisted tape, Heat transfer enhancement

Publications 12

STEP—A new graphical tool for simultaneous targeting and design of a heat exchanger network

For 40 years, composite curves (CCs) and grid diagram (GD) have been among the most popular graphical tools for designing optimal heat exchanger networks (HEN). However, since CCs represent the temperature versus enthalpy plot of composites rather than individual streams, they have some significant limitations. Among others, CCs cannot completely map individual hot and cold process streams, as well as process and utility streams, and cannot be used for HEN design. In addition, CCs cannot be conveniently and effectively used to predict minimum network area and the optimum ΔTmin that should strictly be based on parameters and properties of individual as opposed to composite streams. Grid diagram on the other hand requires designers to provide or calculate stream temperatures as well as enthalpies, to do heat balance and to check temperature feasibility during HEN design as the diagram does not follow any temperature or enthalpy scale.

Keywords: Pinch analysis, Stream Temperature versus Enthalpy Plot (STEP), Heat exchanger network (HEN) design, Targeting, Heat recovery, Maximum heat allocation (MHA)

Publications 13

A new technique for simultaneous water and energy minimisation in process plant

This paper presents a new technique for simultaneous minimisation of water and energy in process plants through a combination of numerical and graphical tools. The technique consists of three steps, namely, setting the minimum water and wastewater targets; design of minimum water utilisation network, and finally, heat recovery network design. This technique offers two key advantages over current state-of-the art techniques. Firstly, it is applicable to mass transfer based and non-mass transfer based water-using operations. Secondly, it introduces a new graphical visualisation tool through a plot of temperature versus stream flowrate, termed as heat surplus diagram to guide water and energy reduction simultaneously. The heat surplus diagram provide insights on the energy demand as well as on stream matching scenarios during design of a maximum water and energy recovery network. A case study on a paper mill plant demonstrates that significant reductions in water and energy consumption can be achieved using this approach.

Keywords: Water minimisation, Energy minimisation, Pinch analysis, Process integration, Heat surplus diagram, Heuristics

Publications 9

A numerical technique for Total Site sensitivity analysis

Total Site Heat Integration (TSHI) is a methodology for the integration of heat recovery among multiple processes and/or plants interconnected by common utilities on a site. Until now, it has not been used to analyze a site’s overall sensitivity to plant maintenance shutdown and production changes. This feature is vital for allowing engineers to assess the sensitivity of a whole site with respect to operational changes, to determine the optimum utility generation system size, to assess the need for backup piping, to estimate the amount of external utilities that must be bought and stored, and to assess the impact of sensitivity changes on a cogeneration system. This study presents four new contributions: (1) Total Site Sensitivity Table (TSST), a tool for exploring the effects of plant shutdown or production changes on heat distribution and utility generation systems over a Total Site; (2) a new numerical tool for TSHI, the Total Site Problem Table Algorithm (TS-PTA), which extends the well-established Problem Table Algorithm (PTA) to Total Site analysis; (3) a simple new method for calculating multiple utility levels in both the PTA and TS-PTA; and (4) the Total Site Utility Distribution (TSUD) table, which can be used to design a Total Site utility distribution network. These key contributions are clearly highlighted via the application of the numerical technique to two Case studies.

Keywords: Total site problem table algorithm (TS-PTA), Total Site, Heat cascade, Numerical approach, Site minimum utility targets, Process integration

Publications 15

Total Site Heat Integration planning and design for industrial, urban and renewable systems

There has been growing interest in developing Locally Integrated Energy Sectors (LIES) as a Process (Heat) Integration approach for synergising the industrial thermal energy systems that include renewable energy resources with urban (i.e. civic, residential, business and service complexes). The aim is to enhance the regional energy efficiency and minimise greenhouse gas (including carbon) emissions. However, a comprehensive planning and design framework is crucial at the onset of its development, which is accounting for supply and demand sides, but there have been limited works directed to this scope to date. For the development of such framework, this paper reviews the energy consumption targeting methodologies via Total Site Heat Integration for estimating and designing the capacity of the utility have been reviewed in this work, inclusive of both insight-based Pinch Analysis and mathematical modelling approaches. As a final outcome of the review, suggestions are provided for investigating key factors for integration of industrial, residential, commercial, institutional and service energy systems, maximising the integration and reuse of waste and low potential heat, including renewables to boost sustainability aspects.

Keywords: Total Site Heat Integration, Locally Integrated Energy Sectors, Industrial, Urban and renewable energy systems, Process Integration

Publications 16

Water pinch analysis for an urban system: a case study on the Sultan Ismail Mosque at the Universiti Teknologi Malaysia (UTM)

This paper describes how the water cascade analysis (WCA) technique, based on the pinch analysis concept, was adapted to establish the minimum water targets for the Sultan Ismail Mosque at the Universiti Teknologi Malaysia. The WCA is a numerical alternative to the graphical water targeting technique known as a water surplus diagram. Two cases were analysed using WCA to predict potential savings with reuse as well as with reuse and regeneration. The results were compared with the savings predicted via a conventional water management solution. The conventional system predicted reductions of 25% fresh water and 19.8% wastewater. The WCA technique predicted savings of 65.1% fresh water and 51.5% wastewater with reuse only, and up to 85.5% fresh water and 67.7% wastewater with reuse and regeneration. The WCA technique based on the pinch analysis concept can rapidly yield accurate minimum water targets, pinch-point locations and water allocation targets for an urban water network.

Keywords: Pinch analysis, Minimum water targets, Urban system, Water cascade analysis, Regeneration

Publications 17

Potential of biogas production from farm animal waste in Malaysia

Anaerobic digestion of renewable feedstocks has been known as a prospective technology for the production of clean energy in the form of biogas. Biogas is a sustainable energy carrier which is mainly composed of methane (60%) and carbon dioxide (35–40%). Among the raw substances, organic matters obtained from farm animal waste are pivotal sources for biogas production. In recent years, the number of animal husbandry has drastically grown in Malaysia. Accordingly, a large amount of animal waste including manure, blood and rumen content are produced which provide a tremendous source of biogas generation. This paper presents biogas potential from the organic waste obtained from the farm animals and slaughterhouses in Malaysia. The findings of this study indicated that biogas potential of 4589.49 million m3 year−1 could be produced from animal waste in Malaysia in 2012 which could provide an electricity generation of 8.27×109 kWh year−1.

Keywords: Biogas production, Anaerobic digestion, Farm animal waste, Renewable energy

Publications 18

Review of distributed generation (DG) system planning and optimisation techniques: Comparison of numerical and mathematical modelling methods

An overview of numerical and mathematical modelling-based distributed generation (DG) system optimisation techniques is presented in this review paper. The objective is to compare different aspects of these two broad classes of DG optimisation techniques, explore their applications, and identify potential research directions from reviewed studies. Introductory descriptions of general electrical power system and DG system are first provided, followed by reviews on renewable resource assessment, load demand analysis, model formulation, and optimisation techniques. In renewable resource assessment model review, uncertain solar and wind energy resources are emphasised whereas applications of forecasting models have been highlighted based on their prediction horizons, computational power requirement, and training data intensity.

Keywords: Distributed generation (DG), Energy planning, Renewable resources, Numerical methods, Mathematical modelling methods, Optimisation

Publications 19

Optimal process network for municipal solid waste management in Iskandar Malaysia

Ineffective management of municipal solid waste (MSW) may cause degradation of valuable land resources and create long-term environmental and human health problems. A sustainable and efficient waste management strategy is needed to balance the need for development, the quality of human life and the environment. This study aims to synthesis a MSW processing network to produce energy and value-added products for achieving economic and environmental competitiveness. An optimisation model that integrates four major utilisation technologies was incorporated to facilitate a cost-effective processing network. The model is able to predict the best mix of waste treatment technologies, forecast the production of by-product from waste treatment process, estimate the facility capacity, forecast the greenhouse gas (GHG) emission of the system, and eventually generate an optimal cost-effective solution for municipal solid waste management (MSWM).

Keywords: Municipal solid waste (MSW), Resource processing network, Waste treatment technologies, Optimisation, Mixed integer linear programming (MILP)

Publications 20

Energy and emissions benefits of renewable energy derived from municipal solid waste: Analysis of a low carbon scenario in Malaysia

Ineffective waste management that involves dumping of waste in landfills may degrade valuable land resources and emit methane gas (CH4), a more potent greenhouse gas than carbon dioxide (CO2). The incineration of waste also emits polluted chemicals such as dioxin and particle. Therefore, from a solid waste management perspective, both landfilling and incineration practices pose challenges to the development of a green and sustainable future. Waste-to-energy (WtE) has become a promising strategy catering to these issues because the utilisation of waste reduces the amount of landfilled waste (overcoming land resource issues) while increasing renewable energy production. The goal of this paper is to evaluate the energy and carbon reduction potential in Malaysia for various WtE strategies for municipal solid waste (MSW). The material properties of the MSW, its energy conversion potential and subsequent greenhouse gases (GHG) emissions are analysed based on the chemical compositions and biogenic carbon fractions of the waste.

Keywords: Waste-to-energy (WtE), Landfill, Incineration, Municipal solid waste (MSW), Carbon emission reduction

Publications 21

Review on the renewable energy and solid waste management policies towards biogas development in Malaysia

The development of renewable energy is of paramount importance towards the energy security and environment integrity of Malaysia. The Malaysia government has been implementing various policies that could facilitate the advancement of renewable energy technology and increase its contribution to the national energy mix to reduce the country dependency on fossil fuels. On the other hand, due to rapid urbanization and population growth, there is also increasing concern over the high production rate of organic waste. Among the renewable energy available, biogas is of great interest due to its ability to treat organic waste and generate power addressing both concerns simultaneously. This paper aims to review some of the important policies on renewable energy followed by the emphasis on solid waste management policies towards effective implementation of biogas generation from municipal solid waste. The biogas network is divided into three phases on a life cycle basis, namely MSW as feedstock, biogas production and biogas utilization. Under each phase, several important stages were identified. Analysis was performed to identify the role of currently implemented policies as well as the lacking support and challenges.

Keywords: Renewable Energy Policies, Malaysia, Biogas, Solid Waste Management, RE incentives, Case studies

Publications 22

Optimal scheduling of energy storage for renewable energy distributed energy generation system

Energy storage (ES) is an important device to ensure operation stability and efficiency of a renewable energy based distributed energy generation (DEG) system. As such, many researchers have modelled the operation (scheduling) of energy storage in a DEG system, where it is mostly portrayed to operate on a daily cycle. In this paper, an analysis of the operation mode of energy storage is presented. Two modes of operation are defined, daily mode (DM) (ES operates in daily cycles) and weekly mode (WM) (ES operates in weekly cycles) which are modelled accordingly. This paper then attempts to analyse and compare between both modes in term of operation and cost. The analysis is performed through a mixed integer linear programming (MILP) model programmed via the General Algebraic Modelling System (GAMS). In general, with high capital cost of ES, it is advisable to program the ES to operate in a DM. The reason to this conclusion is mainly due to three factors, intermittency of renewable resources, varying weather conditions, and discharge rate of ES(s).

Keywords: Energy storage, Optimization, Renewable energy, Sustainability, Scheduling

Publications 20

A retrofit framework for Total Site heat recovery systems

Heat Pinch Analysis retrofit projects are typically performed by evaluating and maximising the heat recovery potentials within the individual process units. Once the potential improvements from the individual units have been assessed, the Total Site (TS) Heat Integration analysis is performed. Such approach may steer designers away from the promising retrofit opportunities and to lead towards suboptimal heat exchanger networks (HEN). This paper presents an effective retrofit framework for a TS system to determine the most cost-effective retrofit options and maximise the potential savings. Instead of performing the typical unit-wise process retrofit, the strategy is to determine the baseline total site consumption and benchmark targets, and to identify retrofit options from the TS context. This TS retrofit framework has been tested on a case study involving a petrochemical plant comprising of multiple process sections. The results of the analysis show that significant energy savings can be realised when both direct and indirect heat recovery retrofit options are evaluated. Further energy savings can be achieved via the Plus–Minus Principle that helps pinpoint the correct locations of heat surpluses and deficits and lead to the appropriate TS retrofit solution. As a conclusion, energy retrofit projects should be approached from the TS context, followed by the unit-wise retrofit (i.e., retrofit of the individual process sections).

Keywords: Pinch Analysis, Retrofit, Total Site, Heat Integration, Energy conservation

Publications 24

Waste Management Pinch Analysis (WAMPA): Application of Pinch Analysis for greenhouse gas (GHG) emission reduction in municipal solid waste management

Improper waste management happened in most of the developing country where inadequate disposal of waste in landfill is commonly practiced. Apart from disposal, MSW can turn into valuable product through recycling, energy recovery, and biological recovery action as suggested in the hierarchy of waste management. This study presents a method known as Waste Management Pinch Analysis (WAMPA) to examine the implication of a dual-objective – landfill and GHG emission reduction target in sustainable waste management. WAMPA is capable to identify the capacity of each waste processing strategy through graphical representation. A general methodology of WAMPA is presented through a demonstration of a SWM case followed by a detailed representation of WAMPA for five waste types. Application of the WAMPA is then applied on a case study for sustainable waste management planning from year 2015 to 2035. Three waste management strategies are incorporated into the case study – landfill, Waste-to-Energy (WtE), and reduce, reuse, and recycle (3R).

Keywords: GHG emission, Pinch Analysis (PA), Solid waste management (SWM), Waste-to-Energy (WtE), Reduce, reuse, and recycle (3R)

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