Linsha Ma

Renewable energy desalination is gaining much attention in remote off-grid communities facing challenges in accessing clean water. Typically, batteries ensure the continuous operation of small-scale renewable reverse osmosis (RO) desalination systems; however, they are expensive and have relatively shorter lifespans. This study investigates the imp...

The aim of the study was to investigate the impact of adding kaolin on the partitioning of chemical elements in the particulate matter (PM) when virgin and waste woody biomass fuels were fired in a 250 kW grate boiler. A comprehensive analysis of the chemical compositions of the PM has been conducted, including alkali and non-volatile species, size...

Concentrated solar power (CSP) has gained traction for generating electricity at high capacity and meeting base-load energy demands in the energy mix market in a cost-effective manner. The linear Fresnel reflector (LFR) is valued for its cost-effectiveness, reduced capital and operational expenses, and limited land impact compared to alternatives s...

Due to their outstanding structural, transport and electrical characteristics, nickel foams serve as excellent candidate materials for gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs). In this work, a new three-dimensional PEFC model was developed to explore the local and global fuel cell performance with nickel foam-based GDLs...

Particle size distribution in pre-treated organic substrates significantly impacts microbial fermentation efficiency, with smaller particles offering greater specific surface area, potentially reducing retention times and operational costs, particularly beneficial for remote and urban areas. Laboratory tests compared manual chopping, shredding, gri...

Dear Colleagues, I am guest-editting a special issue for MPDI-Energies with Prof Lin Ma and Prof Hao Zhou. It is an open-acess journal with IF 3.2. The submission deadline has been extended to 31/December/2023. Any topic in solid fuel conversion technologies is highly welcomed. More details, Please see the link below: https://www.mdpi.com/journal/e...

This study aims to experimentally evaluate the impact of a double-sided microporous layer coating on gas diffusion layers in terms of their key properties and fuel cell performance, in comparison to conventional single-sided coated gas diffusion layers (GDLs). Vulcan black and Ketjenblack were used as the carbon black materials. This was to investi...

When undertaking wind assessment around buildings using large eddy simulation (LES), the implementation of the integral length scale at the inlet for inflow generation is controversial, as real atmospheric length scales require huge computational domains. While length scales significantly influence inflow generation in the domain, their effect on t...

The farming sector like any other industry needs to be decarbonized. Hence, it is essential to meet the energy demands of the farms by adopting energy systems with a low-carbon footprint. Depending on the weather conditions, heating or cooling is needed. Within this context, this study presents a new hybrid renewable decentralized energy system tha...

Nickel foams feature superior structural and transport characteristics and are therefore strong candidates to be used as gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs). In this work, the impact of compression on the key structural and transport properties has been investigated, including employing a specially designed compres...

A new three-dimensional numerical model of a polymer electrolyte fuel cell (PEFC) with a single straight channel was developed to primarily investigate the important impact of the double-sided microporous layer (MPL) coating on the overall performance of the fuel cell and the distribution of the current and the oxygen concentration within the catho...

Researchers, power companies, and state politicians have given concentrated solar power (CSP) much attention for its capacity to generate large amounts of electricity whereas overcoming the intermittent nature of solar resources. Among all CSP technological types, the linear Fresnel reflector is well known for cost reduction, low land use factor, a...

Purpose This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell. Design/methodology/approach A comprehensive three-dimensional polymer electrolyte membrane fuel cell model has been developed, and a set of conservation equations has been solved. The flow is assumed to be steady, f...

A new three-dimensional numerical model of a polymer electrolyte fuel cell (PEFC) with a single straight channel has been developed to primarily investigate the important impact of the double-sided microporous layer (MPL) coating on the overall performance of the fuel cell and the distribution of the current and the oxygen concentration within the...

The present study proposes a novel hybrid blade design that is the combination of a conventional airfoil, namely the NACA0018, and its J-shaped profile to increase the torque generation at the start-up stage of the turbine while decreasing the potential efficiency loss at the high tip speed ratios. Therefore, a new 2D-based design methodology was p...

Rotating packed bed (RPB) technology shows great potential for post-combustion capture. However, the capture process inside the full RPB is difficult to simulate, due to the complexity of the process and the neglect of the CO2 capture in the outer cavity zone. In this paper, a full 3D CFD model, including the packing and the inner and outer cavity...

The Vertical Axis Wind Turbines (VAWTs) have an increasing global market and this emphasis the need for to improve the performance of VAWTs, especially at relatively low wind speed. This paper utilises the Response Surface methodology to optimise the performance of a VAWT. A three bladed VAWT configuration was considered with a NACA0015 profile. Th...

Proton exchange membrane fuel cells (PEMFC) are a viable means to meet global energy demand, reduce dependence on fossil fuels, and mitigate carbon dioxide emissions. Despite recent progress in their development, water saturation remains a challenge to current PEMFC design and efficiency. The addition of a microporous layer improves fuel cell perfo...

This paper reviews some of these new innovations in both the macroporous substrate and the microporous layer (MPL). A diverse range of macroporous substrates and designs is shown, encompassing various carbon-based and metal-based materials and innovative fabrication methodologies. A critical assessment of innovative MPL materials and designs for pe...

Nickel foams are excellent candidate materials for gas diffusion layers (GDLs) for polymer electrolyte fuel cells (PEFCs) and this is due to their superior structural and transport properties. A highly computationally-efficient framework has been developed to not only estimate the key structural and mass transport properties but also to examine the...

Purpose This paper aims to numerically investigate the impact of gas diffusion layer (GDL) anisotropic transport properties on the overall and local performance of polymer electrolyte fuel cells (PEFCs). Design/methodology/approach A three-dimensional numerical model of a polymer electrolyte fuel cell with a single straight channel has been develo...

The main objective of the current work is to assess the hybridization of a solar power tower's solar field with wind turbines and the potential of this integration to compensate the energy losses caused by aerosols attenuation of the reflected irradiance. The combined solar power tower and wind turbines configurations are assessed over the range of...

The use of a fully renewable energy system (RES) to power mid- and low-scale off-grid systems is an attractive alternative solution to replace fossil fuel technologies in order to meet the ever-growing demand and tackle environmental problems. In this study, the design optimization of a hybrid solar biogas, Organic Rankine Cycle (ORC-Toluene) and A...

The use of a fully renewable energy system (RES) to power mid-and low-scale off-grid systems is an attractive alternative solution to replace fossil fuel technologies in order to meet the ever-growing demand and tackle environmental problems. In this study, the design optimization of a hybrid solar biogas, Organic Rankine Cycle (ORC-Toluene) and Ai...

This work evaluates the Solar Power Tower performance in arid regions where elevated aerosols levels and water scarcity threaten solar applications feasibility. The work conducts an aerosols aware modelling and techno-economic assessment by considering possible aerosols effects on the solar field’s reflected irradiance; an effect that is typically...

Two dynamic models have been built for air-breathing and conventional polymer electrolyte fuel cells (PEFCs) in order to comparatively investigate the impacts of some key parameters on the transient response to load alterations and the steady-state performance for each fuel cell type. It was found that with load alterations, the dynamic response of...

In this paper, a novel layout of concentrating solar power linked in series with anaerobic digestion is presented to power an Organic Rankine cycle (ORC-Toluene) and Air Gap Membrane Distillation (AGMD) for desalination and electric power generation. The novelty emerges from some facts which are centralized around the use of a hybrid electric gener...

Although the J-shaped aerofoil is a possible solution to enhance the torque generation at the low tip speed ratios, the effect of the J-shaped aerofoil on the overall and the dynamic start-up performances of the H-type VAWT has not been extensively studied. Therefore, for the first time, the present study is aimed at exploring the impact of the J-s...

This study explores the opportunities in deploying split Stirling and combined Stirling and organic Rankine cycle (ORC) in circuit charging and load following dispatch modes, respectively as the back-up of a hybrid renewable energy system. The optimal number of system components in each dispatch mode that simultaneously minimises the loss of power...

Two mathematical models have been built for air-breathing and conventional polymer electrolyte fuel cells to explore the reasons affecting the cell performance. A parametric study has been conducted to (i) investigate how each type of fuel cells responds to changes in some key parameters and (ii) consequently obtain some insights on how to improve...

In this study, rule-based energy management strategies (EMS) based on the modifications of the traditional load following (LF) and circuit charging (CC) have been proposed and developed to effectively coordinate the operation of an integrated multi-carrier hybrid energy system. The proposed EMS aim to overcome some of the challenges of the traditio...

A new integrated hybrid solar thermal and wind-based microgrid power system is proposed. It consists of a concentrated parabolic solar dish Stirling engine, a wind turbine, and a battery bank. The electrical power curtailment is diminished, and the levelised cost of energy is significantly reduced. To achieve these goals, the present study conducts...

Liquid dispersion is very important for the modelling of liquid flow in a rotating packed bed (RPB) when an Eulerian porous medium approach is employed. For investigating the effect of the liquid dispersion in a practical RPB, a 3D Eulerian porous medium model has been established coupled with the appropriate interfacial, drag and dispersion forces...

The Concentrating Solar Power - Parabolic Trough (CSP-PT) technology with dry-cooled condenser system is an alternative option for arid climate locations such as Kuwait. In this work, the performance of various CSP-PT design configurations is evaluated, including 19 configurations that have been reported in the literature as being optimal. These ha...

The increasing interest in renewable microgrids have motivated the exploration of more sustainable alternatives to traditional energy supply. In this study, a novel hybrid renewable energy-based microgrid power system is proposed, designed and techno-economically assessed. The system consists of a concentrated parabolic solar dish Stirling engine a...

The aerodynamic shapes of the blades are still of high importance and various aerodynamic designs have been developed in order to increase the amount of energy production. In this study, a swept horizontal axis wind turbine blade has been optimized to increase the aerodynamic efficiency using the Computational Fluid Dynamics method. To illustrate t...

Prediction models for renewable energy sources are frequently used to manage stand-alone micro grid systems. Such prediction models are important due to the high cost or even the unavailability of real-world data in many regions. Herein, a new technique based on the Feed-forward Back-propagation Artificial Neural Network (FBANN) model has been deve...

Ground source heat pumps (GSHPs) are considered to provide very efficient air conditioning systems, and this assists in achieving sustainability goals as well as reducing electricity consumption and carbon emissions. The design of such systems, however, depends on the climatic conditions and the geological characteristics of the site; in practice,...

The concentration of an aqueous solution of amine affects the solvent regeneration energy requirement in the Post-combustion CO2 Capture (PCC) process. Therefore, this study investigates the performance of the impact of Selective Exhaust Gas Recirculation (S-EGR) under the influence of 40 wt(%) MEA i.e. 10 % above the benchmark Monoethanolamine (ME...

The compressibility, the gas permeability and the thermal stability of 4 commercially available uncoated GDLs (or carbon substrates) and MPL-coated GDLs are, with/without Teflon and silicone sealing gaskets, investigated before and after performing ex-situ compression tests mimicking the compressive stresses within the fuel cell. The results show t...

The rapid expansion of renewable energy technologies in the electricity sector introduces new significant challenges for power systems due to their high intermittency. Therefore, more flexibility is needed to ensure that the system can operate reliably and cost-effectively with large shares of variable renewable energy sources (RES). Electricity en...

A dynamic model for an air-breathing PEFC has been built to investigate the transient response of the fuel cell to load changes. The sensitivities of the dynamic response, as well as the steady state performance, to: the ambient temperature and relative humidity; the thickness and the thermal conductivity of the cathode GDL; and the fuel utilisatio...

Computational Fluid Dynamics (CFD) simulations are currently one of the most popular methods for the modelling of a Vertical Axis Wind Turbine (VAWT) that gives good insight on the turbine aerodynamics. The current study provides an assessment of the quality of the 2D and 3D CFD predictions of two highly recommended models in the literature, namely...

The design optimisation of a hybrid Stirling-organic Rankine cycle driven micro-CCHP utilising biomass fuel and exhaust waste heat to produce power, cooling and heating is presented. Four objectives have been formulated from thermodynamic and economic points of view to optimise the design of the system including the energy utilisation efficiency, e...

In this work, a concentrated parabolic solar dish Stirling engine (CPSD-SE) and a horizontal axis wind turbine (HWT) are integrated to generate power for a low to medium scale microgrid application. The predicted power that is generated by the system is in the range 100kWe and 1500kWe and the system performance across one year has been investigated...

In a hot and dry country such as Saudi Arabia, air-conditioning systems consume seventy per cent of the electrical energy. In order to reduce this demand, conventional air -conditioning technology should be replaced by more efficient renewable energy systems. These should be compared to the current standard systems which use air source heat pumps (...

This work evaluates the concentrating solar power (parabolic trough) technology for electricity generation in Kuwait. The assessment is performed on an existing plant in Spain, and the model is validated using published data. The Direct Normal Irradiance (DNI) of Spain exceeds that of Kuwait by a difference of 176.2 kWh/m2a, but the overall perform...

Polymer Electrolyte Fuel Cells (PEFC) are electro-chemical energy conversion devices capable of providing sustainable transport, stationary and portable solutions, owing to their high-power density and fast start-up time. However, water management remains one of the largest barriers limiting fuel cell efficiency and the wide scale deployment of PEF...

Stirling engines (SE) offer good part load performance and high heat sink temperatures which make it a suitable candidate to serve as a prime mover in micro-combined cooling, heating and power (μ-CCHP) applications. In this study, a novel μ-CCHP configuration hybridising a SE prime mover with an ORC to utilise the waste heat from the SE to produce...

The objective of this work is to demonstrate the viability of applying Adjoint methods to aerodynamic optimisation of VAWTs. Adjoint methods are very powerful optimisation techniques which have been implemented effectively in other fields, yet there is an absence of such work within VAWT literature. A ‘semi-transient’ optimisation process is propos...

The dynamic stall phenomenon in Vertical Axis Wind Turbines (VAWTs) appears under some operating conditions that have not been very well established. Some studies have focused on describing the topology of the dynamic stall but little attention has been paid to understand how all the operating VAWT parameters influence the moment of stall inception...

In this study, a CFD start-up model has been built after conducting the sensitivity studies to evaluate the self-starting behaviour of the H-type vertical axis wind turbines (VAWTs). The self-starting behaviour of a well-investigated VAWT is used for the model validation, and then the details of aerodynamics of the start-up process have been examin...

Detailed studies on wind turbines have been attracting increasing attention in recent years to save fossil resources and protect the environment. Vertical axis wind turbines ( VAWTs ) are not as popular as horizontal axis wind turbines ( HAWTs ) because of their relatively low efficiency. Based on CFD approaches, this paper studies the influence of...

In this paper, comprehensive governing differential equations of Stirling engines have been developed by coupling the effect of gas leakage through the displacer gap, gas leakage into the crank case and the shuttle heat loss into the traditional model. Instantaneous pressures and temperatures of the working fluid in the engine were evaluated at sam...

The rocket-based combined cycle (RBCC) engine is believed to be an ideal propulsion system for the space round trip mission in the future. The mission planning process is limited because there is no available performance data on the RBCC engine. This paper proposed a thermodynamic analysis tool of the RBCC engine. Working over a wide speed range, t...