Md.Rezwanul Karim

• Doctor of Philosophy
• Professor at Islamic University of Technology

A hybrid Photovoltaic/Thermal (PV/T) solar system can simultaneously provide electricity and heat, achieving a higher conversion rate of the absorbed solar radiation than that of a standard PV module. This system consists of a PV module coupled with water or air heat extraction devices. In this paper an experimental study of a PVT dual system, both...

Four built-in-storage type solar water heaters (BSWH) of equal volume, equal projected area is tested simultaneously under identical working conditions for their performance comparison in terms of efficiency and heat energy absorbed. Three of these heaters of BSWH are painted with three different colours (black, blue and red brown) and one is left...

In the current study, the air-side turbulent thermal and hydraulic characteristics of finned tube heat exchanger of staggered tube arrangement are simulated with steady-state solvers using ANSYS CFX12.0, a Commercial CFD code for turbulent flow regimes. The k-ω model was used to predict the turbulent flow characteristics through the finned tube hea...

This study focuses on evaluating the impact of a fully twisted inner pipe along with conical rings turbulator by conducting a numerical analysis of the double-pipe heat exchanger (DPHE), considering both parallel and counterflow configurations for heat transfer. As modification, a straight elliptical pipe compared with two other pipes with three tw...

Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their remarkable electronic, optical, and chemical properties. Their atomic thinness also imparts flexibility, making them ideal for flexible and wearable devices. However, our understanding of the mechanical characteristics of molybdenum ditelluride (MoTe2)...

Bangladesh, a fast-progressing country in terms of economy, infrastructure, and industries faces the risk of power shortage in the near future as its energy sector is heavily dependent on non-renewable resources. To achieve the target of gaining the status of a developed country set by the government of Bangladesh within 2041, an uninterrupted powe...

In this study, we investigated the mechanical responses of molybdenum ditelluride (MoTe2) using molecular dynamics (MD) simulations. Our key focus was on the tensile behavior of MoTe2 with trigonal prismatic phase (2H-MoTe2) which was investigated under uniaxial tensile stress for both armchair and zigzag directions. Crack formation and propagation...

This study introduces a numerical model to assess the thermal and frictional properties of LBE crossflow over tube bundles on the shell side of a Helical-coiled Once-Through Steam Generator (H-OTSG) considering different arrangements, including inline, obliquely staggered, triangular, and rotated square configurations. The k-ω SST turbulence model...

Following the groundbreaking discovery of graphene, the scientific community has witnessed a surge of interest in two-dimensional (2D) materials during recent times, remarkable capabilities and versatility for technological applications. Apart from graphene, a lot of promising work has been reported from other two-dimensional materials, including b...

The alarming rate at which the deposit of non-renewable or fossil energy resources are depleting around the world has been nudging us in the direction of green energy for quite a long time. Considering the current and upcoming global energy crisis, we have no choice but to pay our serious attention to renewable resources to meet the energy demand o...

Adopting renewable energy technologies is becoming more and more popular, particularly in the industrial sector. Evacuated Flat Plate Collector (EFPC) is a promising technology which combines advantages of Flat Plate and Evacuated Tube Collector. It can be a potential device to be integrated into industrial process heating systems. In the current p...

Taking into account the energy crisis and concerns about the effect of burning fossil fuels on the environment, the utilization of renewable energy technologies is being promoted extensively. Despite having significant potential, the feasibility of utilizing solar thermal energy as industrial process heat in Bangladesh is yet to be assessed and thi...

In this study, we systematically investigated the mechanical response of monolayer molybdenum ditelluride (MoTe2) using molecular dynamics simulations. The tensile behavior of the trigonal prismatic phase (2H phase) MoTe2 under uniaxial strain was simulated in both the armchair and zigzag directions. We also investigated the crack formation and pro...

Flat Plate Solar Collectors (FPSCs) have been widely employed in the production of renewable energy for a significant period. To enhance their thermal performance, the utilization of nanofluids as heat transfer fluids has emerged as a popular approach. However, many research works were only carried out with conventional metal-based nanofluids. This...

The main objective of this study is to assess the use of carbon capturing and sequestration (CCS) technology in the existing plant to reduce the emissions leading to retrofitting. A typical 125 MW tangentially coal-fired Barapukuria Thermal Power Plant (BTPP), Bangladesh has been scrutitinized considering air-firing (existing) and five different ox...

This study aimed to examine numerically the effects of a dimpled surface over a mini-channel heat exchanger on the flow characteristics and heat transfer across a serpentine channel with a uniform rectangular cross-section. The dimples were arranged in parallel with a spanwise (y/d) distance of 3.125 and streamwise (x/d) distance of 11.25 along jus...

In recent years, the power sector of Bangladesh has seen a major development in terms of generation capacity. But as before, it is heavily dependent on fossil fuels overlooking the potential of renewable energy resources. The scope for grid-connected renewable energy systems has not been explored too far and in terms of solar thermal energy and con...

The continuous increase in global energy consumption as a result of rapid population growth, combined with the detrimental impact of fossil fuels on the atmosphere, has made it critical to extract renewable energy through various technologies and turn it into electricity. A hybrid photovoltaic-thermal collector can be an innovative alternative to h...

Bangladesh is a small country, located in south-east Asia having a fast-progressing economy and exemplary development in industry, architecture and engineering sectors. With such developments, demand of power is also on the rise exponentially. Although the generation capacity of the country has seen a major boost, lack of proper distribution, negli...

This paper investigates the thermochemical and physical conversion processes in coal gasification numerically with particular interest on calcination in a bubbling fluidized bed furnace. A comprehensive Eulerian-Eulerian three-dimensional model is developed for studying the gasification process. Three calcination cases are carried out under differe...

The bubble size distribution has a significant effect on gas holdup, residence time distribution and mass transfer in bubble column reactors. The occurrence of small gas bubbles causes potentially advantageous outcomes. These outcomes include a limited residence time distribution and perfect contact of gas‐liquid phases. It was demonstrated in the...

Biomass combustion in a bubbling fluidized bed has become a competitive technology due to its unique advantages of fuel flexibility and less pollutant emission. Numerical modelling of bubbling fluidized bed is a complex issue and recent models can’t describe the fuel movement and conversion due to the complicated combustion phenomena. In this work,...

The performance of a bubbling fluidized bed largely depends on the dynamics of solids. Therefore, it is very important to predict the bubble size and shape for modelling the degree of mixing of solid particles. The complicated non-linear characteristics of a bubbling fluidized bed make it difficult to study and model the hydrodynamic behaviour. Hen...

In this investigation, a series of experiments were conducted to explore the effects of liquefied petroleum gas (LPG) mixture of 60% propane and 40% commercial butane as a drop-in auxiliary for refrigerant R134a in a household refrigerator under subtropical conditions in Bangladesh. Experiments were conducted for both continuous and cycling operati...

A comprehensive 3D CFD model has been developed for analyzing thermal conversion of woody biomass fuel in a large reciprocating grate boiler under air/oxy-fuel condition. A number of sub-models representing solid conversion processes such as drying, devolatilisation and char combustion, gas phase flow and chemical reactions, solid and gas phase int...

This study presents the numerical investigation of co-firing behaviour of pulverized straw particles with coal in air and O2/CO2 mixtures. Validation is conducted in a semi-technical once-through 30 kW swirl-stabilized furnace. Reference air-fuel (21% O2) and oxy-fuel (30% O2) cases were considered for four different coal/straw ratios (100% coal, 2...

Vibration effects on thermal performances of the rectangular flat plate under natural convection condition are experimentally investigated in both horizontal and slightly inclined from horizontal orientations in multiple angles. The effects of Rayleigh number and vibrational Reynolds number on the average heat-transfer coefficient are also examined...

Moving grate boilers are suitable for biomass combustion and used worldwide for domestic heating applications. However, these boilers cause emission of harmful pollutants and requires optimization technique for reducing emission and increasing efficiency. Numerical study can be helpful in this regard to predict different combustion parameters and e...

In this work, a 3D numerical model for biomass combustion in packed bed furnace has been developed for studying the combustion phenomenon of biomass fuels under oxy-fuel condition. This model has been validated with the results of an experimental study for biomass combustion. Commercial CFD software AVL Fire is used for simulation of oxy-fuel bioma...

In the current study, a 3D numerical model for biomass combustion in a packed bed furnace has been developed to study combustion of four types of biomass fuels (wood pellet, poplar pellet, olive stone and pine shavings) with different chemical composition and physical properties. A number of sub models representing various processes of the fuel the...

Increasing demand for energy and rising concerns over global warming has urged the use of renewable energysources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions....

In this study, a numerical investigation has been conducted to describe the pulp zone properties by predicting the local gas holdup and bubble size distribution accounting for the effect of bubble-particle aggregate on the flow dynamic of slurry bubble column. Modelling calculations have been conducted using Eulerian–Eulerian multiphase approach wi...

Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It has no adverse effect on environment as it reduces carbon dioxide emissions. Biomass combustion is a difficult phenomenon due to its properties with less carbon, more volatile matters and lower calorific value. Fixed bed combustion is a us...

Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global w...

Vortex shedding in a bank of three rectangular burner-jets was investigated using a CFD model. The jets were angled to the wall and the whole burner was recessed into a cavity in the wall; the ratio of velocities between the jets varied from 1 to 3. The model was validated against experimentally measured velocity profiles and wall pressure tapings...

The aerodynamics of fully turbulent jets supplied from rectangular slot-burners was modelled using the Reynolds Averaged Navier–Stokes (RANS) model. Three different turbulent models were considered, such as standard k-ε, RNG k-ε and Reynolds stress turbulence models. The recessed-type nozzle geometry was investigated to determine the effect of burn...

This study presents the experimental and numerical investigation of coherent structure dynamics on mass transfer in a separated cavity flow. The flow field dynamics of a cavity type stagnation zone with a length to width ratio of 2 were studied. The cavity was driven by a channel flow with a Reynolds number of 1.8E5. The study utilised flow visuali...

Inefficient process in the thermal power station leads to greenhouse gas emission. Reductions in emissions are largely dependent on the improvement of efficiency, with lower fuel consumption as a 1% improvement in power station efficiency delivering an almost 3% reduction in CO2 emissions. Maximum CO2 reduction is also possible through the use of a...

Bio mass is a readily available renewable energy source for heating and power generation which reduces carbon dioxide emissions. Analysis of biomass combustion is complicated due to its large variations and physical structures. The physical and chemical processes involved in biomass combustion are necessary to understand which will improve applicat...

Rice parboiling boiler is low pressure boiler traditionally fabricated by local artisan as their own idea. Proper selection of different parameters is omitted during the fabrication of traditional rice parboiling boiler. As a result huge amount of energy is wasted during the operation of boiler creating a hazardous environment. There are about fort...

Hybrid photovoltaic thermal (PV/T or PVT) solar system combines a simultaneous conversion of the absorbed solar radiation into electricity and heat. The solar radiation converted into heat increases the temperature of the PV modules, resulting in the drop of their electrical efficiency. This undesirable effect can be partially avoided by applying a...