Research
Advanced Materials | Thermal Science | Energy Storage | Fluid Mechanics | Soft Materials
Advanced Materials | Thermal Science | Energy Storage | Fluid Mechanics | Soft Materials
Graduate Research at Penn State
This project addresses a critical challenge in energy storage: designing soft, biocompatible power sources, specifically those inspired by mimicking the anatomy of electric eels, which currently suffer from low performance. The power that that electric eel provides is insufficient to power a device, for example, an LED valve. Torpedo rays help to overcome these limitations, as electrocytes are arranged in both series (improving voltage) and parallel (improving current) connections instead of only in series arrangements of electrocytes like electric eel fish. Salinity gradients across selective hydrogel layers are used by these bio-inspired cells to produce energy, but careful control over ion transport is necessary to provide reliable output. Still, there is a huge difference between the performance of artificial organs and electric eels. One of the main reasons behind this difference is that contact resistance is high for artificial organs. To reduce the contact resistance, we need to reduce the thickness of hydrogels more. In our lab, we used the layer-by-layer spin coating method to develop an ultrathin layer of power stack, which is comparable to biological organ dimension and provides more power. The power stacks consist of five layers of hydrogels following High Salinity, cation selective, low salinity, anion selective, and high salinity order to generate power. Cation and Anion passing through the cation and anion-selective layers, respectively, provides charge separation in the low-salinity layer generating voltage. The major problem of this power system is that the self-discharge rate is too high once the assembly is formed, which limits the usage of this for a longer period of time. The main aim of my work is to achieve high-fidelity ion selectivity and maximize key performance indicators such as power density and discharge duration. This study uses interfacial transport tuning to overcome inherent material and architectural inefficiencies in the selective layers, making the technology viable for flexible and bio-integrated applications.
Undergraduate Thesis and Other Research at BUET.
THESIS: Mechanical Characteristics of Crumpled Graphene Electrode Under Uniaxial Dynamic Tensile Loading using Molecular Dynamics Approach.
Software USED: LAMMPS, MS EXCEL, OVITO, MATLAB, Tecplot 360
In this study, the mechanical response of crumpled graphene (CG) with different magnitudes of crumpling and porosity to tensile loading has been investigated by molecular dynamics simulation. A single graphene sheet (5 nm x 5 nm) is crumpled and stabilized for creating the CG structure, a 3D nanomaterial with higher surface area, and conductivity. Initially, compared to flat graphene, crumpling in CG electrodes causes a considerable decrease in both fracture toughness and elastic modulus up to a specific radius. These mechanical properties do, however, get better with a higher degree of crumpling. A fall of 24% in fracture toughness and a 30% reduction in elastic modulus are observed as the crumpling radius reduces from 26.5 Å to 19.3 Å. Although the mechanical performance of CG is adversely affected by even a small amount of porosity, this reduction is largely offset by higher crumpling, especially at smaller radii. Porous CG electrodes show almost the same strength as their non-porous counterparts at lower radii, where crumpling is more prominent. The anisotropy in the CG structure is examined by applying load along all three axes, and the variation of strain energy in non-porous CG during deformation is analyzed. The effect of compressive load (for a crumpling radius of 7.6 Å) and the morphological structure of the system on the mechanical behavior of crumpled graphene is also explored and reported.
Other Research Work
CFD Study of MHD Mixed Convection in a Quadrantal Cavity With a Heat-Conducting Rotating Cylinder.
The current numerical study investigates the magnetohydrodynamic mixed convective thermal energy transport inside a quadrantal enclosure with a heat-conducting rotating cylinder. The vertical wall of the enclosure is kept at a cold temperature while the horizontal wall is heated isothermally. The cylinder is the only heat-conducting element rotating either clockwise or counter-clockwise direction. The conjugate mixed convective flow inside the cavity is described using Navier-Stokes and heat energy equations. This numerical analysis is carried out using the finite element approach and the simulation is conducted for different values of Reynolds, Grashof, and Richardson numbers, along with the variation of other parameters such as Hartman number, Ha = 0 and 20, and cylinder diameter (0.2L to 0.4L, where L is the radius of the quadrant. In this study, a variation in Nu (average Nusselt number) has been observed. The Nusselt number i.e., the heat transfer shows a decreasing trend with a rise in the magnetic field and the Richardson number, the mixed convection effects. As the Reynolds number increased, the heat transfer increased as well. There is a significant impact of cylinder diameter on heat transfer. A larger diameter causes more transfer of heat. All the above parameters have been studied for the heat-conducting cylinder's clockwise and counterclockwise motion. Study shows that the effect of rotation direction i.e. CW (Clockwise) or CCW (Counter-clockwise) is also significant in different cases. The average temperature plot has also been studied along with Nu for 3 different cases.
Analysis of internal temperature control system in a C shaped channel using P, PI, and PID controllers.
The objective of this study was to develop and validate a mathematical model for investigating a C-shaped enclosure with an isothermal heat source using the Galerkin finite element method. In addition, we wanted to create a cooling system that can be utilized in electronic chips that are small in size. The cooling system should be able to respond rapidly to maintain the optimal temperature range for the electronic chip. From the control analysis, it is concluded that P controllers exhibit poorer steady-state performance at low gains and become unstable with oscillations at higher gains. Maximum overshoot increases with gain, while PI controllers, though slower, effectively eliminate steady-state error, with performance depending on Ki values. PID controllers further stabilize the system, producing smoother responses and minimizing the steady-state error to zero.