Dr. AFROZA NAHAR - Academia.edu (original) (raw)

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Papers by Dr. AFROZA NAHAR

3D numerical model Finite element method Outdoor experiment Parallel plate flow channel a b s t r... more 3D numerical model Finite element method Outdoor experiment Parallel plate flow channel a b s t r a c t Solar energy is universally accepted as the most potential alternative power source due to its inexhaustible availability, diverse conversion technology and environmental friendly nature. Hybrid photovoltaic-thermal (PV/T) system is an optimized solar energy system that produces electricity and thermal energy simultaneously from the same physical profile. The basic problem of the hybrid collector is the removal and transfer of heat in an efficient way. In this article, PV/T system with a novel design of thermal collector excluding the absorber plate has been introduced to resolve the above mentioned problem. A parallel plate thermal collector without absorber plate has been attached directly to the PV module backside by means of thermal paste only and the performance of the PV/T is evaluated numerically and validated by experimental data for different operating conditions. A 3D numerical analysis of the PV/T system has been performed using finite element method (FEM) based software COMSOL Multiphysics Ò . The outdoor experimental investigation has been done under the typical climatic condition of Malaysia. Elevation head of water has been employed to ensure passive cooling of PV module. The numerical simulation results are found in well agreement with those of experimental measurements. Thermal performance of PV/T without absorber plate is found almost as good as that with absorber plate. The numerical and experimental values for maximum overall efficiency of the PV/T system was found 84.4% and 80%, respectively under the irradiation level at 1000 W/m 2 with both inlet and ambient temperatures being 34°C. The developed simulation model can be extended for other designs of thermal collector using different materials.

Interest of renewable energies is increasing due to the revising the energy policies for fighting... more Interest of renewable energies is increasing due to the revising the energy policies for fighting against the emission of Carbon-dioxide. To make the development of the civilization sustainable and cause less harm to the environment, clean energy resources are very important. Many alternative renewable energy resources are available that can be used instead of fossil fuels. Solar energy is one of the potential alternative renewable energies. This paper presents differents types of Photovoltaic cell materials which is one of the most effective parameter for improvement of photovoltaic cell as well as Photovoltaic system performance.

Energy is an indispensable factor for the economic growth and development of a country. Energy co... more Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration.

Global energy demand and environmental concerns are the driving force for use of alternative, sus... more Global energy demand and environmental concerns are the driving force for use of alternative, sustainable, and clean energy sources. Solar energy is the inexhaustible and CO 2-emission-free energy source worldwide. The Sun provides 1.4 Â 10 5 TW power as received on the surface of the Earth and about 3.6 Â 10 4 TW of this power is usable. In 2012, world power consumption was 17 TW, which is less than 3.6 Â 10 4 TW. Photovoltaic (PV) cells are the basic element for converting solar energy into electricity. PV cell technologies, energy conversion efficiency, economic analysis, energy policies, environmental impact, various applications, prospects, and progress have been comprehensively reviewed and presented in this paper. This work compiles the latest literature (i.e. journal articles, conference proceedings, and reports, among others) on PV power generation, economic analysis, environmental impact, and policies to increase public awareness. From the review, it was found that PV is an easy way to capture solar energy where PV based power generation has also rapidly increased.

Performance of photovoltaic (PV) module decreases significantly with increasing cell temperature ... more Performance of photovoltaic (PV) module decreases significantly with increasing cell temperature due to its overheating. Photovoltaic thermal (PVT) is an optimized technology that facilitates effective removal and utilization of this excess heat leading to enhanced electrical performance. In this article, a 3D numerical model has been developed and analyzed to investigate the PVT performance with a new pancake-shaped flow channel design. This flow channel is attached directly to the backside of PV module by using thermal paste. The governing equations are solved numerically by using Galerkin's weighted residual finite-element method (FEM), which has been developed using COM-SOL Multiphysics V R software. The numerical results show that the cell temperature reduces on an average 42 C, and the electrical efficiency and output power increase by 2% and 20 W, respectively, for both aluminum and copper channels with an increase in inlet velocity from 0.0009 to 0.05 m/s. On the other hand, overall efficiency of the PVT system drops about 13% in both cases as the inlet temperature increases from 20 C to 40 C. Cell temperature is found to increase approximately by 5.4 C and 9.2 C for every 100 W/m 2 increase in irradiation level of the PV module with and without cooling system, respectively. Regarding flow channel material, it has been observed that use of either copper or aluminum produces almost similar performance of the PVT module.

— Electing leader is a vital issue not only in distributed computing but also in communication ne... more — Electing leader is a vital issue not only in distributed computing but also in communication network [1, 2, 3, 4, 5], centralized mutual exclusion algorithm [6, 7], centralized control IPC, etc. A leader is required to make synchronization between different processes. And different election algorithms are used to elect a coordinator among the available processes in the system such a way that there will be only one coordinator at any time. Bully election algorithm is one of the classical and well-known approaches in coordinator election process. This paper will present a modified version of bully election algorithm using a new concept called election commission. This approach will not only reduce redundant elections but also minimize total number of elections and hence it will minimize message passing, network traffic, and complexity of the existing system.