• Energy Research

Abstract Solar thermal collectors have significant importance due to its wide use in solar thermal technology. Augmentation of heat transfer is a key challenge for solar thermal technology. A quarter circular solar thermal collectors is investigated throughout the paper introducing carbon nanotube (CNT)–water nanofluid in the cavity. Tilt angle of this type of collector plays a vital role and heat transfer can be maximized for a particular tilt angle and solid volume fraction of the nanofluid. Galerkin weighted residual of FEM has been applied for the numerical solution of the problem. Grid independency test and code validation have been assessed for the accuracy of numerical solution. In this paper a wide range of solid volume fraction (δ = 0 to δ = 0.12) and tilt angle (ϕ = 0 to ϕ = 60°) has been investigated for Rayleigh number (Ra = 105–108) with varying dimensionless times. It has been found that both solid volume fraction and tilt angle play vital roles for the augmentation of heat transfer and a good heat transfer characteristic can be obtained by compromising between these two parameters. The results are shown using streamline, isotherm contour and related graph and chart.

AbstractIn this paper, natural convection heat transfer has been analyzed for a C-shaped cavity filled with ferrofluid. Cobalt-kerosene ferrofluid is selected here for different solid volume fractions (φ=0 ∼ 0.15). Galerkin weighted residual method is applied to obtain the numerical solution. Simulations are carried out for a wide range of Rayleigh (Ra=103 ∼ 107) and Hartmann (Ha=0 ∼ 100) numbers for both the ferrofluid and the plain fluid. From this work, it is found that higher Rayleigh number enhances the heat transfer rate significantly, whereas presence of magnetic field tries to retard convection. Moreover, addition of 15% solid volume fraction of nanoparticle can augment the heat transfer rate up to 52.65% at moderate Rayleigh number compared to the base fluid. By an optimization of these parameters, effective heat transfer control equipment can be developed. Results are interpreted on the basis of streamline and isotherm patterns, and average Nusselt number of the heated wall and average fluid temperature of the cavity.

Abstract Nanofluids have been introduced for the enhancement in the heat transfer phenomena in the last few years. In this paper a corrugated bottom triangular solar collector has been studied introducing water based nanofluids inside the enclosure. The corrugated bottom is kept at a constant high temperature whereas the side walls of the triangular enclosure are kept at a low temperature. Three types of nanoparticles are taken into consideration: Cu, Al2O3, and TiO2. The effect of solid volume fraction (ϕ) of the nanoparticle of nanofluid has been studied numerically by Galerkin weighted residual method of finite element for a wide range of Grashof number (Gr) 104–106. Calculations are carried out for ϕ = 0, 0.05, 0.08, and 0.1 and dimensionless time, τ = 0.1, 0.5, and 1. For the specified conditions streamlines and isotherm contours are obtained and detailed results of the interaction between different parameters are studied using overall Nusselt number. It has been found that both Grashof number and solid volume fraction have significant influence on streamlines and isotherms in the enclosure. It is also found that heat transfer increased by 24.28% from the heated surface as volume fraction ϕ increases from 0% to 10% at Gr = 106 and τ = 1 for copper water nanofluid.

P (proportional), PI (proportional-integral), and PID (proportional-integral-derivative) controllers are popular means of controlling industrial processes. Due to superior response, accuracy, and stable performance, PID controllers are mostly used in control systems. This paper presents a mathematical model and subsequent response analysis regarding regulation of flow in mixed convection through a T-shaped open cavity by temperature dependent controllers. The T-shaped cavity has cold top and hot bottom walls, while air is flowing through the inlet at surrounding temperature. The inflow is regulated by a controlled gate which operates according to the signal received from the controller. Values of proportional gain (kp), integral gain (ki), and derivative gain (kd) are varied to obtain the desired system response and to ensure a stable system with fastest response. At first, only P controller is used and eventually PI and finally PID control scheme is applied for controller tuning. Tuning of different cont...

A lot of water resources which have some potential to meet the local power demand are wasted in Bangladesh. This paper encompasses a new concept to use the road side canal water flow potential and convert it in small scale (micro or mini) scale power generation which can meet the local power demand of Bangladesh. A numerical investigation has been done on the water flow rate and head of the canal water and in the light of this data total power is calculated. Power cost relation along with environmental feasibility also been showed to evident that this is a promising future technology for meet the power crisis in Bangladesh.