scholarly journals Numerical Modelling of a Photovoltaic Thermal (PV/T) System Using Nanofluid With Parallel Flow Thermal Absorber

2021 ◽  
Vol 945 (1) ◽  
pp. 012013
Author(s):  
J. Kubenthiran ◽  
S. Baljit ◽  
A. S. Tijani ◽  
Z. A. K. Baharin ◽  
M.F. Remeli ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Thermal Efficiency ◽  
Pure Water ◽  
Fluid Velocity ◽  
Parallel Flow ◽  
Working Fluid ◽  
Volume Percentage ◽  
Electrical Efficiency ◽  
T System

Abstract In the present study, a numerical model of photovoltaic thermal (PV/T) system using alumina (Al2O3) nanofluid, and pure water are used as working fluid. The proposed PV/T model consists of parallel riser tubes that are connected to two header tubes and it is attached to an absorber plate to simulate the conduction and convection heat transfer mechanism of a conventional PV/T system. The energy efficiency of the PV/T model is analyzed by varying the solar radiation (Heat Flux), inlet fluid velocity, and the volume percentage of the nanofluids. The numerical simulation is performed by using a conjugate heat transfer method with a computational fluid dynamics (CFD) software. According to the simulation data, the energy efficiency and the heat transfer coefficient of the PV/T system increased by increasing the inlet fluid velocity. In comparison with water, alumina nanofluid showed better thermal and electrical efficiency due to its high thermal conductivity. The thermal efficiency increased by 5.55% for alumina, compared to pure water and the electrical efficiency increased by 0.15% for alumina. Moreover, the effect of inlet fluid velocity ranging from 0.04m/s to 0.2m/s was also evaluated, and the results showed that the increase in thermal efficiency for pure water and alumina are 18.15% and 25.77%, respectively. Subsequently, the electrical efficiency increased by 0.52% and 0.56% for pure water and alumina using the new parallel flow thermal absorber, respectively.

Performance Study of Flowing-Over PV/T System with Different Working Fluid

2014 ◽  
Vol 488-489 ◽  
pp. 1173-1176 ◽  
Author(s):  
Li Qing Tang ◽  
Qun Zhi Zhu
Keyword(s):  
Thermal Efficiency ◽  
Experimental System ◽  
Experimental Results ◽  
Working Fluid ◽  
Performance Study ◽  
Electrical Efficiency ◽  
Overall Efficiency ◽  
T System

This paper studied the performance of a flowing-over PV/T system with water and Al2O3 nanofluid as the working fluid. The experimental system was built in the outdoors. The parameters of the experiment obtained for processing, analysis, accessing to the electrical efficiency and thermal efficiency. Experimental results show that the flowing-over PV/T system with Al2O3 nanofluid as working fluid has a higher overall efficiency than that with water.

Experimental investigation of the novel BIPV/T system employing micro-channel flat-plate heat pipes

2018 ◽  
Vol 39 (5) ◽  
pp. 540-556 ◽  
Author(s):  
Zhangyuan Wang ◽  
Zicong Huang ◽  
Fucheng Chen ◽  
Xudong Zhao ◽  
Peng Guo
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Water Flow ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Heat Pipes ◽  
Micro Channel ◽  
Plate Heat ◽  
Electrical Efficiency ◽  
T System

In this paper, the micro-channel flat-plate heat pipes-based BIPV/T system has been proposed, which is expected to have the characteristics, e.g. reduced contact thermal resistance, enhanced heat transfer area, improved heat transfer efficiency and building integration. The proposed system was constructed at the laboratory of Guangdong University of Technology (China) to study its performance. The temperatures of the glass cover, PV panel, micro-channel flat-plate heat pipes, and tank water were measured, as well as the ambient temperature. The thermal and electrical efficiency was also calculated for the system operated under the conditions with different simulated radiations and water flow rates. It was found that the proposed system can achieve the maximum average overall efficiency of 50.4% (thermal efficiency of 45.9% and electrical efficiency of 4.5%) for the simulated radiation of 300 W/m2 and water flow rate of 600 L/h. By comparing the proposed system with the two previous systems employing the conventional heat pipes, the thermal efficiency of the proposed system was clearly improved. The research will develop an innovative BIPV/T technology possessing high thermal conduction capability and high thermal efficiency compared with the conventional BIPV/T system, and helps realise the global targets of reducing carbon emission and saving primary energy in buildings. Practical application: This novel BIPV/T employing micro-channel flat-plate heat pipes will be potentially used in buildings to provide amount of electricity and thermal energy. The generated electricity will be used by the residents for electrical devices, and the thermal energy can be used for hot water, even for space heating and cooling.

scholarly journals Optimization of Thermophysical and Rheological Properties of Mxene Ionanofluids for Hybrid Solar Photovoltaic/Thermal Systems

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 320
Author(s):  
Balaji Bakthavatchalam ◽  
Khairul Habib ◽  
R. Saidur ◽  
Navid Aslfattahi ◽  
Syed Mohd Yahya ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Ionic Liquid ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Efficiency ◽  
High Performance ◽  
Binary Solution ◽  
Working Fluid ◽  
Electrical Efficiency ◽  
The Impact

Since technology progresses, the need to optimize the thermal system’s heat transfer efficiency is continuously confronted by researchers. A primary constraint in the production of heat transfer fluids needed for ultra-high performance was its intrinsic poor heat transfer properties. MXene, a novel 2D nanoparticle possessing fascinating properties has emerged recently as a potential heat dissipative solute in nanofluids. In this research, 2D MXenes (Ti3C2) are synthesized via chemical etching and blended with a binary solution containing Diethylene Glycol (DEG) and ionic liquid (IL) to formulate stable nanofluids at concentrations of 0.1, 0.2, 0.3 and 0.4 wt%. Furthermore, the effect of different temperatures on the studied liquid’s thermophysical characteristics such as thermal conductivity, density, viscosity, specific heat capacity, thermal stability and the rheological property was experimentally conducted. A computational analysis was performed to evaluate the impact of ionic liquid-based 2D MXene nanofluid (Ti3C2/DEG+IL) in hybrid photovoltaic/thermal (PV/T) systems. A 3D numerical model is developed to evaluate the thermal efficiency, electrical efficiency, heat transfer coefficient, pumping power and temperature distribution. The simulations proved that the studied working fluid in the PV/T system results in an enhancement of thermal efficiency, electrical efficiency and heat transfer coefficient by 78.5%, 18.7% and 6%, respectively.

EXPERIMENTAL STUDY ON THERMAL TRANSPORT PHENOMENON OF NANOFLUIDS AS WORKING FLUID IN HEAT EXCHANGER

2014 ◽  
Vol 22 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUICHI TORII
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanoparticles Concentration ◽  
Transfer Behavior

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanoparticles flowing through a horizontal tube heated under constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement and the possibility of nanofluids as the working fluid in various heat exchangers. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanoparticles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) enhancement is intensified with an increase in the Reynolds number and the nanoparticles concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanoparticles.

scholarly journals Effects of radiative heat transfer on the structure of turbulent supersonic channel flow

2011 ◽  
Vol 677 ◽  
pp. 417-444 ◽  
Author(s):  
S. GHOSH ◽  
R. FRIEDRICH ◽  
M. PFITZNER ◽  
CHR. STEMMER ◽  
B. CUENOT ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Radiative Heat Transfer ◽  
Radiation Effects ◽  
Radiative Heat ◽  
Pure Water ◽  
Molecular Transport ◽  
Working Fluid ◽  
Mean Flow ◽  
Total Energy Balance

The interaction between turbulence in a minimal supersonic channel and radiative heat transfer is studied using large-eddy simulation. The working fluid is pure water vapour with temperature-dependent specific heats and molecular transport coefficients. Its line spectra properties are represented with a statistical narrow-band correlated-k model. A grey gas model is also tested. The parallel no-slip channel walls are treated as black surfaces concerning thermal radiation and are kept at a constant temperature of 1000 K. Simulations have been performed for different optical thicknesses (based on the Planck mean absorption coefficient) and different Mach numbers. Results for the mean flow variables, Reynolds stresses and certain terms of their transport equations indicate that thermal radiation effects counteract compressibility (Mach number) effects. An analysis of the total energy balance reveals the importance of radiative heat transfer, compared to the turbulent and mean molecular heat transport.

Thermal Performance of Water-Based Suspensions of Phase Change Nanocapsules in a Natural Circulation Loop

2013 ◽  
Author(s):  
C. J. Ho ◽  
Chi-Ming Lai
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Natural Circulation ◽  
Pure Water ◽  
Circulation Loop ◽  
Core Material ◽  
Working Fluid ◽  
Outer Diameter ◽  
Natural Circulation Loop ◽  
Water Based

Experiments were conducted to investigate the heat transfer characteristics of water-based suspensions of phase change nanocapsules in a natural circulation loop with mini-channel heat sinks and heat sources. A total of 23 and 34 rectangular mini-channels, each with width 0.8 mm, depth 1.2 mm, length 50 mm and hydraulic diameter 0.96 mm, were evenly placed on the copper blocks as the heat source and heat sink, respectively. The adiabatic sections of the circulation loop were constructed using PMMA tubes with an outer diameter of 6 mm and an inner diameter of 4 mm, which were fabricated and assembled to construct a rectangular loop with a height of 630 mm and a width of 220 mm. Using a core material of n-eicosane and a shell of urea-formaldehyde resin, the phase change material nanocapsules of mean particle size 150 nm were fabricated successfully and then dispersed in pure water as the working fluid to form the water-based suspensions with mass fractions of the nanocapsules in the range 0.1–1 wt.%. The results clearly indicate that water-based suspensions of phase change nanocapsules can markedly enhance the heat transfer performance of the natural circulation loop considered.

scholarly journals Heat transfer and entropy generation in a microchannel with longitudinal vortex generators using Nanofluids

2020 ◽  
Author(s):  
Amin Ebrahimi ◽  
Farhad Rikhtegar Nezami ◽  
Amin Sabaghan ◽  
Ehsan Roohi
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Single Phase ◽  
Pure Water ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Working Fluid ◽  
Two Phase ◽  
Rectangular Microchannel ◽  
Important Conclusion

Conjugated heat transfer and hydraulic performance for nanofluid flow in a rectangular microchannel heat sink with LVGs (longitudinal vortex generators) are numerically investigated using at different ranges of Reynolds numbers. Three-dimensional simulations are performed on a microchannel heated by a constant heat flux with a hydraulic diameter of 160 μm and six pairs of LVGs using a single-phase model. Coolants are selected to be nanofluids containing low volume-fractions (0.5%–3.0%) of Al2O3 or CuO nanoparticles with different particle sizes dispersed in pure water. The employed model is validated and compared by published experimental, and single-phase and two-phase numerical data for various geometries and nanoparticle sizes. The results demonstrate that heat transfer is enhanced by 2.29–30.63% and 9.44%–53.06% for water-Al2O3 and water-CuO nanofluids, respectively, in expense of increasing the pressure drop with respect to pure-water by 3.49%–16.85% and 6.5%–17.70%, respectively. We have also observed that the overall efficiency is improved by 2.55%–29.05% and 9.78%–50.64% for water-Al2O3 and water-CuO nanofluids, respectively. The results are also analyzed in terms of entropy generation, leading to the important conclusion that using nanofluids as the working fluid could reduce the irreversibility level in the rectangular microchannel heat sinks with LVGs. No exterma (minimums) is found for total entropy generation for the ranges of parameters studied.

scholarly journals Augmentation of the Heat Transfer Performance of a Sinusoidal Corrugated Enclosure by Employing Hybrid Nanofluid

2014 ◽  
Vol 6 ◽  
pp. 147059 ◽  
Author(s):  
Behrouz Takabi ◽  
Saeed Salehi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heated Surface ◽  
Pure Water ◽  
Maximum Error ◽  
Temperature Fields ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Transfer Performance ◽  
Lower Temperature

This paper numerically examines laminar natural convection in a sinusoidal corrugated enclosure with a discrete heat source on the bottom wall, filled by pure water, Al2O3/water nanofluid, and Al2O3-Cu/water hybrid nanofluid which is a new advanced nanofluid with two kinds of nanoparticle materials. The effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanofluid (in volume concentration of 0% ≤ ϕ ≤ 2%) as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated. The finite volume discretization method is employed to solve the set of governing equations. The results indicate that for all Rayleigh numbers been studied, employing hybrid nanofluid improves the heat transfer rate compared to nanofluid and water, which results in a better cooling performance of the enclosure and lower temperature of the heated surface. The rate of this enhancement is considerably more at higher values of Ra and volume concentrations. Furthermore, by applying the modeling results, two correlations are developed to estimate the average Nusselt number. The results reveal that the modeling data are in very good agreement with the predicted data. The maximum error for nanofluid and hybrid nanofluid was around 11% and 12%, respectively.

Energy Efficient Refrigerators: The Effect of Door Gasket and Wall Insulation on Heat Transfer

2003 ◽  
Author(s):  
Mir-Akbar Hessami ◽  
Arnd Hilligweg
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Energy Efficiency ◽  
Power Consumption ◽  
Thermal Efficiency ◽  
Air Temperatures ◽  
Insulation Thickness ◽  
Two Stages ◽  
Experimental Rig ◽  
The Doors

The energy efficiency of refrigerators not only depends on the efficiency of the various components used in the cycle but also on their thermodynamics cycle efficiency as well the thermal efficiency of the cabinet housing the components. Efficiency improvements to the thermodynamics cycle and refrigerator components have been the subject of various papers published in the open literature. Not many researchers have looked at reducing the heat leakage into the refrigerator cabinet with the explicit objective of reducing the power consumption of the unit and hence improving its thermal efficiency. This paper is based on an experimental study of this topic, and includes information on the experimental rig used and the results obtained. This research was performed in two stages: The first stage was focused on improving the energy efficiency by changing wall insulation while the second stage was to study the heat transfer through the doors’ gaskets. For the first part, a domestic refrigerator was instrumented with many thermocouples and heat flux meters to measure the inside and outside air temperatures and the heat transfer through the wall of the unit, respectively. These measurements were taken under different environmental conditions as well as different insulation thickness in the walls of the cabinet. For the second part, using a specially designed and manufactured experimental rig, various door gaskets were placed between a warm and a cold chamber and heat transfer through the gasket was measured. The results showed that by adding 30 mm polystyrene insulation to the walls of the refrigerator, the heat transfer through the walls reduced by around 35%. The power consumption data agreed very well with the measured heat flux through the walls. The percentage heat transfer through the doors’ gaskets was confirmed to be about 13% of the total heat transferred into the unit.

Turbulent Nanofluid Flow Analysis Passing a Shell and Tube Thermal Exchanger with Kays-Crawford Model

2021 ◽  
Vol 10 (4) ◽  
pp. 518-537
Author(s):  
R. Nasrin ◽  
S. A. Sweety ◽  
I. Zahan
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Pure Water ◽  
Fluid Velocity ◽  
Solid Volume Fraction ◽  
Heat Transfer Analysis ◽  
Inlet Temperature ◽  
Industrial Sectors ◽  
Shell And Tube ◽  
Thermal Exchanger

Temperature dissipation in a proficient mode has turned into a crucial challenge in industrial sectors because of worldwide energy crisis. In heat transfer analysis, shell and tube thermal exchangers is one of the mostly used strategies to control competent heat transfer in industrial progression applications. In this research, a numerical analysis of turbulent flow has been conceded in a shell and tube thermal exchanger using Kays-Crawford model to investigate the thermal performance of pure water and different concentrated water-MWCNT nanofluid. By means of finite element method the Reynold-Averaged Navier-Stokes (RANS) and heat transport equations along with suitable edge conditions have been worked out numerically. The implications of velocity, solid concentration, and temperature of water-MWCNT nanofluid on the fluid flow formation and heat transfer scheme have been inspected thoroughly. The numerical results indicate that the variation of nanoparticles solid volume fraction, inflow fluid velocity and inlet temperature mannerism considerably revolutionize in the flow and thermal completions. It is perceived that using 3% concentrated water-MWCNT nanofluid, higher rate of heat transfer 12.24% is achieved compared that of water and therefore to enhance the efficiency of this heat exchanger. Furthermore, a new correlation has been developed among obtained values of thermal diffusion rate, Reynolds number and volume concentration of nanoparticle and found very good correlation coefficient among the values.

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