A numerical study on induced flowrate and thermal efficiency of a solar chimney with horizontal absorber surface for ventilation of buildings

2020 ◽  
Vol 28 ◽  
pp. 101050 ◽  
Author(s):  
Y.Q. Nguyen ◽  
J.C. Wells
Keyword(s):  
Thermal Efficiency ◽  
Numerical Study ◽  
Solar Chimney ◽  
Absorber Surface

The Comparison of CFD Flow Field between Slope Solar Energy Power Plant and Traditional Solar Chimney Power Generating Equipment

2013 ◽  
Vol 561 ◽  
pp. 614-619 ◽  
Author(s):  
Qing Ling Li ◽  
Xiao Qing Xie ◽  
Jun Chao ◽  
Xuan Xin ◽  
Yan Zhou
Keyword(s):  
Power Plant ◽  
Velocity Field ◽  
Solar Energy ◽  
Numerical Study ◽  
Solar Chimney ◽  
Heat Collector ◽  
Fluent Software ◽  
Generating Equipment ◽  
The Cost ◽  
Power Generating Equipment

A numerical study with FLUENT software has been carried out as to air performance in the slope solar energy power plant. The velocity field, temperature and pressure fields in the solar chimney, and the simulated result were compared with the simulated result of traditional solar chimney power generating equipment. The simulation results show that distribution of the temperature field and the velocity field in slope solar energy power plant and traditional solar chimney power generating equipment. In the case of the same height, the velocity of traditional is slightly larger than the slope style's, but there is little difference. In order to achieve the same power generation effect, the overall height of slope style is more than the traditional style, but the vertical chimney height of traditional style is greater than the slope style. The cost of construction of vertical chimney is expensive, and many problems have been considered, like radix saposhnikoviae and earthquake prevention, the heat collector also need to be cleaned on time. The slope style can take full advantage of land, the height of vertical chimney will be reduced, so the construction of the chimney will be relatively easy. Rainwater can clean the heat collector when it runs down from it. All things considered. The slope solar energy power plant has more development prospects.

Simulation of Extended Expansion Lean Burn Spark Ignition Engine

2004 ◽  
Author(s):  
A. Manivannan ◽  
R. Ramprabhu ◽  
P. Tamilporai ◽  
S. Chandrasekaran
Keyword(s):  
Heat Transfer ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Numerical Study ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Closure ◽  
Intake Valve ◽  
Lean Burn ◽  
Atkinson Cycle

This paper deals with Numerical Study of 4-stoke, Single cylinder, Spark Ignition, Extended Expansion Lean Burn Engine. Engine processes are simulated using thermodynamic and global modeling techniques. In the simulation study following process are considered compression, combustion, and expansion. Sub-models are used to include effect due to gas exchange process, heat transfer and friction. Wiebe heat release formula was used to predict the cylinder pressure, which was used to find out the indicated work done. The heat transfer from the cylinder, friction and pumping losses also were taken into account to predict the brake mean effective pressure, brake thermal efficiency and brake specific fuel consumption. Extended Expansion Engine operates on Otto-Atkinson cycle. Late Intake Valve Closure (LIVC) technique is used to control the load. The Atkinson cycle has lager expansion ratio than compression ratio. This is achieved by increasing the geometric compression ratio and employing LIVC. Simulation result shows that there is an increase in thermal efficiency up to a certain limit of intake valve closure timing. Optimum performance is attained at 90 deg intake valve closure (IVC) timing further delaying the intake valve closure reduces the engine performance.

Energy Conversion by Nanomaterial-Based Trapezoidal-Shaped Leg of Thermoelectric Generator Considering Convection Heat Transfer Effect

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Abu Raihan Mohammad Siddique ◽  
Franziska Kratz ◽  
Shohel Mahmud ◽  
Bill Van Heyst
Keyword(s):  
Heat Transfer ◽  
Thermoelectric Materials ◽  
Thermal Efficiency ◽  
Waste Heat ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Peltier Effect ◽  
Convection Heat ◽  
Cold Surface ◽  
Current Output

Thermoelectric generators (TEGs) can harvest energy without any negative environmental impact using low potential sources, such as waste heat, and subsequently convert that energy into electricity. Different shaped leg geometries and nanostructured thermoelectric materials have been investigated over the last decades in order to improve the thermal efficiency of the TEGs. In this paper, a numerical study on the performance analysis of a nanomaterial-based (i.e., p-type leg composed of BiSbTe nanostructured bulk alloy and n-type leg composed of Bi2Te3 with 0.1 vol % SiC nanoparticles) trapezoidal-shaped leg geometry has been investigated considering the Seebeck effect, Peltier effect, Thomson effect, Fourier heat conduction, and surface to surrounding irreversible heat transfer loss. Different surface convection heat transfer losses (h) are considered to characterize the current output, power output, and thermal efficiency at various hot surface (TH) and cold surface (TC) temperatures. Good agreement has been achieved between the numerical and analytical results. Moreover, current numerical results are compared with previous related works. The designed nanomaterial-based TEG shows better performance in terms of output current and thermal efficiency with the thermal efficiency increasing from 7.3% to 8.7% using nanomaterial instead of traditional thermoelectric materials at h = 0 W/m2K while TH is 500 K and TC is 300 K.

Applying CFD for Studying the Dynamic and Thermal Behavior of Solar Chimney Drying System with Reversed Absorber

2017 ◽  
Vol 13 (11) ◽  
Author(s):  
Souheyla Khaldi ◽  
A. Nabil Korti ◽  
Said Abboudi
Keyword(s):  
Thermal Behavior ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Numerical Study ◽  
Packed Bed ◽  
Maximum Temperature ◽  
Storage Material ◽  
Solar Chimney ◽  
Solar Dryer

AbstractThis article provides numerical study of the solar chimney (SC) assembled with a reversed absorber and packed bed for the indirect-mode solar dryer. The present study was designed to determine the effects of using the SC in three configuration and physical proprieties of the packed (thickness and porosity) on the dynamic and thermal behavior of airflow. The results reveal that (1) using SC without storage material can increase the maximum mass flow rate up to 5%. However, integrating a storage material in the SC can improve the mass flow rate up to 32% during nighttime; (2) the use of a packed bed can decrease the crops temperature fluctuation until about 76% and increase the operating time of the solar dryer up to 12.5 hours rather than 10 hours in the case without packed bed; (3) increasing the porosity from 0.1 to 0.8 can increase the maximum temperature by about 10°C.

Virtual Height Aided Solar Chimney: A New Design

2011 ◽  
Author(s):  
Khaled I. E. Ahmed ◽  
Ali K. Abdel-Rahman ◽  
Mahmoud Ahmed ◽  
Wael M. Khairaldien
Keyword(s):  
Electric Power ◽  
Co2 Emissions ◽  
Conversion Efficiency ◽  
Numerical Study ◽  
Air Flow ◽  
Flow Speed ◽  
Numerical Results ◽  
Solar Chimney ◽  
Virtual Height ◽  
Wide Range

Renewable energy source deployment is growing rapidly as it reduces CO2 emissions and increases diversity and security of supply. Solar chimney (SC) is a promising large-scale power technology, which absorbs solar radiation and converts parts of solar energy into electric power free of CO2 emissions. A major problem of Solar Chimney Power Plant (SCPP) is its low conversion efficiency as determined by the thermal performance of the system. However, the conversion efficiency of SCPP significantly increases with the SC height increase. The current paper proposes a new design of a virtual height aided solar chimney. In this new system the solar chimney is aided with a passive cooling system at the top of the chimney and a passive solar heater at its base to virtually mimic larger heights of the chimney. The new design has been simulated numerically for development and optimization. The numerical study is done in two stages to examine this concept. In the first stage, numerical results are obtained for the effect of the chimney height on the inside air flow speed. Then, in the second stage, the effect of decreasing the temperature at the chimney exit and the effect of increasing the temperature at the chimney base on the air flow speed are examined separately for small chimney heights. Then the combined effect of the two actions is investigated at a wide range of chimney heights. The numerical results have shown that the localized base heating and exit cooling have significantly enhanced the chimney performance for chimney heights up to 500m. A chimney with height of 300m gains an increase in the air velocity more than 25% due to the heating and cooling actions. Virtual height aided Chimney with original height of 300m acts similarly to a conventional chimney with height of 500m due to the effect of base heating and exit cooling actions. This air flow velocity increase reflects 100% increase in the expected generated electric power. Further detailed results are presented and discussed.

A Numerical Study on Integral Solar Air Collector

2013 ◽  
Vol 860-863 ◽  
pp. 146-150
Author(s):  
Fu Sheng Dong ◽  
Ming Fu Hu ◽  
Xiao Chun Huang
Keyword(s):  
Mathematical Model ◽  
Solar Radiation ◽  
Thermal Efficiency ◽  
Radiation Intensity ◽  
Numerical Study ◽  
One Dimension ◽  
Inlet Temperature ◽  
Solar Radiation Intensity ◽  
Solar Air Collector ◽  
Matlab Programming

A mathematical modeling method was devoted to study the thermal performance of integral solar air collector. A mathematical model of heat transfer was set up based on one-dimension assumptions at first, and then numerical solution was brought out by using finite-difference method under one-dimension steady heat exchange. Through the MATLAB programming, the approximate solutions for the local air temperature and thermal efficiency were obtained at the quasi-steady state. After calculation, the influence of air inlet velocity, inlet temperature, solar radiation intensity and height of flow channel on the performance of collector was analyzed. It is discovered that the mathematical model is reasonable, the thermal efficiency decreases with temperature of inlet air increasing and increases with air velocity increasing, on which the solar radiation intensity have little influence. Depth of the channel and optimum flow both have a best value.

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