scholarly journals Exergy Analysis of Modified Solar Still

2015 ◽  
Vol 10 (2) ◽  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Brackish Water ◽  
Solar Collector ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Volume Flow Rate ◽  
Exergy Efficiency ◽  
Solar Still

A new design of solar still consist of flat plate solar collector, heat exchanger and cooling tower, was built and tested under Iraq weather at March. The still was tested under different mass flow rate of brackish water entering the flate plate solar collector, ranging from 0.01 to 0.015 kg/s. The volume flow rate of air through cooling tower was 0.0195 m3 /s. A full details of overall system as well as for system components exergy analysis were achieved. It was found that the maximum daily exergy efficiency of the still is less than 1%. While the maximum hourly exergy efficiency and maximum productivity for such combination were 3.46 kg/day and 1.6% , respectively, when the mass flow rate of brackish water was 0.013 kg/s.

Improved Quantification of Exergy Destruction in Mechanical Cooling Tower Considering All Tower Inlet Parameters

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Kuljeet Singh ◽  
Ranjan Das
Keyword(s):  
Water Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Air Flow ◽  
Exergy Destruction ◽  
Air Humidity ◽  
Exergy Performance

The present work establishes an improved experimentally validated analysis to predict performance and exergy-related parameters of a mechanical draft cooling tower involving wooden splash fills. Unlike earlier studies, which accounted for the effect of at most three tower inlet parameters for the exergy analysis, the present study simultaneously considers all five inlet parameters affecting the tower exergy performance. To simultaneously predict outlet air and water conditions, an optimization algorithm involving discrete functions of dry- and wet-bulb temperatures is used in conjunction with the mathematical model derived from mass and energy conservations within the control volume involving Bosnjakovic correlation. From practical point of view, five inlet parameters such as dry-bulb temperature, relative humidity, water temperature, water, and air flow rates are selected for the exergy analysis. Thereafter, the influence of all inlet parameters on the tower performance is analyzed on various important exergy-related factors. The quantitative analysis reveals that the inlet air humidity, water inlet temperature, and the inlet water mass flow rate significantly influence the air and water exergy changes. The present study also reveals that among the five inlet parameters, the water temperature, air humidity, and air mass flow rate are primarily responsible for the exergy destruction. Furthermore, it is observed that the second law efficiency is mainly governed by the inlet air flow rate. The present study is proposed to be useful for selecting the tower inlet parameters to improve exergy performance of mechanical cooling towers.

First and second thermodynamic law analyses applied to a solar dish collector

2014 ◽  
Vol 39 (4) ◽  
Author(s):  
Vahid Madadi ◽  
Touraj Tavakoli ◽  
Amir Rahimi
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Flow Rates ◽  
Energy And Exergy ◽  
Mass Flow Rates

AbstractThe energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The effect of receiver type, inlet temperature and mass flow rate of heat transfer fluid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the effect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal efficiency. The cylindrical receiver has greater energy and exergy efficiency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy efficiency is minimum for a specified HTF mass flow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass flow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass flow rates than the above mentioned values are recommended.

scholarly journals Efficiency Enhancement in Double-Pass Perforated Glazed Solar Air Heaters with Porous Beds: Taguchi-Artificial Neural Network Optimization and Cost–Benefit Analysis

2021 ◽  
Vol 13 (21) ◽  
pp. 11654
Author(s):  
Roozbeh Vaziri ◽  
Akeem Adeyemi Oladipo ◽  
Mohsen Sharifpur ◽  
Rani Taher ◽  
Mohammad Hossein Ahmadi ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Exergy Efficiency ◽  
Wire Mesh ◽  
Double Pass ◽  
Artificial Neural

Analyzing the combination of involving parameters impacting the efficiency of solar air heaters is an attractive research areas. In this study, cost-effective double-pass perforated glazed solar air heaters (SAHs) packed with wire mesh layers (DPGSAHM), and iron wools (DPGSAHI) were fabricated, tested and experimentally enhanced under different operating conditions. Forty-eight iron pieces of wool and fifteen steel wire mesh layers were located between the external plexiglass and internal glass, which is utilized as an absorber plate. The experimental outcomes show that the thermal efficiency enhances as the air mass flow rate increases for the range of 0.014–0.033 kg/s. The highest thermal efficiency gained by utilizing the hybrid optimized DPGSAHM and DPGSAHI was 94 and 97%, respectively. The exergy efficiency and temperature difference (∆T) indicated an inverse relationship with mass flow rate. When the DPGSAHM and DPGSAHI were optimized by the hybrid procedure and employing the Taguchi-artificial neural network, enhancements in the thermal efficiency by 1.25% and in exergy efficiency by 2.4% were delivered. The results show the average cost per kW (USD 0.028) of useful heat gained by the DPGSAHM and DPGSAHI to be relatively higher than some double-pass SAHs reported in the literature.

scholarly journals Selecting the Optimal Configuration for a Solar Air Heater Using the Grey–Taguchi Method

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 317
Author(s):  
Raheleh Nowzari ◽  
Nima Mirzaei ◽  
Kiyan Parham
Keyword(s):  
Taguchi Method ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Solar Collector ◽  
Optimal Configuration ◽  
Solar Air Heater ◽  
Double Pass ◽  
Grey Taguchi

In this study, a typical Grey–Taguchi method has been applied in order to select the optimal configuration of a solar air heater to achieve optimum performance. The analysis is performed for different system configurations in terms of collector type, mass flow rate, and cover type. The Grey–Taguchi method, which requires the minimum possible numbers of the demanded experiments for accomplishing a robust statistical decision for a given experimental problem, has been employed, and temperature difference and thermal performance have been used as the two main criteria. It is found that by considering the temperature difference criterion, at a mass flow rate of 0.011 kg/s, the best configuration is the double-pass solar collector owning a one-fourth pierced Plexiglas cover with a distance of 60 mm between the centers of the holes. On the other hand, by considering the thermal performance as the criterion, the best configuration at a mass flow rate of 0.032 kg/s is found to be the double-pass solar collector holding a half-pierced Plexiglas cover and a distance of 60 mm distance between the centers of the holes. Finally, once both factors are taken into consideration, the optimal configuration suggested by the method is the double-pass collector with a one-quarter pierced Plexiglas cover. The method also suggests keeping a 30 mm distance between the centers of the holes and applying 0.032 kg/s of the mass flow rate to achieve the highest performance.

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