Exergy Optimization of a Novel Combination of a Liquid Air Energy Storage System and a Parabolic Trough Solar Collector Power Plant

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Shahram Derakhshan ◽  
Mohammadreza Khosravian
Keyword(s):  
Energy Storage ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Design Parameters ◽  
Parabolic Trough ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Parabolic Trough Solar Collector

In this paper, a parabolic trough solar collector (PTSC) plant is combined with a liquid air energy storage (LAES) system. The genetic algorithm (GA) is used to optimize the proposed system for different air storage mass flow rates. The roundtrip exergy ratio is considered as the objective function and pressures of six points and mass flow rates of five points are considered as design parameters. The effects of some environmental and key parameters such as different radiation intensities, ambient temperatures, output pressures of the second compressor, and mass flow rates of the collectors fluid on the exergy ratio are investigated. The results revealed that the system could produce 17526.15 kJ/s (17.5 MW) power in high demands time and 2233.48 kJ/s (2.2 MW) power in low demands time and the system shows that a value of 15.13% round trip exergy ratio is achievable. Furthermore, the exergy ratio decreased by 5.1% when the air storage mass flow rate increased from 10 to 15 kg/s. Furthermore, the exergy ratio decreases by increasing the collectors inside fluid mass flow rate or by decreasing radiation intensity.

Influence of Dimensionless Parameter on De-Ionized Water-alumina Nanofluid Based Parabolic Trough Solar Collector

2020 ◽  
Vol 13 (3) ◽  
pp. 206-221
Author(s):  
Vijayan Gopalsamy ◽  
Karunakaran Rajasekaran ◽  
Logesh Kamaraj ◽  
Siva Sivasaravanan ◽  
Metin Kok
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Solar Collector ◽  
Dimensionless Parameter ◽  
Parabolic Trough ◽  
Alumina Nanofluid ◽  
Parabolic Trough Solar Collector

Background: Aqueous-alumina nanofluid was prepared using magnetic stirrer and ultrasonication process. Then, the prepared nanofluid was subjected to flow through the unshielded receiver of the parabolic trough solar collector to investigate the performance of the nanofluid and the effects of the dimensionless parameter were determined. Methods: The experimental work has been divided into two sections. First, the nanofluid was prepared and tested for its morphology, dimensions, and sedimentation using X-Ray Diffraction and Raman shift method. Then, the nanofluids of various concentrations from 0 to 4.0% are used as heat transfer fluid in unshielded type collector. Finally, the effect of the dimensionless parameter on the performance was determined. Results: For the whole test period, depending upon the bulk mean temperature, the dimensionless parameters such as Re and Nu varied from 1098 to 4552 & 19.30 to 46.40 for air and 2150 to 7551 & 11.11 to 48.54 for nanofluid. The enhancement of thermal efficiency found for 0% and 4.0% nanoparticle concentrations was 32.84% for the mass flow rate of 0.02 kg/s and 13.26% for the mass flow rate of 0.06 kg/s. Conclusion: Re and Nu of air depend on air velocity and ambient temperature. Re increased with the mass flow rate and decreased with concentration. Heat loss occurred by convection mode of heat transfer. Heat transfer coefficient and global efficiency increased with increased mass flow rate and volume fraction. The thermal efficiency of both 0% and 4.0% concentrations became equal for increased mass flow rate. It has been proven that at high mass flow rates, the time available to absorb the heat energy from the receiver is insufficient.

Thermodynamic Analysis of an Integrated Solar-Based Cooling System in UAE

2014 ◽  
Author(s):  
Mohamed Gadalla ◽  
Amani Al Hammadi
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Irradiance ◽  
Solar Collector ◽  
Cooling System ◽  
Constant Mass ◽  
Parabolic Trough ◽  
Energy And Exergy ◽  
Parabolic Trough Solar Collector

Renewable energy resource is considered by many developed and developing countries as a promising and a cost effective candidate to provide energy. The operation of cooling systems in the United Arab Emirates (UAE) have some operating problems especially in summer such as severe grid dependent, excessive energy consumption, high emissions and high costs. So, more economically and environmentally friendly HVAC systems are desired to provide the required electricity demands for cooling loads while saving energy and having low emissions to the environment. In this paper, a parabolic trough solar collector is integrated with a triple effect absorption cooling system for sustainable development. A computer code is developed using Engineering Equation Solver (EES) software to obtain all required thermodynamic properties of water-lithium bromide (H2O/LiBr) solution and to optimize all operating parameters and carry out all detailed energy and exergy analyses for a 10 kW cooling capacity. In addition, the parabolic trough solar collector (PTSC) is also designed for the required cooling load and its overall dynamic behavior is also investigated. The solar irradiance available in the UAE on a monthly basis is used in the analysis of a PTSC-based HVAC cooling system. Energetic and exergetic efficiencies of the PTSC for every month are also evaluated under different operating conditions. The Overall monthly energy and exergy efficiencies of the integrated PTSC-based HVAC system for a constant mass flow rate of Therminol-66 and concentration ratio are calculated. The dynamic variation of the coefficient of performance of the integrated system with the solar irradiance and mass flow rate of the oil are also evaluated. Results show that both energetic and exergetic COPs are decreased with increasing the solar irradiance for a constant mass flow rate of oil and constant concentration ratio. It is found that increasing the mass flow rate of the oil from 0.1 to 0.5 kg/s results in decreasing the energetic COP from 2.15 to 1.98 and the exergetic COP from 2.05 to 1.93.

The Dynamic Behavior of Once-Through Direct Steam Generation Parabolic Trough Solar Collector Row Under Moving Shadow Conditions

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Su Guo ◽  
Yinghao Chu ◽  
Deyou Liu ◽  
Xingying Chen ◽  
Chang Xu ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Dynamic Behavior ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Outlet Temperature ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Direct Steam ◽  
Parabolic Trough Solar Collector

Compared with recirculation and injection modes, once-through direct steam generation (DSG) parabolic troughs are simpler to construct and require the lowest investment. However, the heat transfer fluid (HTF) in once-through DSG parabolic trough systems has the most complicated dynamic behavior, particularly during periods of moving shadows caused by small clouds and jet contrails. In this paper, a nonlinear distributed parameter dynamic model (NDPDM) is proposed to model the dynamic behavior of once-through DSG parabolic trough solar collector row under moving shadow conditions. Compared with state-of-the-art models, the proposed NDPDM possesses three characteristics: (a) adopting real-time local values of the heat transfer and friction resistance coefficients, (b) simulating the whole collector row, including the boiler and the superheated sections, and (c) modeling the disturbance of direct normal irradiance (DNI) level on DSG parabolic trough solar collector row under moving shadow conditions. Validated using experimental data, the NDPDM accurately predicts the dynamic characteristics of HTF during periods of partial and moving DNI disturbance. The fundamental and specific dynamic process of fluid parameters for a DSG parabolic trough solar collector row is provided in this paper. The results show the following: (a) Moving shadows have a significant impact on the outlet temperature and mass flow rate, and the impact lasts up to 1000 s even after the shadows completely leave the collector row. (b) The time for outlet steam temperature to reach a steady-state value for the first time is independent of the shadow width, speed, and moving direction. (c) High-frequency chattering of the outlet mass flow rate can be observed under moving DNI disturbance and will have a longer duration if the shadow width is larger or the shadow speed is slower. Compared with cases in which the whole system is shaded, partially shading cases have shown a longer duration of high-frequency chattering. (d) Both wider widths and slower speeds of shadow will cause a larger amplitude of responses in the outlet temperature and mass flow rate. When the shadow speed is low, there is a longer delay time of response in the mass flow rate of the outlet fluid. (e) The amplitude of response in the outlet temperature does not depend on the direction of clouds movement. However, if the DNI disturbance starts at the inlet of the collector row, there will be significant delay times in both outlet temperature and mass flow rate, and a larger amplitude of response in outlet mass flow rate.

An Experimental Study of the Flow of R-407C in an Adiabatic Spiral Capillary Tube

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
M. K. Mittal ◽  
R. Kumar ◽  
A. Gupta
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Flow Rates ◽  
Tube Test ◽  
Mass Flow Rates ◽  
R 134A

The objective of this study is to investigate the effect of coiling on the flow characteristics of R-407C in an adiabatic spiral capillary tube. The characteristic coiling parameter for a spiral capillary tube is the coil pitch; hence, the effect of the coil pitch on the mass flow rate of R-407C was studied on several capillary tube test sections. It was observed that the coiling of the capillary tube significantly reduced the mass flow rate of R-407C in the adiabatic spiral capillary tube. In order to quantify the effect of coiling, the experiments were also conducted for straight a capillary tube, and it was observed that the coiling of the capillary tube reduced the mass flow rate in the spiral tube in the range of 9–18% as compared with that in the straight capillary tube. A generalized nondimensional correlation for the prediction of the mass flow rates of various refrigerants was developed for the straight capillary tube on the basis of the experimental data of R-407C of the present study, and the data of R-134a, R-22, and R-410A measured by other researchers. Additionally, a refrigerant-specific correlation for the spiral capillary was also proposed on the basis of the experimental data of R-407C of the present study.

Evaluation of Effects of Different Design Parameters on Axial Fan Performance Using CFD

2015 ◽  
Author(s):  
Racheet Matai ◽  
Savas Yavuzkurt
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Chord Length ◽  
Design Parameters ◽  
Axial Fan ◽  
Blade Length ◽  
Resistor Networks ◽  
Mass Flow Rates

The performance of an industrial fan was simulated using CFD and results were compared with the experimental data. The fan is used to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. It has a diameter of 24 inches (0.6096m) and rotates at different speeds ranging from 2500 to 3900 RPM depending on the requirements. CFD simulation results were also verified by simulating performance of the same fan at different speeds and comparing the results with what was expected from fan affinity laws. The CFD results matched almost exactly (with ∼0.2% difference for pressure at a given flow rate) with the performance being predicted by the affinity laws. The effect of variation of different parameters such as the blade length, number of blades, and blade chord length was studied. Increasing the blade length at the same RPM increased the mass flow rate (by ∼17%) for the same pressure. Increasing the chord length while keeping the same number of blades, at a given RPM, made the performance curve (pressure versus flow rate, i.e. PV curve) steeper and blades stalled at a higher mass flow rate (8.77 kg/sec compared to the previous 8.44 kg/sec). For the same total blade surface area, less number of blades with longer chords stalled at lower mass flow rates (9.22 kg/sec for a 33% shorter chord and 36 blades compared to 8.3 kg/sec for the original rotor which had 24 blades).

Permeability and Inertial Coefficients of Porous Media for Air Bearing Feeding Systems

2007 ◽  
Vol 129 (4) ◽  
pp. 705-711 ◽  
Author(s):  
G. Belforte ◽  
T. Raparelli ◽  
V. Viktorov ◽  
A. Trivella
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Darcy’S Law ◽  
Darcy's Law ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Thrust Pad ◽  
Gas Bearing ◽  
Forchheimer’S Law

In porous resistances, Darcy’s law provides a good approximation of mass flow rate when the differences between upstream and downstream pressures are sufficiently small. In this range, the mass flow rates are proportional to the porous resistance’s permeability. For gas bearings, the pressure difference is normally higher, and it is known experimentally that the mass flow rates are lower than would result from Darcy’s law. Forchheimer’s law adds an inertial term to Darcy’s law and, when an appropriate coefficient is selected for this term, provides a good approximation of flow rates for the same applications even with the highest pressure differences. This paper presents an experimental and theoretical investigation of porous resistances used in gas bearing and thrust pad supply systems. The porous resistances considered in the investigation were made by sintering bronze powders with different grain sizes to produce cylindrical inserts that can be installed in bearing supply devices. The paper describes the test setup and experimental results obtained for: (i) mass flow rate through single porous resistances at different upstream and downstream pressures and (ii) mass flow rate and pressure distribution on a pneumatic pad featuring the same porous resistances. The theoretical permeability of the chosen porous resistances was calculated, and the results from setup (i) were then used to obtain experimental permeability and to determine the inertial coefficients. The results, which are expressed as a function of the Reynolds number, confirmed the validity of using Forchheimer’s law. The mass flow rates from setup (ii) were compared to those from setup (i) at the same pressure differentials across the resistance.

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.

Effect of nozzle angle, turbine inlets and mass flow rate on the performance of a bladeless turbine

2019 ◽  
Vol 234 (8) ◽  
pp. 1101-1107
Author(s):  
Muhammad Ali Kamran ◽  
Shahryar Manzoor
Keyword(s):  
Experimental Study ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Working Fluid ◽  
Operating Parameters ◽  
Lower Mass ◽  
Flow Rates ◽  
Significant Parameter ◽  
Mass Flow Rates

A comprehensive experimental study on the effects of different operating parameters on the efficiency of tesla turbine is reported. A bladeless turbine with nine discs and up to four turbine inlets was used, with water as the working fluid. The parameters investigated are the nozzle angle, number of turbine inlets and mass flow rates. Contrary to earlier studies, an effort was made to determine the performance under varying loading conditions, and hence identify the complete performance characteristics. The study revealed that efficiency of the turbine increases at lower nozzle angles and higher number of turbine inlets. It was observed that the nozzle angle becomes a significant parameter when the number of turbine inlets is increased. Efficiencies up to 78% were achieved when the working fluid entered the turbine through two nozzles at an angle of 7°. It was also noted that the turbine is most efficient at the designed mass flow rate, and the efficiency reduces appreciably if lower mass flow rates are fed to the turbine. The results obtained are an important contribution to the available knowledge and can be used as design references for further studies.

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