Exergy Analysis for the Performance of Solar Collectors

1983 ◽  
Vol 105 (2) ◽  
pp. 163-167 ◽  
Author(s):  
M. Fujiwara
Keyword(s):  
Performance Evaluation ◽  
Pressure Drop ◽  
Exergy Analysis ◽  
Operating Conditions ◽  
Exergy Loss ◽  
Optimum Operating ◽  
Solar Collectors ◽  
Optimum Control ◽  
Friction Process ◽  
And Performance

The optimum control and performance evaluation of solar collectors are analyzed from the standpoint of exergy. The pressure drop inside the collector is introduced to the analysis using the Hottel-Whillier model. By treating the friction process as exergy loss, the optimum operating conditions are presented in a simple statement. The maximum capability of collectors is determined and expressed by a relationship among the collector parameters and the environment in which they operates.

Design and Performance Evaluation of Large Field of Flat Plate Solar Collectors Network for Industrial Application

2021 ◽  
Author(s):  
Ehab Sabry Rashed ◽  
Osama Ahmed Elsamni ◽  
Hesham A. Elkaranshawy ◽  
Mahmoud B. Elsheniti
Keyword(s):  
Performance Evaluation ◽  
Flat Plate ◽  
Industrial Application ◽  
Large Field ◽  
Solar Collectors ◽  
And Performance

Flow Coefficient Evaluation of Poppet Valves Used in Reciprocating Compressors for LDPE

2008 ◽  
Author(s):  
Enzo Giacomelli ◽  
Massimo Schiavone ◽  
Fabio Manfrone ◽  
Andrea Raggi
Keyword(s):  
Pressure Drop ◽  
Time Pressure ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Operating Life ◽  
High Fatigue ◽  
Strongly Connected ◽  
And Performance ◽  
Poppet Valves

Poppet valves have been used for a long time for very high pressure reciprocating compressors, as for example in the case of Low Density Polyethylene. These applications are very critical because the final pressure can reach 350 MPa and the evaluation of the performance of the machines is strongly connected to the proper operation and performance of the valve itself. The arrangement of cylinders requires generally a certain compactness of valve to withstand high fatigue stresses, but at the same time pressure drop and operating life are very important. In recent years the reliability of the machines has been improving over and over and the customers’ needs are very stringent. Therefore the use of poppet valves has been extended to other cases. In general the mentioned applications are heavy duty services and the simulation of the valves require some coefficients to be used in the differential equations, able to describe the movement of plate/disk or poppet and the flow and related pressure drop through the valves. Such coefficients are often determined in an experimental way in order to have a simulation closer to the real operating conditions. For the flow coefficients it is also possible today to use theoretical programs capable of determining the needed values in a quick and economical way. Some investigations have been carried out to determine the values for certain geometries of poppet valves. The results of the theory have been compared with some experimental tests. The good agreement between the various methods indicates the most suitable procedure to be applied in order to have reliable data. The advantage is evident as the time necessary for the theoretical procedure is faster and less expensive. This is of significant importance at the time of the design and also in case of a need to provide timely technical support for the operating behavior of the valves. Particularly for LDPE, the optimization of all the parameters is strongly necessary. The fatigue stresses of cylinder heads and valve bodies have to match in fact with gas passage turbulence and pressure drop, added to the mechanical behavior of the poppet valve components.

Exergy Analysis of a Combined Power and Refrigeration Thermodynamic Cycle Driven by a Solar Heat Source

2003 ◽  
Vol 125 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Afif Akel Hasan ◽  
D. Y. Goswami
Keyword(s):  
Heat Source ◽  
Exergy Analysis ◽  
Thermodynamic Cycle ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Mixture ◽  
Exergy Destruction ◽  
Ammonia Water ◽  
Solar Heat

Exergy thermodynamics is employed to analyze a binary ammonia water mixture thermodynamic cycle that produces both power and refrigeration. The analysis includes exergy destruction for each component in the cycle as well as the first law and exergy efficiencies of the cycle. The optimum operating conditions are established by maximizing the cycle exergy efficiency for the case of a solar heat source. Performance of the cycle over a range of heat source temperatures of 320–460°K was investigated. It is found that increasing the heat source temperature does not necessarily produce higher exergy efficiency, as is the case for first law efficiency. The largest exergy destruction occurs in the absorber, while little exergy destruction takes place in the boiler.

Exergy analysis and performance evaluation of CNG to LNG converting process

2008 ◽  
Vol 5 (2) ◽  
pp. 164 ◽  
Author(s):  
S. Farhad ◽  
M. Younessi Sinaki ◽  
M.R. Golriz ◽  
F. Hamdullahpur
Keyword(s):  
Performance Evaluation ◽  
Exergy Analysis ◽  
And Performance

scholarly journals Exergy Analysis of Phase-Change Heat-Storage Coupled Solar Heat Pump Heating System

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5552
Author(s):  
Chuanhui Zhu ◽  
Shubin Yan ◽  
Xiaodong Dong ◽  
Wei Zhang ◽  
Biyi Huang ◽  
...  
Keyword(s):  
Solar Energy ◽  
Phase Change ◽  
Heat Pump ◽  
Exergy Analysis ◽  
Heat Storage ◽  
Heating System ◽  
Exergy Loss ◽  
Solar Collectors ◽  
Solar Heat ◽  
Northern Regions

With the rapid development of industrialization, the excessive use of fossil fuels has caused problems such as increased greenhouse gas emissions and energy shortages. The development and use of renewable energy has attracted increased attention. In recent years, solar heat pump heating technology that uses clean solar energy combined with high-efficiency heat pump units is the development direction of clean heating in winter in northern regions. However, the use of solar energy is intermittent and unstable. The low-valley electricity policy is a night-time electricity price policy. Heat pump heating has problems such as frosting and low efficiencies in cold northern regions. To solve these problems, an exergy analysis model of each component of a phase-change heat-storage coupled solar heat pump heating system was established. Exergy analysis was performed on each component of the system to determine the direction of optimization and improvement of the phase-change heat-storage coupled solar heat pump heating system. The results showed that optimizing the heating-end heat exchanger of the system can reduce the exergy loss of the system. When the phase-change heat-storage tank meets the heating demand, its volume should be reduced to lower the exergy loss of the tank heat dissipation. Air-type solar collectors can increase the income exergies of solar collectors.

The Design and Performance of High-Pressure Injectors as Gas Jet Boosters

1970 ◽  
Vol 185 (1) ◽  
pp. 755-766 ◽  
Author(s):  
M. L. Hoggarth
Keyword(s):  
High Pressure ◽  
Distribution System ◽  
Theoretical Study ◽  
Distribution Networks ◽  
Operating Conditions ◽  
Optimum Operating ◽  
One Dimensional ◽  
And Performance ◽  
Optimum Working ◽  
Working Point

Injectors have a large potential application as jet boosters in gas distribution networks by using the gas from high-pressure supplies to boost the pressure of gas from low-pressure holders to that required by the distribution system. A theoretical study of the design and performance of injectors for this purpose is described. A one-dimensional theory which takes friction into account is proposed for predicting the performance of injectors with driving pressure ratios up to 14:1. Optimization of the theoretical equations is carried out so that the most suitable dimensions can be chosen for any specified performance. Alternatively, the best operating conditions for a given geometry may be predicted. Experimental results compared well with predictions from the proposed theory particularly in the region close to the optimum working point. Where deviations did occur these are explained by the excessive recirculation of the driving gas at the inlet to the mixing throat, when operated away from the optimum working point at low injection ratios and high pressure lifts. By moving the driving nozzle closer to the inlet of the throat and dispensing with the inlet cone, marked improvements in performance could be obtained at these off-optimum operating conditions.

scholarly journals Exergy analysis and performance evaluation of Kizildere Geothermal Power Plant, Turkey

2004 ◽  
Vol 1 (3) ◽  
pp. 316 ◽  
Author(s):  
Eda Didem Yildirim ◽  
Gulden Gokcen
Keyword(s):  
Performance Evaluation ◽  
Power Plant ◽  
Exergy Analysis ◽  
Geothermal Power Plant ◽  
Geothermal Power ◽  
And Performance

Energy, Exergy analysis and performance evaluation of a vacuum evaporator for solar thermal power plant Zero Liquid Discharge Systems

2019 ◽  
Vol 139 (2) ◽  
pp. 1275-1290 ◽  
Author(s):  
M. Akbari Vakilabadi ◽  
M. Bidi ◽  
A. F. Najafi ◽  
Mohammad Hossein Ahmadi
Keyword(s):  
Performance Evaluation ◽  
Power Plant ◽  
Thermal Power Plant ◽  
Exergy Analysis ◽  
Thermal Power ◽  
Solar Thermal ◽  
Solar Thermal Power ◽  
Liquid Discharge ◽  
And Performance

scholarly journals Development and Performance Evaluation of a Double Barrel Cassava Grating Machine

2020 ◽  
pp. 133-140
Author(s):  
Okonkwo Ugochukwu Chuka ◽  
Okafor Christian Emeka ◽  
Ihueze Christopher Chukwutoo
Keyword(s):  
Performance Evaluation ◽  
Feed Rate ◽  
Optimum Operating ◽  
Optimum Operating Condition ◽  
Operating Condition ◽  
Average Mass ◽  
Abrasive Surface ◽  
And Performance ◽  
Double Discharge ◽  
Central Composite

In this study, a double barrel cassava grating machine with double discharge outlet has been developed and its performance evaluated and optimized. The machine was designed to ensure very high throughput, easy decoupling and coupling and reduction in grating time. The performance evaluation of the grating machine was carried out using Design Expert Software. A central composite rotatable design of response surface methodology (RSM) was adopted in determining the optimum operating condition of the machine. The optimum operating condition obtained from the machine shows an optimum abrasive surface hole size of 6mm, feed rate of 11.8kg/min and an optimum feed rate of 20.16 kg/min; a through put capacity of 730.8kg/hr. The average mass loss, partially grated and completely grated were found to be 1.43kg, 1.48kg and 22.09kg, respectively for 25kg sample; which indicates effective grating and waste was drastically reduced with an average grating efficiency of 86.23%.

Hydrodynamic Analysis of Direct Steam Generation Solar Collectors

1999 ◽  
Vol 122 (1) ◽  
pp. 14-22 ◽  
Author(s):  
S. D. Odeh ◽  
M. Behnia ◽  
G. L. Morrison
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Operating Conditions ◽  
Tube Length ◽  
Solar Collectors ◽  
Flow Conditions ◽  
Steam Generation ◽  
Frictional Pressure Drop ◽  
Wide Range ◽  
Direct Steam

Direct steam generation collectors are considered with the aim to improve the performance of a parabolic trough collector leading to a reduction of operating costs of solar electric generation systems. In this study a hydrodynamic steady state model is developed and linked with a thermal model to optimize the performance of once-through direct steam generation solar collectors. The hydrodynamic model includes flow pattern classification and a pressure drop model. Flow pattern maps for typical DSG collectors with horizontal and inclined absorber tubes are generated to investigate the variation of flow conditions with radiation level, tube diameter, tube length and flow rate. Two-phase flow frictional pressure drop correlations for the range of operating conditions in a DSG collector are selected from the wide range of published correlations by comparison with experimental data for typical steam-water flow conditions in a DSG collector. Pressure drop is calculated for different operating conditions for both horizontal and inclined solar absorber tubes. Alternative operational strategies are evaluated to achieve optimum performance of a direct steam generation collector at different radiation levels. [S0199-6231(00)00101-5]

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