scholarly journals The Description of “Temperature Self-Limiting” in Jordanian Solar Generators with Natural Cooling

2021 ◽  
Vol 39 (3) ◽  
pp. 938-946
Author(s):  
Mohammed Awwad Ali Al-Dabbas
Keyword(s):  
Solar System ◽  
Check Valve ◽  
Control Element ◽  
Piping System ◽  
Primary Control ◽  
Cell Temperature ◽  
Excessive Heat ◽  
Operating Environments ◽  
Solar Generator ◽  
Experiential System

This study helps to make the sustainability of the experiential system reg of solar generator device better, particularly the unexpected inactiveness of drainage liquid throughout the solar system which is generating power. Stagnation situations can be disastrous for solar system units. Various methods to mitigating the consequences of the stagnation state have been established and tested. Some suggested approaches are not appropriate for all device designs and implementations. The tested reg generator systems in experiments can continue to work although the collector of the piping system is cut off. furthermore, the absorber layer is a challenge because it absorbs general solar incandesce regardless of cell temperature, causing the piping system to become inactive. This research depicts the experiential data that was tracked and mentioned in dealing with stagnation. The hydrodynamic flowing in the experiential solar generator was simulated using rigid flow. The measuring and processing of the data allowed the identification of excessive heat and stagnation issues in real-world operating environments. Daily, the test logging data of the prototype reg device was monitored to guide the incipience of inactivity and excessive heat. Most items have been utilized in the study; solenoid check valve and the Reflux Pipe in the Check Valves have been utilized as primary control items within the experimental reg unit, while normal cooling was utilized as the subaltern control element. Under stagnation phases, an air path is installed at the rear of the absorber to cool it normally. In general, there are agreement between the experimental and simulation results.

Effects of Valve Disc on Flow Characteristics Inside a Swing Check Valve During Opening and Closing Processes

2021 ◽  
Author(s):  
Yi-xiang Xu ◽  
Qiang Ru ◽  
Huai-yu Yao ◽  
Zhi-jiang Jin ◽  
Jin-yuan Qian
Keyword(s):  
Flow Field ◽  
Working Conditions ◽  
Power Plants ◽  
Flow Characteristics ◽  
Check Valve ◽  
Opening Angle ◽  
Piping System ◽  
Total Moment ◽  
Valve Disc ◽  
Opening And Closing

Abstract The check valve is one of the most important devices for safety protection of the piping system in thermal and nuclear power plants. As the key component of the check valve, the valve disc accounts for a major effect on the flow characteristics especially during the opening and closing processes. In this paper, a typical swing check valve is taken as the research object. In order to make a comparative study, three working conditions of 30% THA (Turbine Heat Acceptance), 50% THA and 100% THA are selected. Focusing on the effects of valve disc, how does the valve disc motion interact with the flow field around the valve disc is analyzed with the help of the dynamic mesh technology. The results show that under the combined action of fluid force and gravity, the check valve can be opened and closed quickly. During the opening process, the maximum total moment of the disc appears between 45° ∼ 50° opening angle, and during the closing process the maximum total moment occurs when the disc fully closed. The flow field near the valve disc has similar variation rules with the rotation of the valve disc in the three working conditions, and the pressure near the valve disc reaches the maximum value at the moment of opening and closing. This study can provide some suggestions for the further optimal design of similar swing check valve.

Development and Simulation of a Magnetohydrodynamic Solar Generator Operated With NaCl Electrolyte Solution

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Steffanie Jiménez-Flores ◽  
J. Guillermo Pérez-Luna ◽  
J. Joaquín Alvarado-Pulido ◽  
Antonio E. Jiménez-González
Keyword(s):  
Current Density ◽  
Check Valve ◽  
Electrical Energy ◽  
Solar Thermal ◽  
Working Fluid ◽  
Thermal System ◽  
Mhd Generator ◽  
Solar Generator ◽  
Neodymium Magnets ◽  
Solar Thermal System

Abstract A magnetohydrodynamic (MHD) generator is a device that generates electrical energy through the interaction between a conductive fluid and a magnetic field. This method of direct energy conversion allows the use of a renewable energy source such as solar energy and represents an alternative to tackle the greenhouse effect. This paper presents the development of an MHD solar generator, which is constituted by a solar thermal system and an MHD cell. The solar thermal system consists of a set of tubes with copper fins, connected in parallel and placed inside of a 1 m2 panel. In which, an electrolytic mixture of H2O and NaCl at 20% vol. was introduced as a working fluid. In order to increase the kinetic energy of the fluid, the panel was exposed to solar radiation, where it reached temperatures above 373 K and pressures above 96 kPa. This solar thermal system operates in closed cycle conditions by including a check valve in its inlet–outlet junction; in this way, the fluid travels through the MHD generator. The MHD cell was composed of a block of polytetrafluoroethylene, two cylindrical stainless-steel electrodes, and four neodymium magnets. For simulation purposes, comsol multiphysics was used to reproduce the current density produced by the MHD solar generator. Pressure and temperature quantities obtained experimentally in the MHD cell were employed as boundary conditions. The experimental maximal current density obtained corresponds to 4.30 mA/m2, and the comparison between theoretical and experimental results shows that the model fits fairly well.

Acoustic and Ultrasonic Signals as Diagnostic Tools for Check Valves

1993 ◽  
Vol 115 (2) ◽  
pp. 135-141 ◽  
Author(s):  
M. K. Au-Yang
Keyword(s):  
Nuclear Power ◽  
Structural Integrity ◽  
Operating Experience ◽  
Check Valve ◽  
Nuclear Regulatory Commission ◽  
Nuclear Plant ◽  
Diagnostic Tools ◽  
Piping System ◽  
Proper Training ◽  
Regulatory Commission

A typical nuclear plant has between 60 and 115 safety-related check valves ranging from 2 to 30 in. The majority of these valves control water flow. Recent studies done by the Institute of Nuclear Power Operations (INPO), Electric Power Research Institute (EPRI) and the US Nuclear Regulatory Commission (NRC) found that many of these safety-related valves were not functioning properly. Typical problems found in these valves included disk flutter, backstop tapping, flow leakage, disk pin and hinge pin wear, or even missing disks. These findings led to INPO’s Significant Operating Experience Report (SOER, 1986), and finally, NRC generic letter 89-04, which requires that all safety-related check valves in a nuclear plant be regularly monitored. In response to this need, the industry has developed various diagnostic equipment to monitor and test check valves, using technologies ranging from acoustics and ultrasonics to magnetic—even radiography has been considered. Of these, systems that depend on a combination of acoustic and ultrasonic techniques (Au-Yang et al., 1991) are among the most promising for two reasons: these two technologies supplement each other, making diagnosis of the check valves much more certain than any single technology, and this approach can be made nonintrusive. The nonintrusive feature allows the check valves to be monitored and diagnosed without being disassembled or removed from the piping system. This paper shows that by carefully studying the acoustic and ultrasonic signatures acquired from a check valve, either individually or in combination, an individual with the proper training and experience in acoustic and ultrasonic signature analyses can deduce the structural integrity of the check valve with good confidence. Most of the conclusions are derived from controlled experiments in the laboratory where the diagnosis can be verified. Other conclusions were based on test data obtained in the field.

PENENTUAN DAYA MAKSIMUM PHOTOVOLTAIK DENGAN METODE GROUP

2013 ◽  
Vol 14 (2) ◽  
Author(s):  
Harsono Hadi
Keyword(s):  
Photovoltaic System ◽  
Group Method ◽  
Model Parameters ◽  
Cell Temperature ◽  
Current Output ◽  
Current Voltage ◽  
Solar Generator ◽  
And Performance ◽  
Power Point ◽  
The Relationship

The maximum power point (MPP) is equivalent to maximum IxV at the I-V curve under G and T conditions. Characteristic and performance of the solar cell, module photovoltaic and solar generator of the photovoltaic system is possible to be evaluated through the MPP. The relationship among model, parameters and constants are expressed by a mathematical model of the exponential equation. Calculation of the MPP value at the intensity irradiation (G) and the cell temperature (T), the maximum voltage (Vmax) are fixed firstly by the current output equal to zero. The voltage output (Vout) is slowly dropped step by step (V=Vmax – n DV, where n = 1, 2, 3, . . . . m) and the current output (I) is founded. The MPPn (Iout x Vout) must be compared to the previous value of the MPPn-1 or MPPn – MPPn-1 ³ 0 Calculating process: the current-voltage (I-V) output, the MPP value is relative complicated and involves measured datum at the various irradiation and cell temperature. To simplifythe calculation of the MPP and I-V output, the group method is used to allocate the each datum [ Gn,Tn, In(In1, In2, In3, . . . Inm), Vn(Vn1, Vn2, Vn3, . . . Vnm), MPPn, Qn, Hn, . . . etc] in its dimensions [ {G1, G2,G3, . . . .Gn}, {T1, T2, T3, . . . .Tn}, {I1, I2, I3, . . . .In}, {V1, V2, V3, . . . .Vn}, {MPP1, MPP2, MPP3, . . ..MPPn}, {Q1, Q2, Q3, . . . .Qn},etc ].

Fluid Transient Responses With Check Valves in Pipe Flow System With Air Entrainment

1997 ◽  
Author(s):  
T. S. Lee ◽  
L. C. Leow
Keyword(s):  
Transient Flow ◽  
Flow System ◽  
Check Valve ◽  
Air Entrainment ◽  
Pipeline System ◽  
Piping System ◽  
Transient Responses ◽  
Fluid System ◽  
Free System ◽  
Fluid Transient

A common flow system arrangement in piping system consists of a lower reservoir, a group of pumps with a check valve in each branch, and a pipeline discharging into a upper reservoir. In earlier studies of check valves performances in transient flow, none considered the effects of air entrainment into a pipeline system and the subsequent effects on the check valve performances in transient flow. Studies on pressure surges during pump tripped in pumping systems showed that by including an air entrainment variable wave speed model, reasonable predictions of fluid transient responses with proper phasing and attenuation of pressure peaks can be obtained. The most severe case where all the pumps in the station fail simultaneously due to power failure was analysed for their maximum and minimum pressure variation along the pipeline. A numerical model is now set up in the present work to investigate the check valve performances in transient flow for a pumping system with air entrainment. The analyses examine a fluid system with a variable air entrainment content (ε) and studied numerically it effects on the flow reversal time and hence determine the appropriate valve selection for a given fluid system to minimize problems of check valve slamming. Present numerical computations show that the air content in a fluid system can adversely affect the check valve transient responses. With the fluid system operating within a critical range of air entrainment values, analysis showed that there is a possibility of “check valve slamming” when the check valves were selected based on the analysis of an air free system. The above phenomena is confirmed through physical field measurements.

Evaluation of Potential to Air Ingestion From RWT Following RAS

2006 ◽  
Author(s):  
Young S. Bang ◽  
Ingoo Kim ◽  
Sweng W. Woo
Keyword(s):  
Water Level ◽  
Power Plants ◽  
Transient Flow ◽  
Cooling System ◽  
Check Valve ◽  
Transient Behavior ◽  
Piping System ◽  
Water Tank ◽  
Two Phase ◽  
Pipe Line

At the Recirculation Actuation Signal (RAS) when the Refueling Water Tank (RWT) water level decreased to a certain value following Loss-of-Coolant Accident (LOCA), the isolation valves of Containment Recirculation Sump (CRS) of the Korean Standard Nuclear Power Plants (KSNP) are open automatically while the RWT isolation valves would be closed manually. It was concerned whether the design has a potential to air ingestion to Emergency Core Cooling System (ECCS) pumps before completion of the manual action to close RWT isolation valves. To support the safety evaluation on this issue including the evaluation of design adequacy, an analysis of the hydraulic transient within the ECCS piping following the RAS in KSNP is performed. RELAP5/MOD3.3 code is used to calculate the transient behavior of the piping network. The code was known to have capability to calculate one-dimensional two-phase transient flow with noncondensible gas in the complex piping. Substantial portion of ECCS are modeled including RWT, CRS, each pipe line from RWT and CRS to connection point with its own isolation valve and check valve, a common pipe line to ECCS header, each pipe line from the header to High Pressure Safety Injection (HPSI) pump, Low Pressure Safety Injection (LPSI) pump, and Containment Spray (CS) pump. Transient hydraulic behavior in the piping system following RAS after LOCA is calculated. It is found that the RWT water level was always higher than the elevation of the check valve at the connecting point by more than 15 ft. It indicates the air intrusion to the check valve can be sufficiently prevented by this amount of water head.

An Advanced Surge Dynamic Model for Simulating Emergency Shutdown Events and Comparing Different Antisurge Strategies

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Klaus Brun ◽  
Sarah Simons ◽  
...  
Keyword(s):  
Experimental Data ◽  
Dynamic Model ◽  
Mechanical Damage ◽  
Check Valve ◽  
Test Facility ◽  
Piping System ◽  
Southwest Research Institute ◽  
Emergency Shutdown ◽  
Piping Systems ◽  
Rapid Transients

The compressor surge is a phenomenon which has to be avoided since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components. As a consequence, compression system models have a crucial role in predicting the phenomena which can occur in the compressor and pipelines during operation. In this paper, a dynamic model, developed in the matlab/simulink environment, is further implemented to allow the study of surge events caused by rapid transients, such as emergency shutdown events (ESD). The aim is to validate the model using the experimental data obtained in a single-stage centrifugal compressor installed in the test facility at Southwest Research Institute. The test facility consists of a closed loop system and is characterized by a recycling circuit, and thus a recycling valve, which is opened in case of surge or driver shutdown. Simulations were carried out at 17,800 and 19,800 rpm; the comparison with experimental data showed the accuracy of the model in simulating different opening rates and different sizes of the recycle valve, at both low and high suction pressure (HSP). Moreover, different actions for recovering/preventing surge were simulated by controlling different valves along the piping system and by adding a check valve immediately downstream the compressor. The results demonstrated the fidelity of the model and its capability of simulating piping systems with different configurations and components, also showing, qualitatively, the different effects of some alternative actions which can be taken after surge onset.

The Numerical and Experimental Investigation Into Hydraulic Characteristics of a No-Load Running Check Valve due to Fluid-Structure Interaction

2018 ◽  
Author(s):  
Xiang-yuan Zhang ◽  
Zhi-jun Shuai ◽  
Chen-xing Jiang ◽  
Wan-you Li ◽  
Jie Jian
Keyword(s):  
Flow Rate ◽  
Ambient Pressure ◽  
Check Valve ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Pipeline System ◽  
Piping System ◽  
Hydraulic Characteristics ◽  
Mass System ◽  
Excited Vibration

Valve is a very important unit in pipeline system. The valve flow fluctuation brings about structural vibration and unpopular noise, and even leads to the safety problems and disasters. In this paper, a special no-load running check valve is investigated. The check valve is structural complex with one inlet and two outlets. It can be simplified as a spring-mass system which manipulates the flow rate by combine action of the ambient pressure of medium and the spring deformation. The three-dimensional model of the valve is established and also the relationship between pressure drops and flow rate of the valve is obtained in various openings and operating conditions. The structure modals were verified by the field tests and thus its fixing boundaries are obtained correctly. The mechanism causing self-excited vibration of a piping system is determined using a dynamic model which couples the hydraulics of internal flow with the structural motion of a three-ports passive check valve. The coupling is obtained by making the fluid flow coefficient at the check valve to be a function of valve plug displacement. The results are compared with the experimental data, which verifies the correctness of the theoretical results. It is shown that the special valve has its own hydraulic characteristics, which greatly influence its flow distribution as it has two outlets. It was also testified that the coupling between fluid and structure changes its natural frequencies and has a non-negligible impact on the pressure fluctuation while working.

An Advanced Surge Dynamic Model for Simulating ESD Events and Comparing Different Anti-Surge Strategies

2018 ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Klaus Brun ◽  
Sarah Simons ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Mechanical Damage ◽  
Check Valve ◽  
Low Flow ◽  
Stable Region ◽  
Test Facility ◽  
Piping System ◽  
Southwest Research Institute ◽  
Piping Systems ◽  
Rapid Transients

Despite advancements in research and industry, compressors still have to operate in the stable region of the characteristic curves otherwise, at low flow ranges, they enter an unstable regime. The worst instability that can arise in industrial compressors is called surge, which involves the whole system in view of the fact that it generates dangerous pressure and mass flow fluctuations. Thus, this phenomenon has to be prevented since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components. It is clear that, currently, compression system models have a crucial role in predicting the phenomena which can occur in the compressor and pipelines during operation. In this paper, a dynamic model, developed in the Matlab/Simulink environment, is further implemented to allow the study of surge events caused by rapid transients, such as emergency shutdown events (ESD). The aim is to validate the experimental data obtained in a single stage centrifugal compressor installed in the test facility at Southwest Research Institute. The test facility consists of a closed loop system and is characterized by a recycling circuit, and thus a recycling valve, which is opened in case of surge or driver shutdown. In this work, the recycling circuit is implemented in the model as well, and comparisons between recorded data and simulations were carried out. Moreover, different actions for recovering/preventing surge are simulated by controlling different valves along the piping system and by adding a check valve immediately downstream the compressor. The results demonstrated the fidelity of the model and its capability of simulating piping systems with different configurations and components, also showing, qualitatively, the different effects of some alternative actions which can be taken after surge onset.

Simulation and Design for Bidirectional Hydraulic Control Check Valve of a Logging Instrument

2012 ◽  
Vol 524-527 ◽  
pp. 1565-1568
Author(s):  
Min Qiang Dai ◽  
Sheng Dun Zhao ◽  
Wei Cai
Keyword(s):  
Ambient Temperature ◽  
Simulation Model ◽  
Heat Dissipation ◽  
Check Valve ◽  
Structure And Function ◽  
Control Element ◽  
Hydraulic Control ◽  
Formation Pressure ◽  
And Function ◽  
Continuous Working

Logging instrument are work in severe environment such as 140 MPa formation pressure, H2S corrosive content, 50 hours continuous working time, 175 °C ambient temperature without heat dissipation etc. The paper designed the bidirectional hydraulic control check valve which is a key control element of MDT logging instrument. And a simulation model was established based on AMESim to analyze the structure and function of the design.

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