A Comparative Investigation of Two Types of MHPA Flat-Plate Solar Air Collector Based on Exergy Analysis

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
T. T. Zhu ◽  
Y. H. Diao ◽  
Y. H. Zhao ◽  
C. Ma ◽  
T. Y. Wang ◽  
...  
Keyword(s):  
Flat Plate ◽  
Mass Flow ◽  
Exergy Analysis ◽  
Comparative Investigation ◽  
Exergy Efficiency ◽  
High Mass ◽  
Condenser Section ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass

In this study, a comparative investigation of two types of microheat pipe array (MHPA) flat-plate solar air collectors (FPSAC) based on exergy analysis has been conducted. The thermal performance of MHPA-type solar air collectors (SACs) with two different shaped fins is experimentally evaluated. A detailed parametric study is also conducted to examine the effects of various fins, operation parameters, and inlet air temperature at different mass flow rates on thermal and exergy efficiencies. Results indicated that using V-shaped slotted fins at the specified range of mass flow rates can enhance exergy efficiency. Exergy efficiency can be considered as the main criterion to evaluate the performance of MHPA FPSACs. Attaching V-shaped slotted fins on the condenser section of MHPA is more effective than attaching rectangular fins at high mass flow rates. By contrast, the latter is more effective than the former at low mass flow rates.

scholarly journals Simulation and Modeling of Flow in a Gas Compressor

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Anna Avramenko ◽  
Alexey Frolov ◽  
Jari Hämäläinen
Keyword(s):  
Steady State ◽  
Mass Flow ◽  
Gas Flow ◽  
Simulation Method ◽  
High Mass ◽  
Ansys Fluent ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass ◽  
Flow Through

The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

EFFERVESCENT ATOMIZATION AT LOW MASS FLOW RATES. PART I: THE INFLUENCE OF SURFACE TENSION

1993 ◽  
Vol 3 (1) ◽  
pp. 77-89 ◽  
Author(s):  
M. T. Lund ◽  
Paul E. Sojka ◽  
Arthur H. Lefebvre ◽  
P. G. Gosselin
Keyword(s):  
Surface Tension ◽  
Mass Flow ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass

Experimental and Numerical Investigation of Different Rectangular Volute Geometries for Large Radial Compressors

2011 ◽  
Author(s):  
Michael Bartelt ◽  
Thomas Kwitschinski ◽  
Thomas Ceyrowsky ◽  
Daniel Grates ◽  
Joerg R. Seume
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
High Mass ◽  
Local Flow ◽  
Flow Rates ◽  
Reduced Dimensions ◽  
External Reference ◽  
Mass Flow Rates ◽  
Compressor Map ◽  
Operating Points

Increases on mass flow rates of modern radial process compressors result on larger machine components. In particular, the dimensions of the outlet volutes increase strongly, resulting in disproportionately large machines whose technical feasibility is restricted due to technological and economical reasons. A resulting aim is to design modern radial compressors much more compact, while improving the efficiency and the pressure ratio. Therefore, the present experimental investigation addresses the compressor behaviour for reduced dimensions of rectangular volutes. Furthermore, the experimental setups are numerically modelled and different operating points are simulated with a commercial CFD-Code. A rectangular, external reference volute is equipped with differently shaped blockage-inlays and the global compressor parameters are measured for all variants. Additionally, the pressure and velocity distributions of the local flow field are determined experimentally for varying mass flow ratios at different circumferentially distributed volute layers. The decrease of the volute cross-section results in a reduction of the compressor map width especially at high mass flow rates. Recommendations are given for designing compact volutes of large radial compressors.

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 An experimental study of solar thermal system with storage for domestic applications

2018 ◽  
Vol 12 (4) ◽  
pp. 4098-4116
Author(s):  
M. Abid ◽  
B. A. A. Yousef ◽  
M. E. Assad ◽  
A. Hepbasli ◽  
K. Saeed
Keyword(s):  
Heat Exchanger ◽  
Mass Flow ◽  
Solar Collector ◽  
Exergy Efficiency ◽  
Solar Thermal ◽  
Secondary Circuit ◽  
Water Heating ◽  
Flow Rates ◽  
Energy And Exergy ◽  
Mass Flow Rates

Building sector consumes a greater portion of energy for heating and cooling applications. The utilization of fossil fuels for space and water heating in buildings cause a negative effect on the environment by producing larger CO2. In this study solar thermal water heating system for building application have been analyzed from the first and second law perspectives of thermodynamics considering various scenarios and water consumption pattern. The solar flat collector is very commonly used to extract energy from sunlight. Therefor energy and exergy efficiency curves for the solar flat collector were presented. The energetic and exergetic values for the system were calculated based on the experimental values for the overall system, the heat exchanger and the pumps using the approach of exergetic product/fuel basis. The greatest and lowest relative irreversibility’s occurred at the solar collector and the heat exchanger with values of 85.73% and 2.45%, respectively, and the system overall exergy efficiency was determined to be 20.28%. The energy and exergy efficiencies of the solar collector were analyzed at three different cases depending on the mass flow rates in the solar collector and the secondary circuit of the system. Three different mass flow rates were applied to the inlet of the secondary circuit to observe the efficiency effect on the solar collector circuit. This study can assist in selecting a proper solar collector and storage size for buildings of various capacity and possible improvement in the design of the system components.

Design and Development of a Radial Turbine for Low Flow Turbocharging

2019 ◽  
Author(s):  
Dhinagaran Ramachandran ◽  
Srinivasa Rao Billa ◽  
Balamurugan Mayandi ◽  
Perumal Balappan ◽  
Shyamaprasad Kanthila ◽  
...  
Keyword(s):  
Transient Response ◽  
Mass Flow ◽  
Aerodynamic Performance ◽  
Low Flow ◽  
Angle Distribution ◽  
Turbine Wheel ◽  
Structural Requirements ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass

Abstract The scope of this study is to develop a turbocharger turbine wheel with improved aerodynamic performance at low mass flow rates and with reduced inertia for better transient response. The contrasting effect of geometrical shape and size parameters on the objectives of aerodynamic performance and transient response gives rise to the need to explore the design space for the best design having good trade-off between the multi-objective requirements. The search for an optimum aerodynamic design is a challenge due to structural requirements as well. A turbine wheel that is best suited for the current application is selected from the library as a baseline and this wheel is further optimized to meet the targets. Preliminary screening allowed the identification of parameters having major impact on the objectives and these results have been used to train a Response Surface (RS). Further, in the interest of reducing computational cost, a virtual optimization algorithm based on the RS has been employed to predict optimum design within the design constraints. The optimum designs thus obtained are validated with Computational Fluid Dynamics simulations for flow performance and Finite Element solver for satisfying structural requirements. This approach has allowed for application-based design of turbine wheel for instance, by changing key parameters like blade angle distribution, number of blades, axial length, blade height and width. An inertia reduction up to 10% has been obtained while retaining the performance at low mass flow rates.

Experimental investigation of an active inclined solar panel absorber solar still - Energy and Exergy analysis

2021 ◽  
Author(s):  
Mohamed Thalib Mohamed Rafeek ◽  
Vimala Muthu ◽  
Muthu Manokar Athikesavan ◽  
Ravishankar Sathyamurthy ◽  
Abd Elnaby Kabeel
Keyword(s):  
Mass Flow ◽  
Average Energy ◽  
Electrical Energy ◽  
Exergy Efficiency ◽  
Solar Panel ◽  
Water Yield ◽  
Flow Rates ◽  
Pv Panel ◽  
Energy And Exergy ◽  
Mass Flow Rates

Abstract The objective of the current study is to investigate the performance of the Inclined Solar Panel Basin Still (ISPBS) incorporated with a Spiral Tube Collector (STC) for various mass flow rates of water (mf). The maximum potable water yield of 8.1, 6.9 and 6.1 kg is obtained for different mass flow rates of 1.8, 3.2 and 4.7 kg/hr in each instance. Also, for mf values of 1.8, 3.2 and 4.7 kg per hour, the daily average energy and exergy efficiency of the ISPBS is recorded to be 47.9, 39.3 and 31.02 % and 9.8, 7.9 and 5.6 % in each instance. The average electrical, energy and exergy efficiency of the PV panel is noted to be 6.5, 7.1 and 7.5 %, 15.67, 17.1 and 18.04 % and 20.03, 22.21 and 23.36 % for mf values of 1.8, 3.2 and 4.7 kg/hr in each instance. The rise in mf causes a drop in the fresh water production yield, thermal, exergy and overall thermal effectiveness and an enhancement in the power production of the panel, electrical, thermal, exergy and overall exergy efficiency of the system.

A Comparison of a Mono, Twin and Double Scroll Turbine for Automotive Applications

2015 ◽  
Author(s):  
Jason Walkingshaw ◽  
Georgios Iosifidis ◽  
Tobias Scheuermann ◽  
Dietmar Filsinger ◽  
Nobuyuki Ikeya
Keyword(s):  
Mass Flow ◽  
Flow Characteristics ◽  
High Mass ◽  
Flow Rates ◽  
Engine Simulation ◽  
Engine Model ◽  
Trade Offs ◽  
Mass Flow Rates ◽  
The Individual ◽  
The Impact

As a means of meeting ever increasing emissions and fuel economy demands car manufacturers are using aggressive engine downsizing. To maintain the power output of the engine turbocharging is typically used. Due to the miss-match of the mass flow characteristics of the engine to the turbocharger, at low engine mass flow rates, the turbocharger can suffer from slow response known as “Turbolag”. Mono-scroll turbines are capable of providing good performance at high mass flow rates and in conjunction with low inertia mixed flow turbines can offer some benefits for transient engine response. With a multi-entry system the individual volute sizing can be matched to the single mass flow pulse from the engine cylinders. The exhaust pulse energy can be better utilised by the turbocharger turbine improving turbocharger response, while the interaction of the engine exhaust pulses can be better avoided, improving the scavenging of the engine. The behaviour of a mono-scroll turbocharger with the engine using engine simulation tools has been well established. What requires further investigation is the comparison with multi-entry turbines. CFD (Computational Fluid Dynamics) has been used to examine the single admission behaviour of a twin and double scroll turbine. Turbocharger gas stand maps of the multi-entry turbines have been measured at full and single admission. This data has been used in a 0D engine model. In addition, the turbine stage has been tested on the engine and a validation of the engine model against the engine test data is presented. Using the validated engine model a comparison has been made to understand the differences in the sizing requirements of the turbine and the interaction of the mono-scroll and multi-entry turbines with the engine. The impact of the different efficiency and mass flow rate trends of the mono and multi-entry turbochargers are discussed and the trade-offs between the design configurations regarding on engine behaviour are investigated.

Heat removal from VVÉR fuel assemblies for low mass flow rates

1990 ◽  
Vol 68 (4) ◽  
pp. 337-341
Author(s):  
B. G. Gordon ◽  
V. N. Pomel'nikov
Keyword(s):  
Mass Flow ◽  
Heat Removal ◽  
Flow Rates ◽  
Vver Fuel ◽  
Fuel Assemblies ◽  
Mass Flow Rates ◽  
Low Mass

scholarly journals Applying the Concepts of Efficiency and Effectiveness to Analyze the Influence of the Number of Passes in the Shell and Tubes Condenser Thermal Performance

2021 ◽  
Vol 8 (1) ◽  
pp. F1-F10
Author(s):  
E. Nogueira
Keyword(s):  
Heat Exchanger ◽  
Mass Flow ◽  
Thermal Performance ◽  
High Mass ◽  
Saturated Steam ◽  
Inlet Temperature ◽  
Flow Rates ◽  
Efficiency And Effectiveness ◽  
Mass Flow Rates ◽  
Number Of Passes

The work analyzes the influence of the number of passes in a shell and tubes condenser heat exchanger, with an inlet pressure of R134a refrigerant in the shell equal to 1.2 MPa. The fluid that circulates in the tubes is water or water-based nanofluid with a fraction of aluminum oxide nanoparticles (Al2O3), and the methodology used subdivides the heat exchanger into three distinct regions: the overheated region, the saturated region, and the subcooled region. The main parameters used to analyze the thermal performance of the heat exchanger were efficiency and effectiveness. Efficiency in the superheated steam region is close to 1.0. There is scope for increasing thermal effectiveness, which can be improved with more significant passes in the tube. The saturated steam region process is efficient for lower mass flow rates of the fluid in the tube, but it is ineffective. However, it is highly effective for high mass flow rates. There is ample scope for increasing effectiveness in the subcooled region. Still, the fluid inlet temperature in the pipe and the work refrigerant pressure are the limiting factors for greater heat exchange in the subcooled region.

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