@article { author = {Mohajer, Abbas and Zirak, Saadat and Abbasi, Eshagh}, title = {Development of a compression system dynamic simulation code for testing and designing of anti-surge control system}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {99-110}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35843}, abstract = {In recent years, several research activities have been conducted to develop knowledge in analysis, design and optimization of compressor anti-surge control system. Since the anti-surge control testing on a full-scale compressor is limited to possible consequences of failure, and also the experimental facility can be expensive to set up control strategies and logic, design process often involves analyses using compression system dynamic simulation. This research focuses on developing and validating a physics-based, modular, non-linear and one-dimensional dynamic model of a compression system: centrifugal compressor and its surrounding process equipment like the scrubber, cooler, recycle line with control and check valves. The mathematical approach of the model is based on laws of conservation and the included ordinary differential equations (ODEs) which describe the system dynamics. It is solved by using a computational method in an in-house FORTRAN code. Compressor characteristics maps generated from company compressor test bench are used to determine compressor pressure ratio and efficiency. All equipment and inlet/outlet accessories as well as test instructions, follow the requirements of ASME PTC10. The simulation within a wide range of operating conditions allows a parametric study to be performed and the optimal values of the control parameters to be selected. In order to check the validity of the model, the simulation results are then compared with experimental data of company industrial compressor test facility and also with operational field measurements.}, keywords = {compression,Simulation,Dynamic,Anti-Surge,Control}, url = {https://www.energyequipsys.com/article_35843.html}, eprint = {https://www.energyequipsys.com/article_35843_ed1d133657fb4ca410ea1e351595ea12.pdf} } @article { author = {Keyvanmajd, Shayan and Sajadi, Behrang}, title = {Toward the design of zero energy buildings (ZEB) in Iran: Climatic study}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {111-119}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35844}, abstract = {In this research, a combination of passive and active methods is used to design a nearly zero energy building in four major climatic regions of Iran, including cold, mild, dry-warm, and wet-warm ones. The annual energy consumption analysis is performed using DesignBuilder® software. The passive strategies include Trombe Wall, blue roof, and thermochromic windows, and the active methods are using GSHP, LEDs with the linear controller, and photovoltaic systems. Also, the rainwater harvesting system is discussed, and the amount of rainfall which may be collected in different climates is summarized. The results show that Iran has a great potential to develop near zero energy buildings, especially in the cold region in which more than 60% reduction in annual energy consumption may be achievable.}, keywords = {Zero Energy Building (ZEB),DesignBuilder,Passive Method,Active Method,Rainwater Harvesting}, url = {https://www.energyequipsys.com/article_35844.html}, eprint = {https://www.energyequipsys.com/article_35844_f678516849392ef3d20abf4684b9f9a9.pdf} } @article { author = {Sobhani, Aria and Pourtaba, Hamidreza and Amini Nouri, Tayebeh}, title = {Effect of impeller geometry on performance characteristics of centrifugal compressor}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {121-132}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35845}, abstract = {Centrifugal Compressors play an essential role in oil, gas and petrochemical industries. Their extensive usage is due to their smooth operation and high reliability compared to other other compressor types. One of the main characteristics of these turbomachines is their performance curve, which is an important criterion for selecting the appropriate compressor for a desired working condition. In the presented article, the effect of impeller’s geometry on performance curve and other compressors characteristics is numerically investigated. The 3D CFD code is used to achieve the performance curves that are dedicated to each geometrical configuration. The results indicate that some of the selected geometrical parameters have a significant effect on performance curve margins. Increasing the shroud angle moves the surge point to the higher flow coefficients, while the pressure ratio remains constant and increasing the blade’s trailing edge angle, leads to increase in pressure ratio.}, keywords = {CFD,Centrifugal Compressor,Optimization}, url = {https://www.energyequipsys.com/article_35845.html}, eprint = {https://www.energyequipsys.com/article_35845_b2fbe74277ab9f12c26b1ad8ba550ca6.pdf} } @article { author = {Karrabi, Hadi and Sajjadi, Meysam and Baghani, Mostafa}, title = {Effect of aging and manufacturing tolerances on multi-stage transonic axial compressor performance}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {133-147}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35846}, abstract = {The Axial compressor is an integrated part of a gas turbine. The central part of compressors is its blades. Blade aerodynamic has a significant effect on compressor performance. Because of the adverse pressure gradient in the compressor, any deviation in the blade profile has a significant influence on the flow field as well as the compressor performance. During the manufacturing and operation of a compressor, the blade profile may deviate from the nominal design. This deviation may happen within the manufacturing process, e.g., changing in stagger angle of the blade, changing in the maximum thickness of the blade profile or may occur in an operation process, e.g., increasing the blade surface roughness. By the way, these deviations affect the compressor performance. In this research, a numerical investigation is carried out to understand better the effects of geometry variability of the blades, including maximum thickness, blade surface roughness, and rotor blades stagger angle on the Transonic Axial compressor performance parameters, including the efficiency and pressure ratio. A CFD code, which solves the Reynolds-averaged Navier–Stokes equations, is employed to simulate the complicated 3D flow field of the axial compressor. The code is validated against experimental data for the axial compressor. The numerical result is in good agreement with the test dataand error at the design point for the efficiency was computed to be 0.3%, which shows high accuracy of the numerical method. Then, the effect of geometry variability on the axial compressor blade performance parameters is studied. Results show that increase in the surface roughness, blade thickness, and the rotor blades twist lowers the efficiency, pressure ratio and mass flow significantly in the compressor. Results show with a 10% increase of the blade installation angle at the design point, the mass flow rate decreases 1.93%, and the efficiency and pressure ratio decreases 0.35% and 1.8%, respectively. The blade surface roughness reduces the mass flow rate, total pressure ratio and efficiency of the compressor. The results show that imposing the roughness at the design point of the compressor, mass flow rate and efficiency is reduced 1.8% and 2.75 %, respectively. Meridional view of this compressor is shown in figure 1 in which the blade profiles for the first to fourth stages are DCA type [1].}, keywords = {Transonic Axial Compressor,numerical simulation,Roughness,performance map,Stagger Angle,Efficiency,Twist}, url = {https://www.energyequipsys.com/article_35846.html}, eprint = {https://www.energyequipsys.com/article_35846_47e444a9db737f9beae667b518aa4820.pdf} } @article { author = {Yadollahi Farsani, Rouhollah and Raisi, Afrsiab and Ahmadi Nadooshan, Afshin and Shahsavar, Amin}, title = {Investigation with rheological behavior of liquid paraffin/Al2O3 nanofluid: Experimental approach}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {149-158}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35847}, abstract = {Liquid paraffin can be used as a coolant fluid in electronic and cutting devices due to its suitable capabilities such as electrical insulating, high heat capacity, chemical, and thermal stability, and high boiling point. In this study, the dynamic viscosity of paraffin containing the alumina nanoparticles has been examined experimentally. The nanofluids with different composition of alumina (0, 1, 2, and 3%) with the diameter of 20 nm were prepared by two-step method and tested by professional Brookfield rheometer in the temperature range of 20 oC to 60 oC and the shear rates of 12 s-1 up to 200 s-1. Experimental results indicated that the nano-lubricant behaves as Newtonian fluid in the volume fraction of 0 and 1% only at the temperatures of 50 and 60 oC. While it behaves as non-Newtonian fluid in the volume fraction of 2 and 3% for all measured temperatures. The results showed that the power law model represents the best curve fitting of the experimental data. Therefore, the coefficient values of power-law model including, consistency index and flow index were reported. Finally, an equation of relative viscosity based on the volume fraction and temperature of the combination was proposed by applying the curve fit technique on the experimental data.}, keywords = {Experimental Correlation,Al2O3,Liquid Paraffin,nanofluid,Rheological Behavior}, url = {https://www.energyequipsys.com/article_35847.html}, eprint = {https://www.energyequipsys.com/article_35847_7f6f97e2dd22f466cb587f8c445c1481.pdf} } @article { author = {Esmaeili, Mostafa and Afshari, Asghar}, title = {LES/FMDF of premixed methane/air flow in a backward-facing step combustor}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {159-173}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35848}, abstract = {In the present study, a hybrid Eulerian-Lagrangian methodology is utilized for large eddy simulation (LES) of premixed fuel/air flow over a three-dimensional backward facing step (BFS). The fluid dynamic features are obtained by solving the Eulerian filtered compressible transport equations while the species are predicted by using the filtered mass density function method (FMDF).  Some scalar fields are duplicated in FD and MC solvers to examine the numerical consistency between them. A good agreement is achieved by comparing the essential characteristics of the BFS flow (such as the mean and RMS values of the velocity and temperature fields and also the reattachment length) obtained from numerical results with the measurements. This ensures that the proposed hybrid method is reliable for studying the reacting flow in relatively complex combustion systems. Additionally, the performance of several SGS models are assessed, and the results indicate that the dynamic Smagorinsky and WALE models are superior to standard Smagorinsky and MKEV models.}, keywords = {Backward Facing Step,Turbulent Reacting Flow,LES,FMDF}, url = {https://www.energyequipsys.com/article_35848.html}, eprint = {https://www.energyequipsys.com/article_35848_2d2832dab8f84fba6a06f31e1b62ced8.pdf} } @article { author = {Jha, Prabhakar and Das, Biplab and Rezaie, Behnaz}, title = {Significant factors for enhancing the life cycle assessment of photovoltaic thermal air collector}, journal = {Energy Equipment and Systems}, volume = {7}, number = {2}, pages = {175-197}, year = {2019}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2019.35858}, abstract = {Due to the rapid industrialization and development across the entire globe, there is the increasing demand for energy. However, the energy sources from fossil fuels are not abundant in every part of the world. India has to import fuel from other parts of the world which consumes a major portion of Government funds. So, currently improving solar energy technologies efficiency is one of the most promising researches in India. This study is mostly about life cycle assessment (LCA) of photovoltaic thermal (PVT) air collectors. All the important parameters like Energy payback time (EPBT), Energy production factors (EPF), Lifecycle conversion efficiency (LCCE), Embodied energy, Life cycle cost assessment (LCCA) and carbon emissions are investigated in this study as well. The role of these parameters in the LCA study is depicted in this study since LCA greatly impacts the effectiveness and cost of PVT air collector. Results revealed that the EPBT, GPBT, EPF, and LCCE are in the range of 0.8 to 14 years, 1 to 4 years, 0.4 to 22, and 0.10 to 2.86. }, keywords = {Solar Energy,Photovoltaic Thermal Air Collectors,Energy Payback Time,Energy Production Factor,Carbon emissions}, url = {https://www.energyequipsys.com/article_35858.html}, eprint = {https://www.energyequipsys.com/article_35858_aae61e24a8c6fd1317109328c56a5a92.pdf} }