Optimization Of Thermal Module Solar Photovoltaic Using CFD-Simulation

Photovoltaic panels can directly generate electricity by converting solar energy, but the panels temperature reduce the efficiency of photovoltaic cells. The photovoltaic thermal PVT system technology is used to improve the electrical performance. In this study, the daily and monthly global solar radiation on a horizontal surface for Iraq have been measured and presented then used with PVT water system. ANSYS software is used to simulate the water temperature differences behavior and measure the surface temperature of PVT model using the collected irradiation with the mass flow rate at 0.01 and 0.02 kg per second. The CFID results were validated with previous studies and observed a good agreement. The simulation tests apply a constant input temperature to the PVT system in all the yearly weather conditions in order to enhance the surface temperature. The results observe the PVT thermal efficiency behavior and show the maximum enhancement which is reached to 61% with the mass flowrate 0.03 kg per second and constant low input temperature.

Best Practice Methodology to Enhance Modeling Inflow Control Technologies in Dynamic Reservoir Simulators

The methodology presented here will expand on current modeling of Autonomous Inflow Control Devices (AICD) to generalize for a wider range of fluid flow rates and phases. It will also address the challenges of modeling multiphase behavior of the reservoir fluid flow. This paper presents proposed methods for selected devices, and device models supported by simulations. The proposed methods show the potential for qualified benchmarking of Inflow Control Technology (ICT) completed wells in dynamic reservoir simulations compared to the generic models currently in use. New single-phase models for segregated and sequential flow are presented, and these have a potential for greatly simplifying mass flowrate predictions for multi-phase flow leading to more accurate analysis within dynamic reservoir simulators.

Chaotic Assessment of the Heave and Pitch Dynamics Motions of Air Cushion Vehicles

In this study, three degrees of freedom nonlinear air cushion vehicle (ACV) model is introduced to examine the dynamic behavior of the heave and pitch responses in addition to the cushion pressure of the ACV in both time and frequency domains. The model is based on the compressible flow Bernoulli's equation and the thermodynamics nonlinear isentropic relations along with the Newton’s second law of translation and rotation. In this study, the dynamical investigation was based on numerical simulation using the stiff ODE solvers of the Matlab software. The chaotic investigations of the proposed model is provided using the Fast Fourier Transform (FFT), the Poincaré maps, and the regression analysis. Three control design parameters are investigated for the chaotic studies. These parameters are: ACV mass (M), the mass flowrate entering the cushion volume (m ̇_in), and the ACV base radius (r). Chaos behavior was observed for heave, and pitch responses as well as the cushion pressure.

Chaotic Assessment of the Heave and Pitch Dynamics Motions of Air Cushion Vehicles

In this study, three degrees of freedom nonlinear air cushion vehicle (ACV) model is introduced to examine the dynamic behavior of the heave and pitch responses in addition to the cushion pressure of the ACV in both time and frequency domains. The model is based on the compressible flow Bernoulli's equation and the thermodynamics nonlinear isentropic relations along with the Newton’s second law of translation and rotation. In this study, the dynamical investigation was based on numerical simulation using the stiff ODE solvers of the Matlab software. The chaotic investigations of the proposed model is provided using the Fast Fourier Transform (FFT), the Poincaré maps, and the regression analysis. Three control design parameters are investigated for the chaotic studies. These parameters are: ACV mass (M), the mass flowrate entering the cushion volume (m ̇_in), and the ACV base radius (r). Chaos behavior was observed for heave, and pitch responses as well as the cushion pressure.

Behaviors of a Hole-Pattern Seal With Wet-Gas

Hole-pattern (HP) seals are widely used in centrifugal compressors to control leakage. This paper investigates the behaviors of an HP with wet-gas mixtures. The mixture consists of oil and air with inlet liquid volume fraction (LVF) up to 8%. Injecting oil into the air stream increases the leakage mass flowrate. Direct stiffness K is frequency-dependent and increases with increasing excitation frequency Ω. Injecting oil into the airflow makes this stiffening effect more pronounced. At low frequencies, increasing inlet LVF shows no appreciable impact on K; however, as Ω increases, the effects of changing LVF become more pronounced; i.e., at high frequencies, increasing LVF increases K. The effective damping Ceff value at half of the running speed is indicative of the system stability because many compressor rotors frequently show instabilities at ∼50% of the running speed. At 50% of the running speed, Ceff is positive, and it increases with increasing inlet LVF. Predictions based on San Andrés's (2011) homogenous-mixture bulk-flow model show a good agreement with test results for leakage mass flowrate, K, and the Ceff value near 50% of the running speed. When Ω = 0.5ω, the predicted value of Ceff is smaller than the measured value by ∼12.5%, giving a safe margin for the compressor design.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Energy And Exergy Assessment of North Refineries Company (NRC) Steam Cycle Based on Air Mass Flowrate of Main Condenser

The present work depends on the previous energy and exergy analysis study for a steam cycle of North Refineries Company (NRC)/Baiji, Iraq, which was conducted at real and rated operating loads. After the results of that study are presented, this current study is conducted and aimed to produce the engineering solutions for improving the cycle performance through studying the operational choices that are actually available in the plant as investigating the effect of increasing the air mass flow rate in the main condenser of the cycle. The calculations were done by using the MATLAB program. The results showed that increasing the air mass flow rate or increasing the number of fans in service from 8 to 14 fans will reduce the energy losses in the main condenser and in the cycle. The energy loss reduction can be enhanced in the improvement of the energy efficiency by raising it from 30.11 % to 48.61 % at real load and from 33.49 % to 48.93 % at rated load. On the other hand, the exergy analysis showed that the exergy destructions for the main condenser and for the cycle would decrease if the number of fans increased. This decreasing of exergy destruction in the main condenser will raise the exergy efficiency from 21.95 to 27.06 % at real load and from 21.18 % to 25.45 % at rated load.

Experimental Study of Vaneless Diffuser Rotating Stall Development and Cell-Merging Phenomena

This paper describes the vaneless diffuser rotating stall (VDRS) development and cell-merging phenomena. A centrifugal compressor’s lifespan may be limited by flow instabilities occurring in off-design operation. One such instability is the VDRS, which generates oscillating, asymmetrical flow fields in the diffuser and, thus, undesired forces acting on the rotor. Understanding and prevention of VDRS behavior are crucial for achieving safe and undisturbed compressor operation. Experimental measurements of centrifugal compressors operating under the influence of VDRS have been presented. Two different approaches were used for the identification of VDRS: pressure measurements and two-dimensional (2D) particle image velocimetry (PIV). Frequency analysis based on spectral maps and cell development processes were investigated. The presented results showed that mass flowrate has an impact on the rotating frequency of both the entire structure and single cells. Additionally, it affects radial cell size, which grows with compressor throttling and ultimately reaches the length of the diffuser. During the experiments, the cell-merging phenomenon was observed which has not been widely described in the literature. The results presented in this paper allow a better understanding of vaneless diffuser rotating stall behavior. The phenomenon of the change of cell size and frequency could be very important for machine fatigue. Cell-merging could also have an impact on the machine’s vibrations and flow stability. Since it is believed that VDRS is one of the factors inducing surge, its understanding and prevention may have a positive influence on surge margins.

A Method to Design and Optimize Axial Flow Cyclones for Gas-Liquid Separation

This paper provides a detailed design guide, optimization, and performance assessment for air-water separation of an axial flow cyclone. Axial flow cyclones (also known as swirl tube demisters, mist eliminators, or Austin-Write cyclones) have a range of applications in several different industries. This method of gas-liquid separation offers many benefits. Among these are high separation efficiency in high pressure applications (over 90% at 1 MPa) and an inline design that allows them to be more easily fitted into existing piping structures. Despite these benefits, there is a lack of recent literature on their design criteria and performance optimization. This research fills the gap in the literature by quantifying the effect of design parameters on water collection efficiency, ?_(water collection), and the air bypass efficiency, ?_(air bypass), defined as the ratio of the air mass flowrate exiting through the desired air outlet over the inlet air mass flowrate. A set of wide-ranging experiments were conducted to study the effects of gas-liquid flow rates, tube geometry, and relative injection angles to optimize water collection and air bypass efficiencies. The water collection efficiency exceeded 99.8% when the liquid streamline came in direct contact with the water drainage exit. An empirical correlation was developed to predict the swirl pitch as a function of the above design parameters. Predictions from the correlation were within 10% of the experimental results. The correlation can be used to design highly efficient in-line gas-liquid separators.