This study investigated the thermal performance of the heat pipe and conducted on the effects of working fluids with wick and vertical position. The experiments were conducted using a copper heat pipe with ) a 20.8( mm inner diameter, and the length of the evaporator, the condenser, and the adiabatic regions were 300 mm, 350 mm, and 300 mm, respectively. The working fluids selected were water, Methanol, Ethanol, and different binary mixtures (50: 50) %, (30: 70) %, and (70: 30) % mixing ratios. The filling ratio for all working fluids remained constant with the value of 50% of the evaporator volume, and the heat input values were 20, 30, 40, and 50 watts. The results show that the heat pipe charged with Methanol has a thermal resistance of (0.7666 o
C/W) which is the lowest value of thermal resistance. The lowest thermal resistance of using mixtures is (0.7466 o
C/W) for (70 % methanol: 30% ethanol). Both are achieved at 50 W heat input. Also, the highest value of heat transfer coefficient when using water as a working fluid is (519.1073 W/m2
C), and for using a mixture (70 % water: 30% methanol) is (805.89 W/m2
C). Both are achieved at 50 W heat input.
Composite sandwich structures are gaining attention due to their inherent properties, such as lightweight, low density, and high strength. The forced vibration response of these structures was studied experimentally to investigate the effects of external loads on these structures. In this work, four composite sandwich structures were manufactured using carbon fiber, glass fibers, and foam and tested on a specially designed vibration test rig by hitting the specimen with an impact hammer. The response was recorded by an accelerometer attached to the specimens. The accelerometer signal was amplified, and the input and output signals were transferred to LABVIEW via a data acquisition card and were processed in MATLAB. The impact hammer acts as an external excitation source, and the frequency response function was found for each specimen under various edge boundary conditions. Bode plots were plotted for each test, and the peak frequency and the phase difference were compared. It was found that composite sandwich specimens made of carbon fiber skins and carbon fiber honeycomb core showed a higher frequency response among all specimens (400 Hz). Furthermore, it was found that the foam core layer reduces the phase difference between the input and output signals from (360degrees) to (180degrees) compared with other honeycomb cores. Therefore, the procedure outlined in this research can be applied to other structures to investigate their vibration response. In addition, this work could be beneficial for the diagnosis of structure stability using a forced vibration response procedure.
The printed circuit heat exchanger is one of the most recent important heat exchangers, especially in the nuclear power plant and aerospace applications, due to its very compact geometry and small print foot. This paper presents a 3D numerical investigation of the thermo-hydraulic performance of PCHE with a new non-uniform channel design configuration. The new channel design consists of two different fins and shape inserts: the diamond and biconvex shapes. The influence of two design parameters on the heat exchanger performance was studied and optimized, the longitudinal and transverse pitch length (Pl) and (Pt). Air with constant properties as the working fluid with constant heat flux at the walls envelope. The Reynolds number varied from 200 to 2000. Different Pitch lengths were used (Pl=20, 30, 40, and 50) mm and (Pt=3, 4, and 5) mm. Three performance parameters were studied the Nusselt number, friction factor, and the overall performance evaluation factor. Results show that the thermal performance enhanced with decreasing the pitch lengths, and it was shown that this enhancement was found only at high Reynolds numbers above 1400. The higher enhancement factor was with NACA 0020 airfoil fins at pt=3 mm and pl=20mm of η=2.75 at Re=2000, while the worst performance was obtained with biconvex fins. The main reason behind the enhancement is the disruption of the boundary layer and the good mixing induced in the fluid flow.
Photosynthesis requires additional energy. Such energy can be obtained by building a greenhouse, which traps sunlight's heat. The primary challenge in greenhouse growing is stabilizing temperature swings. Adapting conventional heating and cooling systems can provide additional energy to the greenhouse. In the greenhouse, solar energy is a vital energy source that is directly connected to the power supply. The greenhouse control systems have been adapted and implemented to meet the demands of plant cultivation due to wireless automation, design, control, and monitoring services. This study provides an effective automation system for greenhouses. It lowers the power, leads to consumption, and allows for remote control and monitoring. They show that the control model monitors sensing data are an accurate tool for computing sensing and the self-management of output devices. It was also found that this technology has several positive attributes such as easy network management and motor controls, soil moisture, humidity, temperature, and sensor to solar panel voltage. It measures the four sensors included in the suggested design system. Each sensor measures changes in the environment inside the greenhouse. All sensors are accessible in varied ratios to run devices plugged for different operations because irrigation, refrigeration, and air conditioning always start when depletion occurs.
Conserving energy and reducing emissions has become a global consensus. However, most air conditioning systems are highly energy-consuming, affecting global warming and the ozone layer because they use chlorine and fluorine refrigerating fluids. Evaporative cooling systems are one of the most important environmentally friendly air conditioning systems with low energy consumption. However, their performance is negatively affected by the high humidity of the inlet air. One of the solutions to control the relative humidity of the inlet air is using desiccant material. In this paper, a silica gel-coated heat exchanger was designed and constructed as a dehumidifying unit. The effect of airflow rate, hot water flow rate, cold water flow rate, and regeneration temperature on the system's performance has been studied. It was found that increasing the hot water flow rate improves the removing moisture from the desiccant. However, increasing the hot water flow rate has a negative effect on the thermal performance of the heat exchanger. The effectiveness of the heat exchanger was 53% in the regeneration phase and 52% in the cooling phase for the outside air temperature of 40 ºC, W=20 g/kg, and an airflow rate of 0.48 m³/s. From the results shown above, it was noticed that the system could work efficiently in hot and high humidity climates and be used in Iraqi weather.
The purpose of this paper is to present a vibration monitoring analysis of a hydrodynamic journal bearing working with nano-additives lubricants.The vibration response is generated on bearings at various rotational speeds and dynamic load conditions.These bearings were tested experimentally by adding two types of nano additives; Bismuth (3) oxide (Bi2
), which is considered a green, nontoxic metal, as well as a new additive, and nano Titanium dioxide (TiO2
), which is moderately toxic, with SN150 base oil.The performance of additives was studied on the base oil. The comparisons between the two nano-additives Bi2
with (1, 2, and 4 wt. %) and TiO2
with (1 and 1.25 wt. %) were studied experimentally with the SN150 base oil. And the obtained results manifested that at different concentrations of Bi2
in the SN150 base oil for each rotational speed and dynamic load, there was a reduction in the vibration system response, where Bi2
has a good performance at a wide range of rotational speed and dynamic load. At the same time, TiO2
performs better at higher rotational speed and dynamic load.
This paper presents an experimental and numerical study to investigate the heat transfer enhancement in a horizontal circular tube using hybrid nanofluid (CuO, Al₂O₃/ distilled water) and fitted with twisted tape (typical twisted tape, with twist ratios (TR=9.2). Under fully developed turbulent flow and uniform heat flux conditions, the studied hybrid nanofluid concentrations are (=0.6, 1.22, and 1.8% by volume). The experimental test rig includes all the required instruments to study the heat transfer enhancement. All the tests were carried out with a Reynolds number range of 3560-8320 and uniform heat flux (13217.5 W/m². The twisted tape, manufactured from polylactic acid (PLA) by 3-dimensional printer technology, was inserted inside the tube. In this numerical study, the finite volume method (CFD) procedure was employed to pattern the forced convection turbulent flow through the tube. For hybrid nanofluid with twisted, the maximum enhancement in the maximum thermal performance factor was 2.18 for φ = 1.8%, while for a tube (water with twisted) under the same conditions, it was (2.04). A high Nusselt number was obtained with a concentration of 1.8% and an enhancement in the heat transfer of about 6.70%) than water.
Rotating machine health monitoring is critical for system safety, cost savings, and increased reliability. The need for a simple and accurate fault diagnosis method has led to the development of various monitoring techniques. They incorporate vibration, motor’s current signature, and acoustic emission signals analysis in condition monitoring. So, based on using vibration signal analysis, a test rig was built for bearing fault identification. The test rig replicates and investigates various bearing problems, such as those found in the inner and outer races. An accelerometer, type ADXL335, was interfaced to a data acquisition device (DAQ USB-6215) for collecting vibration signals under various operating circumstances. In addition, a load cell was embedded with the test rig, interfaced with a digital panel meter, and used for recording the applied load on the bearings. The time-domain signal analysis technique was used after acquiring vibration signals at various bearing health states. Then, the time-domain signal was converted to the frequency domain using the fast Fourier transform, and the result was analyzed to investigate the generated fault frequencies. Finally, the obtained frequencies were compared with the theoretical values extracted from the theoretical equations, and the method proved its effectiveness in detecting the fault generated.
The most common component of mechanical systems today is rotating machines. In these systems, vibration is caused by rotating components. As a result, to decrease the amplitude of vibrations created by rotating equipment, it’s required to understand the behavior of the system. In this work, the problem of vibrations in conventional bearing systems and the effect of adding active magnetic bearings to rotating machines to reduce the amplitude of vibrations are discussed. In this paper, the vibrations in the rotary bearing system were studied theoretically and analytically by using simulation programs to calculate the natural frequencies and parameters affecting the performance. In the theoretical part, the shaft of the rotating bearing was analyzed by the Jeffcott method depending on several parameters changed with the frequency value to observe the amplitude of the vibrations in the shaft. In an analytical aspect by simulation, a representative model of active magnetic bearings was built using the COMSOL 2020 program, and the effect of adding these bearings on capacitance, vibration reduction, and frequency behavior was examined. SolidWorks 2018 software was used to analyze the magnetic field and its distribution in the magnetic bearing coil. The results indicate that when magnetic active bearings were introduced to the rotating bearing shafts, the vibration amplitude was reduced by approximately 60%. From this work, it can be concluded that the system becomes more stable when the active magnetic bearing is added to the rotating bearing shaft, giving it a more stable and firm nature.
Resistance Spot Welding (RSW) is one of the most important welding techniques used in the automotive industry because it is an economic process and is suitable for many materials. Many parameters affect the mechanical and microstructural properties of nugget formation and its strength, like welding current, electrode force, and welding time. Therefore, optimizing the RSW process to get the optimum welding parameters is necessary for automobile manufacturing companies. High-strength steel is widely used in the automotive industry because of its superior characteristics such as high strength-weight ratio, ductility, fatigue, and corrosion resistance. This paper presents an optimization process for RSW using the Taguchi method for high strength low alloy steel (HSLA) DOCOL 500 LA, considered a new steel grade. Two spots were used in this work.The mechanical and microstructural tests are achieved to get the maximum nugget strength, nugget diameter, different welding zones microstructures, microhardness values, and failure modes. The results showed that optimum welding parameters were welding current of 8800 Amp, welding time of 20 cycles, and electrode force of 1900 N. The failure mode for optimum conditions was a full pullout with tearing of the welded sheets because of high plastic deformation and absorbed energy. The maximum microhardness value is in the fusion zone, the heat-affected region, and finally, in the base material due to the nugget zone's rapid melting and solidification process.
Due to the rising demand for treated water, the enhancement of potable water yield technologies, such as traditional solar distillers, is a pressing concern. Solar desalination is one of the easiest techniques for producing fresh water from salt water. It has several benefits, not the least. It utilizes free solar energy. Moreover, it is a simple and inexpensive technique compared to other alternatives. They are, nevertheless, relatively inefficient devices. Many studies have been done to boost the daily output of solar stills by using many active strategies to produce a large amount of evaporation and condensation compared to a basic standard type distiller. The magnetic field (MF) is one of the most important and recent techniques affecting the productivity of the solar still due to its positive impact on the water evaporation rate. The primary focus of the current study is to review the effects of magnetic field approaches on the distillate production, performance, and thermal efficiency of several types of solar distillers. Based on previous studies, the magnetic field is responsible for increasing the partial pressure difference between water and glass cover. The change occurs in the hydration shells of the saltwater, which should enhance the evaporation rate and improve the performance of solar still. Besides, the magnetic field significantly reduces the surface tension of salty water, which leads to increased evaporation. Furthermore, the intensity, direction, position, and magnet sizes of magnetic have a strong effect on the rate of water evaporation as well as the rate of heat transfer.
The gas turbine-based propulsion systems were responsible for the emission of pollutants that damage the ecosphere. Commercial aviation represented a large portion of carbon emissions within the aviation industry, so this study focused on novel aircraft propulsion systems for large commercial aircraft. Electric propulsion was considered to be an alternative to conventional propulsion systems. Therefore, this report analyzed the various electric aircraft concepts within the aerospace industry to see whether they have environmental benefits. A flying wing aircraft was compared to a conventional tube-and-wing aircraft using Computational Fluid Dynamics to determine which aircraft requires more power. The lift forces acting on the conventional aircraft and flying wing at cruise speed were 269,110 N and 10681 N, while the drag forces acting on the conventional aircraft and Flying Wing Aircraft at cruise speed were 260,940N and 7679N, respectively. More electric aircraft approach has allowed the older power subsystems to be replaced by electrical systems within modern aircrafts such as the Boeings, airbus, etc. This has increased fuel efficiency. The result of the lift power requirement should be a boost for battery companies to develop FWA.Conclusively, the result inferred that the Flying Wing Aircraft is more aerodynamic and, therefore, would improve aircraft efficiency and emit less emission.
Determination of Temperature-Time Profile by the Lumped thermal mass analysis (LTMA) method using Tiger-Nut Juice as the impinging fluid on the cooling system was carried out. With a stationary hot steel plate on a modified run-out table for the top surface controlled the accelerated cooling process. This was evaluated with pipe diameters of 10mm, 15mm, 30mm, 35mm, and 40mm by single jet Tiger-Nut Juice impinging fluid, impingement gaps of 115mm, 125mm, 135mm, 145mm, and 155mm, initial surface temperatures from 450o
C – 410o
C and at sub-cooled temperatures from 150o
C. The analysis reveals a faster cooling rate for both diameters at an impingement gap of 155mm. Diameter 10mm with 1.8o
C/sec average rate, for impingement gap of 115mm, 1.8o
C/sec for impingement gaps of 125mm, 135mm and 145mm and 1.9o
C for 155mm. This optimal temperature-time profile of Tiger Nut Juice impingement cooling infers that a higher cooling rate is achieved using smaller pipe diameter D and higher impingement gap H. In addition, it showed evidence of less Leiden frost phenomenon; hence, extracted tiger nut juice fluid can perfectly serve as a substitute for water at smaller pipe diameters and higher impingement gaps. Also, it was inferred that it also cools at a bigger pipe diameter with a lower impingement gap.