Theoretical study of thermoelectric cooling system performance

This work provides a theoretical investigation to study the effect of different operational parameters on theperformance of TE cooling system including the system COP and the rate of heat transfer. The parametersinvestigated are, the applied input power, inlet working fluid velocity, the arrangement of utilized TECs modules andfluid type. The geometry is created with ANSYS multi-physics software as a two-dimensional base case, it isconsisted from two attached horizontal ducts of length (520 mm) and (560 mm), the interface surface between the twoducts contains three thermoelectric modules (4 mm height by 40 mm wide and 40 mm length). The distance betweentwo consecutive thermoelectric modules (150 mm), the inlet and outlet duct diameter (15 mm) and the height of eachduct (10 cm), the inlet voltage to thermoelectric modules ranges from 8.0 V to 12 V and the water inlet velocity to thetwo ducts from 0.001 to 0.01 m/s. Theoretical results showed that the overall COP of TE cooling system is increasedwith the applied input power up to 8.0 W then it decreases with input power up to 18 W after that it takes nearly aconstant value, a noticeable enhancement in the COP is found when the three TECs are in use (Case 10) and the COPof TE cooling system using pure water and nanofluid with 0.05% of nanoparticles as coolants takes the maximumvalue

Thermal and entropy behavior of sustainable solar energy in water solar collectors due to non-Newtonian power-law hybrid nanofluids

Introduction: Nanofluids, hybrid nanofluid possesses thermophysical features that boost the fluid performance. This research work is motivated by the utilization of water solar collectors that incorporate non-Newtonian, power-law hybrid nanofluid in a three-dimensional model, considering the two-phase model.Method: The primary objective of this study is to transform the governing equations of the flow model into a set of ordinary differential equations by employing the three-parameters group technique. Based on the innovative discoveries, two models incorporating new associated functions have been successfully developed for two distinct scenarios characterized by the power-law index, n. The impact of physical factors on the velocity profile, temperature distribution, concentration field, and entropy output of the system is clearly illustrated through a variety of graphs.Results: The results indicated that the inclination angle of 20° had the best thermal characteristics compared to other inclinations. The entropy generation reached its maximum value at temperature difference of 13 K due to irreversibility of the system, which indicates that the system is more efficient.Discussion: Furthermore, the increasing percentage in Nusselt number is predicted to be 28.18% when the Prandtl number is taken a range. The Sherwood number enhanced up to 18.61% with a range of Brownian motion. A quantitative comparison is conducted between the present results and the literature in order to validate the superior efficiency of the used method

Performance Enhancement of Reverse Osmosis (RO) Membrane Using Nanocomposite Materials

Many attempts were made to enhance the performance of reverse osmosis (RO) membranes in the desalination process. Using ion exchange (IX) bed before RO process and modifying the structure of RO membranes are some of these attempts. Thin film nanocomposite (TFN) membrane is the novel type of RO membranes which is the best in nanofiltration applications. TFN membranes have many new advantages due to the change of their structure in comparison with traditional membranes. In this study the performance of a TFN membrane was compared with that of standard thin film composite (TFC) spiral wound water desalination RO membrane for filtration of IX produced water. The results from the filtration process showed that the flux and water permeability of TFN are 1.55 and 1.56 times that of TFC for feed water with 2050 ppm NaCl concentration with nearly unchanged level of the membrane salt rejection, which will reduce the filtrated water cost

CFD STUDY OF USING DIFFERENT HEAT SINKS FOR ELECTRONIC EQUIPMENTS COOLING

Cooling of Electronic equipment’s is an attractiveresearch area in engineering applications. Continuedminimization of electronic system has resulted in dramaticincrease in the amount of heat generated per unit volume, Theaim of this study is to use computational Fluid Dynamics inorder to draw a CFD model for forced cooling conjugate heattransfer analyses in heat generating electronic systems andcompare between a collection of actual commercial heat sinksdifferent from in geometry ,material , and number of fins .Acomplete computer chassis model with heat sinks and fansinside was created and parametric analyses were performed tocompare the effects of different turbulence models, meshresolutions, and radiative heat transfer. The CFD software wasused, ANSYS Icepack 18.0 for preprocessing and fluent forsolution and post processing. The road map was applied to fivedifferent heat sinks and another three heat sink as a validationmodeled into the full chassis. Numerical results were comparedwith the available experimental data and they were in goodagreement

Design of a Circular Concentric Microstrip Patch Antenna Array for WI-FI Band Energy Harvesting

Wireless networks have gone through unprecedented changes in the last decade owing to the rise in the number of users. Radio frequency (RF) energy harvesting (EH) (termed as RF-EH) can be a potential solution to exploit this traffic in communication systems, one of the key issues is designing a compact antenna array while providing reliable capturing characteristics over the operating band. In energy harvesting systems, printed slot antennas have received much attention owing to their matching characteristics. In addition, they present really appealing physical features, such as simple structure, small size, and low cost. In this paper, a small circular concentric antenna array utilizing rectangular radiating patch elements and defected ground structure for RF-EH is proposed. The antenna is designed using the CST Microwave Studio software package and realized on a Roger 5880 substrate with ���� = 2.2 and ℎ = 3.18 ����. The simulations demonstrated the effective performance of the proposed circular antenna array structure in terms of high gain of about 15.8 dBi, high efficiency, and the possibility to collect RF power from all direction

Vibration Analysis of Material Size-Dependent CNTs Using Energy Equivalent Model

This study presents a modified continuum model to investigate the vibration behavior of single and multi-carbon nanotubes (CNTs). Two parameters are exploited to consider size dependence; one derived from the energy equivalent model and the other from the modified couple stress theory. The energy equivalent model, derived from the basis of molecular mechanics, is exploited to describe size-dependent material properties such as Young and shear moduli for both zigzag and armchair CNT structures. A modified couple stress theory is proposed to capture the microstructure size effect by assisting material length scale. A modified kinematic Timoshenko nano-beam including shear deformation and rotary inertia effects is developed. The analytical solution is shown and verified with previously published works. Moreover, parametric studies are performed to illustrate the influence of the length scale parameter, translation indices of the chiral vector, and orientation of CNTs on the vibration behaviors. The effect of the number of tube layers on the fundamental frequency of CNTs is also presented. These findings are helpful in mechanical design of high-precision measurement nano-devices manufactured from CNTs

Heat Transfer Performance of a Gasketed Plate Heat Exchanger Subjected to Mechanical Vibration

Heat transfer characteristics in terms of heat transfer coefficient, overall heat transfer coefficient and heat exchanger effectiveness of a vertical counter flow Gasket plate heat exchanger (GPHE) are experimentally investigated. The tested PHE is made of stainless-steel plates with 30° chevron angle (β=30°). The surface enlargement factor, Ф for all plates was 1.17. Six plates were installed; providing two hot channels and three cold channels in counter flow arrangement. The vibration effect on tested GPHE has been performed and compared with non-vibration model. Vibration frequencies (ω) are in the range of 13.33 to 46.67 cps and vibrational dimensionless amplitude (A/De) varied from 9.14*10-3 to 52.66*10-3 at various oscillating Reynolds numbers were employed. It is found that the heat transfer performance of the GPHE is enhanced when vibration is applied. The maximum enhancement percentage of the GPHE heat transfer coefficient, overall heat transfer coefficient and effectiveness due to vibration are 43%, 31% and 18%, respectively. These maximums are occurred at oscillation Reynolds number of 211.34 and A/De = 52.66*10-3 which after the resonance condition. The GPHE performance after and before resonance condition are obtained. Finally, correlations for GPHE Nusselt number, when vibration is and is not applied, are obtained with an acceptable error of 3.99%

Heat Transfer Performance of a Gasketed Plate Heat Exchanger Subjected to Mechanical Vibration أداء إنتقال الحرارة لمبادل حراري من النوع اللوحي مجهز بمانع تسريب يهتز إهتزازا ميکانيکيا

Heat transfer characteristics in terms of heat transfer coefficient, overall heat transfer coefficient and heat exchangereffectiveness of a vertical counter flow Gasket plate heat exchanger (GPHE) are experimentally investigated. The testedPHE is made of stainless-steel plates with 30° chevron angle (β=30°). The surface enlargement factor, Ф for all plateswas 1.17. Six plates were installed; providing two hot channels and three cold channels in counter flow arrangement.The vibration effect on tested GPHE has been performed and compared with non-vibration model. Vibration frequencies(ω) are in the range of 13.33 to 46.67 cps and vibrational dimensionless amplitude (A/De) varied from 9.14*10-3 to52.66*10-3 at various oscillating Reynolds numbers were employed. It is found that the heat transfer performance of theGPHE is enhanced when vibration is applied. The maximum enhancement percentage of the GPHE heat transfercoefficient, overall heat transfer coefficient and effectiveness due to vibration are 43%, 31% and 18%, respectively.These maximums are occurred at oscillation Reynolds number of 211.34 and A/De = 52.66*10-3 which after theresonance condition. The GPHE performance after and before resonance condition are obtained. Finally, correlationsfor GPHE Nusselt number, when vibration is and is not applied, are obtained with an acceptable error of 3.99%

Numerical Investigation of Combustion in HCCI Diesel Engine Fuelled with Biodiesel Blends

Homogeneous Charge Compression Ignition (HCCI) is an advanced combustion technology being considered for internal combustion engines due to the potential for high fuel conversion efficiency and extremely low particulate matter (PM) and Nitrogen Oxides (NOx) emissions. In HCCI engines, there is no direct control method for auto ignition time. A common method to indirectly control the ignition timing in HCCI combustion engines is altering engine’s parameters which can affect the combustion. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This work introduces a new predictive multi-zone model for the description of combustion in HCCI engines. A multi zone model with reduced fuel chemistry was developed to simulate the combustion process in HCCI engines and predict engine performance. In this work, a parametric study on Diesel/Biodiesel blends(D80B20) HCCI combustion is conducted in order to identify the effect of equivalence ratio values (0.1786, 0.27, 0.37, and 0.4762) on combustion and engine performance parameters. Two kinds of parameters will be discussed. First, in-cylinder pressure, temperature and net heat release rate diagrams at altering Diesel/Biodiesel dose (0%, 20%, 40%, 60%), then the second category, the variation of start of combustion and combustion duration which are performance parameters of HCCI Diesel Engine