Effect of the Fins Length for the Passive Cooling of the Photovoltaic Panels

A two-dimensional (2D) numerical model was used to simulate the use of a phase change material linked to a PV system to control the temperature rise of the PV cells. The predicted temperatures using the 2D model have been compared with experimental and numerical data of the literature and a good agreement was obtained for both the isotherm contours and time evolution of the temperature.An extended surface (fins) has been used in order to improve conductive heat transfer and to reinforce the thermal homogeneity. Concerning the inner fins included on the PV panel (Front), the obtained results show that these fins reduce significantly the temperature. Furthermore, the configurations of L = 25, 30 and 35 mm allow better cooling of the PV panel. On the other hand, the back inner fin used reduces dramatically the performance of the PV/PCM system for cooling the panel

Numerical analysis of the influence of maximum residual thermal stresses on the intensity factor between the matrix and particle interfaces in metal matrix composite

A critical problem in the application of metal matrix composites is the presence of high residual thermal stresses induced during the development process. These thermally induced stresses are generally detrimental to the service life of this type of composite. This article discusses the influence of maximum residual stresses on the intensity factor. The results interpreted in terms of damage, allowed us to identify the risk zones; characterized by a significant level of maximum residual stresses (S11Max, S22Max, S33Max), namely the particle/Matrix interface. The results also show that the loading conditions and the inter-distance between matrix and particle with two interfacial cracks have an important effect on max residual stresses and stress intensity factors. &nbsp

The Investigation of the Mixed Convection from a Confined Rotating Circular Cylinder

In this paper, a numerical study on the two-dimensional laminar mixed convective flow and heat transfer from an rotating circular horizontal and isothermal cylinder confined in a horizontal channel. The blockage ratio and the Prandtl number are fixed at 0.05 and 0.7 respectively. The continuity, momentum and energy equations are solved via the finite-volume method. Our results are in very good agreement with those resulting from preceding studies to Ri=0 and a=0, which makes it possible to validate on important extension of present work. The mixed convective flow and heat transfer is simulated by the Reynolds number is studied in the range 1 <Re <40, the Richardson number (Ri) demonstrating the influence of thermal buoyancy ranges from 0 to 1 and for rotational rate from α=0 to α=4. Major emphasis is given to the effect of rotating a circular cylinder on the mixed convection and also on the measurements of the local and average Nusselt numbers are also obtained. Furthermore, the representative streamlines and isotherm patterns are presented and discussed

Simultaneous Excitation of Helium by Means of an Electron and a Photon: A Joined Experimental and Theoretical Study

We report on a joined experimental and theoretical study of differential cross-sections resulting from inelastic scattering of a monoenergetic electron by helium atoms in the presence of an intense carbon dioxide laser. In particular, we measured the signals of the scattered electrons during the simultaneous electron–photon excitation of He 21P state for the first three microseconds of the laser pulse. The signals were measured for an incident electron energy of 45 eV and showed a structure that emerged at small scattering angles. The latter was found to be sensitive to the nature of the transferred photons, as well as the intensity of the laser field. The experimental findings were supported by quantum calculations based on the second-order Born approximation in which the correlated electron–electron interactions were taken into account.publishedVersio

The Effect of Operating Parameters on Total Cross-membrane Flux in a PVDF Flat Sheet Membrane

Membrane distillation (MD) is an emerging thermal membrane technology that involves water vapor driven by a vapor pressure gradient over a hydrophobic membrane. MD faces several challenges, one of which is the flux of water vapor. The total cross-membrane flux in membrane distillation was investigated in this paper using the co-current PVDF flat sheet for direct contact. membrane distillation applications. The goal of this research is to improve total cross-membrane flux. The effect of various operational parameters is studied, including feed inlet temperature (333.15–358.15 K), feed flow rate (1–2.5 kg/s), permeate inlet temperature (288.15–313.15 K), and feed inlet NaCl concentration (0.035 to 0.485 kg/kg). To acquire a good value of total cross-membrane flux, their interactions with the total cross-membrane flux are studied in this work. The obtained results were computed during MATLAB-Simulations under several scenarios adopting the Trial-&-Error approach. This last inputs various parameters' values and thus draws the required curves to be discussed and analyzed. The results indicated that the PVDF flat sheet membranes provide a significantly higher total cross-membrane flux at higher feed input temperatures, producing a 73.2075 kg/(m2 h) at a feed inlet temperature of 358.15 K, a permeate inlet temperature of 293.15 K, and a flow rate of 2.5 kg/s, with a feed inlet NaCl concentration of 0.035 kg/kg. Feed inlet temperature significantly affected the total flux through the membrane; however, flow rate, permeate inlet temperature, and feed inlet NaCl concentration had a less significant effect

Performance Investigation of the Solar Membrane Distillation Process Using TRNSYS Software

Membrane distillation (MD) is a separation process used for water desalination, which operates at low pressures and feeds temperatures. Air gap membrane distillation (AGMD) is the new MD configuration for desalination where both the hot feed side and the cold permeate side are in indirect contact with the two membrane surfaces. The chapter presents a new approach for the numerical study to investigate various solar thermal systems of the MD process. The various MD solar systems are studied numerically using and including both flat plate collectors (the useful thermal energy reaches 3750 kJ/hr with a total area of 4 m2) and photovoltaic panels, each one has an area of 1.6 m2 by using an energy storage battery (12 V, 200 Ah). Therefore, the power load of solar AGMD systems is calculated and compared for the production of 100 L/day of distillate water. It was found that the developed system consumes less energy (1.2 kW) than other systems by percentage reaches 52.64% and with an average distillate water flow reaches 10 kg/h at the feed inlet temperature of AGMD module 52°C. Then, the developed system has been studied using TRNSYS and PVGIS programs on different days during the year in Ain Temouchent weather, Algeria

Modeling solar desalination with reverse osmosis (RO) powered by concentrating solar power (CSP) plan

This article deals with the desalination of seawater and brackish water, which can deal with the problem of water scarcity that threatens certain countries in the world; it is now possible to meet the demand for drinking water.  Currently,  among  the  various  desalination  processes,  the  reverse  osmosis  technique  is  the  most  used. Electrical energy consumption is the most attractive factor in the cost of operating seawater by reverse osmosis in desalination plants.  Desalination  of  water by  solar  energy  can be  considered  as a  very  important  drinking  water alternative.  For  determining  the  electrical  energy  consumption  of  a  single  reverse  osmosis  module,  we  used  the  System  Advisor  Model  (SAM)  to  determine  the  technical  characteristics  and  costs  of  a  parabolic  cylindrical installation and Reverse Osmosis System Analysis (ROSA) to obtain the electrical power of a single reverse osmosis module. The electrical power of a single module is 4101 KW; this is consistent with the manufacturer's data that this power must be between 3900 kW and 4300 KW. Thus, the energy consumption of the system is 4.92 KWh/m3.Thermal power produced by the solar cylindro-parabolic field during the month of May has the maximum that is 208MWth, and the minimum value during the month of April, which equals 6 MWth. Electrical power produced by the plant varied between 47MWe, and 23.8MWe. The maximum energy was generated during the month of July (1900 MWh) with the maximum energy stored (118 MWh)

Techno-economic analysis of stand-alone solar desalination at variable load conditions

The operation of large-scale reverse osmosis units in combination with different solar power plants, both, Concentrating Solar Power (CSP) and Photovoltaics (PV) has been evaluated under variable load conditions. In the case of the Reverse Osmosis (RO) unit, configurations with and without an energy recovery device have been considered. In the case of the CSP plant, a thermal storage system with several capacities (8-14 h) covers the periods with low solar radiation and no storage has been taken into account for the PV plant due to the prohibitively high cost of batteries at large scale. The analysis has been done for a specific location in Algeria, considering different scenarios to adapt the operation of the RO unit at partial load in order to assure a stable operation. The dynamic performance of the RO unit is presented for each scenario, together with an economic analysis

Thermo-convective Study of a Shell and Tube Thermal Energy Storage Unit

In this paper, we have studied numerically thermo-convective characteristics between a heat transfer fluid (HTF) and phase change material (PCM) in shell and tube thermal energy storage (TES) unit. The paraffin wax is considered as a PCM, filled in a shell which is thermally isolated with the external environment, while the water plays a role of a HTF and flows inside the tube at the moment of charging and discharging cycle. The heat transfer between HTF and PCM is performed by conduction and forced convection, this transfer allows to change the physical state of PCM solid-liquid to obtain a quantity of storable heat in order to create a thermal battery. Enthalpy formulation is used to analyze the heat transfer during melting and solidification process. A good agreement was found between our numerical predictions and the results of the literature. On the other hand, we have investigated the effect of geometrical parameters (tube length and shell diameter) and Reynolds number on the charging and discharging cycles. The obtained results reveal that the tube length and the shell diameter are the most influential parameters on the time of storage system. Similarly, the Reynolds number has much impact on the HTF outlet temperature and the time of solidification and melting process. Furthermore, we have proposed a new thermal storage unit containing the Paraffin wax and RT60 that it gives us a good rate and time of storage compared to the first unit that has only the paraffin wax