Enhancement of solar evacuated tube unit filled with nanofluid implementing three lobed storage unit equipped with fins.

This study discusses an evacuated tube collector-type solar water heater (ETCSWH) using a phase change material (PCM) chamber with fins, nanofluid, and nano-enhanced phase change material (NEPCM). First, the charging phenomena in a horizontal triplex tube heat exchanger (TTHX) equipped with fins, natural convection, and an ETCSWH system without PCM is simulated to validate the solution. The impact of adding fins and nanoparticles with a volume fraction of 3% of Al2O3 and Cu to paraffin wax and water-based fluid, respectively, on the unit's efficiency has been examined. The proposed system for the PCM melting process, heat storage, fluid flow behavior in the system, and velocity distribution and temperature contour in the storage tank and three parts of the absorber tube have been evaluated using ANSYS FLUENT software in a three-dimensional and transient simulation. The results show that Case 8 has improved by 39.7% compared to Case 1 and Case 4 by 5.2% compared to Case 1 within 4 h of the melting process. Also, Case 8 with a 43% and 6.4% shorter melting time than Cases 1 and 5 has the best performance and the greatest heat transfer rate. The productivity of the ETCSWH system is considerably enhanced by the use of fins, NEPCM, and nanofluid.

Numerical simulation for impact of implement of reflector and turbulator within the solar system in existence of nanomaterial.

Turbulent flow of oil based hybrid nanofluid within an absorber tube of concentrated solar system has been evaluated in this article. To concentrate the solar irradiation, the parabolic plate has been located below the tube and variable heat flux was considered as the boundary condition of the tube. The presence of a turbulator within the circular tube causes secondary flow to increase. Both thermal (Sgen,th) and frictional (Sgen,f) components of irreversibility were reported in outputs. As Re increases, the residence time decreases and lower outlet temperature has been achieved. Sgen,th decreases about 57.36% with growth of Re while Sgen,f increases about 17.44 times. As the number of rows of tapes increases, the value of Sgen,f enhances about 69.23% while the value of Sgen,th decreases around 3.67%. Increase of pitch ratio causes Sgen,th to decrease about 11.25% while frictional component increases around 76.7%.

Simulation of melting paraffin with graphene nanoparticles within a solar thermal energy storage system.

In this paper, applying new structure and loading Graphene nanoparticles have been considered as promising techniques for enhancing thermal storage systems. The layers within the paraffin zone were made from aluminum and the melting temperature of paraffin is 319.55 K. The paraffin zone located in the middle section of the triplex tube and uniform hot temperatures (335 K) for both walls of annulus have been applied. Three geometries for the container were applied with changing the angle of fins (α = 7.5°, 15° and 30°). The uniform concentration of additives was assumed involving a homogeneous model for predicting properties. Results indicate that loading Graphene nanoparticles causes time of melting to decrease about 4.98% when α = 7.5° and the impact of ϕ improves about 5.2% with reduce of angle from 30° to 7.5°. In addition, as angle declines, the period of melting decreases around 76.47% which is associated with augmentation of driving force (conduction) in geometry with lower α.

Hybrid nanofluid flow within cooling tube of photovoltaic-thermoelectric solar unit.

In this work, the thermoelectric generator (TEG) layer has been combined with conventional layers of photovoltaic-thermal (PVT) modules to use the waste heat and increase the efficiency. To reduce the cell temperature, there exists a cooling duct in the bottom of the PVT-TEG unit. Type of fluid within the duct and structure of duct can change the performance of the system. So, hybrid nanofluid (mixture of Fe3O4 and MWCNT with water) has been replaced instead of pure water and three various configurations of cross section [STR1 (circular), STR2 (rhombus), STR3 (elliptic)] have been implemented. Through the tube incompressible laminar flow of hybrid nanofluid has been solved while in solid layers of panel, pure conduction equation has been simulated involving heat sources resulting from optical analysis. According to simulations, the third structure (elliptic) has the best performance and rise of inlet velocity causes overall performance to enhance about 6.29%. The values of thermal and electrical performances for elliptic design with equal fractions of nanoparticles are 14.56% and 55.42%, respectively. With the best design, electrical efficiency improves about 16.2% in comparison with an uncooled system.

Entropy generation and thermal analysis of nanofluid flow inside the evacuated tube solar collector.

In the current investigation, the thermal and thermodynamic behavior of a buoyancy-driven evacuated tube solar collector (ETSC) has undergone precise evaluation, and the efficacy of nanoparticle dispersion in the testing fluid was scrutinized. The natural convection process was analyzed in different vertical sections of the absorber tube. The outputs for water and the utilized nanofluid were compared at various cutting planes along the tube during the simulation time. In this problem, CuO nanoparticles with optimum thermal properties were distributed in the base fluid. According to the surveyed results, the temperature distribution analysis illustrates that the mean wall temperature experiences more enhancement when the nanofluid is used. The comparison of the heat transfer coefficient between the two simulated cases show the competency of utilizing CuO-[Formula: see text] nanofluid and highlight its crucial character in improving the thermal treatment of the operate fluid through the collector pipe. Based on irreversibility assessment, the irreversibility due to fluid friction rises when the nanofluid is applied during the flow time. In contrast, the entropy generation of pure water owing to heat transfer surpasses the case with nanofluid. More specifically, the heat transfer entropy generation experience a reduction of about 6.3% (0.143-0.134 W/K) by utilization of CuO with a volume fraction of 5% after 1 h of flow time, whereas the entropy generation by fluid viscosity enhances up to 23% when the nanofluid is applied in the system. The irreversibility originated from heating and fluid viscosity has significant difference in value, owing to the fluid's low-velocity range in the natural convection process.

Heat transfer intensification of nanomaterial with involve of swirl flow device concerning entropy generation.

The thermal features of hybrid nano-powder turbulent motion through a pipe employing helical turbulator is numerically simulated via Finite Volume Method (FVM). The hybrid nanofluid (MWCNTs + Fe3O4 + H2O) is obtained by uniformly dispersing MWCNTs + Fe3O4 nanomaterials in H2O. The characteristics features of thermal energy transfer of hybrid nanofluid are investigated by varying the pitch ratio (P) of the helical turbulator and Reynolds number (Re) of the fluid. The outputs of the study are depicted in terms of contour plots of temperature, velocity, frictional irreversibility Sgen,f, and thermal irreversibility Sgen,th. The variation of Sgen,f, and Sgen,th with changing P and Re are also displayed by 3D plots. It is found that making the fluid more turbulent by increasing Re, the temperature of the fluid drops whereas the fluid velocity augments. The frictional irreversibility enhances, whereas the thermal irreversibility drops with the increasing turbulent motion. The decreasing P causes to drop the temperature of the higher turbulent fluid flow, while opposite effect is observed for smaller Re. The decreasing P causes to enhance the fluid mixing and thus augments the fluid velocity. Sgen,f and Sgen,th both augment with decreasing P. The comparison of current outputs with the older article shows an acceptable accuracy. The results of the present investigation will be useful in modelling of efficient thermal energy transfer systems.

Upshot of heterogeneous catalysis in a nanofluid flow over a rotating disk with slip effects and Entropy optimization analysis.

The present study examines homogeneous (HOM)-heterogeneous (HET) reaction in magnetohydrodynamic flow through a porous media on the surface of a rotating disk. Preceding investigations mainly concentrated on the catalysis for the rotating disk; we modeled the impact of HET catalysis in a permeable media over a rotating disk with slip condition at the boundary. The HOM reaction is followed by isothermal cubic autocatalysis, however, the HET reactions occur on the surface governed by first-order kinetics. Additionally, entropy minimization analysis is also conducted for the envisioned mathematical model. The similarity transformations are employed to convert the envisaged model into a non-dimensional form. The system of the modeled problem with ordinary differential equations is analyzed numerically by using MATLAB built-in bvp4c function. The behavior of the emerging parameters versus the thermal, concentration, and velocity distributions are depicted graphically with requisite discussion abiding the thumb rules. It is learned that the rate of the surface catalyzed reaction is strengthened if the interfacial area of the permeable media is enhanced. Thus, a spongy medium can significantly curtail the reaction time. It is also noticed that the amplitude of velocity and thermal profile is maximum for the smallest value of the velocity slip parameter. Heat transfer rate declines for thermophoresis and the Brownian motion parameter with respect to the thermal slip parameter. The cogency of the developed model is also validated by making a comparison of the existing results with a published article under some constraints. Excellent harmony between the two results is noted.

Exploration of dual solutions for an enhanced cross liquid flow past a moving wedge under the significant impacts of activation energy and chemical reaction.

The mathematical modeling and numerical simulation are conferred to offer the novel perception of binary chemical reaction with an activation energy aspect on magneto flow comprising Cross liquid inspired by a moving wedge. The influences of Soret and Dufour are also presented. The similarity procedure is utilized to modify the leading PDEs into a non-linear system of ODEs and then analyzed through a significant technique namely bvp4c based on the collocation method. The impacts of varying distinct parameters under the temperature and the velocity distribution are explored and discussed with the support of the graphs. The outcomes indicate that the multiple results are attained for a specific amount of shrinking/stretching constraint. Furthermore, the Weissenberg number reduces the skin factor and speed up the heat and mass transport rate in the lower and upper branch solutions. Also, an assessment of current results with earlier published literature is made in the limiting case.

Modeling of entropy optimization for hybrid nanofluid MHD flow through a porous annulus involving variation of Bejan number.

We numerically investigate the non-Darcy magnetohydrodynamic hybrid nanoparticle migration through a permeable tank using control volume finite element method through entropy generation. The roles of various amounts of Permeability, Lorentz and Rayleigh (Ra) number are investigated upon the various aspects of the hybrid nanofluid flow through contour and 3-D plots. Through curve fitting technique, analytical expressions for Nuave and Bejan number as functions of Ra, Ha and Da are obtained. It is found that the strength of the vortexes decline and temperature of the inner wall augments with the higher magnetic field, while temperature drops with increasing buoyancy forces and medium permeability. The irreversibility terms associated with the generation of the thermal energy and applied magnetic field (Sgen,th, Sgen,M) enhance while the other terms (Sgen,f, Sgen,p) drop with the rising values of the magnetic field strength. These quantities show exactly opposite behavior with augmenting Da. The Bejan number drops while Nuave augments with the rising buoyancy forces. The agreement with the previous published results confirms the accuracy of the employed computational model.

Magnetohydrodynamic nanofluid radiative thermal behavior by means of Darcy law inside a porous media.

Radiative nanomaterial thermal behavior within a permeable closed zone with elliptic hot source is simulated. Darcy law is selected for simulating permeable media in existence of magnetic forces. Contour plots for various buoyancy, Hartmann numbers and radiation parameter were illustrated. Carrier fluid is Al2O3-water with different shapes. Outputs prove that conduction mode augments with enhance of Ha. Nu augments with considering radiation source term.

Uniform magnetic force impact on water based nanofluid thermal behavior in a porous enclosure with ellipse shaped obstacle.

In the present research, aluminum oxide- water (Al2O3-H2O) nanofluid free convection due to magnetic forces through a permeable cubic domain with ellipse shaped obstacle has been reported. Lattice Boltzmann approach is involved to depict the impacts of magnetic, buoyancy forces and permeability on nanoparticles migration. To predict properties of Al2O3- water nanofluid, Brownian motion impact has been involved. Outcomes revels that considering higher magnetic forces results in greater conduction mechanism. Permeability can enhance the temperature gradient.

Non-equilibrium Model for Nanofluid Free Convection Inside a Porous Cavity Considering Lorentz Forces.

In current article, transportation of CuO nanoparticles through a porous enclosure is demonstrated. The enclosure has complex shaped hot wall. Porous media has been simulated via two temperature equations. Magnetic force impact on nanofluid treatment was considered. Control volume based finite element method has been described to solve current article in vorticity stream function form. Single phase model was chosen for nanofluid. Nanofluid characteristics are predicted via KKL model. Roles of solid-nanofluid interface heat transfer parameter (Nhs), porosity, Hartmann and Rayleigh numbers have been illustrated. Outputs illustrated that conduction mode reduces with augment of Ra. Increasing magnetic forces make nanofluid motion to decrease. Temperature gradient of nanofluid decreases with augment of Nhs. Reducing porosity leads to enhance in Nusselt number.

Three-dimensional flow of nanofluid induced by an exponentially stretching sheet: an application to solar energy.

This work deals with the three-dimensional flow of nanofluid over a bi-directional exponentially stretching sheet. The effects of Brownian motion and thermophoretic diffusion of nanoparticles are considered in the mathematical model. The temperature and nanoparticle volume fraction at the sheet are also distributed exponentially. Local similarity solutions are obtained by an implicit finite difference scheme known as Keller-box method. The results are compared with the existing studies in some limiting cases and found in good agreement. The results reveal the existence of interesting Sparrow-Gregg-type hills for temperature distribution corresponding to some range of parametric values.

Design and implementation of series elastic actuators for a haptic laparoscopic device.

The design of a laparoscopic haptic device based on a 4-DOFs mechanism and Series Elastic Actuators (SEA) is described and the results of the theoretical and experimental examinations are presented. With a sufficient bandwidth and low impedance, the system provided a stable interaction with soft tissues, e.g., human liver, in virtual environments.

Variations in the detection of ZAP-70 in chronic lymphocytic leukemia: Comparison with IgV(H) mutation analysis.

Lack of immunoglobulin heavy chain genes (IgV(H)) mutation in patients with chronic lymphocytic leukemia (CLL) is associated with rapid disease progression and shorter survival. The zeta-chain (T-cell receptor) associated protein kinase 70 kDa (ZAP-70) has been reported to be a surrogate marker for IgV(H) mutation status, and its expression in leukemic cells correlates with unmutated IgV(H). However, ZAP-70 detection by flow cytometry varies significantly dependant on the antibodies used, the method of performing the assay, and the condition of the cells in the specimen. The clinical value of ZAP-70 testing when samples are shipped under poorly controlled conditions is not known. Furthermore, testing in a research environment may differ from testing in a routine clinical laboratory. We validated an assay for ZAP-70 by comparing results with clinical outcome and the mutation status of the IgV(H). Using stored samples, we show significant correlation between ZAP-70 expression and clinical outcome as well as IgV(H) mutation at a cut-off point of 15%. While positive samples (>15% positivity) remain positive when kept in the laboratory environment for 48 h after initial testing, results obtained from samples from CLL patients tested after shipping at room temperature for routine testing showed no correlation with IgV(H) mutation status when 15% cut-off was used. In these samples, cut-point of 10% correlated with the IgV(H) mutation (P = 0.0001). This data suggests that although ZAP-70 positivity correlates with IgV(H) mutation status and survival, variations in sample handling and preparation may influence results. We show that IgV(H) mutation results, unlike ZAP-70 remain correlated with CD38 expression and beta-2 microglobulin in shipped samples, and ZAP-70 testing should not be used as the sole criterion for stratifying patients for therapy.

Study on DNA diversity of Iranian populations of Erysiphe betae causal agent of sugar beet powdery mildew.

107 samples of E. betae were collected on infected leaves from all over Iranian beet cultivation areas. Their choosing were based on geographical and host origin(sugar beet, red beet, fodder beet and wild beet). 30 isolates were single colonized and grown on sugar beet susceptible genotype 7233. 107 specimens were analyzed by restriction fragment length polymorphism (RFLP) of the ribosomal internal transcribed spacers (ITS) and 5.8s DNA which previously amplified by the polymerase chain reaction (PCR) with 2 universal primers, ITS1 and ITS4. PCR product was affected by 9 different restriction enzymes. PCR product was a 645 bp band for all of the isolates. 3 restriction enzymes; CfoI, MspI and HaeIII could cut this fragment into smaller bands, but electrophoretic patterns were identical for all of the isolates. 30 single colonized isolates were used in RAPD experiments. In RAPD-PCR experiment genetic diversity was investigated with 30 isolates from different parts of the country. 59 random primers were used and then 21 primers that displayed good consistency and reproducibility were selected. Most of the primers revealed identical patterns between 3 to 14 bands. 5 primers that showed more polymorphism were selected to analyze 30 isolates. For these 5 primers 61 distinct bands were obtained which 62% of these bands were polymorphic. Results indicated that there is no relationship between cluster grouping and geographical origin and the isolates showed a high similarity.

Study on the overwintering of cleistothecia and conidia of Erysiphe betae causal agent of sugar beet powdery mildew in Iran.

Sugar beet leaves covered by sexual (cleistothecia) and asexual forms (mycelia and conidia) of Erysiphe betae were gathered at harvest time and maintained under natural outdoor conditions. In order to determine the function of cleistothecia and also conidia in the overwintering of E. betae some experiments were performed. The results showed that ascospores were unable to be released in petri dishes but their release under natural conditions occurred after 4 months. Under In vitro conditions ascospores did not germinate but on the leaves germination was rarely possible, however these ascospores were degraded after 7 days and didn't have pathogenicity. Conidia could induce pathogenicity after 3 but not 4 months. The period after inoculation until appearance of disease symptoms increased with aging of conidia. The results for conidial germination showed that fresh conidia had 80 percent germination on glass slides but it decreased sharply after 2 weeks and reached to 0 percent after 4 weeks. Although their germination on the leaves was not more than 46 percent of fresh conidia but they had good germination after 2 and 4 weeks. The results for the experiment to observe the first appearance of the disease in the field suggested that the first conidia were trapped by spore-trap in early June and the first symptoms appeared 20 days later. The conclusive results showed that ascospores had no function in the survival of the fungus and air-borne conidia are the main source of primary infections.

PCR production of a digoxigenin-labeled probe for the detection of human cytomegalovirus in tissue sections.

In situ hybridization (ISH) provides a means for identifying viral genomes in the context of tissue pathology. We have developed a specific and sensitive ISH probe for the detection of cytomegalovirus (CMV) DNA in formalin-fixed, paraffin-embedded tissue sections. Digoxigenin-11-dUTP was incorporated into a 435-base pair fragment of the CMV Major Immediate Early (MIE) gene with use of the polymerase chain reaction (PCR). Hybridized probe was detected by reaction with antidigoxigenin antibody coupled to alkaline phosphatase and chromogenic substrates. This method has detected CMV infection in routine clinical specimens from a variety of tissue types, including colon, kidney, liver, and stomach. Infection in cells with and without characteristic inclusions is revealed with this probe. The background is so low that single infected cells are detected unambiguously. No cross-hybridization was observed with cells infected with other viruses of Herpesviridae. This approach may be useful for producing probes for the detection of other viral genomes in tissue sections.