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A cross-flow turbine (CFT) is a drum-shaped impulse turbine where water flows across the turbine. Usually, it works in two-phase conditions, but in some cases, it is also submerged. During the internal flow, water flows in semi-free flow conditions where water within the blades is rotated, and water at the main flow translates. This condition induces a recirculation vortex, especially inside the void location where the primary or rotated flow does not pass it. Several studies found that the recirculation flow creates a 15% loss. However, the loss must be elaborated on; at least, there are two types of secondary flow inside the CFT, which are loss source: the wake region in the main flow and the recirculation flow. Based on the review of previous studies, the free flow after the first stage has Reynolds numbers ranging from 60k to 600k. The loss at the main flow is less than the recirculation effect inside the void. It is recommended that a strain-stress relations study be conducted on it.

Urine is primarily composed of water (about 95%), with urea (around 2%), creatinine (approximately 0.1%), uric acid (about 0.03%), and various ions. Although human urine constitutes 1% of the volume of domestic wastewater, it contains significant amounts of chemical oxygen demand (COD) (∼10%). This study focused on the elimination of COD in urine using a cross-flow filtration system and testing the effectiveness of various membranes (microfiltration (MCE01), ultrafiltration (UP005 and UP010), and nanofiltration (NP010 and NF270)). The steady-state flux of the NF270 membrane increased from 10.8 to 23.9 L/m2/h as the pressure increased from 10 to 25 bar. A significant COD removal efficiency was obtained for the NF270 membrane at an operating pressure of 25 bar. COD concentration decreased from 7,392 to 1,270 mg/L with 82.8% rejection. In contrast, none of the membranes performed well in terms of urea removal efficiency. According to the findings, urea concentration decreased from 6,712 to 6,043 mg/L with 9.9% rejection. Moreover, ion contents (calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), ammonium (NH4+), phosphate (PO43−), sulfate (SO42−), and chloride (Cl−)) of the membrane permeates were also measured.

This study focuses on the filtration of high concentration palm biodiesel fuels, which are increasingly being used in marine diesel engines due to their environmental benefits and cost-effectiveness. The existing filtration systems for biodiesel fuels are reviewed, highlighting their limitations in handling high concentration blends. The primary objective is to design and develop a cross-flow ceramic membrane filter rig specifically tailored for marine diesel engines. A novel cross-flow ceramic membrane filter rig is designed and constructed to address the unique challenges posed by high concentration palm biodiesel fuels. The rig is equipped with a high-pressure pump, temperature control system, and a filtration chamber to simulate real-world marine diesel engine conditions. Experimental tests are conducted to evaluate the filter’s efficiency in removing contaminants and ensuring smooth fuel flow under various operating conditions. The results show the permeate productivity of the cross-flow ceramic membrane filter rig for filtering the high concentration palm biodiesel fuels, at different pressures. The study concludes by highlighting the potential of this innovative filtration system to enhance the performance and reliability of marine diesel engines operating on high concentration biodiesel blends.

One of the methods of analyzing a heat exchanger consists in determining the heat transfer rates and outlet temperatures of the fluids for known mass flows, inlet temperatures, and exchanger type and size. This requires calculating the exchanger performance for known transfer surface area but unknown outlet temperatures. The concept of the heat transfer effectiveness (HTE) can be applied to determine the heat transfer rate of the specified heat exchanger without knowing the outlet temperatures of the fluids. This article presents the results of calculations of the HTE parameter for a cross-flow heat exchanger with staggered tube banks. The analysis takes into account six different models of convection heat transfer over the tube banks. In this scenario, the impact of the applied convection model on the value of HTE for the considered heat exchanger was examined. For the considered calculation cases, the value of the HTE parameter is in the range from 0.3 to 0.48 and it decreases with the increase of the flow rate of both air and the flue gases. It has been shown that the results of all four models are very similar, while the other two models bring about either an increase or a decrease of the values of the parameter investigated. It was found that for the analyzed heat exchanger a simplified criterion for the convection heat transfer over tube banks can be used to determine the effectiveness of the heat transfer with the Reynolds number being the only parameter.

Isolation of extracellular vesicles (EVs) from cell culture supernatant or plasma can be accomplished in a variety of ways. Common measures to quantify relative success are: concentration of the EVs, purity from non-EVs associated protein, size homogeneity and functionality of the final product. Here, we present an industrial-scale workflow for isolating highly pure and functional EVs using cross-flow based filtration coupled with high-molecular weight Capto Core size exclusion. Through this combination, EVs loss is kept to a minimum. It outperforms other isolation procedures based on a number of biochemical and biophysical assays. Moreover, EVs isolated through this method can be further concentrated down or directly immunopurified to obtain discreet populations of EVs. From our results, we propose that cross-flow/Capto Core isolation is a robust method of purifying highly concentrated, homogenous, and functionally active EVs from industrial-scale input volumes with few contaminants relative to other methods.

This work addresses retrofitting the infrastructure of multiple-effect vacuum membrane distillation (V-MEMD) units by using cross-flow configuration (CFC). In this configuration, the feed water is evenly divided and distributed over the effects. In this case, the feed water stream for each effect is kept at a high temperature and low flow rate. This will lead to an increase in the vapor pressure gradient across the hydrophobic membrane and can also maintain the thermal energy of the stream inside the individual effect. It is found that CFC improves internal and global performance indicators of productivity, energy, and exergy. A mathematical model was used to investigate the performance of such a modification as compared to the forward-flow configuration (FFC). The cross-flow configuration led to a clear improvement in the internal performance indicators of the V-MEMD unit, where specifically the mass flux, recovery ratio, gain output ratio, and heat recovery factor were increased by 2 to 3 folds. Moreover, all the global performance indicators were also enhanced by almost 2 folds, except for the performance indicators related to the heat pump, which is used to cool the cold water during the operation of the V-MEMD unit. For the heat pump system, the specific electrical energy consumption, SEEC, and the exergy destruction percentage, Ψdes, under the best-operating conditions, were inferior when the feed water flow was less than 159 L/h. This can be attributed to the fact that the heat rejected from the heat pump system is not fully harnessed.

The publication presents the results of the study on vertical cross-flow wind turbine with frontal arc-shaped and flat deflectors that increase the turbine’s power coefficient by up to 0.08. The optimal development angle of the arc-shaped deflector has been determined. The obtained results are compared with those of numerical and physical studies published in various reputable journals. Relevant fields of application are discussed. The research is carried out at test bench No. 7C (wind turbines) in the Laboratory of Hydropower and Hydraulic Turbomachinery at the Technical University of Sofia.

The present work experimentally analyses the surface heat transfer from a thermally active copper rod of circular cross-section placed in different arrangement of dummy rods. All the rods are arranged in cross-flow. Wind-tunnel experiments for nine different arrangements of heated rod at a Reynold’s number of 12600 were investigated. Temperature variation, heat transfer and vertical velocity distribution downstream of the cylinder were studied. Higher heat transfer rate was obtained when the heated rod was placed in downstream position due to the rubbing action of vortex shedding phenomena of upstream rod. Maximum heat transfer rate was reported in tandem arrangement of rod with the thermally active cylinder placed in the downstream row. The wall effect becomes dominant near the wall region and affects the flow and heat transfer in the vicinity of wall. Pressure and logarithmic value of temperature has been reported at suitable positions to explain the thermofluid physics.

The use of passive mode of heat transfer enhancement are most commonly used for the performance improvement with conservation of conventional fuels. In recent times, to visualize the insight of fluid flow analysis, the numerical simulations are mostly preferred. The number of grid points present in the in the fluid domain near the wall governs the accuracy and precision of the numerical study. Hence in the present study, three different near wall grid systems are consider to evaluate its effect on Nusselt number friction factor for the staggered tube bank arrangements. It is reported that y+ as 10, insensitive to boundary layer effects at higher flow rate, while y+ as 1.0, and 0.10 are in close approximation.

ross flow turbines are widely used as turbines for driving micro-scale hydropower plants in rural areas, but their efficiency is still low because cross flow turbines only use one nozzle. The utilization of the potential energy of water is not optimal yet to be converted into pressure and kinetic energy of water in the nozzles with high water velocity hitting the turbine blades. The problem of cross flow turbines with one nozzle has an uneven flow of water to the turbine blades, and it is not effective in converting potential energy into power in the turbine. The purpose of this research is to develop a four-nozzle Cross Flow turbine and test its performance. The method used is to conduct experimental testing in a laboratory that tests the performance of a cross flow turbine using four nozzles. A cross flow turbine with four nozzles has better performance than a cross flow turbine using only one nozzle. The results obtained that the cross flow turbine with four nozzles where the water jets out of the nozzle is more evenly distributed and the flow of water enters the turbine blade runner, resulting in a good impulse reaction in the blades. The conclusion is that the performance of the four nozzle cross flow turbine is able to produce higher turbine rotation, power and efficiency.