Improving the Stepped Distiller Performance in Combination with Vertical Corrugated Wick Solar Still and Finned Absorber

Optimal concentration of El Oued sand grains as energy storage materials for enhancement of hemispherical distillers performance

The present study aims to reach the best design of the fins installed on the basin absorber surface that achieves the highest performance of the hemispherical solar distillers. The fins represent one of the most important improvement techniques utilized to increase the evaporation rates inside the solar distillers, by increasing the heat transfer area between the absorption surface and the basin water. However, some designs of the fins have negative effects due to the shading problem, which causes a reduction of the absorption rates of solar rays. Therefore, the current study aims to find the best design of the fins that achieve the least shading effects and the highest performance of hemispherical solar distillers. To achieve this idea, two types of fins (cylindrical and conical) with a diameter of 1.5 cm and a height of 3 cm, with different gap distances of 3, 3.75, and 4.5 cm were studied. To achieve these, three hemispherical solar stills were tested under the same weather conditions, first is a conventional hemispherical still without fins (CHSWF) which is the reference distiller. The second is the hemispherical distiller with cylindrical fins (CyFHS), and the third is the hemispherical distiller with conical fins (CoFHS). The results show that the hemispherical distiller with cylindrical fins (CyFHS) productivity values are 5.55, 6.00, and 6.70 kg/m2, respectively, while the hemispherical distiller with conical fins (CoFHS) productivity values are 6.20, 6.65, and 7.15 kg/m2 at the gap distances of 3, 3.75, and 4.5 cm, respectively, compared to 4.20 kg/m2 produced by CHSWF. The results showed that the use of conical fins with a gap distance of 4.5 cm represents the optimal fin design that achieves the least shading and the highest performance of hemispherical solar distillers, with improvement rates of 70.24% compared to reference distiller (CHSWF).

Sustainable desalination can be achieved by adopting renewable energy-based low-cost and low-impact desalting techniques. In this investigation, capability of inclined felt sheet solar distiller in desalting seawater is assessed by evaluating its performance, distillate water quality, economics, and environmental impacts. The distiller with 1.18-m2 aperture area produced around 4.60L/day of distillate for a cumulative incident solar radiation intensity of about 20.52MJ/m2day. Its pollutant removal efficiency is very much superior to other available solar stills reported in literatures. Thermal model developed for estimating distiller's performance is able to predict its productivity with reasonable accuracy (only 8.0% deviation from experimental values) and was used for estimating distiller's performance in various seashore locations in India with varying clear days (191 to 246). Yearly mean distillate production and thermal and exergy efficiencies of the proposed distiller range between 3.60 to 4.50L/day, 36.45 to 42.39%, and 2.85 to 3.65%, respectively, in east seashore locations of India. Moreover, 18.46tons of CO2, 132.72kg of SO2, and 54.20kg of NO emission can be mitigated by adopting the distiller for potable water production. Distillate production cost of inclined felt sheet solar distiller is in the range of 1.15 to 2.29 INR/L and highly depends on the interest rate at which the distiller is financed. Generation of reasonable quantity of high-quality potable water at low cost with huge environmental benefits makes proposed inclined felt sheet solar distiller a suitable option for quenching thirst in coastal and remote locations.

Fabrication of hydrophobic flat sheet and hollow fiber membranes from PVDF and PVDF-CTFE for membrane distillation

In recent years, deep learning models have been extensively researched and applied in fault diagnosis. However, they often require substantial storage resources, posing challenges for deployment on embedded devices. A prevalent solution to this is leveraging knowledge distillation (KD) between teacher-student models. Through the distillation process, the student model can acquire knowledge from the teacher model without introducing additional parameters, thereby enhancing its performance. Nevertheless, when utilizing a powerful teacher model, the distillation performance is not always optimal. This is attributed to the teacher model’s significantly higher complexity compared to the student model, potentially leading to a diminished simulation effect by the student model. To address this issue, the variable-temperature gradient TOP-K KD (VTGTK-KD) method is proposed, which employs multiple pruned, medium-sized teacher models to facilitate a gradual distillation learning process. Furthermore, these models share the same architecture, fostering better knowledge transfer conditions at the logical layer. To further elevate distillation performance, VT distillation is introduced to ensure a balance between distillation speed and accuracy. Additionally, the Gradient TOP-K algorithm is utilized to eliminate erroneous knowledge from the teacher network. Ultimately, classification experiments were conducted on two bearing datasets. The experimental results demonstrate that the proposed VTGTK-KD method enhances distillation performance, surpassing other advanced KD approaches.

Bearing fault detection and classification under a diagnostics model with fewer parameters has been a challenging problem. A common solution is knowledge distillation (KD) using teacher–student models. Through the distillation process, the student model can acquire knowledge from the teacher model to enhance performance without introducing extra parameters. However, when using a powerful teacher model, distillation performance is not always ideal. This is because a more powerful teacher model can generate more specific classification strategies, which may result in poorer distillation performance. To this end, the multiassistant KD (MAKD) method is proposed, which bridges the gap between the teacher–student models by incorporating several intermediate-sized assistant models (AMs). Moreover, these AMs have the same architecture, which creates a better knowledge transfer condition at the logit layer. To further optimize the network structure to improve the distillation performance, decreasing threshold channel pruning (DTCP) is proposed to generate better AMs. DTCP leverages the scatter value of the decreasing function to prune the channels of the teacher model, which retains more channels that are beneficial to distillation. Finally, four-class and ten-class classification experiments are conducted on two bearing datasets. The experimental results demonstrate that the proposed DTCP-MAKD method improves distillation performance and outperforms other state-of-the-art KD methods.

Development of a self-sustained model to predict the performance of direct contact membrane distillation

Experimental study of the impact of low-cost energy storage materials on the performance of solar distillers at different water depths

In order to meet people's increasing demand for water, it is urgent to transform undrinkable water resources such as seawater and brackish water into water suitable for human use. Membrane distillation has become a water treatment technology with great development potential due to its advantages of high desalination rate, good water quality, high water recovery and low operating cost. It can effectively solve the problem of desalination of seawater and brackish water, and has broad application prospects in solving the shortage of fresh water resources. However, membrane fouling and polarization effect limit the performance of membrane distillation in seawater desalination. This paper briefly describes the working principle of membrane distillation technology, analyzes the formation mechanism of polarization effect and membrane fouling, and introduces the technical methods for enhancing the performance of membrane distillation. In addition, the future research direction of membrane distillation is prospected.

Experimental investigation of a novel egg steel trays covered with wick materials effects on the performance of conical solar distillers: A 4E analysis and multi-objective optimization

In this research, a reactive distillation in which chemical reactions and separations occur simultaneously is applied for the synthesis of tert-amyl ethyl ether (TAEE) from ethanol (EtOH) and tert-amyl alcohol (TAA). A rate-based kinetic model for liquid-phase etherification and an equilibrium stage model for separation are employed to study the reactive distillation. The calculation is carried out using the commercial software package, Aspen plus. The simulations are performed to examine the effects of design variables; i.e., numbers of rectifying, reaction and stripping stages on the performance of reactive distillation. It has been found that an optimal column configuration for the TAEE production under the rang of study comprises no rectifying, 4 reaction and 8 stripping stages. With the optimum column, effects of various operating variables on the TAA conversion and TAEE selectivity are further investigated and the results have shown that the reflux ratio and operating pressure are the most important factors for the operation of the reactive distillation. In addition, the pervaporation, a membrane process for separation of liquid mixtures that are difficult or not possible to separate by conventional methods, is incorporated in the reactive distillation. Removal water through the pervaporation membrane improves the performance of the reactive distillation.

The experimental study in this manuscript aims to enhance the performance of tubular solar distillers. The tubular distillers are characterized by having a large surface area for receiving and condensing compared to a single-slope distiller, and accordingly, the use of floating sponge layers is a good and very effective choice in increasing the rate of evaporation and thus improving the cumulative yield of the tubular distillers. In order to obtain the optimum specifications of the sponge layers that achieve the highest performance of the tubular distillers, four tubular distillers were designed and constructed; the first is a reference distiller without sponge and the other three tubular distillers contain the sponge layers with different specifications. The experimentations were conducted in two stages: in the first stage, three different thicknesses of the sponge layer (20, 30, and 40 mm) were studied. In the second stage, three different densities of the sponge layer (16, 20, and 30 kg/m3) were studied. All test cases were compared with reference distiller under the same climatic conditions of Egypt. The results show that the utilization of a floating sponge improves the tubular distiller performance. The peak improvement in the accumulative yield of tubular distillers was achieved in case of utilizing a sponge layer with a 30-mm thickness and 16-kg/m3 density. The reference distiller gives maximum accumulative yield of 3.72 L/m2 day while the floating sponge layer utilization improves the accumulative yield to 5.92 L/m2 day with 59.2% improvement. Also, the utilization of floating sponge layer reduced the cost of distillate yield by 36.3% compared to reference distiller.

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with /day capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were for sea water inlet temperature, /hour sea water inlet volume flow rate, for hot water inlet temperature, 2.4, 3.6, and /hour for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce /day of fresh water. Based on the results of this study, It makes possible to secure economics of desalination system with solar energy which is basically needed development of high efficiency fresh water generator.

Investigation of performance and entropy generation rate of Direct Contact Membrane Distillation (DCMD) with Static Mixer (SM): 3D CFD study

Mitigating near-surface polarizations in membrane distillation via membrane surface decoration