scholarly journals Enhanced Performance of Membrane Distillation Using Surface Heating Process

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 866
Author(s):  
Fei Han ◽  
Shuxun Liu ◽  
Kang Wang ◽  
Xiaoyuan Zhang
Keyword(s):  
Energy Consumption ◽  
Energy Performance ◽  
High Energy ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Surface Heating ◽  
Commercial Application ◽  
Heating Process ◽  
Temperature Polarization ◽  
Vacuum Membrane Distillation

Membrane distillation (MD) is a thermally driven desalination process that has excellent application prospects in seawater desalination or hypersaline wastewater treatment, while severe temperature polarization (TP) and the resulting relatively high energy consumption have become principal challenges limiting the commercial application of MD. Therefore, the design of novel systems to overcome the shortage of conventional MD requires urgent attention. Here, we developed three surface heating vacuum membrane distillation systems, namely, SHVMD-1, SHVMD-2, and SHVMD-3, according to the different positions of the thermal conducting layer in the cell. The distillate flux, TP, and energy performance of these systems under different operating conditions were investigated. All three systems showed stable performance, with a salt rejection >99.98% for 35 g/L NaCl, and the highest flux was close to 9 L/m2·h. The temperature polarization coefficients were higher than unity in SHVMD-2 and SHVMD-3 systems, and the SHVMD-2 system produced the lowest specific energy consumption and the highest thermal efficiency. In addition, we tested the intermittent surface heating process, which can further improve energy performance through reducing specific electrical energy consumption in vacuum membrane distillation. This paper provides a simple and efficient membrane system for the desalination of brines.

scholarly journals Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1500
Author(s):  
A. Najib ◽  
J. Orfi ◽  
H. Alansary ◽  
E. Ali
Keyword(s):  
Energy Consumption ◽  
Pilot Plant ◽  
Membrane Distillation ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Performance Ratio ◽  
Cold Temperatures ◽  
Energy And Exergy ◽  
Vacuum Membrane Distillation ◽  
The Impact

A comprehensive study was conducted to elucidate the effect of operating conditions on the performance of a multi-effect vacuum membrane distillation pilot plant. A theoretical assessment of the energy and exergy efficiency of the process was achieved using a mathematical model based on heat and mass transfer, which was calibrated using experimental data obtained from the pilot plant. The pilot plant was a solar vacuum multi-effect membrane distillation (V-MEMD) module comprising five stages. It was found that a maximal permeate mass flux of 17.2 kg/m2·h, a recovery ratio of 47.6%, and a performance ratio of 5.38% may be achieved. The resulting gain output ratio (GOR) under these conditions was 5.05, which is comparable to previously reported values. Furthermore, the present work systematically evaluated not only the specific thermal energy consumption (STEC), but also the specific electrical energy consumption (SEEC), which has been generally neglected in previous studies. We show that STEC and SEEC may reach 166 kWh/m3 and 4.5 kWh/m3, respectively. We also observed that increasing the feed flow rate has a positive impact on the process performance, particularly when the feed temperature is higher than 65 °C. Under ideal operational conditions, the exergetic efficiency reached 21.1%, and the maximum fraction of exergy destruction was localized in the condenser compartment. Variation of the inlet hot and cold temperatures at a constant differential showed an interesting and variable impact on the performance indicators of the V-MEMD unit. The difference with the lowest inlet temperatures exhibited the most negative impact on the system performance.

scholarly journals Mathematical Model of Pressure Formation Process along the Helix Channel Length of Screw Grinder

2020 ◽  
Author(s):  
Valery Pelenko ◽  
Ilkhom Usmanov ◽  
Vyacheslav Pokholchenko ◽  
Irina Smirnova
Keyword(s):  
Energy Consumption ◽  
Mathematical Description ◽  
Analytical Description ◽  
High Energy ◽  
Channel Length ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Mining Equipment ◽  
Technological Parameters ◽  
Total Energy Consumption

The improvement of the technical equipment effectiveness is currently becoming particularly important. This applies not only to large and high-energy-intensive machines, but also to household appliances, the total energy consumption of which often exceeds the energy consumption of the overall equipment. These types of devices include, in particular, grinding and cutting equipment. The mathematical description of the processes carried out on this equipment is generalized and can be extended to a wider class of machines, including waste processing and mining equipment. The technological parameters, the design of screw grinders, and the processes of movement, deformation, extrusion and cutting carried out in them are characterized by a significant number of factors affecting the energy intensity. The main ones are the geometric parameters of the screw, machine’s body, cross knife, grinding plate’s thickness, the number and diameter of holes in it, as well as the product’s physical-mechanical characteristics and operating conditions. The most important for the mathematical description are the zones and processes where the main share of the consumed power is spent. The complexity of their analytical description is due to a simplified consideration of either individual technological zones of grinders’ existing designs, or the use of unreasonable simplifications.

A review on acoustic methods of algal growth control by ultrasonication through existing and novel emerging technologies

2017 ◽  
Vol 33 (5) ◽  
Author(s):  
Aditi Mullick ◽  
Sudarsan Neogi
Keyword(s):  
Energy Consumption ◽  
Algal Blooms ◽  
Nutrient Loading ◽  
Algal Growth ◽  
High Energy ◽  
Operating Conditions ◽  
Process Efficiency ◽  
Industrial Water ◽  
Algal Toxins ◽  
Algae Growth

AbstractThe uncontrolled proliferation of algae and algal blooms due to excessive nutrient loading in natural and industrial water bodies is a major issue for water quality maintenance. It reduces usability of the water, imposes hazardous effects of algal toxins released from algal blooms, and creates nuisance in the operation of several industrial water units. Among several existing water treatment methods to diminish the post-algae growth effects, ultrasonication has emerged as an environmentally safe technology that does not involve any use of algaecide. The interaction of several parameters, including climatic and environmental conditions with algae growth rate, have been reviewed in this article. The effects of different acoustic operating conditions for inhibition of algae growth have also been discussed. Concern about high energy consumption led other technologies to be integrated with ultrasonication. It has enhanced the process efficiency and reduced the energy consumption as reported in some long-term field investigations and patent proposals. Several issues that require further research for making this technology widely applicable or to install an effective system design have been highlighted in this article.

Membrane Distillation Desalination System With Gap Circulation and Cooling Using a Built-in Heat Exchanger

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Atia E. Khalifa
Keyword(s):  
Energy Consumption ◽  
Heat Exchanger ◽  
Specific Energy Consumption ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Water Desalination ◽  
Module Design ◽  
Membrane Surfaces ◽  
Best Value ◽  
Feed Temperature

Abstract A comprehensive experimental investigation is conducted to evaluate the performance of a new flux-enhanced compact water gap membrane distillation (WGMD) module design with gap circulation and cooling for water desalination. The new design uses a separate circulation loop to circulate the gap water, and a built-in heat exchanger coil implanted inside the coolant stream channel for cooling the circulated gap water. The WGMD modules with circulation and with circulation and cooling are compared with conventional WGMD without circulation. Variations of distillate flux, temperatures, and energy consumption are presented at different design operating conditions. Circulation and cooling of the gap water greatly enhance the output flux due to gap water motion and increase the temperature difference between membrane surfaces. However, the enhancement in flux was achieved at the expense of energy consumption. Circulation and cooling of gap water are more effective with bigger gap widths. Feed flowrate showed significant effects with gap water circulation and cooling. The electrical specific energy consumption (SEC) showed the best value of 7.9 and 8.8 kWh/m3 at a feed temperature of 70 °C for both conventional WGMD and WGMD with circulation modules, while the best value of SEC for the WGMD module with gap circulation and cooling was 9.4 kWh/m3 at a feed temperature of 80 °C.

scholarly journals A novel internal heat recycling concept for reducing energy consumption and increasing flux through three-stage air-gap–water-gap membrane distillation system

2020 ◽  
Vol 20 (7) ◽  
pp. 2858-2874
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Xiaolong Lu ◽  
Shaozhe Zhang
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Energy Consumption ◽  
Heat And Mass Transfer ◽  
Waste Heat ◽  
Internal Heat ◽  
High Energy ◽  
Membrane Distillation ◽  
Air Gap ◽  
Air Gap Membrane Distillation

Abstract The low flux and high energy consumption problems of the conventional three-stage air-gap membrane distillation (AG-AG-AG)MD system caused by the low temperature difference between hot and cold feed at both sides of the membrane and high boundary layer thickness were solved successfully by replacing one of the three stages of air gaps by a water gap. The novel three-stage air-gap–water-gap membrane distillation (AG-AG-WG)MD system reduced energy consumption and increased flux due to efficient internal heat recycling by virtue of a water-gap module. Heat and mass transfer in novel and conventional three-stage systems were analyzed theoretically. Under a feed temperature of 45 °C, flow rate of 20 l/h, cooling temperature of 20 °C, and concentration of 340 ppm, the (AG-AG-WG)MD promoted flux by 17.59% and 211.69%, and gained output ratio (GOR) by 60.57% and 204.33% compared with two-stage (AG-WG)MD and one-stage AGMD, respectively. This work demonstrated the important role of a water gap in changing the heat and mass transfer where convection heat transfer across the water gap is faster by 24.17 times than conduction heat transfer through the air gap. The increase in flux and GOR economized the heating energy and decreased waste heat input into the system. Additionally, the number of MD stages could increase the achieving of a high flux with operation stability.

Experimental Study and Numerical Simulation of the Air Gap Membrane Distillation (AGMD) Process

2016 ◽  
Vol 11 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Ehsan Karbasi ◽  
Javad Karimi-Sabet ◽  
J. Mohammadi Roshandeh ◽  
M. A. Moosavian ◽  
H. Ahadi
Keyword(s):  
Numerical Simulation ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Air Gap ◽  
Operating Conditions ◽  
Permeate Flux ◽  
Air Gap Membrane Distillation ◽  
Temperature Polarization ◽  
Output Ratio ◽  
Cfd Method

Abstract Some challenges, including inappropriate distribution of currents on the membrane surface, poor hydrodynamics and existing severe temperature polarization (TP) phenomenon in MD modules, impede industrialization of MD process. Computational fluid dynamics (CFD) method was used for numerical simulation of hydrodynamics in air gap membrane distillation modules. One of two simulated modules in this work is a novel developed one in which heat and mass transfer data was compared with available literature data. Moreover, the effect of using baffles in module was investigated. Comparison between the novel module and conventional module indicates higher trans-membrane mass flux and gained output ratio (GOR) coefficient by 7% and 15%, respectively. Moreover, the effects of different operating conditions including feed temperatures and feed flow rates on permeate flux were investigated.

scholarly journals Benchmarking of energy consumption in municipal wastewater treatment plants – a survey of over 200 plants in Italy

2018 ◽  
Vol 77 (9) ◽  
pp. 2242-2252 ◽  
Author(s):  
M. Vaccari ◽  
P. Foladori ◽  
S. Nembrini ◽  
F. Vitali
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Municipal Wastewater ◽  
Energy Savings ◽  
Wastewater Treatment Plants ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Energy Performance ◽  
High Energy ◽  
Municipal Wastewater Treatment

Abstract One of the largest surveys in Europe about energy consumption in Italian wastewater treatment plants (WWTPs) is presented, based on 241 WWTPs and a total population equivalent (PE) of more than 9,000,000 PE. The study contributes towards standardised resilient data and benchmarking and to identify potentials for energy savings. In the energy benchmark, three indicators were used: specific energy consumption expressed per population equivalents (kWh PE−1 year−1), per cubic meter (kWh/m3), and per unit of chemical oxygen demand (COD) removed (kWh/kgCOD). The indicator kWh/m3, even though widely applied, resulted in a biased benchmark, because highly influenced by stormwater and infiltrations. Plants with combined networks (often used in Europe) showed an apparent better energy performance. Conversely, the indicator kWh PE−1 year−1 resulted in a more meaningful definition of a benchmark. High energy efficiency was associated with: (i) large capacity of the plant, (ii) higher COD concentration in wastewater, (iii) separate sewer systems, (iv) capacity utilisation over 80%, and (v) high organic loads, but without overloading. The 25th percentile was proposed as a benchmark for four size classes: 23 kWh PE−1 y−1 for large plants > 100,000 PE; 42 kWh PE−1 y−1 for capacity 10,000 < PE < 100,000, 48 kWh PE−1 y−1 for capacity 2,000 < PE < 10,000 and 76 kWh PE−1 y−1 for small plants < 2,000 PE.

Energy Consumption Discussions of Porcelain Produce with Operating Conditions in a Simplified Model

2014 ◽  
Vol 936 ◽  
pp. 1775-1779
Author(s):  
Jun Liang Yu
Keyword(s):  
Energy Consumption ◽  
High Energy ◽  
Operating Conditions ◽  
Simplified Model ◽  
Net Energy ◽  
Mass Ratio ◽  
Solid Mass ◽  
Fuel Distribution ◽  
Total Energy Balance ◽  
Excess Number

Porcelain produce is a very high energy consumption process. According to total energy balance analysis, a variety of operating conditions are analyzed for effect of net energy consumption. One real porcelain plate produce process is introduced as the reference case. Operating conditions are defined in three parameters, which are air excess number, fuel distribution and solid mass ratio. A simplified model based on finite difference method (FDM) is solved to calculate axial gas and solid temperature profiles and net energy consumption. The net energy consumption in porcelain produce is calculated and discussed in quantity with three operating conditions above separately. Finally, it is concluded that net energy consumption is higher with bigger air excess number and solid mass ratio, while fuel distribution will have no influence on net energy consumption.

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