Application of the Buckingham ∏ theorem to model multiple effect vacuum membrane distillation

2021 ◽  
pp. 1-40
Author(s):  
Abdullah Mohammed ◽  
Jamel Orfi ◽  
Hany Al-Ansary ◽  
Emadadeen Ali
Keyword(s):  
Performance Indicators ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hot Water ◽  
Vaporization Enthalpy ◽  
Design Parameters ◽  
Recovery Ratio ◽  
Actual Behavior ◽  
Dimensionless Parameters ◽  
Output Ratio

Abstract This study aims to develop a dimensionless model of the V-MEMD performance indicator through which a preliminary prediction of the most critical performance indicators can be attained. Buckingham ∏ theorem was utilized to define dimensionless parameters that allow the predicted relationships associating independent input parameters to describe the essential performance indicators of the V-MEMD system. The obtained compact model reduces the design parameters from ten to two effective dimensionless parameters to realize the realistic and actual behavior of the designated system. The self-sustained model stands as a short-cut tool for design and performance analysis avoiding time consuming experimentations and/or complicated theoretical models. The compatibility of the generated model is assessed by matching the expected response of output dimensionless parameters (e.g., recovery ratio, R, and gain output ratio, GOR) to variation in pressure ratio and cooling process. The model is validated with other works, and discrepancies are remarked to be within ±10% and ±25% for recovery ratio and gain output ratio, respectively. Furthermore, the specific thermal energy consumption, STEC is correlated to GOR assuming constant vaporization enthalpy and density of the distillate water. The correlation can predict STEC within 5% accuracy over different operating conditions for the supplied hot water.

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 Influence of design parameters and operating conditions on performance indicators of magnetic fluid seals of electric motor shafts

Vestnik IGEU ◽  
2019 ◽  
pp. 40-47
Author(s):  
A.M. Vlasov ◽  
Yu.B. Kazakov ◽  
V.A. Poletaev
Keyword(s):  
Surface Roughness ◽  
Magnetic Fluid ◽  
Electric Motor ◽  
Performance Indicators ◽  
Rough Surfaces ◽  
Rotation Frequency ◽  
Friction Torque ◽  
Operating Conditions ◽  
Design Parameters ◽  
External Temperature

Magnetic fluid seals (MFS) are beginning to be used to seal rotating shafts in electric motors operating in conditions of high humidity, dust and pollution. Friction torque and heating are the most important operational indicators of MFS depending on the design parameters and operation conditions: rotation frequency, operation time, temperature and clearance (taking into account roughness and waviness). An urgent task is to study the influence of design parameters and operating conditions on the performance indicators of MFS of such electric motor shafts. The modeling of rough surfaces was performed using orthogonal transformations of roughness matrix vectors and a visual representation. The contact area of the magnetic fluid with rough surfaces was determined by mathematical modeling. The experimental studies were performed on a test bench. Wear sleeves and poles made of various steels with different roughness parameters were used. Models of MFS clearances formed by surfaces with different roughness have been obtained. The contact areas of the magnetic fluid with the surfaces of MFS at different roughness values have been determined. Nonlinear dependences and variation limits of the friction torque and MFS temperature on the surface roughness of the poles and sleeves, rotation frequencies of the electric motor, and the external temperature have been obtained. Clearance models allow determining the roughness of MFS surfaces. The developed experimental unit allows carrying out studies on the effect of changes of design parameters and operating conditions on the performance indicators of MFS. At a 5,21 time higher rotation frequency (from 556 to 2897 rpm), the MFS temperature can increase by up to 2 times, the friction torque – by up to 2,2 times. If the temperature rises by 50 оC, the friction torque can drop by up to 3 times. With an increase in the surface roughness from 0,357 to 7,21 μm, the temperature of the MFS can rise by 20 %, and the friction torque by 55 %.

scholarly journals Bispacer Multi-Stage Direct Contact Membrane Distillation System: Analytical and Experimental Study

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1297
Author(s):  
Morteza Aliabadi ◽  
Hassan Ghorashi ◽  
Shamim Shokri Motlagh ◽  
Seyedeh Fatemeh Nabavi ◽  
Seyed Arash Pakzad ◽  
...  
Keyword(s):  
Direct Contact ◽  
Mechanical Stability ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Permeate Flux ◽  
Direct Contact Membrane Distillation ◽  
Multi Stage ◽  
Temperature Polarization ◽  
Output Ratio ◽  
Polarization Coefficient

A multi-staged direct contact membrane distillation (MDCMD) system is designed considering a novel bispacer configuration in the present study. The proposed bispacer DCMD, which has not been addressed in the literature to best of our knowledge, is considered with two purposes, including increasing mechanical stability and turbulence. As increasing turbulence leads to increasing Nusselt number, the bispacer MDCMD provides higher permeate flux. An analytical approach is considered using energy and mass balance correlation. The effect of bispacer and feed operating conditions, including feed temperature, feed flow rate, feed salinity, and the number of stages on permeate flux and salt rejection of the developed MDCMD, are examined both analytically and experimentally. The performance and sustainability of the developed system were investigated by analyzing the parameters, including thermal efficiency (η), gained output ratio (GOR), and temperature polarization coefficient (TPC).

Utilization of Expansion Work in Transcritical CO2 Heat Pumps in Combined Heating and Cooling

2008 ◽  
Author(s):  
Nikola Stosic ◽  
Ian K. Smith
Keyword(s):  
Control Strategies ◽  
Industrial Process ◽  
Power Input ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Hot Water ◽  
Design Parameters ◽  
Working Fluid ◽  
Heating And Cooling ◽  
Twin Screw

The use of CO2 as a refrigerant in transcritical vapour compression cycles has significant advantages, for systems which require simultaneous heating and cooling at approximately equal rates. However, then need for a compressor, to operate across high pressure differences, and the large throttle losses associated with these pressure differences have limited its use. This paper describes a study carried out to evaluate the efficiency gains and cost benefits possible from such a system when a twin screw machine is used to both compress and expand the working fluid in a single unit. It also shows the values of the critical design parameters required to optimise the system’s potential advantages when used in larger combined heating and cooling systems in industrial process and heat generation plants. The results show that recovery of work from the expansion process improves the COP by 15 to 20%. For the design conditions specified in this paper, this implies that the expander is worth fitting if it can be installed for a cost of less than approximately €750/kW of shaft power input. Thus, depending on the operating conditions, transcritical CO2 heat pumps using a compressor-expander can produce hot water at 90°C with a COP of approximately 6, with thermal outputs of up to 1.5 MW. This could be extended with simple control strategies up to outputs of 10 MW.

scholarly journals Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2987 ◽  
Author(s):  
Ahmad Abdullah ◽  
Abdulaziz Al-Qahatani ◽  
Mohammed Alquraish ◽  
Colin Bailey ◽  
Ahmed El-Shazly ◽  
...  
Keyword(s):  
Contact Angle ◽  
Composite Membrane ◽  
Pure Water ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hot Water ◽  
Hydrophobic Nature ◽  
Porosity Characterization ◽  
Graphene Nanoplates

Membrane distillation is an active technique that provides pure water with very good rejection and could be applied to water of extremely high salinity. The low productivity of membrane distillation needs intensive efforts to be competitive with other desalination techniques. In this current study, a composite (PS/GNP) membrane, which is composed of polystyrene (PS) based and 0.25% weight percent graphene nanoplates (GNP) has been fabricated via electrospinning and compared with the blank PS membrane. SEM, FTIR, contact angle and porosity characterization have been performed, and the results show that the validity of the predefined conditions, and the contact angle of the composite membrane, which is found to be 91.68°, proved the hydrophobic nature of the composite membrane. A numerical simulation using Ansys 2020 software has been introduced to study the performance of the fabricated composite membrane when used in direct contact membrane distillation (DCMD). The numerical model has been validated with experimental work from the literature and showed an excellent match. The blank PS and composite PS/GNP membranes have been investigated and compared at different operating conditions, i.e., hot water supply temperature and system flow rate. The results show that the composite PS/GNP membrane outperforms the blank PS membrane at all studied operating conditions.

scholarly journals Enhancement of the air gap membrane distillation system performance by using the water gap module

2020 ◽  
Vol 20 (7) ◽  
pp. 2884-2902
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Xiaolong Lu ◽  
Shaozhe Zhang
Keyword(s):  
Membrane Distillation ◽  
Air Gap ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Concentration Boundary ◽  
Air Gap Membrane Distillation ◽  
Distillation System ◽  
Negative Effect ◽  
In Series ◽  
Output Ratio

Abstract The negative effect of an air gap layer presented between the membrane and cooling plate on air gap membrane distillation (AGMD) performance was diminished largely by inserting a water gap membrane distillation (WGMD) module in series. The new design of air-gap–water-gap membrane distillation (AG-WG)MD was evaluated experimentally by comparing with an AGMD system under different operating conditions. In theory, mass and heat transfer in the new (AG-WG)MD and imitative AGMD systems were analyzed. Experimental outcomes showed that a new (AG-WG)MD design profoundly enhanced flux (Pd) and gained output ratio (GOR), and greatly decreased energy consumption (STEC) and heat input (EH.I). At a concentration of 5,000 mg/L, coolant temperature of 20 °C, and flow rate of 18 L/h, Pd was promoted by 76.26%, 40.84%, 35.45%, 30.91%, and GOR by 46.38%, 33.46%, 31.27%, 26.65%, in addition to STEC being reduced about 55.63%, 46.81%, 43.66%, 38.30%, and EH.I around 31.31%, 25.84%, 23.53%, 20.55%, from the AGMD to (AG-WG)MD system at feed temperatures of 50 °C, 60 °C, 70 °C, and 80 °C, respectively. The outcomes proved that the AGMD performance could be significantly promoted by integrating with WGMD in a combined MD system. This combination increased the temperature difference across the membrane and decreased thermal-concentration boundary layers for the AGMD system.

scholarly journals Simulation and Economic Analysis of Solar Thermal Cogeneration System for Production of Heat and Pure Water using Membrane Distillation

2016 ◽  
Vol 11 (1) ◽  
Keyword(s):  
Heat Exchanger ◽  
Membrane Distillation ◽  
Economic Benefits ◽  
Hot Water ◽  
Solar Thermal ◽  
Design Parameters ◽  
Clean Water ◽  
Solar Collectors ◽  
Domestic Hot Water ◽  
Cogeneration System

In this paper, a novel solar thermal cogeneration (termed as solar combi MD; SCMD) system for production of clean water and domestic hot water is modeled and analyzed for the weather conditions of United Arab Emirates (UAE). The system comprises of solar collectors for production of thermal energy, thermal storage for domestic hot water generation and membrane distillation (MD) modules for clean water production gaining energy through a plate heat exchanger. The performance of cogeneration is analyzed with two different solar collectors used for domestic heating – flat plate collectors (FPC) and evacuated tube collector (ETC). The system is modeled and dynamically simulated using TRNSYS software for optimization of various design parameters like collectors tilt angle, mass flow rate through MD loop, thermal store volume and heat exchanger effectiveness. Cogeneration system efficiencies and collector areas has been determined for optimum conditions. Economic benefits are analyzed for FPC collectors and fuel costs savings compared to individual system operation. Total investment cost of SCMD system for single family application would be around 5000$ with an impressive payback period of 5.5 years which is 30% lower than regular SDHW installations.

scholarly journals Multiphysics Modeling and Analysis of a Solar Desalination Process Based on Vacuum Membrane Distillation

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 386
Author(s):  
Benjamin N. Shuldes ◽  
Mona Bavarian ◽  
Siamak Nejati
Keyword(s):  
Salt Concentration ◽  
Saturation Pressure ◽  
Membrane Distillation ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Recovery Ratio ◽  
Permeate Flux ◽  
Element Analysis ◽  
Vacuum Membrane Distillation ◽  
Polarization Phenomena

A hollow fiber vacuum membrane distillation (VMD) module was modeled using finite element analysis, and the results were used to conduct an exergy efficiency analysis for a solar-thermal desalination scheme. The performance of the VMD module was simulated under various operating conditions and membrane parameters. Membrane porosity, tortuosity, pore diameter, thickness, and fiber length were varied, along with feed temperature and feed configuration. In all cases, polarization phenomena were seen to inhibit the performance of the module. Under VMD operation, polarization of salt concentration was seen to be the main determining factor in the reduction of permeate flux. Within the boundary layer, salt concentration was seen to rapidly increase from the feed mass fraction of 0.035 to the saturation point. The increase in salt concentration led to a decrease in saturation pressure, the driving force for separation. Charging the feed into the shell instead of the lumen side of the membranes resulted in a further decrease in permeate flux. It is shown that adding a baffling scheme to the surface of the fibers can effectively reduce polarization phenomena and improve permeate flux. Increasing the overall recovery ratio was seen to increase the exergy efficiency of the system. Exergy efficiency was seen to have almost no dependency on membrane parameters due to the low recovery ratio in a single pass and the high heating duty required to reach the desired temperature for the feed stream.

scholarly journals The Soil Organic Matter in Connection with Soil Properties and Soil Inputs

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 779
Author(s):  
Václav Voltr ◽  
Ladislav Menšík ◽  
Lukáš Hlisnikovský ◽  
Martin Hruška ◽  
Eduard Pokorný ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Texture ◽  
Management Practices ◽  
Soil Depth ◽  
Operating Conditions ◽  
Hot Water ◽  
Natural Soil ◽  
Soil Productivity ◽  
Linear Regression Models

The content of organic matter in the soil, its labile (hot water extractable carbon–HWEC) and stable (soil organic carbon–SOC) form is a fundamental factor affecting soil productivity and health. The current research in soil organic matter (SOM) is focused on individual fragmented approaches and comprehensive evaluation of HWEC and SOC changes. The present state of the soil together with soil’s management practices are usually monitoring today but there has not been any common model for both that has been published. Our approach should help to assess the changes in HWEC and SOC content depending on the physico-chemical properties and soil´s management practices (e.g., digestate application, livestock and mineral fertilisers, post-harvest residues, etc.). The one- and multidimensional linear regressions were used. Data were obtained from the various soil´s climatic conditions (68 localities) of the Czech Republic. The Czech farms in operating conditions were observed during the period 2008–2018. The obtained results of ll monitored experimental sites showed increasing in the SOC content, while the HWEC content has decreased. Furthermore, a decline in pH and soil´s saturation was documented by regression modelling. Mainly digestate application was responsible for this negative consequence across all soils in studied climatic regions. The multivariate linear regression models (MLR) also showed that HWEC content is significantly affected by natural soil fertility (soil type), phosphorus content (−30%), digestate application (+29%), saturation of the soil sorption complex (SEBCT, 21%) and the dose of total nitrogen (N) applied into the soil (−20%). Here we report that the labile forms (HWEC) are affected by the application of digestate (15%), the soil saturation (37%), the application of mineral potassium (−7%), soil pH (−14%) and the overall condition of the soil (−27%). The stable components (SOM) are affected by the content of HWEC (17%), soil texture 0.01–0.001mm (10%), and input of organic matter and nutrients from animal production (10%). Results also showed that the mineral fertilization has a negative effect (−14%), together with the soil depth (−11%), and the soil texture 0.25–2 mm (−21%) on SOM. Using modern statistical procedures (MRLs) it was confirmed that SOM plays an important role in maintaining resp. improving soil physical, biochemical and biological properties, which is particularly important to ensure the productivity of agroecosystems (soil quality and health) and to future food security.

scholarly journals Experimental Comparison of Innovative Composite Sorbents for Space Heating and Domestic Hot Water Storage

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 476
Author(s):  
Vincenza Brancato ◽  
Larisa G. Gordeeva ◽  
Angela Caprì ◽  
Alexandra D. Grekova ◽  
Andrea Frazzica
Keyword(s):  
Silica Gel ◽  
Xrd Analysis ◽  
Complete Characterization ◽  
Operating Conditions ◽  
Hot Water ◽  
Experimental Comparison ◽  
Space Heating ◽  
Calorimetric Analysis ◽  
Domestic Hot Water ◽  
Composite Sorbents

In this study, the development and comparative characterization of different composite sorbents for thermal energy storage applications is reported. Two different applications were targeted, namely, low-temperature space heating (SH) and domestic hot water (DHW) provision. From a literature analysis, the most promising hygroscopic salts were selected for these conditions, being LiCl for SH and LiBr for DHW. Furthermore, two mesoporous silica gel matrixes and a macroporous vermiculite were acquired to prepare the composites. A complete characterization was performed by investigating the porous structure of the composites before and after impregnation, through N2 physisorption, as well as checking the phase composition of the composites at different temperatures through X-ray powder diffraction (XRD) analysis. Furthermore, sorption equilibrium curves were measured in water vapor atmosphere to evaluate the adsorption capacity of the samples and a detailed calorimetric analysis was carried out to evaluate the reaction evolution under real operating conditions as well as the sorption heat of each sample. The results demonstrated a slower reaction kinetic in the vermiculite-based composites, due to the larger size of salt grains embedded in the pores, while promising volumetric storage densities of 0.7 GJ/m3 and 0.4 GJ/m3 in silica gel-based composites were achieved for SH and DHW applications, respectively.

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