Enhanced Performance of Solar Diffusion Driven Desalination

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Fadi Alnaimat ◽  
James F. Klausner
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
System Performance ◽  
Specific Energy Consumption ◽  
Operating Mode ◽  
Operating Conditions ◽  
Water Production ◽  
Air Inlet ◽  
Air Stream ◽  
Dynamic Operating

This study concerns an improvement in the solar diffusion driven desalination process under dynamic operating conditions for decentralized water production. The utilization of a heat exchanger for the solar diffusion driven desalination (DDD) process to recuperate the latent heat of condensation has been examined. It is found that the recuperated latent heat is best used for preheating the air inlet to the evaporator. Improvements in the system performance are achieved by increasing fresh water production by 30% for the solar DDD with a 0.75 effectiveness in the integrated heat exchanger. A theoretical model is implemented for analyzing the integrated desalination system, and a numerical assessment of the system performance for different operating conditions is presented. It is found that the installation of a heat exchanger for heat recovery in the air stream prior to entering the direct contact condenser increases the water production rate and reduces the specific energy consumption. It is concluded that the delayed operating mode for the solar DDD with an integrated heat exchanger is the best operating mode.

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 Renewable Energy Powered Membrane Technology: Electrical Energy Storage Options for a Photovoltaic-Powered Brackish Water Desalination System

2021 ◽  
Vol 11 (2) ◽  
pp. 856
Author(s):  
Sheying Li ◽  
Ana P. S. G. de Carvalho ◽  
Andrea I. Schäfer ◽  
Bryce S. Richards
Keyword(s):  
Energy Storage ◽  
Brackish Water ◽  
System Performance ◽  
Specific Energy Consumption ◽  
Lithium Ion ◽  
Membrane System ◽  
Water Desalination ◽  
High Temporal Resolution ◽  
Water Production ◽  
Battery Capacity

The potential for lithium-ion (Li-ion) batteries and supercapacitors (SCs) to overcome long-term (one day) and short-term (a few minutes) solar irradiance fluctuations with high-temporal-resolution (one s) on a photovoltaic-powered reverse osmosis membrane (PV-membrane) system was investigated. Experiments were conducted using synthetic brackish water (5-g/L sodium chloride) with varied battery capacities (100, 70, 50, 40, 30 and 20 Ah) to evaluate the effect of decreasing the energy storage capacities. A comparison was made between SCs and batteries to determine system performance on a “partly cloudyday”. With fully charged batteries, clean drinking water was produced at an average specific energy consumption (SEC) of 4 kWh/m3. The daily water production improved from 663 L to 767 L (16% increase) and average electrical conductivity decreased from 310 µS/cm to 274 μS/cm (12% improvement), compared to the battery-less system. Enhanced water production occurred when the initial battery capacity was >50 Ah. On a “sunny” and “very cloudy” day with fully charged batteries, water production increased by 15% and 80%, while water quality improved by 18% and 21%, respectively. The SCs enabled a 9% increase in water production and 13% improvement in the average SEC on the “partly cloudy day” when compared to the reference system performance (without SCs).

scholarly journals Air-side performance of a micro-channel heat exchanger in wet surface conditions

2017 ◽  
Vol 21 (1 Part A) ◽  
pp. 375-385 ◽  
Author(s):  
Raviwat Srisomba ◽  
Lazarus Asirvatham ◽  
Omid Mahian ◽  
Ahmet Dalkılıç ◽  
Mohamed Awad ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Micro Channel ◽  
Surface Conditions ◽  
Air Inlet ◽  
Wet Surface

The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33?C; refrigerant-saturated temperatures ranging from 18 to 22?C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

scholarly journals Modification in energy and productivity of high temperature variable pressure humidification compression

2021 ◽  
Author(s):  
Marzieh Abedi ◽  
Younes Ghalavand
Keyword(s):  
Power Consumption ◽  
Mass Flow ◽  
System Performance ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Variable Pressure ◽  
Water Volume ◽  
Water Production ◽  
Desalinated Water ◽  
Thermal Desalination

Abstract One of the important approaches in the thermal desalination processes is consumed energy reduction. To achieve this aim, three arrangements of humidification-compression (HC) processes are designed. Two single-stage and one double-stage HC processes are designed and their performances are compared based on desalinated water production, gained output ratio (GOR) and power consumption. Attempt is made to reduce the power consumption and improve the system performance. All three processes are simulated to examine the effect of operation parameters on HC performance. To validate these simulations, the theoretical results are compared with an experimental rig with a humidifier column of 1.5 m height. The results indicate that the simulation values conform the experimental data. The effect of minimum approach temperature (ΔTmin) on system performance is investigated for three processes subject to constant operating conditions (feed temperature, water mass flow, air mass flow, and pressure ratio). For this purpose, four values of ΔTmin are considered (7.5, 10, 12.5 and 15 °C) for heat exchanger operations. The results indicate that an increase in ΔTmin in all three cases, increases desalinated water volume and GOR. Also, double-stage HC system, has higher water production rate (66.08 kg/h) and higher GOR (17.19) compared to its counterparts.

scholarly journals Method for determining the actual group of classification (mode of operation) of load-lifting cranes

2021 ◽  
Author(s):  
Oleksiy Nyezhentsev
Keyword(s):  
Specific Energy Consumption ◽  
Operating Mode ◽  
Technical Condition ◽  
Operating Conditions ◽  
Safe Operation ◽  
The Real ◽  
Mode Of Operation ◽  
Definition Of ◽  
Actual Classification

The problems which arise during the period of expert inspection of the load-lifting cranes which have fulfilled regulatory lifetime, at definition of their actual group of classification (operating mode) are analyzed. It is established that the actual group of classification (mode of operation) of operated cranes, which is determined by the regulations on labor protection (NPAOP), often does not coincide with the passport modes of operation of cranes. A new method of diagnosing the actual classification group (operating mode) of operated cranes has been developed, which allows taking into account the real modes of their loading and classes of use using the value of specific energy consumption of cranes. The proposed method allows to reliably determining the actual group of classification of cranes that have served the regulatory lifetime, taking into account the real operating conditions of all crane mechanisms and their technical condition for the entire period of operation. This makes it possible to reasonably and qualitatively establish the terms and conditions of further safe operation of cranes.

Experimental Performance Evaluation of Humidification–Dehumidification System With Direct-Contact Dehumidifier

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Saeed Dehghani ◽  
Farzaneh Mahmoudi ◽  
Abhijit Date ◽  
Aliakbar Akbarzadeh
Keyword(s):  
Production Rate ◽  
System Performance ◽  
Direct Contact ◽  
Seawater Temperature ◽  
Operating Conditions ◽  
Flow Rate Ratio ◽  
Feed Water ◽  
Water Production ◽  
Produce Water ◽  
Water Production Rate

Abstract Humidification–dehumidification (HDH) desalination with direct contact dehumidifier system is designed and fabricated. Experimental tests are performed under various operating conditions in order to explore the influence of temperatures and mass flow rates of seawater and freshwater on system performance by utilizing non-dimensional parameters. It is shown that, for any case, there is an optimum flow rate ratio of water to air, which results in a maximum water production rate. A mathematical model is utilized to evaluate the system performance and compare the outcomes with the experimental results. In addition, the effect of feed water salinity from 0–30% on the water production rate is experimentally investigated. The results showed that the maximum achieved recovery ratio of the proposed HDH system is 5% under the working condition of seawater temperature at 73 °C with 3% salinity and cold freshwater at 28 °C. Furthermore, the system was able to produce water at nearly saturated seawater feed.

scholarly journals Experimental analysis and ANN prediction on performances of finned oval-tube heat exchanger under different air inlet angles with limited experimental data

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 968-980
Author(s):  
Xueping Du ◽  
Zhijie Chen ◽  
Qi Meng ◽  
Yang Song
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Correlation Equation ◽  
Tube Heat Exchanger ◽  
Flow Friction ◽  
Air Inlet ◽  
Comparison Results ◽  
Wide Range ◽  
Oval Tube

Abstract A high accuracy of experimental correlations on the heat transfer and flow friction is always expected to calculate the unknown cases according to the limited experimental data from a heat exchanger experiment. However, certain errors will occur during the data processing by the traditional methods to obtain the experimental correlations for the heat transfer and friction. A dimensionless experimental correlation equation including angles is proposed to make the correlation have a wide range of applicability. Then, the artificial neural networks (ANNs) are used to predict the heat transfer and flow friction performances of a finned oval-tube heat exchanger under four different air inlet angles with limited experimental data. The comparison results of ANN prediction with experimental correlations show that the errors from the ANN prediction are smaller than those from the classical correlations. The data of the four air inlet angles fitted separately have higher precisions than those fitted together. It is demonstrated that the ANN approach is more useful than experimental correlations to predict the heat transfer and flow resistance characteristics for unknown cases of heat exchangers. The results can provide theoretical support for the application of the ANN used in the finned oval-tube heat exchanger performance prediction.

scholarly journals Effect of Twisted Fin Array in a Triple-Tube Latent Heat Storage System during the Charging Mode

2021 ◽  
Vol 13 (5) ◽  
pp. 2685
Author(s):  
Mohammad Ghalambaz ◽  
Jasim M. Mahdi ◽  
Amirhossein Shafaghat ◽  
Amir Hossein Eisapour ◽  
Obai Younis ◽  
...  
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Storage ◽  
Hot Water ◽  
Melting Time ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Storage Rate

This study aims to assess the effect of adding twisted fins in a triple-tube heat exchanger used for latent heat storage compared with using straight fins and no fins. In the proposed heat exchanger, phase change material (PCM) is placed between the middle annulus while hot water is passed in the inner tube and outer annulus in a counter-current direction, as a superior method to melt the PCM and store the thermal energy. The behavior of the system was assessed regarding the liquid fraction and temperature distributions as well as charging time and energy storage rate. The results indicate the advantages of adding twisted fins compared with those of using straight fins. The effect of several twisted fins was also studied to discover its effectiveness on the melting rate. The results demonstrate that deployment of four twisted fins reduced the melting time by 18% compared with using the same number of straight fins, and 25% compared with the no-fins case considering a similar PCM mass. Moreover, the melting time for the case of using four straight fins was 8.3% lower than that compared with the no-fins case. By raising the fins’ number from two to four and six, the heat storage rate rose 14.2% and 25.4%, respectively. This study presents the effects of novel configurations of fins in PCM-based thermal energy storage to deliver innovative products toward commercialization, which can be manufactured with additive manufacturing.

scholarly journals Energetic and exergetic analysis of a convective drier: A case study of potato drying process

2020 ◽  
Vol 5 (1) ◽  
pp. 563-572
Author(s):  
Iman Golpour ◽  
Mohammad Kaveh ◽  
Reza Amiri Chayjan ◽  
Raquel P. F. Guiné
Keyword(s):  
Energy Consumption ◽  
Research Work ◽  
Specific Energy Consumption ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Convective Drying ◽  
Drying Time ◽  
Energy And Exergy ◽  
Exergy Losses

AbstractThis research work focused on the evaluation of energy and exergy in the convective drying of potato slices. Experiments were conducted at four air temperatures (40, 50, 60 and 70°C) and three air velocities (0.5, 1.0 and 1.5 m/s) in a convective dryer, with circulating heated air. Freshly harvested potatoes with initial moisture content (MC) of 79.9% wet basis were used in this research. The influence of temperature and air velocity was investigated in terms of energy and exergy (energy utilization [EU], energy utilization ratio [EUR], exergy losses and exergy efficiency). The calculations for energy and exergy were based on the first and second laws of thermodynamics. Results indicated that EU, EUR and exergy losses decreased along drying time, while exergy efficiency increased. The specific energy consumption (SEC) varied from 1.94 × 105 to 3.14 × 105 kJ/kg. The exergy loss varied in the range of 0.006 to 0.036 kJ/s and the maximum exergy efficiency obtained was 85.85% at 70°C and 0.5 m/s, while minimum exergy efficiency was 57.07% at 40°C and 1.5 m/s. Moreover, the values of exergetic improvement potential (IP) rate changed between 0.0016 and 0.0046 kJ/s and the highest value occurred for drying at 70°C and 1.5 m/s, whereas the lowest value was for 70°C and 0.5 m/s. As a result, this knowledge will allow the optimization of convective dryers, when operating for the drying of this food product or others, as well as choosing the most appropriate operating conditions that cause the reduction of energy consumption, irreversibilities and losses in the industrial convective drying processes.

Effects of Air Temperature on Combustion Characteristics of LPG Diffusion Flame

2020 ◽  
Vol 1008 ◽  
pp. 128-138
Author(s):  
Ahmed M. Salman ◽  
Ibrahim A. Ibrahim ◽  
Hamada M. Gad ◽  
Tharwat M. Farag
Keyword(s):  
Air Temperature ◽  
Diffusion Flame ◽  
Nitrogen Addition ◽  
Flame Length ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Low Oxygen ◽  
Air Temperatures ◽  
Air Stream ◽  
Wide Range

In the present study, the combustion characteristics of LPG gaseous fuel diffusion flame at elevated air temperatures were experimentally investigated. An experimental test rig was manufactured to examine a wide range of operating conditions. The investigated parameters are the air temperatures of 300, 350, 400, 450, and 500 K with constant percentage of nitrogen addition in combustion air stream of 5 % to give low oxygen concentration of 18.3 % by mass at constant air swirl number, air to fuel mass ratio, and thermal load of 1.5, 30, and 23 kW, respectively. The gaseous combustion characteristics were represented as axial and radial temperatures distributions, temperatures gradient, visible flame length and species concentrations. The results indicated that as the air temperature increased, the chemical reaction rate increased and flame volume decreased, the combustion time reduced leading to a reduction in flame length. The NO concentration reaches its maximum values near the location of the maximum centerline axial temperature. Increasing the combustion air temperature by 200 K, the NO consequently O2 concentrations are increased by about % 355 and 20 % respectively, while CO2 and CO concentrations are decreased by about % 21 and 99 % respectively, at the combustor end.

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