This work presents an experimental investigation of the performance of a HDH system operated by heat pump. The novel heat pump system provides the necessary heating for the humidifier and cooling for ...the dehumidifier of the HDH system. The proposed integrated unit is capable of producing freshwater as well as cooling effect for space conditioning through water heated or cooled heat exchange units. Influence of various operating parameters such as feed water flowrate, feed water temperature and chilled water flowrate on the general assessment metrics, including gain output ratio (GOR), recovery ratio (RR), coefficient of performance (COP), energy utilization factor (EUF), Specific electrical energy consumption (SEEC) and productivity are evaluated. The cost of freshwater production from the proposed desalination unit is estimated. Results showed that the integrated system is capable of attaining maximum GOR of 4.07, RR of 4.86%, COP of 4.85, EUF of 3.04, and productivity of 287.8 L/day. The minimum SEEC of the system was found to be 160.16 kWhr per cubic meter of freshwater. The system is also capable of providing cooling load of 3.07 kW while producing the needed desalinated water. The estimated price of freshwater production varied from 10.68 US$ to 20.39 US$ per cubic meter.
•Experimental investigation of the performance of a novel HDH system operated by heat pump.•Water heated and water cooled heat pump evaporator and condenser.•The maximum gained output ratio of 4.07 is attained.•The system produces 287.8 L/day with SEEC of 160.16 kWhr per cubic meter of freshwater.•The system provides cooling load of 3.07 kW.
•This study presents a novel numerical model based on artificial neural network (ANN) model and universal mathematical correlation to forecast bubble point pressure and gas solubility.•The artificial ...neural network model based on back-propagation learning algorithm and sigmoid function with numerous inputs include API gravity, reservoir temperature, and gas specific gravity.
Bubble point pressure and gas solubility are considered vital pressure-volume-temperature properties of crude oil samples as both play a significant role in reservoir and production engineering calculations. These two fluid oil properties can be measured experimentally or using mathematical correlations, the experimental methods are time consuming and expensive, although they give a reliable result. Therefore, using mathematical correlations can be as an alternative way, however, existing correlation having number of limitations. Hence, this study presents a novel numerical model based on artificial neural network (ANN) model and universal mathematical correlation to forecast bubble point pressure and gas solubility. The artificial neural network model based on back-propagation learning algorithm and sigmoid function with numerous inputs include API gravity, reservoir temperature, and gas specific gravity. The ANN model is developed and validated by utilizing more than 450 data points collected from numerous fields located worldwide with various reservoir characterization. In this study, the bubble point pressure is estimated first and then used to forecast gas solubility based on the calculated correlation coefficient. The results of this study concluded that in order to optimize the ANN model, collected data must to be distributed as follows; 65% for training, 20% for testing and 15% for the validation processes with R2 of 0.988 and average absolute percent relative error (AAPRE) =5.56% for the bubble point pressure and 4.5% for the gas solubility. A comparison study is performed between the new ANN extracted correlation and other well-known models (Standing, Petrosky and Frashad, McCain, Vasquez and Beggs, Marhoun, Glaso, Dokla, and Lasater correlations) to show the robustness of the presented correlation. The results show that the presented correlation has the ability to predict bubble point pressure and gas solubility precisely with lowest AAPRE compared to other models.
Humidification dehumidification (HDH) desalination system is a thermal-based desalination technology that is suitable for small-scale water desalination applications. In this paper, we present an ...experimental and thermodynamic analysis of the energetic performance of two HDH cycles. The HDH cycles considered are the basic open-air open-water (OAOW) cycle and the modified closed-water open-air (CWOA) cycle with the options of brine recirculation. An experimental investigation is performed on the modified cycle to validate the theoretical model that is used to assess the energetic performance of both the basic and modified cycles. The theoretical model is found to be in a good agreement with the experimental data with a maximum percentage deviation of 5% from the experimental data. Furthermore, limiting cases of the system are explored. Within the limiting cases, the modified cycle recorded about 100% improvement in the energy performance over the basic cycle due to heat recovery process associated with the modified cycle. Additionally, a cost analysis was performed to determine the cost of freshwater production by the presented desalination cycles. Results show that the freshwater price varied from 4.10 to 6.55 $/m3 and 0.79 to 2.25 $/m3 for the basic OAOW HDH cycle and the modified CWOA HDH cycle, respectively.
•Experimental and analytical investigations of two HDH cycles are carried out.•The HDH cycles considered are both the basic and modified cycles with an option of brine recirculation.•Experimental investigation is performed on the modified cycle to validate the theoretical model.•Limiting cases of component(s) effectiveness (where mixing is justifiable) are defined.•The modified cycle showed about 100% improvement in performance over the basic cycle.
In this study, exergo-economic analysis of two layouts of humidification-dehumidification (HDH) desalination systems driven by a vapor compression heat pump (HP) is presented and discussed. The ...systems are closed-air open-water water-heated cycle coupled with a heat pump (HP-HDH-WH), and modified air-heated cycles integrated with a heat pump (HP-HDH-AH). For the purpose of comparison, a conventional closed-air open-water (CAOW) electric water heated HDH system (E-HDH-WH) is also presented. Exergy destruction, exergetic efficiency and product cost are evaluated for these systems. The influence of input parameters such as mass flowrate ratio, dehumidifier effectiveness, compressor isentropic efficiency, and feed water temperature on second-law efficiency and exergy destruction associated with the major components of the systems are analyzed. The impact of input cost parameters is investigated using two different approaches. The analysis shows that evaporator and compressor are the components with the largest exergy destruction. The exergy efficiency for the HP-HDH air-heated unit, HP-HDH water-heated unit, and E-HDH water-heated unit is found to be 1.097%, 0.06965% and 0.05795%, respectively. The cost of desalinated water evaluated by current analysis for HP-HDH air-heated system, HP-HDH water-heated cycle, and E-HDH water-heated unit is found to vary from 4.61$/m3 to 5.49$/m3, 6.00$/m3 to 7.14$/m3, and 4.44$/m3 to 14.95$/m3, respectively. The results generally reveal that HP-HDH air-heated cycle shows better performance both from energetic and exergetic viewpoints.
•Exergo-economic analysis of HDH desalination systems driven by a heat pump•The influence of performance and design parameters on second-law efficiency and exergy destruction were investigated.•Evaporator and compressor are the components with the largest exergy destruction.•Cost of desalinated water is the lowest for HP-HDH air-heated system, followed by HP-HDH water-heated cycle, and then E-HDH.•HP-HDH air-heated cycle shows best energy and exergy performance.
Here the simultaneous formation of formic acid and formate from the mutually reinforcing anodic GOR and cathodic CO2RR is realized. The cathode and anode can realize high Faraday efficiency of formic ...acid (84.5%) and formate (90.2%), respectively. The mechanism study shows that Cu(OH)2/CF as anode electrocatalyst can generates a large number of hydroxyl radicals, which improves the reaction efficiency. In the cathode area, CO2 molecules can be activated faster at the cathode to generate *CO2– intermediate, and *CO2– intermediate is more likely to generate *COOH rather than *CO.
Display omitted
•The system of GOR coupled with CO2RR could realize the efficient generation of formic acid at both anode and cathode.•Faraday efficiencies of 84.5% for formic acid in the anode area and 90.2% for formic acid in the cathode area are achieved.•Cu(OH)2/CF as anode electrocatalyst can generates a large number of hydroxyl radicals, which improves the reaction efficiency.
Electrocatalytic reduction of CO2 to formate is a promising technology, which has attracted much attention in the field of carbon neutralization. Although, the kinetic-sluggish anodic oxygen evolution reaction (OER) limits the efficiency of CO2 electroreduction. Herein, an electrocatalytic technology for glycerol oxidation reaction (GOR) coupled with CO2 reduction reaction (CO2RR) has been developed to achieve the generation of formic acid and formate. Using GOR instead of OER not only overcomes the kinetic bottleneck of the entire system, but also improves the Faraday efficiency of formic acid (84.5%) and formate (90.2%). Cu(OH)2/FC as anode electrocatalyst can generates a large number of hydroxyl radicals, which enhances the oxidation efficiency of glycerol. The strategy proposed in this work is expected to be widely used in other electrocatalytic reactions.
En el presente trabajo se estudia a través de diversos análisis SIG y estadísticos la organización de las necrópolis megalíticas del río Gor, tomando como muestra dos conjuntos especialmente ...destacables dentro de las mismas: Majadillas y Hoyas del Conquín. A partir de los análisis llevados a cabo podemos observar que existe una planificación en la ubicación de los monumentos, así como ciertas variables que parecen indicar unos patrones de uso cambiantes a lo largo de la horquilla temporal en la que funcionaron los megalitos del río Gor como depósitos funerarios (finales del Neolítico – Edad del Bronce). Entre los resultados cabe destacar la preocupación por dominar visualmente todo el valle a partir de la adición de marcadores sagrados (los dólmenes) que, aun con una visibilidad generalmente reducida desde cada uno de ellos, configuran en su conjunto un sistema totalmente articulado de control visual ritualizado.
Humidification Dehumidification (HDH) desalination is a convenient process to produce drinking water from low temperature saline water in waterfront areas. High energy consumption of the system ...remains as a limiting factor, besides many enhancements done in improving the system performance. Though HDH system cycles are classified on the basis of air and water cycles, detailed performance analysis of different HDH cycles is absent till date. The present study aims at carrying out parametric analysis of possible HDH layouts and finally proposing a layout with high Gain Output Ratio (GOR) and Recovery Ratio (RR) at the low equipment volumes. Simulations are carried out using the Scilab® software. Simulation results are validated using the experimental data obtained from a pilot plant of open-air open-water single stage system. Variation of system parameters like humidifier volume, dehumidifier volume, GOR and RR were analysed in detail for each individual layouts. Out of the eight different layouts investigated, Layout 8 is found to be the best based on GOR, RR, equipment volume and specific energy consumption. Hence it is recommended to use Layout 8 with an inlet temperature of 74 °C and MFR of 2.4 for productivity of 90 LPH.
Display omitted
•Detailed study on the performance analysis of 8 different layouts are carried out for a fixed productivity.•Optimal feedwater temperature in humidifier of layouts are directly related with the GOR and RR of the system.•Least equipment volume and highest RR is obtained at the highest feedwater temperature, independent of type of layout.•Highest GOR is obtained at the least feed water temperature if air or water or both streams operate in closed cycle.•Layout 8 is found to have the highest GOR and RR at the lowest value of specific energy consumption.
Multistage membrane distillation (MD) systems can have significantly higher efficiencies than their single stage counterparts. However, multistage MD system design has received limited attention. In ...this paper, the performance of a multistage vacuum membrane distillation (MSVMD) which is thermodynamically similar to a multi-stage flash distillation (MSF) is evaluated for desalination, brine concentration, and produced water reclamation applications. A wide range of solution concentrations were accurately modeled by implementing Pitzer's equations for NaCl-solution properties. The viability of MSVMD use for zero liquid discharge (ZLD) applications is investigated, by considering discharge salinities close to NaCl saturation conditions. Energy efficiency (gained output ratio or GOR), second law efficiency, and the specific membrane area were used to quantify the performance of the system. At high salinities, the increased boiling point elevation of the feed stream resulted in lower fluxes, larger heating requirements and lower GOR values. The second law efficiency, however, is higher under these conditions since the least heat for separation increases faster than the system's specific energy consumption with increase in salinity. Under high salinity conditions, the relative significance of irreversible losses is lower. Results indicate that MSVMD systems can be as efficient as a conventional MSF system, while using reasonable membrane areas and for a wide range of feed salinities. Given MD's advantages over MSF such as lower capital requirement and scalability, MSVMD can be an attractive alternative to conventional thermal desalination systems.
•A multistage vacuum membrane distillation (MSVMD) system was numerically analyzed.•Effect of salinity and membrane size on energy efficiency was studied.•MSVMD system has higher second law efficiency and lower GOR at higher salinity.•Non-uniform and uniform membrane area designs and tradeoffs were assessed.•MSVMD system can be as efficient as MSF especially at higher salinities.
•Humidification dehumidification desalination system powered by a heat-pump.•Mathematical models based on mass and energy balance for combined system.•A closed-air open-water water-heated, and ...modified air-heated cycles are analyzed.•Maximum GOR of 8.88 were achieved at 80% effectiveness for air heated and water heated cycles.•A maximum GOR greater than 10 can be reached for ideal components.
Humidification-dehumidification is a carrier gas based thermal technique that is ideal for small-scale water desalination applications. One advantage of humidification-dehumidification systems is the ability to utilize low grade and renewable energies as heat source to drive the system. This work presents theoretical investigation of humidification-dehumidification desalination system operated by a heat pump. The model is based on the first law of thermodynamics, describing heat and mass transfer in the combined humidification-dehumidification-heat pump cycle. The model predicts the performance of closed-air open-water water-heated, and modified air-heated cycle coupled with a heat pump. To improve the Gain output ratio and energy recovery of the system, a heat pump is used as the source of heating and cooling for the humidification-dehumidification desalination system. Energy rejected in the condenser is used as a source of heat in the humidifier whereas the cooling effect of the evaporator is used to cool incoming seawater for effective condensation of humid air in the dehumidifier. A parametric study is conducted to investigate the influence of system operating parameters, including water and air flowrate, seawater temperature, and refrigerant flow rate on the system performance. Results indicate a maximum Gain output ratio of 8.88 and 7.63 obtained at 80% components effectiveness and mass flow rate ratio of 0.63 and 1.3 for modified air heated and water heated cycle, respectively. A maximum gain output ratio greater than 10 can be achieved for humidifier and dehumidifier effectiveness of 100% leading to more energy efficient systems. The cost of desalinated water production is calculated and the effect of major parameters on its variation is also presented.
PDF
