Gained Output Ratio Research Articles

Parametric analysis of humidification dehumidification desalination driven by photovoltaic/thermal (PV/T) system

In the present paper, a novel packing dehumidifier based humidification dehumidification (HDH) desalination system, driven by photovoltaic/thermal (PV/T) module, is proposed in purpose of clean and efficient production both for freshwater and electricity. Thermodynamic and economic performance of the PV/T driven HDH desalination system is calculated, and relevant influences from the pinch enthalpy difference during humidification, solar radiation intensity are also investigated. The research results verify the feasibility of the PV/T driven HDH desalination system. Under the assigned input conditions, the maximum water production, gained-output-ratio (GOR) and total cost during desalination arrive at 57.38kgh−1, 1.56 and 4449.97$ at the balance condition of the dehumidifier, with the longest PBP as 7.34y, 6.65y and 5.60y for different appointed water prices with 0.78$t−1, 1.55$t−1 and 3.10$t−1. After the parametric analysis, it is found that the influences from the alternation of the pinch enthalpy difference and solar radiation intensity are different. It is concluded that the thermodynamic and economic performance varies very limited, with the pinch enthalpy difference decreasing from 15kJkg−1 to 5kJkg−1, while it is improved a lot, from 29.63kgh−1, 1.12 kW, 1.02 and 16.24y at 600Wm−2 for the solar radiation intensity to 76.86kgh−1, 4.7 kW, 1.74 and 4.36y at 1000Wm−2 for water production, net output power, GOR, and the payback period (PBP) at the case 1.55$t−1 for the water price.

Improved air gap distillation desalination through induced film condensation

Distillation across an air gap is implemented in several novel small-scale desalination technologies such as air gap distillation and multi-effect solar stills. These systems achieve better energy efficiency than simple solar stills by recovering the enthalpy of condensation towards feed preheating or further evaporation in subsequent effects. The air gap thickness between the evaporating and condensing fluids is a critical design variable that strongly affects overall performance. A thinner gap results in lower resistance to vapor diffusion and therefore helps attain a higher rate of pure water production and lower specific energy consumption, for the same hot and cold stream temperatures. In this manuscript, we experimentally evaluate methods to achieve a gap size lower than 5 mm, which is the thinnest gap size reported in the literature. While a superhydrophobic surface modification is usually applied to enhance condensation heat transfer (through dropwise condensation), here, a superhydrophillic surface modification is proposed. This ensures film condensation and prevents the growth of large condensate drops that can bridge the thin gap and come in contact with the saline feed, thereby getting contaminated with salt. Attaching a thin mesh to the condensation surface helps realize the same objective at lower cost and complexity. A 3 mm air gap is experimentally demonstrated using these modifications, resulting in a gained output ratio of close to 1 even with a small (304 cm2) evaporation surface area.

Thermodynamic, environmental, and economic analysis of a novel power and water production system driven by gas turbine cycle

In the present study, the performance of a creative poly-generation plant generating electricity and freshwater was energetically, exegetically, economically, and environmentally analyzed. The system consists of a gas turbine as the prime mover and Kalina and humidification-dehumidification desalination units for waste heat recovery purposes. A sensitivity analysis was conducted to evaluate the influence of design parameters variation on the proposed system performance. The construction feasibility of the proposed system was assessed by utilizing Net Present Value and the payback period. According to the obtained data from the base simulation conditions, the total gained output ratio, exergetic efficiency, the total cost of products, Levelized total emission, and freshwater production capacity were obtained 0.9574, 43.05%, 20.22$/GJ, 63679kg/kW, and 10.77kg/s. The combustion chamber has the highest exergy destruction rate by 16382kW. Moreover, the sensitivity analysis revealed that an increase in the combustion temperature reduces pollutant emission and enhances the power generation rate and exergy efficiency. Regarding 2.5$/GJ and 0.085$/kWh as the fuel cost and electricity price, a total profit of 18.93$M at the end of economic book life can be obtained, with a payback time of 6.39years, demonstrating the feasibility of the plant for establishment.

Different configurations of humidification-dehumidification desalination systems: Thermal and economic assessment

Drought has hit several water-stressed regions, with serious consequences for water and food security. In this regard, the low-cost and low-grade thermally driven humidification-dehumidification desalination cycle has good potential to provide freshwater in arid regions. From energy and economic point of view, different configurations of the humidification-dehumidification cycle have been proposed in the literature without a comprehensive comparison to identify the most suitable one. Thus, this paper investigates the thermal and economic performance of several multi-humidifier water- and air-heated humidification-dehumidification cycles. Thermodynamic models are structured to study the behavior of each cycle. The models rely on heat and mass transfer balances for each component. The effectiveness method is implemented for humidifiers and dehumidifiers to evaluate heat and mass exchangers. The models are validated using previously published data. The series seawater flow, triple humidifier, water-heated humidification-dehumidification cycle could deliver 151.2 kg/h of fresh water at a maximum temperature of 70 °C, with a gain output ratio of 1.995 and a specific cost of 2.73 $/m3. This cost rises by around 16% when a maximum temperature of 60 °C is employed. Results reveal that using a double-humidifier in an air-heated humidification-dehumidification cycle produces freshwater of 102.2 kg/h at the lowest price of $2.06/m3. It is concluded that the multi-humidifier water-heated humidification-dehumidification cycle produces more freshwater and less gain output ratio than the multi-humidifier air-heated humidification-dehumidification cycle.

Performance investigation of solar-powered direct-contact membrane distillation and humidification–dehumidification hybrid system

This study proposes a novel integrated direct-contact membrane distillation (DCMD) and humidification–dehumidification (HDH) desalination system driven by a solar flat-plate collector (FPC). In this approach, seawater heated by the FPC system is fed to the DCMD system to recover freshwater. The DCMD brine is subsequently processed by the HDH system to recover additional energy and produce freshwater. The DCMD system is incorporated prior to the HDH, as high concentrations of the feed solution can cause membrane fouling and pore wetting. The performance modeling of the FPC, DCMD, and HDH systems utilizing real-time solar irradiation data of Gizan city, Saudi Arabia is considered. The effects of FPC area, solar irradiation, inlet seawater temperature, feed salinity, humidifier dehumidifier effectiveness, and inlet feed flow rate on the FPC outlet seawater temperature, distillate rate (m˙d), recovery ratio (RR), and gain output ratio (GOR) are investigated. The monthly temperature of the seawater output from the FPC is in the range of 53–78 °C with a collector area of 16 m2 and inlet feed flow rate of 1.8 L/min. The highest m˙d, RR, and GOR values are 9.1 kg/h, 8.4%, and 1.3, respectively, under temperature and flow conditions of 78 °C and 1.8 L/min, respectively.

The second law analysis of a humidification-dehumidification desalination system using M-cycle

Humidification-dehumidification desalination (HDD) systems offer a feasible approach for the production of fresh water in inaccessible areas as they can be operational using renewable energy and require little maintenance. Various studies are being carried out to boost the system performance. In this paper, an open air open water HDD system is proposed that exploits the enhanced evaporation and condensation processes by implementing with the Maisotsenko cycle (M-cycle). The system utilizes solar energy as the energy input to heat the saline water. A thermodynamic model is formulated under steady-state conditions, considering the first and second law of thermodynamics. The energetic and exergetic performance of the system is studied. The model is first validated with the experimental data and a good agreement is found where the maximum discrepancy is about 6.0 %. Effects of different operating conditions on key performance parameters such as the Gain Output Ratio (GOR), specific energy consumption (SEC), exergy destruction, and exergy efficiency are analyzed. An improvement is observed in the GOR when the inlet air temperature is raised at constant humidity ratio. The system exhibits better performance in dry air environment when compared with humid air environment. The analysis shows a maximum mass flow rate of desalinated water of 22.3 kg/h, recovery ratio (RR) of 0.223, GOR of 3, SEC of 0.23 kWh/kg and an exergy efficiency of 43.21 %.

Thermodynamic Analysis of the Volumetric Absorption Solar Collector-Driven Direct Contact Membrane Distillation System

Abstract Solar-powered membrane distillation (SP-MD) technology has proven to be an ideal solution for providing fresh water in remote and off-grid locations. In this study, a novel solar energy-driven direct contact membrane distillation (DCMD) cycle is proposed in which a nanofluid-based volumetric absorption solar collector (VASC) is used to drive the DCMD process. The present work focuses on the use of volumetric collector instead of commercially available surface absorption-based solar collector in case of two-loop indirect SP-MD systems, which are installed to control the scaling and corrosion issues in solar collectors. The thermodynamic performance of this two-loop indirect solar-powered DCMD (SP-DCMD) system has been evaluated with the help of a mathematical model prepared in matlab. For modeling the DCMD unit, the ɛ-number of transfer unit (NTU) method used for designing heat exchangers has been employed. The performance of the overall system is evaluated by gained output ratio (GOR), thermal efficiency (η) of the membrane distillation, and water flux (Jw), and effects of various operating parameters related to both DCMD and VASC systems have been understood on the overall system performance. Finally, it has been shown that VASC-driven DCMD system has been approximately 4–15% higher gained output ratio compared to surface absorption-based solar collector (SASC)-driven DCMD system under similar operating conditions.

Concentrating phosphoric acid by direct contact membrane distillation using a low-cost polyethylene separator

The ability to recycle phosphorus (P) components in reusable strength from wastewaters presents a promising opportunity to meet the increasing consumption demand. In this paper, the concentration of a dilute stream of phosphoric acid from 15 to 60 wt% was demonstrated using a high-performing PE separator in direct contact membrane distillation (DCMD), benchmarking against commercial PVDF and PTFE membranes. Combining with morphological/structural/material characterization, the membrane performance and energy efficiency were analyzed in-depth based on a combined heat and mass transfer model, which coupled the effects of both concentration and temperature polarization. The interplay of membrane flux, operating conditions and energy indicators was examined, indicating the significant influence of feed temperature, membrane characteristics and the trade-off relationship between Evaporation Efficiency/ Gained Output Ratio and Specific Energy Consumption. The concentration of 15 wt% H3PO4 stream using the PE separator was operated continuously for 100 h with minimal change in flux (> 40 kg/m2·h at 65 °C). The long-time stability was confirmed by membrane autopsy before and after experiments. The results demonstrated the PE separator as a promising low-cost membrane for acid concentration, providing an alternative for resource recovery from harsh solutions.

Performance improvement of an air gap membrane distillation process with rotating fan

The current paper presents an experimental study on the performance of a novel air gap membrane distillation (AGMD) desalination system where a fan blade is installed within the air gap to improve the system’s productivity and energy utilization. The installed blade creates suction inside the air gap behind the membrane and increases the air turbulence, thereby reducing the vapor mass transfer resistance across the membrane and improving the productivity and energy efficiency of the system. Results revealed that the proposed design and process improve the vapor permeate flux by about 250% when compared to the conventional AGMD module. Furthermore, the average improvement in the gained output ratio of the system is about 67%, with a corresponding 77% reduction in the specific thermal energy consumption. Influences of the feed temperature and the motor speed are dominating the performance of the new system.

Experimental investigation and optimization of a solar desalination unit with high heat recovery ratio using weak air compression process

With the research objective of verifying the feasibility and improving the performance of the novel desalination system, a solar desalination system with high heat recovery ratio using weak air compression process is designed and fabricated in this paper. The experimental investigation and numerical optimization of the proposed system under different operating parameters of seawater and moist air are conducted. The experimental results in feasibility tests indicate that the system has good producibility of fresh water and self-sustainability. Meanwhile, the fresh water yield and the specific electrical consumption can reach 2.91 kg/h and 4.2 kg/kW·h at the hot seawater temperature of 70°C and the pressure difference of 10 kPa. The recommended mass flow rate of moist air is 0.016 kg/s, and the corresponding fresh water yield and specific electrical consumption are 3.2 kg/h and 4.6 kg/kW·h at hot seawater temperature of 70°C. Compared with the optimization of the humidification process and the control process of pressure distribution ratio, increasing the hot seawater temperature is the most feasible method to improve the increasing extent of specific electrical consumption. The experimental specific electrical consumption and corresponding gained output ratio can be increased to 9.57 kg/kW·h and 6.49 when hot seawater temperature increases to 80°C. Finally, a new performance index defined as gained-output-ratio equivalent is proposed to objectively evaluate the comprehensive performance from thermal and electrical energy. The gained-output-ratio equivalent of the proposed system is up to 2.60, which is one of the best records in similar researches.

Thermodynamic analysis of thermal desalination system with humidification–dehumidification cycle

Problems. Today desalination of seawaterprovides a worldwide fresh water productionof 24.5 million m 3 perday.One of the promising desalination methods is thermal humidification-dehumidification process. In spite of significant benefits this technology, it has a key drawback – high thermal energy consumption.The aim of the study. Determine the optimal thermodynamic parameters of working substances (air and water) in elements of desalination system with humidification–dehumidification cycleto obtain maximum performance with a minimum energy consumption.Methodology of implementation. Mathematical modeling of the humidification-dehumidification cycle at different input parameters.The thermodynamic model was createdusing equations of mass and energy balances of the desalination system.Research results. System Gain output ratio(GOR) increases with increasing salt watertemperature at the outlet of the dehumidifier.Maximum valuesof GORand recovery ratio (RR) are observed at the maximum temperature difference (maximum heating) of salt water in the dehumidifier. It is shown that values of GOR and RR increasewith increasing salt water temperature at the inlet to the humidifier. It is found that GOR value is independent of the temperature and humidity of the air at the inlet to the humidifier.Conclusions.The maximum valuesof GOR and RR for the humidification-dehumidification cycle with additional water heating are 3.75 and 6%, respectively. To obtain such results,the temperature of salt water at the inlet tothe system (dehumidifier) should be equal to 10 °C, and the temperature of salt water at the inlet to the humidifier – 70 °C. At the same time, temperature and humidity of the airсan have any values. The use of renewable energy for heating salt water in the heater will significantly increase system GOR

Multi objective optimization of MSF and MSF-TVC desalination systems with using the surplus low-pressure steam (an energy, exergy and economic analysis)

Water is consumed as one of the main fluids in the natural gas refinery which becomes wastewater after undergoing different process. Therefore, it is not possible to reuse or dispose the wastewater to the environment due to contaminant issues. At the same time, a huge amount of heat is wasted in surplus low pressure (LP) steam flow, which is used in natural gas refining process. In present study, it is attempted to model Multi Stage Flash (MSF) and multi stage flash coupled with thermal vapor compressor (MSF-TVC) systems for desalination of existing refinery wastewater utilizing different heat losses occur in the refinery process. In order to optimize the MSF and MSF-TVC systems, effective parameters in the field of energy, exergy and economic including gain output ratio (GOR), exergy efficiency and payback ratio (PBR) are used simultaneously. For this purpose, the Pareto solution and TOPSIS methods are used as the multi objective optimization. As a result, the optimum values of the first stage temperature (maximum system temperature) and number of desalination stages are obtained 130 °C and 32 stages for MSF and 115 °C and 25 stages for MSF-TVC systems. Finally, it is found that the amount of 46,335 ton/year CO2 emission reduction can be achieved by using surplus LP steam heat potential in refinery wastewater desalination.

Performance Analysis of a Novel Cascade Vapor Compression System for Small-Scale Desalination and Cooling

Abstract The demand for improving living standards has led to increasing freshwater consumption and comfort cooling, requiring significant performance improvements. In this regard, a novel and efficient cascade refrigeration system (CRS) for simultaneous generation of considerable freshwater and cooling effect is proposed. The system does not require dedicated components for desalinating seawater because it is a by-product of the proposed CRS. Utilizing the cascade configuration enhances energy efficiency by lowering the compression work while improving energy recovery by utilizing the heat rejected from the condenser of low-temperature cycle to vaporize seawater for desalination in the evaporator of the high-temperature cycle of the proposed cascade system. A mathematical model of the innovative system based on thermodynamic and economic principles has been developed and utilized to predict the proposed system's thermal performance and cost-savings. A comprehensive analysis has been conducted to study the effect of multiple parameters such as the evaporator, condenser, and brine boiling temperatures. The main studied parameters were coefficient of performance (COP), gain output ratio (GOR), freshwater production, and total cost-savings. For a 10 tons of refrigeration (TR) unit, the freshwater production was between 56.11 and 73.36 kg/h, with cost-savings reaching 2226 US$/year. It was found that the freshwater production increased with condenser and brine boiling temperature but decreased with evaporator temperature. The COP improvement can be as much as 26% over the reference cooling system without desalination.

Performance evaluation of an HDH desalination system using direct contact packed towers: experimental and mathematical modeling study

Abstract Humidification–dehumidification desalination (HDH) is one of the suitable methods for desalination of saline and brackish water in a small scale. In this research, an HDH desalination method with a direct contact dehumidifier has been analyzed theoretically and experimentally. The setup consists of two similar packing towers for humidification and dehumidification, 10 inches in diameter, which are filled up to 1 m with Rushing packing. In this new HDH configuration, seawater and freshwater recirculation has been used in humidifier and dehumidifier sections, respectively. A steady-state mathematical model based on the mass and energy equations for each system component is presented. The effect of various input parameters on the freshwater production, gain output ratio (GOR) and specific energy consumption has been investigated. The results revealed that the inlet seawater and air temperature to the humidification tower had the highest and the lowest effect on the produced freshwater, respectively. Also, the maximum value of the GOR is 3.3, which is obtained in the equilibrium condition of the dehumidifier. The experiments show that the freshwater production of the proposed HDH device is 300 L/day, which can provide water for the domestic consumption of a small family.

Psychometric study and performance investigation of an efficient evaporative solar HDH water desalination system

The improvement of the evaporation process can significantly improve water production and the overall efficiency of a solar humidification-dehumidification (HDH) system. This study experimentally investigates the use of novel packing materials to improve the performance of the humidification process. Contact time and area between sprayed water and surrounding air are two critical parameters that considerably influence evaporation. Therefore, using selected packing materials inside the humidifier can increase these two parameters. A wet cooling tower facility is used as a humidifier with instrumentations installed to measure the inlet and outlet air and water conditions. Among different materials tested, it is found that fine-grain foam has the maximum specific humidity difference at different operating temperatures. At a high-water flow rate of 80 L/h and low water temperature of 60 °C, the gain output ratio (GOR) is evaluated to be 4.23. Moreover, a solar HDH system includes a solar collector, out of three options, and a thermal storage (TES), and HDH unit is designed and modeled to provide the required heat. For solar collectors, flat-plate, parabolic-trough, and evacuated-tube are considered. It is found that the flat-plate collector has a maximum efficiency of more than 70% while producing over 25 L/d/m2 of distilled water.

Theoretical analysis and parametric investigation of an innovative helical air gap membrane desalination system

A helical air gap membrane desalination (HAGMD) system is designed in the present study. The condenser is designed as a cylindrical shape with helical fins machined on the outer surface of a hollow copper condenser. A detailed theoretical model, studying heat and mass transfer in the HAGMD module, was developed. The theoretical model for a cylindrical system with fins is developed for the first time and is unique in the MD literature. Experimentation was carried out to examine the behavior of the HAGMD module under diverse design and operating conditions. The effect of cold flow rate, feed flow rate, feed temperature, the height of fins, the number of fins, and the length of the module is determined on the performance of the HAGMD system. Permeate flux and gained output ratio (GOR) were considered as the performance indicators of the system. Results showed that permeate flux increases with cold flow rate, feed temperature, feed flow rate, as well as number of fins, while the increase in height of fins negatively affects the flux. Theoretical model and experimental results are found to be in excellent agreement with only 6.7% of error which shows that the present theoretical model is excellent to predict the performance of any HAGMD system. For similar design parameters, the average flux increased by 135% for the finned HAGMD module, with 35 fins over the one with that only for 1 fin. Maximum experimental distillate flux is found to be 20 kg/m2 hr, and GOR is found to be 0.75.

A floating planting system based on concentrated solar multi-stage rising film distillation process

This work presents a floating planting system based on multi-stage rising film distillation process driven by concentrated solar energy. The proposed system applies desalinated freshwater to directly irrigate hydroponic crops, which saves land area and takes advantage of ocean resources. The hydrophilic wick is selected as the evaporator to form a rising seawater film by capillary suction. Through the vertically arranged multi-stage evaporation and condensation units, the latent heat of vapor can be recovered effectively. To obtain the maximum optical efficiency, the optical simulation of the concentrating section is carried out. Based on optimized structure, an experimental system is built to investigate the effects of different operating parameters on the internal temperature, water production rate, gained output ratio (GOR), and exergy efficiency. Under indoor steady-state conditions, the temperature difference of desalination units is found to be progressively larger under increasing irradiance. In addition, the system could achieve 1.7 of GOR and 6.1% of exergy efficiency with 900 W/m2 irradiance. Results at actual weather reveal that the daily water yield of the system could reach 9.51 kg/m2/day under azimuth tracking condition, which is 97% higher than the fully passive operation condition. Finally, under 28 consecutive days of operation, the average growth height of lettuces cultivated by the system is 13.7 cm.

Experimental Investigation and Exergy Analysis of Dehumidification Performances for a Cascaded Phase Change Heat Storage Dehumidifier

In the humidification and dehumidification solar desalination system, the recovery of vapor condensation latent heat is the key problem. Using a cascaded phase change heat storage method to recover vapor condensation latent heat can improve the phase change heat storage rate and the water production performance of dehumidifier. The exergy analysis and experimental methods are used to study the cascaded phase change storage dehumidifier. The results show that the more stages of phase change materials in the cascaded phase change heat storage device, the greater the exergy efficiency will be. The heat transfer performance of phase change materials increases with the increase of hot and wet air temperature and flow at the inlet of the dehumidifier. The exergy efficiency and gain output ratio of three-stage phase change heat storage are higher than that of the single-stage. The three-stage one is recommended. If the heat recovered by the cascaded phase change heat storage device is supplied to the passive humidification dehumidification desalinator for secondary water output, the water output and gain output ratio will increase by 25% and the water production cost will be reduced by 20%. The results can provide a basis for the design and application of a cascaded phase change heat storage dehumidifier.

Thermo-economical and environmental analyses of a Direct Contact Membrane Distillation (DCMD) performance

As a promising desalination technology, membrane distillation is expected to be developed continuously due to its wide application and low sensitivity to salt concentration in the feed stream. The performance of a direct contact membrane distillation (DCMD) has been investigated based on energy, exergy, economic and environmental analyses in the current study. Performance evaluation of a DCMD unit is comprehensively carried out in terms of the operating parameters, including gained output ratio (GOR), specific energy consumption (SEC), concentration polarization coefficient, temperature polarization coefficient, recovery ratio, exergy efficiency, specific exergy consumption, carbon cost, and cost of water. This study presents one of the most comprehensive investigations on DCMD behavior performed in the available literature by developing a robust computational code in MATLAB software. In addition to pervasive energy and exergy analyses, a complete economic study for freshwater production plants with different capacities based on heat extracted through geothermal energy and wasted heat, and investigation of the environmental effects of using heat recovery MD cycle to reduce greenhouse gas emissions, are presented. The results showed that the utilization of heat recovery heat exchangers significantly improves the system's operating conditions. The exergy efficiency of the DCMD module with and without heat recovery is 38.23% and 56.71%, respectively, indicating a 48.34% improvement in exergy efficiency. Finally, the economic and environmental analyses showed that for a 15000 m3/day desalination unit, recovering the wasted heat could reduce the distillate water production cost down to 1.31 $/m3 while CO2 emissions and energy consumption also decreased by 59%.

Humidification-dehumidification solar desalination system using porous activated carbon tubes as a humidifier

The integration of solar water desalination utilizing humidification dehumidification (HDH) techniques with a cooling system (CS) and hot air flow rate was investigated experimentally during Sept and Oct. 2020 under Egypt's Suez governorate's climate located at 29.9669°N, 32.5499°E. The system performance at various air flow rates, water basin height of the daily production was tested. A porous activated carbon tube (PACT) was utilized as a humidifier where the relative humidity reaches 100%, and the cooling system was used as a dehumidifier. The results revealed that increasing water height (Hw) enhances freshwater productivity. The highest distillate yield occurred at water height 3 cm, increasing 13.75% and 5.5% compared with water height 1 cm and 2 cm, respectively. The optimal hot air flowrate is 0.01156 kg/s with an increase of 100%, 38.46%, 15.9%, and 34.5% compared with 0.0057, 0.0086, 0.0144, and 0.0173 kg/s, respectively. The maximum freshwater production is 6.12 kg/day. The energy and exergy efficiencies and gain output ratio (GOR) are 26.73% and 1.57%, and 1.24, respectively. Economic analysis showed that the cost of 1 L of fresh water is 0.01386 USD.