Humidification Dehumidification Desalination Unit Research Articles

Proposal of a geothermal-driven multigeneration system for power, cooling, and fresh water: Thermoeconomic assessment and optimization

The depletion of fossil fuel reserves and environmental challenges have prompted the exploration of alternative energy sources. Geothermal energy, extractable from within the Earth's crust, emerges as a reliable renewable option throughout the mentioned shift. In this regard, the presented study introduces a geothermal-powered multigeneration system designed to generate power, manage cooling loads, and produce fresh water. This comprehensive system incorporates an organic flash cycle, a half-effect absorption refrigeration unit, a Kalina cycle, and a humidification-dehumidification desalination unit. Evaluating the system's thermoeconomic performance involves considering input parameters and simplifying assumptions to determine the performance profitability of the presented system. Furthermore, a parametric examination is conducted which is followed by the employment of an optimization analysis across three diverse scenarios to identify the most favorable operating conditions. The results of the presented research reveal that the suggested system can deliver power, cooling capacity, and freshwater production at rates of 342.3 kW, 301.7 kW, and 0.233 kg/s, respectively. Additionally, the system demonstrates an exergy efficiency of 31.52 % and achieves a payback period of 5.85 years.

Optimization of a syngas-fueled SOFC-based multigeneration system: Enhanced performance with biomass and gasification agent selection

In light of abundant sources of biomass feedstocks and regarding the higher performance in syngas-fueled-based SOFC systems, this work proposes a novel multigeneration system based on the combination of syngas-fuel SOFC, Kalina cycle, humidification-dehumidification desalination unit, and proton exchange membrane electrolyzer. This system is designed for simultaneous production of power, heating, freshwater, and hydrogen. Comprehensive energy, exergy, exergoeconomic, environmental, and economic analyses have been conducted to evaluate its performance. The optimum input biomasses, gasification agents, and operating conditions were determined using a coupled approach of an artificial neural network, multi-objective Particle Swarm Optimization algorithm, and the Linear Programming Technique for Multidimensional Analysis of Preference decision-making method. Under base input conditions, the energy and exergy efficiencies of the proposed system were found to be 53.66 % and 38.2 %, respectively. The system also demonstrated the capability to produce 0.1633 kg/s of freshwater and generate a net power output of 377.6 kW. The results indicate that using oxygen-enriched air in the gasification process notably enhances efficiency while reducing emissions. Straw and CO₂ were identified as the optimal feedstock and gasification agent, yielding an exergy efficiency of 42.71 % and a total product cost of 6.29 $/GJ at the optimum point. Moreover, with a selling price of $0.20/kWh for electricity and a fuel cost of $6/GJ, the system can achieve total revenue of approximately $1.65 million with a payback period of 4.01 years. These findings underscore the proposed plant's profitability under specific pricing conditions, making it an attractive investment opportunity.

Performance assessment and multi-objective optimization of a humidification-dehumidification desalination unit and dye-sensitized solar cell integrated with wind tower in arid and semiarid regions of Iran

Performance assessment and multi-objective optimization of a humidification-dehumidification desalination unit and dye-sensitized solar cell integrated with wind tower in arid and semiarid regions of Iran

Multi-aspect optimization of a geothermal-based integrated Kalina-proton exchange membrane fuel cell with ejector cooling and desalination systems

In order to use geothermal energy efficiently, a novel poly-generation system is introduced in the present study. In this configuration, the topping system is comprised of the combined modified Kalina cycle and proton exchange membrane fuel cell for power generation. Moreover, the bottoming configuration is composed of an ejector cooling system and a humidification-dehumidification desalination unit for cooling and freshwater production. Furthermore, the output heating is get from the heat rejection stage in the Kalina cycle. The proposed system is examined from energy, exergy, and exergy-economic perspectives through parametric analysis and multi-objective optimization. The effect of changes in geothermal water temperature, the upper pressure of the Kalina cycle, the flash temperature of the Kalina cycle, the outlet temperature of the fuel cell, and the current density of the fuel cell are assessed on the output parameters. Considering exergy efficiency and payback period as the target functions, they are calculated as 43.94 % and 0.859 years. In this case, the considered system can produce 549.1 kW of power, 140.2 kW of cooling, 46.29 kW of heating, and 0.0326 kg/s of freshwater.

Research on Two-stage Humidification-dehumidification Heat Pump Desalination System

For the humidification-dehumidification desalination unit to perform more efficiently, a two-stage humidification-dehumidification heat pump desalination system was proposed. So as to improve the heat and mass transfer effect between seawater and moist air, the two-stage humidifier was employed to recover the waste heat of seawater discharged from the first stage humidifier. The models of a one-stage and two-stage humidification heat pump seawater desalination system were built using Aspen Plus simulation software. Multi-condition simulation studies were carried out for different inlet seawater temperatures, liquid-gas mass ratios, and refrigerant flow rates of the heat pump. According to the comparative examination of the simulation’s outcomes, it is concluded that: with the increase in inlet seawater temperature and liquid-gas flow ratio, the two-stage humidifier system’s recovery rate and gain output ratio are superior to those of the first-stage humidifier system, and the inlet seawater temperature and circulating airflow needed for the two-stage humidifier system to perform at its best are less demanding than those for the first-stage humidifier system., indicating that the two-stage humidifier dehumidification desalination technology of the heat pump has great performance improvement and a broad application prospect.

Modeling of a direct-contact humidification-dehumidification desalination unit in a 256 MW steam power plant using effluent streams: Case study

Considering the waste of fresh water in a 256 MW steam power plant located in the southeast of Iran, and to compensate a part of its water consumption, a humidification-dehumidification (HD) desalination system is proposed. Because of sedimentation problems in indirect-contact HD systems, in this research, the application of direct-contact HD method to recover the effluent stream in a steam power plant is presented. Considering unit cross-sectional area for HD towers and based on primary results of the modeling, up to 119 lit/hr can be produced when the height of both humidifier and dehumidifier is 1.8 m and the flow rate of air is 0.7 kg/s. Three different scenarios based on (I) full capacity of available steam from the blowdown of boilers, (II) available chemical effluent (salt water), and (III) available cooling water, are examined and compared in this research. As, required salt water or/and cooling water are much more than the available amounts in the power plant, scenario I and II are rejected. Based on obtained resulted from the scenario III, the cost of production is 0.8 $/m3 of fresh water, and the GOR of proposed HD desalination unit is 1.03. With consumption of less than 5% and 10% of the available steam and salt water in the power plant, respectively, more than 7.5 m3/day of fresh water can be produced by the proposed direct-contact HD desalination system.

Seawater Greenhouse Equipped with a Novel Solar Humidification-Dehumidification Desalination Unit in MAKRAN Coast: Fabrication and Experimental Study

The purpose of this study is the fabrication and performance evaluation of a new type of solar humidification–dehumidification (HD) desalination unit to supply sufficient fresh water for a seawater greenhouse in the MAKRAN coast in southeast Iran. In the proposed design, a particular type of air-to-air condenser is used. The cold air coming out of the greenhouse ventilation system (fan and pad) in summer and the cold ambient air in winter is used to supply the required cooling of the system. In this way, when cold air passes over the pipes in air-to-air condensers, condensation of water vapor occurs in the moist air inside the pipes, and fresh water is produced. Greenhouse fans, which have an air flow rate of around 20,000 m3/hr, are used to create this air flow. By fabricating two condensers, each using 42 rows of PVC pipes with a diameter of 75 mm, it is possible to produce 400 L of fresh water per day in a 400 m2 greenhouse. The required heating is provided by the solar farm, which includes 96 square meters of flat plate collectors. The steps of unit fabrication are described in detail in this research. However, the effect of greenhouse air temperature and circulating seawater flow rate on freshwater production, energy consumption, and energy intensity are also investigated. By increasing the flow rate of circulating seawater and decreasing the greenhouse air temperature, the production rate of the system increases. When the hot seawater and greenhouse air temperature are 61.7 °C and 26 °C, respectively, the maximum instantaneous production is estimated to be 80 L/h. The energy intensity of the HD desalination unit is varied between 3192 and 4382 kJ/L, and the gain output ratio of the system is around 0.6. The proposed system can be easily paired with conventional greenhouses employing a fan and pad cooling system and produces around 1.25 (L/m2·day) fresh water.

Analysis of a novel solid desiccant evaporative cooling system integrated with a humidification-dehumidification desalination unit

A new configuration of a solid desiccant evaporative cooling system integrated with a humidification-dehumidification (HDH) desalination unit was proposed, and its performance was numerically evaluated. In the proposed system, the humid exhaust air from the desiccant wheel and M-cycle IEC was recycled and supplied to an HDH unit to improve the water production rate. Two operation modes were proposed depending on climate conditions. The system with two operation modes was evaluated under various operating conditions. A case study was performed under Australian climatic conditions. The results showed that Mode 1 had a better cooling performance than Mode 2, with a maximum cooling capacity of 4.76 kW. However, Mode 2 was more energy efficient, with an average COP of 0.71, as no regeneration heat was needed. With the HDH unit, the freshwater produced by the system could fully cover the water usage of the M-cycle IEC in both modes. When the heat source temperature of the HDH unit increased to 70 °C, the water productivity of the system could reach 148.5 kg/h and 42.0 kg/h for Mode 1 and 2, respectively. The findings indicated that the proposed system had good potential for producing freshwater and cooling simultaneously.

Thermo-economic analysis of a hybrid system based on combined heat - isobaric compressed air energy storage and humidification dehumidification desalination unit

To solve the problem of electricity and fresh water supply in different low-efficiency independent systems in coastal areas or remote islands, a hybrid system based on energy cascade utilization principle is proposed for both small-scale electricity and fresh water supply purposes. Such hybrid system is made up by the combined heat - isobaric compressed air energy storage (CH-ICAES) and the water-heated humidification dehumidification (HDH) desalination unit. Meanwhile, the CH-ICAES is a synthesis of ICAES and power to heat (PtH) technologies. In operation, the low-grade heat from CH-ICAES charging and discharging is used to produce fresh water in HDH. The simulated results show that the gained-output-ratio (GOR) and total produced fresh water mass in a roundtrip cycle at design condition are 2.0678 and 851.77 kg, respectively. Meanwhile, the levelized cost of storage (LCOS) and levelized cost of water (LCOW) are 35.45 cents/kWh and 0.57$/ton, indicating a competitive economic performance. Moreover, the GORs in charge and discharge are different due to the non-uniform heat source conditions. In addition, the humidifier inlet seawater temperature, the effectiveness of humidifier and dehumidifier, the relative humidity of dehumidifier inlet air, the HDH operation pressure and some parameters of CH-ICAES have significant effect on hybrid system performance.

Study of a solar HDH desalination unit powered greenhouse for water and humidity self-sufficiency

This study investigates the performances of a self-sufficient greenhouse powered by a solar humidification–dehumidification desalination unit. It aims to achieve an overall integrated system that produces enough fresh water to cover the irrigation demand as well as the air humidification needs of the greenhouse. The humidification–dehumidification operation was numerically simulated using the developed model along with the greenhouse microclimate. The greenhouse model was validated through an experimental real-scale greenhouse. To make the proposed system more flexible, an auxiliary control system is used to easily monitor the greenhouse needs and ensure its satisfaction. The findings revealed that the integrated system, with its two main subsystems and its regulation device, successfully ensures the greenhouse irrigation, the humidification needs and provides an optimal plant growth. For the case study, i.e. cucurbit greenhouse situated at El Hamma (Tunisia), the desalination system can cover more than 200% of the greenhouse water irrigation needs while keeping the greenhouse inside air at a humidity level of 60% at least. The maximum productivity and the best energy efficiency are respectively 5.1 m3/day and 63.25%.

Comprehensive thermodynamic and economic analyses and optimization of a novel poly-generation setup utilizing solar and geothermal sources

• An innovative poly-generation system based on renewable energy sources is designed. • Thermodynamic and thermo-economic analyses and optimizations are implemented. • The simultaneous production of electricity, cooling, hydrogen, and fresh water is considered. • CO 2 utilization in transcritical power and cooling generation cycles is appraised. • Optimum thermal and exergy efficiencies are attained as 32.3% and 19.5, correspondingly. This work studies the 3E aspect (energy, exergy, and economic) of a poly-generation setup via a novel and innovative configuration based on two renewable energy sources through converting the thermal energy to useful energies and energy-based products. This system embraces geothermal energy via a flash-binary cycle and solar power employing a parabolic trough solar collector-based solar field. The other subsystems are a carbon dioxide-based transcritical organic Rankine cycle integrated with a modified transcritical refrigeration cycle to generate electricity and cooling, a humidification-dehumidification desalination unit to provide freshwater, and a proton exchange membrane electrolyzer to produce hydrogen. In this way, the newly designed system has been evaluated respecting the weather data of Beijing city in China throughout the year. Subsequently, the first and second laws of thermodynamics together with thermo-economic analysis and net present value assessment have been implemented. The sensitivity of principal variables regarding crucial design parameters has been examined via a parametric study. Also, the genetic algorithm was the optimization tool to optimize the calculations in different modes. The results indicated that the exergy-cost case of optimization correspondingly led to exergy efficiency and levelized cost of products of 19.2% and 13.9 $/GJ with a payback period of 3.96 years.

Multi-objective optimization and multi-aspect analysis of an innovative geothermal-based multi-generation energy system for power, cooling, hydrogen, and freshwater production

Considering the feasibility of geothermal wells employed worldwide in the energy sector, this study was motivated to examine a novel multi-generation system devised to enhance the feasibility of flash-binary geothermal systems through innovative heat recovery in five stages. Accordingly, the main system consists of a flash-binary geothermal cycle, an ejector refrigeration cycle, a Kalina cycle integrated with another ejector refrigeration cycle, a humidification dehumidification desalination unit, and a low-temperature electrolyzer. Due to the five stages of innovative heat recovery, this system achieved a cost-effective and efficient design framework, introducing it as a high-quality alternative for stand-alone flash-binary geothermal cycles. To study the feasibility of the proposed system, a sensitivity analysis based on energy, exergy, and exergoeconomic concepts was employed. Moreover, the genetic algorithm in different multi-objective optimization scenarios was implemented to reach stable and high-efficiency products. According to the obtained results, the capability of the system to produce electricity, cooling, freshwater, and hydrogen are calculated to be 782 kW, 881.6 kW, 0.286 kg/s, and 0.181 kg/h, respectively. Also, in the exergy-cost optimization scenario, the system's optimum exergy efficiency and sum unit cost of products were obtained to be 46.44% and 3.98 $/GJ, respectively based on LINMAP decision-making method.

On a novel integration of a multistage absorption heat pump with a balanced humidification-dehumidification desalination unit

• A novel absorption system coupled with a desalination unit is investigated. • A single-double-effect absorption can produce desalinated water and a cooling effect. • Energy input from both natural gas and a waste-heat source in the proposed system. • Results reveal that the system daily produces 110–225 L of water at 0.0042–0.0068$/l. • The system has a coefficient of performance of 1.06 and a gained-output ratio of 4.15–8.5. • For optimum performance, the absorber and feed to be around 45 °C, 30–35 °C, respectively. This study investigates a novel cooling-desalination system having a single-double-effect absorption heat pump coupled with a humidification-dehumidification desalination unit. A waste-heat source drives the system in addition to natural gas. Using a waste-heat source lowers the cost of the desalinated water and thus gives the proposed system considerable attention in the water market. The results reveal that the system can produce desalinated water of about 110 l per day for 0.0068 $/l with a gained output ratio of 4.15. When the air extraction technique is applied, the daily water production and the gained output ratio increase to 225 l and 8.5, respectively. The corresponding water cost drops to 0.0042 $/l. Besides, the system has a coefficient of performance and cooling capacity of 1.06 and 0.8 kW, respectively. The performance results show that for optimal performance, the absorber and the feed saline water temperatures should be around 45 °C and 30–35 °C, respectively. Further, compared with other absorption/humidification-dehumidification configurations, a promising performance of the proposed system is observed.

Improving thermal performance of a solar thermal/desalination combisystem using nanofluid-based direct absorption solar collector

Depletion of freshwater resources and reduction of rainfall in arid areas causes water scarcity, which is intensified by population and urbanization growth. In this study, a small-scale solar thermal/desalination combisystem using nanofluid-based direct absorption solar collectors and humidification-dehumidification desalination unit is proposed to supply domestic hot water, space heating, and freshwater demands of a residential building. The dynamic simulation of the system performance in the Hot-Dry climate zone is done using TRNSYS-MATLAB co-simulator. The results indicate that using the proposed combisystem reduces 94.3% and 17% of annual energy consumption for providing domestic hot water and space heating demands, respectively. The freshwater demand is supplied in the range of 11.3% to 100%. In the case of using a flat plate solar collector, the solar fraction for domestic hot water and space heating demands in comparison with nanofluid-based direct absorption solar collectors reduces by 3.7% and 1.7%, respectively. Furthermore, the produced freshwater reduces 18% on average. The payback time using nanofluid-based direct absorption and flat plate solar collectors are 6.4 and 7.8 years, respectively.

Effect of working fluids in a novel geothermal-based integration of organic-flash and power/cooling generation cycles with hydrogen and freshwater production units

One of the essential steps to design energy conversion-based systems is choosing an efficient working fluid under the design goals to access stable products with high efficiency and overcome environmental issues. In this regard, the current paper is motivated to devise and evaluate a novel geothermal-driven multigeneration system under the effect of various working fluids. The proposed system consists of a flash-binary geothermal power plant, an organic flash cycle (OFC), a power/cooling subsystem (an organic Rankine cycle (ORC) and a thermoelectric generator incorporated with a compression refrigeration cycle), and freshwater and hydrogen production units utilizing a humidification-dehumidification desalination unit and a low-temperature electrolyzer. Considering the design potential of the OFC and ORC, four different environmentally-friendly working fluids, i.e., R123 and R600 in the OFC and R1234yf and R1234ze(e) in the ORC are selected and classified in four groups to introduce the best one, under the energy, exergy, and economic (3E analysis) approaches. Also, the whole system is optimized through a genetic algorithm, respecting the optimal solution for the energy efficiency and unit exergy cost of the products. According to the results, R123/R1234ze(e) shows the highest cooling, hydrogen, freshwater production rates, and energy efficiency. Likewise, the maximum power generation and exergy efficiency belong to R600/R1234ze(e). Moreover, R600/R1234yf has the lowest unit exergy cost of products.

Experimentally evaluation of split air conditioner integrated with humidification-dehumidification desalination unit for better thermal comfort, produce freshwater, and energy saving

The present experimental study aims to achieve the better indoor thermal comfort, produce freshwater, and energy saving. To investigate this idea, split air conditioner was integrated with solar assisted humidification-dehumidification (HDH) desalination unit, the HDH desalination unit was designed to produce the freshwater and also used as a pre-cooling unit to cool the condenser of split air conditioner in order to reduce a power consumption, increases the cooling capacity, and COP. To obtain the effect of utilizing the HDH desalination unit as pre-cooling unit on a performance of the split air conditioner, two operating cases were suggested to run the HDH unit and the split air conditioner. In the first operating case, the HDH unit was operated separately from the air conditioner. In the second operating case, the HDH unit was connected to the condenser of air conditioner to cool the condenser. Is this case the cold air leaving from the dehumidifier of the HDH desalination unit was used to cool the condenser of the split air conditioner. The results show that when the HDH desalination unit combined with the split air conditioner, (i) the saving in power consumption of air conditioner reached 18.4%, (ii) COP for the air conditioner improved by 48.5%, (iii) accumulative freshwater production reached 36.49 L day−1, and (iv) the improvement in GOR for utilizing the proposed hybrid system reached 60.9%.

Thermoeconomic assessment of a geothermal based combined cooling, heating, and power system, integrated with a humidification-dehumidification desalination unit and an absorption heat transformer

Population growth, economic challenges, and the environmental crisis force scientists and designers to pay more attention to clean, sustainable, and renewable-based energy systems. In this regard, due to the unlimited geothermal potential in many countries, the geothermal energy resource can be an economical alternative. Therefore, in the present work, a novel multi-generation system, based on a 100% geothermal resource, for power, cooling, heating, and desalination has been designed and analyzed, thoroughly. The system is evaluated from the energy, exergy, and thermo-economic viewpoints, and providing high heating/cooling potentials while reducing the thermoeconomic indexes is the major achievement of this study. The results demonstrate that the system's net power output, freshwater production rate, heating, and cooling capacities are 78.47 kW, 92.1 m3/day, 6251 kW, and 4991 kW, respectively. Moreover, the highest amount of exergy destruction occurs in the absorption heat transformer (42%) and the absorption chiller (35%), respectively. In addition, the chiller’s absorber has the highest cost rate of exergy destruction, and the turbine and the evaporator of the organic Rankine cycle have the highest investment costs. It is found that energy and exergy efficiencies are 60.55% and 17.05%, respectively for summer, and 70.58% and 43.59%, respectively for winter, and the system's total cost rate is 44.12 $/h with the payback period of 5.63 years. Furthermore, the parametric study shows that increasing the ambient temperature and decreasing the terminal temperature difference of the heat transformer’s evaporator lead to higher exergy efficiency and lower total system cost rate.

Hybridization of a triple-effect absorption heat pump with a humidification-dehumidification desalination unit: Thermodynamic and economic investigation

In this study, a novel hybrid desalination/cooling system is investigated. The system combines a triple-effect absorption (TEAB) heat pump (whose working fluid is LiBr/water solution) and a water-heated humidification dehumidification (HDH) desalination unit. The system is investigated for simultaneous production of freshwater and cooling effect. A low-grade energy source (natural gas) is utilized to operate the system, while solar PV panels are used to power the auxiliary components of the system, such as pumps and blowers. A detailed mathematical model is established to explore the influence of different parameters on the thermodynamic and economic performance of the system. From the HDH unit’s side, it is observed that the effectiveness of the HDH components (dehumidifier and humidifier), the mass flow rate ratio, and the inlet conditions of the saline water have a considerable impact on the system performance. On the other hand, from the TEAB system’s side, the performance of the hybrid system is found to be significantly affected by the effectiveness of both the solution heat exchangers and the absorber. The results reveal that the system can produce, at its optimal operating conditions, 10 kg of fresh water per hour for 0.85 ȼ/l with a gained-output-ratio (GOR) value approaching 5.0. Additionally, the system can produce a cooling capacity of about 2.0 kW at a coefficient of performance (COP) value close to 1.5. Furthermore, the proposed TEAB-HDH system shows comparable performance to other heat-pump-powered HDH systems available in the literature.

Experimental Investigation of the Helical Condenser for Humidification Dehumidification Desalination Unit Powered by Solar Energy

In this paper, built the water desalination unit based on the humidification dehumidification (HDH) process powered by solar energy was examined. The unit uses a humidifier of the packing type (HPT) and the dehumidifier (condenser) made a concentric helically tube and shell heat exchanger was investigated. The dehumidifier was used to condensate water vapor from humid air. The Nusselt number (Nu) inside the helical tube was discussed in many studies before, although it is not mentioned before the Nusselt number outside the helical tube for a mixture fluid. In the current study cold water in passing inside a concentric helical tube, while a hot humid air passing over the external surface of the concentric helical tube. The concentric helical tube is positioned inside an insulated shell. Different air flowrates were used, and the experimental results were used to induce a new empirical equation for the shell’s Nusselt number. The water desalination unit was examined by using the solar collectors as a heating source for the saline feed water and the introduced air to the humidifier, and it is found that the freshwater productivity was 8.60 kg/day and to reduce the carbon dioxide released by 4600 g/day.

Experimental and Theoretical Performance Assessment of Small-Scale Humidification–Dehumidification Desalination Unit Using Different Packings in the Humidifier

Experimental and Theoretical Performance Assessment of Small-Scale Humidification–Dehumidification Desalination Unit Using Different Packings in the Humidifier