An innovative air saturator for humidification-dehumidification desalination application

Performance investigation of a novel solar hybrid air conditioning and humidification–dehumidification water desalination system

Experimental study for hybrid humidification–dehumidification water desalination and air conditioning system

This study investigates the performance of a novel humidification dehumidification (HDH) desalination system integrated into a vapor compression (VC) heat pump. The integrated heat pump delivers the necessary heating and cooling loads to the HDH desalination unit. Three different layouts (system A, system B, and system C) of water desalination plants are proposed and evaluated analytically at different operating conditions, such as water temperature, water flowrate, mass flowrate ratio (MR), and humidifier effectiveness. The investigated performance metrics of the proposed HDH desalination system are the gained output ratio (GOR), freshwater production rate, specific electrical energy consumption (SEEC), recovery ratio (RR) and cost of freshwater production. System A is without heat recovery, system B has heat recovery through preheating feed inlet saline water, while system C has heat recovery through preheating inlet air to the humidifier. The parametric analysis indicates that GOR, water productivity, and RR improve with increasing water temperature and humidifier effectiveness, while the specific electrical energy consumption decreases at the same conditions. The findings show the existence of an optimum mass flowrate ratio (MR) at which system performances are maximized. Results also reveal that the systems with the option of energy recovery provide the highest gained output ratio, recovery ratio and productivity, and the least specific electrical energy consumption. Additionally, depending on various system and cost parameters, the price of freshwater production from the proposed systems varies from 34.27 $/m3 to as low as 7.33 $/m3 of freshwater.

A novel configuration of solar integrated waste-to-energy incineration plant for multi-generational purpose: An effort for achieving maximum performance

Performance analysis and optimization of hybrid multi-effect distillation adsorption desalination system powered with solar thermal energy for high salinity sea water

Maisotsenko Humid Air Bottoming Cycle (MHABC) is a viable option for the waste heat recovery of gas turbine topping cycle to attain a higher efficiency point of the combined cycle power plant; thus, having a potential of lower CO2 emissions towards environment. In this work, instead of the typically proposed counter flow configuration of the air saturator, a novel mixed flow configuration is proposed. The proposed configuration uses a hybrid cross-flow and a regenerative counter-flow heat and mass exchanger (HMX). This hybrid HMX is numerically simulated to estimate optimal amount of saturated air which can lead to maximum efficiency and power output. The mathematical model of the mixed flow configuration HMX based air saturator is developed by applying mass and energy balance laws on a selected control volume. The results of the air saturator are initially validated using previously published experimental data for air cooling applications. Furthermore, simulations for high-pressure operations suitable for power generation are performed and a parametric analysis shows that optimal mass flow rate ratio between the working air in the dry channel and incoming air for cross-flow part is 0.65. Optimal mass flow ratio between the working air wet channel and working air dry channel for the counter-flow part is 0.5. The integration of hybrid air saturator in MHABC can yield a maximum of ~57 MW of output work and ~42% of thermal efficiency. The proposed system can achieve a 7% increment in total output work, and 9% increment in thermal efficiency as compared to the counter-flow configuration as an air saturator in the bottoming cycle. Furthermore, the proposed system has ~55% fewer carbon footprint as compared to counter-flow configuration alone as an air saturator.

Desalination technologies reject large amounts of brine with significant value back to sea. The concept of hybridization of different desalination technologies has proven that it can be effective in terms of reducing rejected brine and increasing the freshwater production rate as well as reducing the freshwater cost. In this work, brine recovery to improve water production through a simple modified configuration of integrating a multi-effect desalination (MED) system with humidification–dehumidification system (HDH). The rejected brine of the MED system is used as the feed for the HDH system without the need for preheating the rejected brine since it leaves the MED at a suitable temperature for HDH application. The study focuses on investigating the effect of different operating conditions on the increase in system freshwater production rate and recovery ratio as well as the exergetic efficiency. Parameters investigated include steam temperature, feed salinity, number of brine streams, cooling water flow rate, and ambient temperature. An exergo-economic analysis has also been conducted using the cost flow method to evaluate the freshwater production cost for the modified system. Results indicate that the integration of HDH can increase the water production rate by a maximum of 7.82% and produce fresh water at 2.08 $/m3 compared to 2.094 $/m3 when using the standalone system under the same conditions.

Huge amount of energies is consumed by the air conditioning (A/C) to maintain the required temperature and humidity inside spaces/applications of high humidly. An innovative A/C system that recovers the condenser heat in process air reheating and other useful thermal utilization is presented and investigated in this paper. For high coefficient of performance (COP) of the AC and more energy-efficient system, the cold exhaust air rejected by the air condition system is also utilized to cool the condenser of the AC system. Huge amount of the water condensate from the system is also utilized as freshwater production. Performance of the proposed system is analytically investigated for different operating conditions and system capacities. Mathematical model of the systems is developed and solved numerically using Engineering Equation Solver (EES) software. Results show that the proposed system enhances the COP and decreases the electric power consumption. The saving in electric power consumption, COP, and the freshwater production rate of the system increases with decreasing room-sensible heat factor, fresh air ratio, and outdoor air temperature and humidity. Moreover, the COP of the proposed system is 90% higher than COP of the basis system, and the savings in the running cost of the system increase by 4.5 times with decreasing the room-sensible heat factor (RSHF) from 0.6 to 0.2. In addition, the highest COP attained by the proposed system is 2.72, and the corresponding freshwater production rate is 373.8 kg/h.

Performance analysis of proposed hybrid air conditioning and humidification–dehumidification systems for energy saving and water production in hot and dry climatic regions

Exergy analysis of a hydrogen and water production process by a solar-driven transcritical CO2 power cycle with Stirling engine

Exergoeconomic analysis and optimization of an integrated system of supercritical CO2 Brayton cycle and multi-effect desalination

Solar-powered ejector-based adsorption desalination system integrated with a humidification-dehumidification system

The present study dealt with the generation of freshwater through the direct contact membrane distillation (DCMD) technique, powered by an evacuated tube solar collector (ETSC). The major objective of the present work was to determine the optimum conditions of fluid flow rate and temperature for maximum freshwater productivity across both the feed and permeate sides of the membrane module. A flat hydrophobic membrane composed of polyvinylidene fluoride (PVDF) coated with Teflon was utilized for the DCMD process. The rate of freshwater production was examined with the variation in the feed/permeate flow rates (from 3 to 7 LPM) and feed temperature (from 45 °C to 75 °C) for a constant permeate-side temperature of 30 °C. The experimental results indicated that a maximum freshwater productivity of 45.18 kg/m2h was achievable from the proposed system during its operation with a high solar heated inlet feed temperature of 75 °C and mass flow rates of 7 LPM across both sides of the membrane. Further, a detailed assessment of the performance parameters indicated that the present solar-powered DCMD system exhibited a maximum evaporative efficiency of about 80% and temperature polarization coefficient (TPC) of 0.62 respectively.

Systematic analysis and multi-objective optimization of an integrated power and freshwater production cycle

Fuel cells are chemical energy converted to electric energy, which is today a new technology in energy production. Among the existing fuel cells, solid fuel oxide cells have a high potential for use in synthetic and combined production systems due to their high temperature (700–1000°C). The solid oxide fuel cell (SOFC) output acts as a high-temperature source, which can be used for heat engines such as the Stirling engine as a high-temperature heat source. A hybrid system including solid oxide fuel cell and Stirling engine and reverse osmosis desalinating is a cogeneration plant. This system includes two parts for power generation; the first part is power generated in the SOFC, and the second part is that with use of heat rejection of solid oxide fuel cell to generate power in the Stirling engine. Also, due to the water critical situation in the world and the need for freshwater, it is very common to use desalination systems. In this study, important goals such as power density and exergy destruction, and exergy efficiency, have been investigated. In general, the performance of the hybrid system has been investigated. Firstly, a thermodynamic analysis for all components of the system and then multi-objective optimization performed for several objective functions include exergy destruction density, exergy efficiency, fuel cell power and freshwater production rate. The present optimization is performed for two overall purposes; the first purpose is to improve fuel cell output power, exergy efficiency and exergy destruction density, and the second purpose is to improve the exergy efficiency, the amount of freshwater production and exergy destruction density. In this optimization, three robust decision-making methods TOPSIS, LINMAP and FUZZY are used. Two scenarios are presented; the first scenario is covering power, exergy efficiency and exergy destruction density. The output power and exergy efficiency, and exergy destruction density, have optimum values in the TOPSIS method’s results. The values are 939.393 (kW), 0.838 and 1139.85 (w/m2) respectively. In the second scenario that includes the freshwater production rate, the exergy destruction density and exergy efficiency, three objective functions are at their peak in the FUZZY results, which are 5.697 (kg/s), 7561.192 (w/m2) and 0.7421 respectively.