Desiccant Temperature Research Articles

Eco-friendly atmospheric water generation: A novel desiccant-based variable pressure humidification-dehumidification system

This study introduces a zero-brine discharge approach, eliminating the necessity for continuous seawater input and brine disposal—major drawbacks in traditional desalination methods. This research’s core is a humidification-dehumidification (HDH) system operating under variable pressures, significantly boosting efficiency. The system comprises two synergistic components: a variable-pressure HDH unit and a desiccant-based moisture extractor utilizing a lithium chloride solution. After freshwater is extracted, the concentrated desiccant cycles through the moisture extractor to absorb atmospheric water vapor, diluting it for reuse and thus completing the desiccant loop. The heat and mass transfer processes were scrutinized through mathematical modeling, and parameters for maximizing the Gain Output Ratio (GOR) were optimized. The results underscore the system’s capacity for sustainable, efficient freshwater production. This methodology offers a feasible solution to challenges in desalination and significantly contributes to alleviating global water scarcity, particularly in coastal areas. Further analysis shows that systematic optimization of key parameters, such as pressure ratios and desiccant temperatures, considerably improves performance metrics. Adjusting the pressure ratio from 1.22, where the GOR peaks at 2.44, to 1.56 directly impacts system efficiency. Modulating the maximum desiccant temperature at an optimal pressure ratio of 1.25 reveals that the GOR can increase from 1.635 at 0.7 to 2.44 at an effectiveness of 0.8. Optimized manipulation of these parameters can potentially enhance the GOR by up to 50% and improve mass transfer efficiency by about 20% within the HDH process.

Atmospheric water harvesting by osmotic distillation and direct contact membrane distillation using hydrophobic hollow fiber membranes

The use of a liquid desiccant air dehumidifier is an energy-efficient technology that can improve both indoor air temperature and humidity. However, the risk of concentrated liquid desiccant leakage into the air conditioning system during dehumidification can corrode the system, negatively impact indoor air quality, and potentially harm residents. To address this issue, this study investigates the effectiveness of osmotic distillation (OD) and direct contact membrane distillation (DCMD) for dehumidification and regeneration, respectively. The study analyzes the impact of inlet operating parameters, including liquid desiccant concentration, temperature, and flow rate, and air flow rate on the dehumidification performance and stability of the OD process. Calcium chloride was utilized as the liquid desiccant in this study. The results indicated that the dehumidification performance of the OD process improved with a higher desiccant concentration and lower desiccant temperature. However, the desiccant flow rate did not have a significant impact on dehumidification performance. Furthermore, the dehumidification performance decreased with a higher inlet air flow rate, but the moisture removal rate increased. The OD process demonstrated stable operation during the dehumidification process. DCMD was effective for desiccant regeneration, and no scaling occurred due to the deposition of calcium chloride crystals. However, the permeation flux of DCMD decreased as the feed concentration increased due to a decline in the feed vapour pressure and an increase in concentration polarization effect. In conclusion, the experimental results indicated that OD can effectively dehumidify humid air, while DCMD is a viable option for desiccant regeneration.

A dynamic model of the packed dehumidifier

Liquid desiccant dehumidification, a clean energy technique for creating comfortable environments has received a lot of interest. Several dynamic models have been proposed to predict the outlet air humidity ratio and temperature, however, a study on presenting variations of heat and mass transfer coefficients and thermal mass of desiccant during the dynamic dehumidification process was not encountered according to authors’ best knowledge. This gap is primarily due to the complex nature of the coupled heat and mass transfer processes, which make it challenging to capture the evolution of heat and mass transfer coefficients over time. In this study, variations of these parameters are analyzed at first. A theoretical study is conducted to show the thermal mass of the desiccant can be considered constant when changing the inlet air humidity ratio or desiccant temperature, simplifying the dynamic modeling process. While the variation of heat and mass transfer coefficients show significant impact in such conditions. Subsequently, a new method based on mass conservation is provided to determine the thermal mass of desiccant. By examining the cause-and-effect relationships between heat and mass transfer coefficients and outlet air humidity ratio, the evolution of heat and mass transfer coefficients following exponential laws is deduced by inversion. Then a dynamic model of packed dehumidifiers can be completed easily based on above derivations, and its viability is confirmed by experimental results. Compared to the existing method, the prediction accuracy can improve by 50% based on the proposed methods. This study characterizes evolution rules of heat and mass transfer coefficients over time, and with this, evolutions of outlet air parameters during the dynamic dehumidification process can be acquired conveniently based on the existing steady dehumidification model.

Specific energy analysis of using fertilizer-based liquid desiccants to dehumidify indoor plant environments

Controlling humidity in indoor plant environments is crucial to plant growth, but traditional dehumidification methods can be energy intensive. In this study, we evaluate the energy efficiency of a novel dehumidification concept that uses cold concentrated fertilizer solution as a liquid desiccant agent. This closes the water cycle by recovering water vapor for plant fertigation, and eliminates the need for energy-intensive desiccant regeneration. A theoretical transport model is used to conduct a parametric analysis of the specific energy performance of the system in response to desiccant temperature and other operating conditions. Specific energy of dehumidification is defined here as the ratio of the cooling load to the water vapor removal. Minimum specific energy results between 0.16 and 0.24 Wh/g are achieved at liquid desiccant temperatures between 7 and 14 °C. These results compare very favorably with other dehumidification technologies on the market, and satisfy new energy efficiency standards for indoor plant cultivation. The vapor flux associated with the minimum specific energy ranged from 1.2 to 1.6 g/m2/h. Controlling liquid desiccant temperature is shown to be critical to achieving high dehumidification rates at optimal specific energies. These encouraging results suggest that future research and development along this track can contribute to energy efficient greenhouse cultivation for sustainable food production.

Artificial neural network-based modeling for the prediction of heat and mass transfer coefficient of the adiabatic liquid desiccant system

This work, based on the data obtained from the literature reported by (Varela et al., 2018), aims to use the artificial neural network approach to predict the heat and mass transfer in a dehumidifier system, using lithium chloride as a liquid desiccant. A neural network model was developed in MATLAB environment based on multilayer perceptron that included an input, hidden, and output layer. The network input parameters are air velocity, air temperature, air humidity ratio, liquid desiccant temperature, liquid flow rate, and liquid desiccant concentration. The network output includes two variables which are the heat transfer coefficient (Kh) and mass transfer coefficient (Km). The performance of the ANN model was evaluated using the statistical parameters between the prediction results and experimental values. The performance regression yields R2 and MSE values of 0.9344 and 9.0032, respectively, for the test data set of heat transfer coefficient (Kh). Moreover, for the mass transfer coefficient (Km), the regression parameter R2 and MSE values for the ANN tests were found to be 0.9657 and 2.0414, respectively. In addition, air velocity, air temperature, solution mass flow rate, and solution concentration are the most influential parameters on the heat and mass transfer between the air and liquid desiccant.

Energy saving potential of an innovative membrane contactor hybrid system for vehicles’ climate control

In this paper an innovative Membrane Contactor Hybrid System (MCHS) for automotive air conditioning is presented and its energy needs are evaluated and compared with those of a traditional system for internal combustion engine vehicles and hybrid ones. The proposed system joints a Vapor Compression Cycle (VCC) with a Liquid Desiccant Cycle (LDC) provided with innovative Three-Fluid Membrane Contactors (3F-MCs). These components are crossed by air, liquid desiccant and a third fluid operating as an internal heat source/sink to control the desiccant temperature. The VCC refrigerant undergoes a two-stage compression process: the lower level is used in a conventional evaporator for cooling the air, and the higher level in an absorption 3F-MC to dehumidify the renewal air. A second 3F-MC (desorber) is heated (by means of hot water derived from the vehicle’s engine) in order to reconcentrate the desiccant by discharging water vapor to the environment. Air temperatures between 26 and 32 °C and relative humidity in the range 40–80% are considered to perform the comparisons between the two systems. Results show that energy savings can exceed 40% in the case of the most severe external conditions.

Performance characteristics assessment of hollow fiber membrane-based liquid desiccant dehumidifier for drying application

• Proposed novel integral technique based analytical model to assess HFLDD performance. • Analyzed the influence of inlet and design parameters on HFLDD performance. • Effect of Le and St numbers across and along the HFLDD is evaluated. • Case study on conventional/desiccant dryer performance is analyzed in humid climate. • Desiccant dryer found to be best alternative for humid climatic conditions. In the present study, a novel integral technique based two-point boundary value problem is developed using the simplified polynomial equations to assess the hollow fiber membrane-based liquid desiccant dehumidifier performance for drying application. The developed numerical technique is validated with the experimental data available in the literature and observed a maximum deviation of ± 9.7%. The liquid desiccant chosen is lithium chloride. By considering thermal and moisture effectiveness as performance parameters and choosing the air inlet temperature, air specific humidity, desiccant temperature, and liquid to gas ratio as input parameters, the influence of Lewis number and Stanton number on dehumidifier performance is analyzed. The performance analysis concluded that a high liquid to gas ratio, desiccant temperature, and specific humidity enhance the dehumidifier performance. Further, the variation of performance parameters along the length and thermal mass of the membrane column is also assessed. Moreover, a case study on conventional and desiccant dryers performance in humid climates is assessed and observed that the desiccant dryer is the best alternative compared to the conventional dryer. In addition, for the given operating range and inlet condition, the maximum possible vapour absorption rate (δ VAR ) and energy exchange for the conventional dryer is found to be 93 g/hr and 0.8 kW, whereas, for the desiccant dryer, it is 164 g/hr, and 1.4kW respectively.

Fertilizer-based liquid desiccants: A novel concept for energy efficient dehumidification and water vapor recycling in indoor plant environments

• Membrane-based dehumidification is demonstrated with fertilizer liquid desiccant. • This closes the water cycle and eliminates the need for desiccant regeneration. • The novel concept is validated with several common fertilizers. • Dehumidification flux of up 1.90 g/m 2 /h is achieved under certain conditions. • Liquid desiccant temperature must be controlled to improve operation. Increasing food production to sustainably feed a growing population requires innovation to improve the efficiency of energy, water, and fertilizer use in agriculture. In this paper, we introduce the novel concept of using concentrated fertilizer as a liquid desiccant for energy efficient water recovery and dehumidification of indoor plant environments. The first-ever experimental demonstration of fertilizer dehumidification is provided from laboratory testing using a membrane-based process with dense polydimethylsiloxane hollow fibers. Experimental data is compared to simulation results and shows reasonable agreement, suggesting that fundamental transport dynamics are accounted for. Water vapor flux of up 1.90 g/m 2 /h is achieved under certain conditions, with air relative humidity reduced to as low as 41 %. Dehumidification is observed for calcium nitrate, ammonium chloride, and ammonium sulfate, confirming that a variety of common fertilizers can be used for such applications. The effect of greenhouse air temperature and humidity is studied, and dehumidification is confirmed across a range of standard greenhouse conditions. The effect of key operating parameters is also studied, and liquid desiccant temperature is identified as a critical variable that should be carefully controlled to maximize dehumidification while minimizing energy input.

Simulation study of membrane distillation regenerator based on reduced pressure air gap

To reduce the regeneration energy consumption and improve the regeneration effect of liquid desiccant in membrane-based liquid desiccant air conditioning (M-LDAC), this paper combines the widely used Vacuum Membrane Distillation (VMD) and Air Gap Membrane Distillation (AGMD) methods, and innovatively proposes a reduced pressure air gap membrane distillation regeneration system, and applies the control variable method to simulate the influencing factors (desiccant temperature, flow rate, and air gap side vacuum) in the system. The results showed that the desiccant temperature and air-gap side vacuum had more influence on the system membrane flux than the flow rate, and the simulation showed that there was an optimal range of vacuum, and the membrane flux reached 12.55 kg/(m2·h) when the desiccant temperature was 90 °C, the flow rate was 0.2 m/s, and the vacuum was 40 Kpa, which increased the membrane flux by 14.8% compared with 10 Kpa. The analysis proves that the use of vacuum on the air gap side can effectively improve the membrane flux, which provides a reference for the optimal design of future liquid desiccant regenerator modules.

Economic and Experimental Assessment of KCOOH Hybrid Liquid Desiccant-Vapor Compression System

A liquid desiccant dehumidification cooling system is a promising, energy-saving, high-efficiency, environmentally friendly technology that maintains thermal comfort effectively indoors by utilizing renewable energy sources or waste heat to enhance system efficiency. In this research, a small-scale (6 kW cooling capacity) hybrid liquid desiccant air-conditioning system (HLDAC) is proposed to evaluate the dehumidification performance of a non-corrosive potassium formate (KCOOH) solution. For this, four input parameters, namely, inlet air flow rate, inlet desiccant temperature, inlet desiccant concentration, and inlet specific air humidity, were selected. Moreover, the different combinations of experiments were designed by employing response surface methodology (RSM) to evaluate the dehumidification performance parameters, namely, dehumidifier latent heat load, coefficient of performance of hybrid system, and moisture removal rate (MRR). Further, a comparative performance analysis between the hybrid system and a standalone vapor compression system (VCS) unit was carried out. The result showed a remarkable increase in coefficient of performance, which was observed at about 28.48% over the standalone VCS unit. Furthermore, the economic assessment of the proposed hybrid system is presented in this paper. Finally, from the economic analysis, it was concluded that the hybrid system had a payback time of 2.65 years compared to the VCS unit.

Performance assessment and optimization of liquid desiccant dehumidifier system using intelligent models and integration with solar dryer

Realistic performance predictions are necessary to control the liquid desiccant dehumidification systems effectively. In the present study, the application of artificial intelligence (AI) based artificial neural network (ANN), gene expression program (GEP) and adaptive neuro-fuzzy inference system (ANFIS) is investigated to estimate the dehumidifier effectiveness of desiccant dehumidifier systems while considering the effect of moisture removal rate and sensible heat factor as performance characteristics. It is found that the AI-based GEP model has the best prediction capability compared to the other developed AI models. In addition, the sensitivity analysis of independent parameters on the system performance parameters is estimated using the cosine amplitude method. The results demonstrate that the inlet desiccant temperature and specific humidity have a more substantial influence on the dehumidifier effectiveness and sensible heat ratio. Further, an algorithm involving the combination of multi-objective particle swarm optimization (MOPSO) with the GEP model is developed to optimize the input process parameters and to achieve better dehumidification performance. Lastly, based on obtained optimal operating conditions, a case study on a dehumidifier-integrated solar dryer is proposed for food/agriculture products drying applications using AI-based GEP-MOPSO model. It is also observed that the inlet water temperature and solar intensity have a significant impact on the useful heat gain of the solar collector.

A novel analysis of LiCl solution regeneration experiments

For the desiccant dehumidification, the regeneration process is a critical part. The paper experimentally investigated LiCl solution regeneration performance by analyzing the mass transfer characteristics. The regeneration rate, the regeneration potential and the concentration driving force were analyzed by considering the influence of independent variables such as the desiccant temperature, flowrate, and concentration. The regeneration potential, representing the underutilized mass transfer capacity stored in the outlet air, is determined by the smaller of the equilibrium value and the saturation humidity. The experimental results show the increase in solution temperature causes an increase in regeneration rate, accordingly also causes the regeneration potential and the residual driving forces to increase. It means that more regeneration potential is underutilized or ineffective capability exists. The increase in solution flowrate has no effect on the equilibrium curve. If the equilibrium humidity is less than the saturated humidity, the regeneration potential decreases with the increasing flowrate. Otherwise, it is necessary to consider special data to determine the variation trend. The increase in solution concentration causes a consistent decrease in regeneration rate, the regeneration potential and the residual driving forces.

Comparative Analysis on Dehumidification Performance of KCOOH–LiCl Hybrid Liquid Desiccant Air-Conditioning System: An Energy-Saving Approach

Conventional air conditioners (AC) operate on vapor compression refrigeration (VCR) technology, which is a heavy consumer of electricity, and the used refrigerants harm the environment. In humid and hot areas, a liquid desiccant AC system integrated with a VCR system has been proposed as a better alternative to traditional standalone VCR system, as it is an energy-efficient system that can remove latent air load, air pollutants from the processed air, and it is energy-saving. In this study, a hybrid liquid desiccant air conditioning (LDAC) system with a capacity of 5.5 kW was designed and developed by integrating these two different technologies, and the vapor pressure of potassium formate (KCOOH) solution at different solution temperatures and concentrations were monitored experimentally to determine the optimal concentration range. Moreover, a comparative study was conducted to analyze the dehumidification performance of lithium chloride (LiCl) and KCOOH solutions. Experiments are designed by using Minitab 19 software, which employs the design of an experimental technique through full factorial design by considering four variables, namely, type of desiccant, inlet air flow rate, inlet desiccant temperature, and inlet air humidity. To study and compare dehumidification characteristics of both solutions, three responses were considered, i.e., the coefficient of performance of a hybrid system, the heat load of dehumidifier, and specific humidity change. Experimental results revealed that 70% of KCOOH solution exhibited comparable vapor pressure to that of 36% LiCl solution. Additionally, the dehumidification ability of the KCOOH solution was better than that of the LiCl solutions.

Performance comparison of different flow arrangements of 4-fluid internally-cooled liquid desiccant dehumidifiers

In this study, the performance of 10 different flow arrangements of 4-fluid internally-cooled liquid desiccant dehumidifiers were compared. The four fluids are supply air, exhaust air, liquid desiccant, and water. The comparison was performed using a two-dimensional heat and mass transfer model of the dehumidifier that was solved numerically. The model’s predictions of supply air outlet humidity ratio matched experimental measurements within 6.7%. The two-dimensional variation of the air temperature and humidity ratio in the supply channel showed the importance of using a two-dimensional heat and mass transfer model when at least one of the fluids is in cross-flow with the other fluids. Moreover, a sensitivity analysis was performed to evaluate the effect of nine input parameters (supply air temperature and humidity ratio, exhaust air temperature and humidity ratio, liquid desiccant temperature, concentration, and flow rate, supply air mass flow rate, and exhaust to supply air mass flow rate ratio) on the performance of the dehumidifiers. The results showed that the best performance, in terms of the supply air humidity ratio and enthalpy decrease, was obtained when the supply air was in counter-flow with the exhaust air, liquid desiccant, and water. While the poorest performance was obtained when the supply air was in parallel-flow with the exhaust air and in counter-flow with the liquid desiccant and water. The approximate difference between the best and poorest performing flow arrangements in terms of the decrease in supply air humidity ratio and enthalpy is 4.3% and 10.5%, respectively. The results of the sensitivity analysis showed that for the 10 flow arrangements, the liquid desiccant inlet temperature, and flow rate have the least effects on the performance of the dehumidifier.

Experimental investigations on indirect contact type liquid desiccant cooling systems for high latent heat load application

Heat driven sorption technologies are promising alternatives to traditional vapour compression based systems for comfort cooling. High latent heat load applications and improved indoor air quality are best accommodated by the various sorption technologies available and desiccant-based cooling systems. Liquid desiccant-based systems are preferred over solid desiccant-based systems due to lower pressure drop, the possibility of continuous operation, solar energy for regeneration, and the ease of storage of regenerated desiccant solution. This paper investigates the experimental performance of indirect contact type liquid desiccant cooling systems for applications involving a high latent heat load. An experimental test rig includes a dehumidifier, regenerator, and heat exchanger, all been developed, fabricated and connected to work as one unit. The dehumidifier and regenerator transfer the heat and mass from liquid desiccant to the air membrane making the arrangement an indirect contact type of heat exchanger. Lithium Chloride solution is used as a desiccant solution in experiments, and Polyvinylidene Fluoride is used as a membrane material. The effect on dehumidifier performance parameters like rate of moisture removal, sensible heat effectiveness, and latent heat effectiveness is studied for varying inlet air parameters as well as for various liquid desiccant operating parameters. The inlet air specific humidity ranges from 10 to 13 g/kg da, and the inlet air flow rate varies from 2 to 4.5 kg/hr. The inlet desiccant temperature supplied at 24–32 0C with desiccant concentration varied 30–42%, and the desiccant solution mass flow rate is supplied in the range of 3–11 kg/h. Various dehumidifier performance parameters like rate of moisture removed, latent heat effectiveness and sensible heat effectiveness are discussed. Based on the experimentation, utilizing the optimum values of inlet air parameters or optimum values of desiccant solution parameters has been recommended to achieve the cooling system's highest possible latent heat effectiveness.

Experimental analysis of hollow fiber membrane dehumidifier system with SiO2/CaCl2 aqueous desiccant solution

The liquid desiccant air conditioning system is amongst the promising technologies for the provision of efficient air conditioning, particularly in hot humid climate conditions. By their benefits, membrane-based dehumidification systems have drawn large attention. Various techniques are used to enhance the performance of different dehumidification system types. The effect of using calcium chloride nanofluid solution with the added silicate nanoparticles as a desiccant solution in a hollow fiber membrane contactor system investigated experimentally. The airflow rate through the fibers is 11.2 m3/h with inlet relative humidity and temperature of 60 % and 35 °C, respectively. The sensitivity analysis was made to reveal the effect of desiccant temperatures, nanoparticle concentrations, and solution flow rates on sensible, latent, and total effectiveness and 2nd law efficiency of the system. The results indicate that using nanofluid instead of a pure desiccant solution, the values of sensible and latent effectiveness improved at the condition of high inlet solution temperature. The effect of employing nanofluid on exergy performance is the highest for the highest concentration of nanoparticles and inlet solution temperature. The maximum change of exergy destruction rate resulted by using nanofluid solution took place at a maximum flow rate of 244 ml/min for 1% nanofluid concentration. Using 1 % nanofluid instead of a pure solution, the rate of exergy destruction increased by 82 % and 160 % for 20 °C and 26 °C solution temperatures, respectively.

Performance prediction of a liquid desiccant dehumidifier using artificial neural networks approach

This work aims to develop two main ideas: first, the use of the artificial neural network (ANN) approach to predict the moisture removal rate (MRR) and the dehumidifier effectiveness (ɛ) of a counter-flow liquid desiccant dehumidifier using calcium chloride as an absorption solution. Second, the Garson method is used to identify the most important working parameters influencing the performance of the packed-bed dehumidifier component. A network model was developed in a MATLAB environment based on a multilayer perceptron that included an input, a hidden and an output layer. The network input parameters were the dry and wet bulb temperatures, the air and liquid flow rates, and the liquid desiccant temperature and concentration. The network output included two variables; the MRR and the ɛ. The performances of the ANN predictions were tested using experimental data not employed in the training process. The predicted values were found to be in good agreement with the experimental values, with mean relative errors of less than 4.90% for the MRR and 3.85% for ɛ. In addition, the air wet bulb and dry bulb temperatures were the parameters with the most influence on the MRR and ɛ, with a relative importance of 35% and 25%, respectively.

Numerical investigation of performance trade-off characteristics of a packed bed dehumidifier using aqueous blends of lithium chloride and calcium chloride

Current research in dehumidification systems is mainly focused on thermally driven liquid desiccant systems. However, the selection of proper desiccant solution has a greater significance on the performance of a dehumidifier. In this perspective, current work is presented with governing equations of energy, mass and species balance to study the performance of a dehumidifier. The governing equations are solved using finite difference method coupled with Jacobi’s model for an air–desiccant contact system of a cross-flow packed bed adiabatic dehumidifier operating with different desiccant blends of lithium chloride (LiCl) and calcium chloride (CaCl2) solution. The effect of variation in blend proportion on outlet parameters of a packed bed dehumidifier is patterned under various desiccant to air (L/G) mass flow rate ratios. It is observed that the addition of CaCl2 desiccant solution into LiCl changes the nature of thermo-physical properties of blends‚ which are predicted using non-random two liquid (NRTL) equation. Further, a trade-off analysis among the performance parameters is presented. It demonstrates that dehumidifier performance paradox such as enthalpy effectiveness (ɛh), moisture removal rate (MRR) and moisture effectiveness (ɛm) have a tendency to be optimal for 35% LiCl with 5% CaCl2 blend (BL1) among all blends at L/G ratio of 2. The variation of thermodynamic properties (air temperature, humidity, desiccant temperature and desiccant concentration) inside the dehumidifier module is visualized in terms of contour plots. Furthermore, the irreversibility in heat and mass transfer operation for the optimal blend is investigated in terms of physical and chemical exergy destruction paradigm. The result of such investigation elucidated that the maximum chemical exergy destruction is 0.88 kW, whereas the physical exergy destruction is 0.06 kW.

Experimental investigation of heat and moisture transfer performance of CaCl2/H2O-SiO2 nanofluid in a gas–liquid microporous hollow fiber membrane contactor

In this study, aqueous solution of CaCl2/SiO2 nanoparticles has been used as a desiccant in a gas–liquid hollow fiber membrane (HFM) air dehumidifier contactor system. The heat and mass (H/M) transfer properties HFM energy exchanger with CaCl2/H2O-SiO2 as desiccant solution studied experimentally for first time. Effects of different parameters on H/M transfer characteristics of system, including the nanoparticle concentration, liquid flow rate and liquid temperature were examined experimentally. The experiments arranged for desiccant temperatures of 20 °C and 26 °C, desiccant solutions of 0, 1%wt and 2%wt concentration and flow rates of 1.1, 1.25, 1.4 and 1.7 ml/s. The results indicated that the influence of particles on moisture removal rate is the greatest for the conditions of highest solution temperature and the highest particle. By introducing nanofluid solution as liquid desiccant in system the enhancing effect of reducing desiccant temperature on moisture removal lessens and declined to zero by increasing the solution flow rate with a high descending rate. For 2%wt nanoparticle concentration by 53% increase of absorbent flow rate, the value of temperature effectiveness reduced by 30%. This justifies adiabatic application of hollow fiber membrane systems with nanofluid desiccant.

Experimental study on combined low temperature regeneration of liquid desiccant and evaporative cooling by ultrasonic atomization

Liquid desiccant cooling is a great alternative to vapour compression cooling for air-conditioning system in buildings with immense energy saving potential. After dehumidification of fresh air, the dehumidified water can be used further for evaporative cooling. However, the recovery of water from regenerator exhaust is a slow process and impractical to be utilised as feed water for evaporative cooling. To overcome this problem, low temperature regeneration of diluted desiccant solution with evaporative mist cooling can be achieved by ultrasonic technology. In this work, a novel regenerative evaporative cooler through the Maisotsenko Cycle (M-Cycle) integrated with an ultrasonic atomizer for liquid desiccant regeneration was fabricated. Moisture removal and effectiveness of the system were studied under various air and desiccant temperature, air and desiccant flow rate, humidity ratio and desiccant concentration. Low temperature (35–50 °C) regeneration of diluted desiccant was accomplished by 0.208–0.619 g s−1 of moisture removal rate. Room cooling supply air temperature below the wet-bulb temperature of intake air up to a minimum temperature of 19 °C was effortlessly achieved by evaporative cooling of atomized water mist from the regenerator.