Inlet Air Humidity Ratio Research Articles

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.

Experimental and modeling study of bubble absorption-based deep dehumidification using the ionic liquid: Parametric analysis on heat and mass transfer

Conventional liquid desiccant dehumidification is good at humidity control with energy conservation and stable operation, but is limited by corrosion and crystallization in deep dehumidification. Thus, it is necessary to broaden the humidity adjustment range of liquid desiccant deep dehumidification as well as avoid corrosion. Ionic liquids (ILs) with deep dehumidification potential (e.g., extremely low vapor pressure and non-corrosion) are a promising alternative to traditional salt solutions. Meanwhile, the bubble absorption-based mode can obtain a huge gas–liquid specific interfacial area, which is expected to solve the low wettability and insufficient gas–liquid transfer efficiency in traditional falling-film/packed dehumidifiers using IL. In this work, the bubble absorption-based deep dehumidification using IL (BADD-IL) is investigated. Meanwhile, the heat and mass transfer mathematical model of BADD-IL is established, and a bubble column dehumidifier using the novel IL is experimentally examined under different conditions. The results indicated that the deep dehumidification performance is strongly dependent on operating parameters, and the minimum outlet air humidity ratio is around 1.2 g/kgda. In particular, it is most sensitive to inlet air humidity ratio, followed by liquid height and superficial velocity, and the effect of solution temperature is the least. Notably, the influential mechanism of superficial velocity and solution temperature on volumetric transfer coefficient is different. The increase of superficial velocity promotes both gas–liquid specific interfacial area and heat and mass transfer coefficient. For the IL with lower temperature, its higher heat and mass transfer coefficient makes up for the poor specific interfacial area caused by high viscosity. Additionally, the Lewis factor of bubble column dehumidifier using the novel IL is basically less than 0.6, which is important for the device design and scale-up. This study clarifies the heat and mass transfer mechanism of BADD-IL, and provides guidance for the development of ILs deep dehumidification technology.

Evaluation of new dew point evaporative cooler heat and mass exchanger designs with different geometries

In this study four new geometries of heat and mass exchanger for dew point evaporative cooling are investigated and their performance is compared to that of the commonly used flat plate and corrugated plate exchangers. In the proposed exchangers, each dry channel is completely enclosed by its adjacent wet channels, and each wet channel is completely enclosed by its adjacent dry channels (related detailed information is presented graphically in this paper). In addition, a robust numerical model was developed and is examined under various operational and geometrical conditions. The analysis showed that the proposed dew point evaporative coolers improve the chilled air temperature, water consumption, cooling capacity, and energy efficiency. In particular, the circular concentric tube exchanger, under certain operating conditions (inlet air temperature, humidity ratio, and velocity of 40°C, 6 g/kg, and 3 m/s, respectively), could produce the lowest chilled air temperature of 9.6°C and the highest wet bulb and dew point effectiveness of 148% and 99%, respectively. Additionally, water consumption is reduced to 1.34 L/hr for an inlet air velocity of 1 m/s. A triangular tube exchanger achieved the highest cooling capacity and coefficient of performance, but consumed the largest amount of water. Our geometrical analysis demonstrates that the overall performance of dew point evaporative cooling systems can be improved by employing new geometries for heat and mass exchanger channels. Practical application: The dew point evaporative cooler is an environmentally friendly air conditioning system used in buildings. It is considered the strongest candidate to replace vapour-compression refrigeration systems because it consumes considerably less electricity while achieving high performance. Our research demonstrates that through revised geometry it is possible to further improve the performance of the system leading to improved energy and water efficiency.

Parametric investigations on a novel bubble column liquid desiccant dehumidifier with internal cooling

Increasing demand for space cooling and proportionate demand for electrical power call for less power intensive technology with lower carbon footprint. The liquid desiccant (LD) based air conditioning systems can remove latent heat more efficiently, mainly using heat energy coming from waste or renewable energy source. A novel, simple and corrosion-free bubble column liquid desiccant air dehumidifier (BCLD_ADH) with provision for internal cooling of LD has been developed in this work. The advantages of providing internal cooling and effect of LD concentration as well as ambient conditions are evaluated in this experimental work. Two new type of effectiveness, one based on ambient wet bulb temperature and the other on crystallization temperature of LD are proposed here to give due credit to higher potential of moisture removal available in internally cooled dehumidifier. At 40% concentration of LD, the dehumidifier effectiveness at wet bulb temperature was 67% for adiabatic dehumidifier, but could be increased to 95% using internally cooled dehumidifier. Using higher concentration is necessary for adiabatic dehumidifier but less important for internally cooled dehumidifier as lower LD temperature helps retain higher potential for mass transfer. The inlet air humidity ratio helps to increase change in humidity ratio while higher mass flow rate also helps increase moisture removal rate proportionately.

Three-dimensional numerical analysis of fin-tube desiccant-coated heat exchanger for air dehumidification in tropics

High-performance desiccant-coated heat exchangers (DCHEs) can be employed in air-conditioning systems to improve energy efficiency. While there are significant developments in experimental studies, theoretical approaches for analyzing the DCHE are impeded by the complex and coupled heat and mass transport mechanisms. Therefore, a 3D mathematical model has been developed in this work to study the dehumidification performance of a DCHE. Unlike other works reported in the literature, the developed model is able to simulate the complex coupling between heat and mass transfers in the entire volume of the heat exchanger. The model is calibrated and validated with experimental data, and a maximum discrepancy of ±8 % is recorded. A time-dependent study on the performance of the DCHE is carried out to understand the distribution of temperature, reaction rates, and water uptake in the heat exchanger. Effects of key influencing operational factors are investigated and discussed. It is indicated that the DCHE enters a stable performance state regardless of its initial adsorption state. The regeneration time should be equal to the dehumidification time to optimize the performance. A higher thermal COP is achieved under lower cooling/regeneration temperature, lower air flowrate, and shorter half-cycle time, while higher inlet air humidity ratio. Higher coated desiccant mass also provides a higher thermal COP, but this enhancement levels off once the coating grows. For DCHEs with less coating, reducing cycle time is recommended over increasing the coating amount.

Research on anti-frosting potential of air source heat pump evaporator in hot-summer and cold-winter zone

In this paper, the performance curve of a heat pump evaporator under critical frosting conditions was fitted. The functional relationship between the refrigerant evaporation temperature and the absolute air humidity ratio was obtained. In addition, the transfer unit model of the air source heat pump (ASHP) evaporator was established. The inlet air temperature, humidity ratio, velocity, fin pitch, and row number of evaporators were considered as input parameters. The anti-frosting potential of the heat transfer unit was simulated under critical frosting conditions. The results showed that, based on the heating potential of moist air unit mass under critical frosting conditions, the heating potential is at its minimum at an air humidity ratio of 3.39 g/kga. The maximum difference between the minimum temperature on the fin surface and the refrigerant evaporation temperature was found to be only 0.06 °C. The study findings highlighted that controlling the refrigerant evaporation temperature above the critical frosting temperature is an important method to prevent the evaporator from frosting. Under a low temperature environment, with the increase in the fin pitch and the inlet air velocity, the anti-frosting regulation performance of the two tube rows evaporator was found to improve compared to the single tube case. The aim behind increasing the inlet air velocity is to increase the heat transfer temperature difference between the inlet air and the critical frosting conditions. After optimizing the evaporator’s structural and operational parameters, the evaporator’s fin pitch is set according to the ambient air temperature. This was successful in meeting the requirement that the evaporator does not frost most of the time. Moreover, by adjusting the inlet air velocity, the evaporator will not frost at other times. In hot-summer and cold-winter zone, the operation of the ASHP evaporator with no frost can be achieved.

Dynamic performance analyses and optimization studies on air dehumidifiers using multi-stage desiccant plates

• Dynamic air dehumidification processes of a desiccant plate (DP) were studied. • Three causes for the generation of ineffective sections are found. • For the dehumidifier with multi-stage DPs, recommended stage number is 2. • An advanced dehumidifier is proposed, ineffective DPs of which can be replaced. • Effective working period of the advanced dehumidifier is extended by 2.2%∼34.8%. In this study, a novel transient air dehumidifier that can meet the dehumidification demands at places without a constant energy supply and uses multi-stage desiccant plates was proposed. Based on the simulation methods, parametric and optimization studies were carried out to extend the effective working duration. First, the air handling processes, transient temperature and humidity distribution fields of a typical desiccant plate were investigated. The results indicated that there are three reasons for the generation of ineffective dehumidification sections. To reduce the proportion of the ineffective sections and to increase the effective working duration, parametric analyses were carried out on the desiccant plate, considering factors such as the initial water content ( W ini ), inlet air humidity ratio ( ω a,in ), and length of the desiccant plate. The results show that, if the required outlet humidity ratio ( ω ∗ ) is lower than 12–13 g/kg, W ini = 0.1 kg/kg is preferred for ω a,in between 15 and 19 g/kg. Subsequently, a dehumidifier with multi-stage desiccant plates (original dehumidifier) was designed, and the optimized stage number for different total thicknesses of desiccant plates was investigated to improve the dehumidification performance. When ω ∗ is 10 g/kg, the recommended stage number is two. Finally, an advanced dehumidifier is introduced in which an ineffective desiccant plate can be replaced with a new desiccant plate. For the advanced dehumidifier, the proportion of ineffective sections can be effectively reduced by 14.6%–93.2%, and the effective working duration can be extended by 2.2%–34.8%, compared to the original dehumidifier that has the same total thickness as the desiccant plates.

Performance evaluation of a solar powered solid desiccant evaporative cooling system with different recirculation air ratios

The evaporative cooling technology (ECT) has been regarded as an effective alternative to conventional vapour compression systems due to its energy saving and eco-friendly features. Moreover, when integrating with a solid desiccant unit, ECT can further extend its application in hot and humid environments. This paper proposed and evaluated a solar-assisted solid desiccant Maisotsenko cycle (M−cycle) based indirect evaporative cooling (IEC) system with different recirculation air ratios. Three other cooling systems, including stand-alone Direct Evaporative Cooling (DEC), stand-alone M−cycle IEC, and conventional solid desiccant evaporative cooling system (SD-DEC), were also simulated and compared with the proposed system under various ambient conditions. These systems were assessed in terms of supply air temperature, indoor relative humidity ratio, water consumption rate, coefficient of performance (COP) and solar fraction in this study. A case study of the proposed system was carried out under two typical Australian climates, Darwin and Melbourne. The results indicated that the solar-assisted solid desiccant cooling system integrated with M−cycle IEC had the best cooling performance compared with the other three systems, particularly in hot and humid areas. When increasing the recirculation air ratios from 0% to 60%, a maximum reduction of 23.1% and 41.9% could be observed in the system’s supply air temperature and humidity ratio, respectively. The highest COP was 0.89 when the inlet air temperature was 30 °C, and the COP value would vary as the inlet air temperature and humidity ratio increased. However, a higher water consumption rate was also observed, 31.36% to 57.94% more water would be consumed. This indicates that it requires selecting a proper recirculation air ratio for different climates to achieve the best performance.

Regression Models for Performance Prediction of Internally-Cooled Liquid Desiccant Dehumidifiers

In this study, using response surface methodology and central composite design, regression models were developed relating 12 input factors to the supply air outlet humidity ratio and temperature of 4-fluid internally-cooled liquid desiccant dehumidifiers. The selected factors are supply air inlet temperature, supply air inlet humidity ratio, exhaust air inlet temperature, exhaust air inlet humidity ratio, liquid desiccant inlet temperature, liquid desiccant concentration, liquid desiccant flow rate, supply air mass flow rate, the ratio of exhaust to supply air mass flow rate, the thickness of the channel, the channel length, and the channel width of the dehumidifier. The designed experiments were performed using a numerical two-dimensional heat and mass transfer model of the liquid desiccant dehumidifier. The numerical model predicted the measured values of the supply air outlet humidity ratio within 6.7%. The regression model’s predictions of the supply air outlet humidity ratio matched the numerical model’s predictions and measured values within 4.5% and 7.9%, respectively. The results showed that the input factors with the most significant effect on the dehumidifying process in order of significance from high to low are as follows: supply air inlet humidity ratio, liquid desiccant concertation, length of channels, and width of channels. The developed regression models provide a straightforward means for performance prediction and optimization of internally-cooled liquid desiccant dehumidifiers.

Comparative study on the water uptake kinetics and dehumidification performance of silica gel and aluminophosphate zeolites coatings

Desiccant coated heat exchanger (DCHE) systems have significant potential in improving dehumidification performance. The moisture transfer occurring in one single air channel of DCHE can dominate the overall system performance. In this study, the adsorber with an approximate air channel of DCHE was designed to experimentally investigate the kinetics of silica gel and two aluminophosphate zeolites (FAM Z01 and FAM Z05). Their dehumidification performances also were simulated at regeneration temperature range of 50–80 °C to reveal the applicability in air-cooled cross-flow DCHE. Results showed that linear driving force (LDF) model could well describe the dynamic water uptake behaviors. Adsorption rate coefficient kads increased with increasing inlet air humidity ratio and velocity, but decreased with increasing coating thickness. It is worth noting that increasing regeneration temperature had a little effect on kads, while desorption rate coefficient kdes increased significantly. Simulation results showed that moisture removal capacity (MRC) and dehumidification coefficient of performance (DCOP) of FAM Z05 coated DCHE could reach 0.495 g/kg and 0.57 at regeneration temperature of 50 °C, which were 2.3 and 15.4 times higher than these of silica gel and FAM Z01 coated DCHEs. It demonstrated that FAM Z05 was more promising to utilize lower-grade heat energy.

Preliminary study on air-to-air latent heat exchanger fabricated using hollow fiber composite membrane for air-conditioning applications

In this study, an air-to-air type hollow fiber composite membrane latent heat exchanger was built and its latent heat exchange characteristics were experimentally investigated under various test conditions. Based on experiments conducted on four prototypes, polyethersulfone with 9 wt% of polyvinyl-pyrrolidone was selected as the membrane material suitable for the latent heat exchanger. Using the selected material, shell-and-tube structured hollow fiber membrane modules were fabricated and tested under various operating conditions. The experimental data showed that the proposed membrane modules exhibited 35.3%–82.7% latent effectiveness and moisture removal rates of 0.027–0.124 g/s under various operating conditions; furthermore, the modules could provide latent cooling with few temperature changes. In addition, the results of the parametric analysis indicated that the inlet primary air humidity ratio was a critical factor affecting the latent cooling performance of the proposed system and the optimal ratio of the secondary to primary air flow was 1.0. The number of mass transfer units (NTUm) in the membrane module design should be higher than 1.7 to attain satisfactory latent cooling performance, that is, higher than 70% latent effectiveness.

Comparative Study on the Water Uptake Kinetics and Dehumidification Performance of Silica Gel and Fams Coatings

Desiccant coated heat exchanger (DCHE) systems handling sensible and latent heat simultaneously have significant potential in improving dehumidification performance. The DCHEs consist of a series of open air channels coated with porous desiccant, and the moisture transfer occurring in DCHEs usually can be represented by one single channel due to their structural symmetry. In this study, the adsorption kinetics of an adsorber with a parallel air channel coated with three low-temperature regenerative desiccants respectively, i.e. silica gel, FAM Z01 and FAM Z05 was experimentally investigated. Their dehumidification performances in DCHEs also were simulated at regeneration temperature range of 50-80°C. Results showed that the linear driving force (LDF) model can well describe the dynamic behavior of water uptake. Adsorption rate coefficient [[EQUATION]] increased with the increase in inlet air humidity ratio and air velocity, but decreased with increasing coating thickness. It is worth noting that the increasing regeneration temperature had a little effect on the [[EQUATION]] , while desorption rate coefficient [[EQUATION]] increased significantly. Simulation results indicated that the DCOP of Z05 DCHE can reach 0.66 at regeneration temperature of 50°C, which is 2.4 and 8.9 times higher than these of silica gel and Z01 DCHEs, respectively.

Dynamic operational characteristics and preliminary control of a packed liquid desiccant dehumidifier

Liquid desiccant dehumidifiers (LDDs) has attracted much attention due to its advantages of energy-saving and environmental protection. However, dynamic characteristics of LDDs, which are essential to develop appropriate control methods, are still not clear at present. In this paper, the performance of a packed LDD was investigated under changes of desiccant inlet temperature and flow rate as well as air inlet humidity ratio, temperature and flow rate. Due to the random packings and interaction between air and desiccant, the air is normally distributed randomly during a dynamic process of LDDs and air outlet humidity ratio at the sampling point is serrated with time going. It was found that exponent function could be utilized to smooth the experimental result of air outlet humidity ratio, providing a simple way to determine the evaluation indexes like the response delay and response time as well as response rate, which could facilitate to evaluate dynamic characteristics of the dehumidifier. And through comparing those evaluation indexes corresponding to changes of different inlet parameters, it was revealed that air outlet humidity ratio was more sensitive to the change of desiccant or air flow rate, but not desiccant inlet temperature as indicated in a previous research getting from quasi-steady state experiments. Therefore, it would be more reasonable to select the desiccant or air flow rate as control variables instead of desiccant inlet temperature. Furthermore, preliminary control experiments were conducted to compare the performance of control algorithms developed based on the steady state characteristics and expert experience of dynamic characteristics. Results show that the control algorithm developed based on the expert experience of dynamic characteristics performs much better, which indicates that the obtained steady state characteristics in existing researches are unsuitable for developing control algorithms for a packed LDD. The dynamic characteristics revealed in current research paves the way for the future development of appropriate control algorithms.

Thermal Analysis of a Hybrid Air Conditioning System with Geothermal Energy

Hybrid air conditioning systems can allow significant energy saving and emissions reductions with respect to conventional air-conditioning systems. Thermal analysis of a desiccant wheel, a heat exchanger, a ground source circulation system, and a solar collector for a hybrid air conditioning system is performed in this study. The effects of these parameters have been studied: Inlet air temperature, Inlet air humidity ratio, wheel speed, regeneration temperature, regeneration mass flowrate, heat exchanger effectiveness, ground source circulation effectiveness, and solar radiation on the behavior of the outlet air temperature and the outlet air humidity ratio from the desiccant wheel, the area of solar air collector, the solar collector efficiency, the cooling coil load, and the coefficient of performance. The hybrid system is more efficient than the vapor compression system. The hybrid system significantly decreases the cooling coil load, the cooling coil load of the hybrid system is approximately 48 % lower than the vapor compression system.

Effect of Operational and Design Parameters on Desiccant-Assisted Hybrid Air-conditioning Systems Performance

Energy savings are a major goal in our lives because energy consumption is continuously increasing. We have studied in this paper four air conditioning systems, so that each system mainly consists of a vapor compression cycle and a rotating desiccant wheel. The thermodynamic analysis for air conditioning system, the heat exchanger, the ground heat exchanger and the evaporative water spray cooler were presented. Design and operating parameters including outlet air temperature, outlet air humidity, regeneration air temperature, and desiccant wheel speed are studied to assess its effect on the performance of the systems considered. This hybrid system significantly decreases the supplied air temperature at different four Systems. When the inlet air humidity ratio and the regeneration air temperature increase, the COPth of the air conditioning system decreases. When the desiccant wheel speed increased, the COPth of the air conditioning system decreases. COPth decreases with the increasing of the cooling load for the space and also decreases with the decreasing of the inlet air humidity ratio at process air. The results show that in these four systems, COPth is the highest at system 4 which contains desiccant wheel, heat exchanger and ground source circulation achieving an improvement of about 48 % and a consequent power consumption reduction of 20 %.

Investigating Solid and Liquid Desiccant Dehumidification Options for Room Air-Conditioning and Drying Applications

This study reports on the investigation of the performance of single and two-stage liquid and solid desiccant dehumidification systems and two-stage combined liquid and solid desiccant dehumidification systems with reference to humid climates. The research focus is on a dehumidification system capacity of 25 kW designed for room air conditioning application using the thermal models reported in the literature. RD-type silica gel and LiCl are used as solid and liquid desiccant materials, respectively. In this study, the application of proposed system for deep drying application is also explored. Condensation rate and moisture removal efficiency are chosen as performance parameters for room air conditioning application, whereas air outlet temperature is chosen as performance parameter for deep drying application. Further, for a given range of operating parameters, influences of air inlet humidity ratio, flow rate, and inlet temperature on performance parameters of the systems are investigated. In humid climatic conditions, it has been observed that a two-stage liquid desiccant dehumidification system is more effective for room air conditioning application, and two-stage solid desiccant dehumidification system is more suitable for deep drying application in the temperature range of 50 to 70 °C, while single-stage solid desiccant and two-stage combined liquid and solid desiccant dehumidification systems are more effective for low temperature, i.e., 30 to 50 °C deep drying application.

Thermodynamic analysis of internally-cooled membrane-based liquid desiccant dehumidifiers of different flow types

Internally-cooled membrane-based liquid desiccant dehumidifier (IMLDD) can well alleviate the dehumidification deterioration due to the increase of desiccant solution temperature. In the IMLDD, air channels and desiccant solution channels are separated on both sides of semi-permeable membrane. Cooling media flows through tubes inside solution channels to reduce desiccant solution temperature. There exist many flow patterns of fluids (air, desiccant solution and cooling water), which have been proved to have significant effects on the performance of IMLDD. Therefore, to find the optimal flow type of IMLDD and operating conditions, the mathematical model for IMLDD was developed and validated experimentally, and the exergy and entransy theories were first adopted to analyze the effects of inlet parameters on the performance of IMLDD of various flow types. The results showed that counter flow arrangement between air and solution and parallel flow arrangement between solution and cooling water had the best dehumidification performance. The trend of dehumidification efficiency was opposite to exergy efficiency with the increase of inlet air humidity ratio and solution concentration. The increase of inlet cooling water temperature improved exergy efficiency but decreased dehumidification efficiency accordingly. The research of this paper is helpful for the design and optimization of IMLDD.

Experimental investigation on the performance of packed tower for regeneration of liquid desiccant

In a liquid desiccant air conditioning system the regenerator is one of the essential components. The effectiveness of the regenerator directly influences the system performance. An experimental investigation on the performance of packed tower for regeneration of liquid desiccant is carried out. The experimental test unit has been designed and installed in the combustion Lab., Faculty of Engineering, Mansoura University, Egypt. A solution of calcium chloride is used as a working desiccant with a packing of burned clay pieces with a random shape, its porosity is about 0.22 and the average size and weight of the piece are about (90.25 cm3, 88.4 gram) respectively. The input variables used in the experiment are air inlet temperature, air flow rate and solution flow rate. The outlet parameters which are measured or calculated from the experimental results are air outlet temperature, air humidity ratio, desiccant solution outlet temperature and concentration. To illustrate the effect of air and liquid desiccant parameters on the outlet variables the experimental results are plotted. Based on these results, higher air inlet temperature (Tai = 60, 80, 100 and 120 °C) where the air inlet humidity ratio (0.0127, 0.0123, 0.0114 and 0.0130 kg/kgda) results in higher average air humidity ratio (0.0206, 0.0232, 0.0249 and 0.0334 kg/kgda) and the %age change of desiccant solution concentration (0.63, 1.13, 1.95 and 2.25 %) respectively. And higher air flow rate (Ma = 0.0252, 0.0529, 0.0659 and 0.0683 m3/s) where the air inlet humidity ratio (0.0147, 0.0177, 0.0178 and 0.0184 kg/kgda) results in higher average air humidity ratio (0.0245, 0.0293, 0.0302 and 0.0312 kg/kgda) and the %age change of desiccant solution concentration (0.78, 2.21, 2.57 and 3.01 %) respectively. Increase in solution flow rate (Ms = 1, 2 and 3 LPM) where the air inlet humidity ratio (0.0175, 0.0151 and 0.0148 kg/kgda) results in lower average air humidity ratio (0.0278, 0.0274 and 0.0267 kg/kgda) and the %age change of desiccant solution concentration (2.86, 2.58 and 2.23 %) respectively.

Investigation on the Performance of a Novel Dehumidifier for a Combined Solar Chimney and Liquid Desiccant Plant

A dehumidifier was one of the main component in the hybrid liquid desiccant system and solar chimney micro-plant. The performance of the hybrid liquid desiccant system and solar chimney micro-plant was strongly depended on the performance of it dehumidifier, but it is yet to be analyzed in any of the previous studies. Therefore, moisture removal rate (MRR) and dehumidification effectiveness (ε) were two parameters that had been chosen to evaluate the performance of the cross flow, cellulose panel structured bed dehumidifier in this study. Calcium Chloride (CaCl2) desiccant solution was the only liquid desiccant solution used in this application. From the experiment, it was found that the highest effectiveness of the dehumidifier was about 22.78% and the highest moisture removal rate was about 0.22ml/s. Besides that, parametric analysis had been conducted on five inlet parameters: desiccant inlet concentration, desiccant inlet temperature, inlet air humidity ratio, inlet air mass flow rate and inlet air temperature; the most influencing parameter was found to be the inlet air humidity ratio, ya1. MRR increased by 52.68% and ε of the dehumidifier increased by 48.59% when ya1 increased from 0.0175-0.0200. Finally, three improvement strategies had been recommended: increasing the concentration of liquid desiccant, changing the type of liquid desiccant and increasing the thickness of the dehumidifier.

Experimental Study of Dehumidification Process by CaCl2 Liquid Desiccant Containing CuO Nanoparticles

A conditioning dehumidifier system is a simple technology to improve air quality and also reduces air conditioning costs. This experimental study evaluated the performance of a liquid desiccant system by adding copper oxide nanoparticles (NPs). The effect of operating parameters, such as inlet air humidity ratio and desiccant flow rate on air dehumidification rate, was also investigated. The desiccant solution contained 48[Formula: see text]wt.% CaCl2 and 0.35[Formula: see text]vol.% of CuO NPs. Comparison of liquid desiccants demonstrated a mean difference of 4.5[Formula: see text]g/s[Formula: see text][Formula: see text][Formula: see text]m2 in the air dehumidification rate by solutions with and without CuO NPs.