Humidification Process Research Articles

Exergo-enviro-economic analyses of solar energy based novel air cooling system

Implementation of heating, ventilation, and air conditioning units in buildings for space cooling represents a passive method for achieving thermal comfort and reducing power consumption. This paper introduces solar energy assisted in-direct evaporative cooling system with a novel multi-passage dry channel. The main objectives are to evaluate exergy variations, sustainability, and total cooling cost based on the inlet conditions for four modes: A, B, C, D (without evaporative cooling, with evaporative cooling, preheating, and preheating with humidification). This comparative study explores thermal performance enhancement of an indirect evaporative cooling system across four operational modes. Mainly, the exergy outlet values increase significantly by 77.39%, while exergy destruction decreases by 54.86%. Both energetic and exergetic coefficient of performances witness remarkable enhancements, with energetic Coefficient of Performance (COP) rising by 321.32%. Exergy efficiency experiences a notable enhancement of 29.974%, and sustainability index shows a consistent upward trend, with a 119.34% increase observed in Mode D compared from Mode A. Entropy generation decreases significantly, indicating improved system efficiency. Total capital cost per unit of cooling capacity decreases notably, highlighting cost savings. These findings underscore the effectiveness of incorporating preheating and humidification processes in optimizing indirect evaporative cooling system performance, emphasizing both exergy efficiency and cost-effectiveness.

Ultrasonic atomization technique for enhancing humidification process in thermal desalination

The need for desalination is expected to evolve, and interests in novel techniques to enhance thermal desalination are developing. Research studies on ultrasonic atomization for desalination application has been observed in the last few years. Hence, this study aims to examine humidification process enhancement using ultrasonic atomization and interaction of atomized droplets with hot air in the humidifier. In the Humidification and Dehumidification (HDH) desalination system examined, the humidifier is equipped with a single ultrasonic atomizer unit which operates continuously with preheated hot air entering the humidifier chamber. The system is investigated for different air flowrates (40 – 100 LPM) and hot air temperatures (40, 50, and 60 °C). The average relative humidity at the humidifier outlet was maximum reaching 94 % for the highest flowrate. The results indicate that increasing hot air temperatures have significant improvement in droplet evaporation which causes higher relative humidity at the outlet, and increasing hot air flowrates have significant impact on the faster response of the humidification process to reach equilibrium.

Performance Evaluation of a Solar Humidification – Dehumidification Desalination Unit

This paper is to investigate the use of solarenergy in desalination by humidification and dehumid-ification process (HD). Here, a proposal for the desalinationunit has been come out with cylindrical shape containing the evaporator in the middle and surrounded by the condenser.The hot feed water coming from the solar thermal system issprayed at the top of the evaporator where the air flowsfrom the bottom. In the evaporator the air is humidified until it gets out saturated, then introduced to the condenser,where it is dehumidified to obtain the fresh water andcirculated back to the evaporator. Practically there aremany parameters influence on the performance of thisdesalination unit, which are environmental, design and operational. In the current study these parameters are takenin consideration to formulate mathematical models whichgovern the performance of the main components of this unit,which are the evaporator, the condenser and the solarthermal system. The deduced mathematical models have been interpreted in many programs in visual basic languageas a computer software. This software contains many pageswhich help in introducing and analyzing the most influentialparameters. In this case many operational parameters havebeen studied such as feed water temperature, mass flow rate and salinity, in addition to cooling water mass flow rate andinlet temperature, as well as quantity of solar irradiancewith others. At these inputs many outputs have beenobtained which are related to the performance of thedesalination unit such as fresh water productivity, energy consumption, humidifier volume, recovery ratio and gainoutput ratio.

Flow-through moisture meter for measuring grain moisture as part of an automated grain moisture control system

The methods of increasing the accuracy and efficiency of the production process, as well as ensuring high quality of final products in the grain processing industry, are investigated. It is shown that to solve the problem of insufficient quality control of grain materials, an automated system for monitoring the properties and characteristics of bulk granular materials is necessary. The features of the construction of automatic and automated systems for monitoring the properties and characteristics of bulk granular materials are considered. Measurement methods and control devices of the main technological parameters used in the management of grain processing facilities are briefly described. It is proposed to include a flow moisture meter in the automated grain moisture control system. The physical properties of grain and grain materials, measurement conditions and instrumentation for grain moisture control are analyzed. The use of devices based on the dielkometric method in the subsystem of an automated process control system is discussed. The application of intelligent sensors of a measuring system with a complex multilevel hierarchy is described. The structure of the interconnection of measuring devices for intellectual support of humidification processes and quality control of the studied materials is given. A functional diagram and metrological characteristics of a prototype grain moisture monitoring device, a flow moisture meter, are presented. The metrological characteristics of this device meet the requirements of the grain processing industry and allow it to be used as part of a humidity control system

Design and development of water purifier using humidification and dehumidification process by using renewable energy

Design and development of water purifier using humidification and dehumidification process by using renewable energy

Assessment Effects of Humidification of Guitars by Complexity Measures of the Sound Level During Sustain

Air humidity significantly affects the sound of wooden instruments. The sound quality decreases when the instrument is exposed to low humidity for an extended period. Therefore, the instrument is treated with a humidifier to improve sound quality. This study aimed to verify the effectiveness of the humidification process by analyzing the quality of guitar sound with the methods used in signal complexity studies, such as Higuchi’s fractal dimension (HFD), symbolic analysis, and empirical mode decomposition (EMD). The sound quality was determined by the sound levels measured before, during, and after the guitars’ humidification. The methods used consistently confirmed the improvement of the guitar sound quality after the humidification process. Moreover, it was concluded that the sound quality changes irregularly during the humidification process.

Humidification during Invasive and Non-Invasive Ventilation: A Starting Tool Kit for Correct Setting.

The humidification process of medical gases plays a crucial role in both invasive and non-invasive ventilation, aiming to mitigate the complications arising from bronchial dryness. While passive humidification systems (HME) and active humidification systems are prevalent in routine clinical practice, there is a pressing need for further evaluation of their significance. Additionally, there is often an incomplete understanding of the operational mechanisms of these devices. The current review explores the historical evolution of gas conditioning in clinical practice, from early prototypes to contemporary active and passive humidification systems. It also discusses the physiological principles underlying humidity regulation and provides practical guidance for optimizing humidification parameters in both invasive and non-invasive ventilation modalities. The aim of this review is to elucidate the intricate interplay between temperature, humidity, and patient comfort, emphasizing the importance of individualized approaches to gas conditioning.

Experimental study on a compact solar driven two-stage humidification-dehumidification desalination system with shared dehumidifier

The low-cost and low-grade solar driven humidification-dehumidification desalination is considered a promising process for small and medium capacity freshwater production. Nevertheless, the enhancement of the unit volume water production rate is hindered by the disparity in mass transfer coefficient and the incongruity between heat and mass flow rate in the humidification and dehumidification process. This paper proposes a compact solar driven two-stage humidification-dehumidification desalination system with shared dehumidifier. It contains two humidifiers and a dehumidifier, wherein the dehumidifier is stacked between the vertically placed humidifiers. The circulating air is humidified by hot seawater in the top and bottom humidifiers respectively, and then goes to the middle dehumidifier to condense via a freshwater absorption process. Its design scheme and operating principle are introduced and a mathematical model describing its internal energy and mass flow process is established. An experimental setup with compound parabolic concentrator areas of 6 m2 is developed, and a sequence of experiments is carried out. The results indicate that its freshwater productivity can reach 29.6 kg/h with a gained output ratio of 0.84 when the feed seawater temperature is 80 ℃. Due to its compact structure, the freshwater production per volume unit per day reaches up to 224.1 kg/(day⋅m3). This work may promote the development of solar humidification and dehumidification systems towards low cost and high efficiency.

Study on the fracture behavior in clayey geomaterials under moisture diffusion by phase field modeling

Clayey geomaterials are prone to cracking under changing moisture conditions, which substantially compromises their engineering properties. When moisture intrusion and boundary constraints act in tandem on geomaterials, the relevance of multi-physics field processes to complex cracking phenomena remains underexplored. To provide deeper insight into the effect of moisture transport on the cracking behavior of clayey geomaterials, a theoretical model for moisture-induced fracture is proposed. The model combines moisture diffusion, volume deformation dependent on moisture conditions, and phase field fracture, and is solved using the finite element method with a user-defined element subroutine. The developed subroutine is applied to simulate soil desiccation experiments and mudstone water absorption tests. The results reveal that moisture gradients induce non-uniform expansion or shrinkage within the clayey geomaterials. The neighboring geomaterial particles mutually constrain these deformations, resulting in an internal stress field that serves as the primary cause of cracking. Stability and sensitivity analyses validate the reliability of the numerical framework. The proposed model can effectively simulate crack initiation, extension, and convergence during humidification or desiccation processes in both two and three dimensions. This study charts a feasible path for numerical simulation and mechanical mechanism exploration of cracking behaviors in clayey geomaterials during water migration.

Performance analysis of heat pump polygeneration system

A heat pump polygeneration system is a promising technology to meet daily needs such as drinking water, power, space cooling or heating, and hot water generation. This work is focused on integrating the solar heat pump and two-stage humidification–de-humidification with a minimum space requirement. In this integrated cycle, the desired outputs i.e. condenser heat and evaporator heat are used for maximizing hot water and desalinated water production with minimal thermal pollution. For warm or hot air generation, an air reheater device is used after the heat pump. By using the switching operation, the air reheater is used accordingly as per climatic conditions. So in this integrated cycle, a coconut coir-packed humidifier is used for the humidification process, and a water-cooled heat exchanger and heat pump evaporator are used for the dehumidification process to meet the desired outputs from the system. The MATLAB simulation tool is used to simulate the thermodynamic model of the integrated cycle, and it is focused on studying the effect of mass flow rate, atmospheric temperature, relative humidity, evaporator temperature, and hot/cold water temperature, on outputs, as well as the energy conversion factor of the plant and cycle. At 25°C ambient air temperature, the energy conversion factor of the plant and cycle are 0.866 and 2.2, respectively. Similarly, at 75% humid air and 35°C surrounding air temperature, the gained output ratio and coefficient of performance are 4.03 and 1.964, respectively. And also, the plant and cycle energy conversion factors are 0.903 and 2.4.

Wetter trend in source region of Yangtze River by runoff simulating based on Grid-RCCC-WBM

Exploring the future hydroclimatic conditions of source region of Yangtze River (SRYaR), an alpine affected by climate change significantly, is essential for basin water resources management and development ss global climate change intensifies and the process of climate warming and humidification in Northwest China. This study proposed a practical framework for assessing water resource response to the context of climate changes in alpine catchments from the respective of both runoff and hydroclimatic conditions. Utilizing Grid-RCCC-WBM driven by corrected climatic forcing from the global climate models, this study estimate the prospective overall warmer and wetter pattern in the source region of Yangtze River. The key results indicated that: (1) Under all future scenarios, both temperature and precipitation within the catchment exhibit a significant upward trend. Projections from multi-model ensembles (MME) suggest that during the mid-term period (2041–2060, MT), temperatures are expected to rise by [0.74 °C, 3.08 °C] compared to the baseline period (1995–2014), with precipitation changes ranging from [4.8%, 21.4%]. (2) Future runoff within the catchment exhibits a consistent increase, with a linear trend rate of 1.1 mm/decade. runoff changes in MT compared to the baseline period vary from [−5.1%, 33.7%]. Runoff decreases in the northern part of the catchment, while notable increases occur in the southeastern and western regions. (3) In the future, the ratio of catchment evaporation capacity to precipitation decreases in comparison to the baseline period with an augmentation in soil moisture, enhancing its capacity for water retention and reducing the conversion of precipitation to evaporation, resulting a wetting trend of the catchment. (4) The future snowpack in the catchment continues to decrease, with a significant reduction in both the proportion of snowfall relative to total precipitation and the proportion of snowmelt runoff relative to total runoff, the risk of water resources crisis in the watershed is escalating.

Predicting Runoff from the Weigan River under Climate Change

With the warming and humidification process in the Northwest Arid Zone over the past 30 years, the runoff of a vast majority of rivers has been affected to different degrees. In this paper, the runoff from the Weigan River, a typical inland river in the arid zone of Northwest China, is taken as an example, and seven types of CMIP6 data are selected with the help of a SWAT model to predict the runoff volume of the Weigan River in the next 30 years under climate change. The results show that (1) the SWAT model can simulate the runoff from the Weigan River well and has good applicability in this study area. (2) With an increase in radiative forcing, the temperature, precipitation and runoff in the study area show an increasing trend. (3) Under the four radiative forcing scenarios in 2030 and 2050, the runoff from the Weigan River out of the mountain is predicted to be maintained at 25.68 to 30.89 × 108 m3, which is an increase of 1.35% to 21.91% compared with the current runoff, of which the contribution to the increase in future runoff caused by the changes in temperature and precipitation is 68.71% and 27.24%, respectively. It is important to explore the impact of climate change on the runoff from the Weigan River to understand the impact of climate change on the Northwest Arid Region scientifically and rationally, and to provide a scientific basis for evaluating the risk of climate change and formulating policies to deal with it.

Experimental investigation of flow characteristics of a jet in low atmospheric pressure conditions on the Tibetan Plateau

The indoor humidity of heated buildings on the Tibetan Plateau can be as low as 5%RH. Indoor air humidification is very important to people's life and health. Due to the low atmospheric pressure on the plateau, the air physical parameters and wet component diffusion characteristics are different from those of standard atmospheric pressure. This paper investigates experimentally the effects of horizontal and vertical wet jets with various initial velocities, pipe diameters, ambient temperatures, and moisture temperatures on the indoor temperature and humidity field. It is shown that low atmospheric pressure will lead to an increase in relative humidity nearly the jet outlet, but the effective moisture delivery distance becomes shorter and the actual moisture load increases. When the same relative humidity is reached, the specific humidity under low atmospheric pressure is about 1.5–2.5 times as that under standard atmospheric pressure. The average relative humidity of jets produced by the ultrasonic humidification source is 10% higher than the evaporative humidification source during the same time. During the actual humidification process, it is necessary to consider the balance between the initial velocity of the jet and the humidification distance and select the jet tube diameter according to the humidification space area. Additionally, choosing a jet with a temperature slightly higher than the ambient temperature can avoid reducing the indoor temperature. This study should be helpful to the plateau humidification jet characteristics and parameter selection.

Performance analysis of a novel two-bed adsorption humidification-dehumidification desalination system using Metal-organic framework 801

Adsorption desalination techniques have been increasingly studied over the last century as a sustainable option for meeting the rapidly growing demand for fresh water. One of the attractive factors for using adsorption desalination systems is the use of low-grade thermal energy normally wasted in the atmosphere. The current study introduces a novel adsorption desalination system integrated with a humidification dehumidification system for producing potable water. Four system configurations are presented. The main distinction between them is the source of hot water used for the humidifier. Scheme #1 utilizes the heat of condensation, Scheme #2 applies the heat of condensation plus the heat of adsorption, while Scheme # 3 adds the outlet of heating water from the desorber as a source of heat to the humidifier. Scheme #4 is a standalone adsorption desalination system that applies chilled water to cool the condenser. The novelty of this system is the application of the chilled water from the evaporator to the dehumidifier to create the highest possible temperature difference necessary for the humidification and dehumidification process. This advantage allows larger water productivity, especially in hot humid regions. In this case, it is possible to extract water vapour in the ambient humid air, water vapour gained from the humidification process and water vapour condensed in the condenser of the adsorption desalination system. Moreover, we have used a novel material Metal Organic Frameworks 801 as an adsorbent for a highly efficient process. Based on the results, Scheme #3 produced the maximum amount of fresh water, 210 kg/h while Scheme #2 obtained the maximum gained output ratio, 4.4 with a minimum cost of 0.0079 $/L. A standalone adsorption system produced the minimum amount of distillate water and the lowest gained output ratio. It is not advisable to use a standalone adsorption system to produce distillate water; as the full desalination potential is not achieved.

Performance investigations of hybrid adsorption and thermo electric dehumidification desalination system

In recent years, thermally driven Adsorption Desalination Systems (ADS) have been gaining attention as an eco-friendly and energy saving solution for water scarcity. However, ADS faces challenges related to low water productivity and scalability issues associated with the adsorbent. To overcome these challenges, it is advantageous to integrate ADS with other desalination technologies, thereby creating a decentralised, small-scale hybrid desalination system. The current study introduces an innovative approach to enhance the performance of ADS by integrating it with a Thermo Electric Dehumidification (TED) unit that utilises the cold side of Thermo Electric Coolers (TECs). The proposed hybrid system is designed to operate at the elevated evaporator temperature ranges from 35 °C to 60 °C. This is achieved by connecting the hot side of the TECs to the evaporator of the ADS. This approach facilitates a fundamental shift from the conventional adsorption desalination cycle, enabling the system to work at higher evaporator temperature and pressures. A small-scale hybrid ADS integrated with a Thermo Electric Dehumidification unit (hybrid AD-TED desalination system) has been designed and developed to investigate performance parameters such as Coefficient of Performance (COP) and water productivity. Experimental study of the hybrid AD-TED system has been carried out in two operating modes: open flow and closed flow modes of water between the hot side of TEC and the evaporator. These operating modes are tested with and without implementing humidification process in the humidifier. The results have shown that the hybrid AD-TED desalination system working in open flow mode with humidification process has produced the highest water productivity of 1.25 l during one cycle of operation, lasting one hour. Furthermore, when operating in open flow mode without humidification, the hybrid AD-TED system can generate dehumidified air within a temperature range of 16–28 °C, making it suitable for cooling applications. Closed flow mode is the preferred choice for desalination applications. In the closed flow mode with and without humidification condition, the water productivity is found to be 1.15 l/hr and 1.05 l/hr, respectively. The significant feature of this hybrid AD-TED system is that it can be operated in two working modes with an elevated adsorption desalination cycle, making it a unique option compared to the single operating mode of standalone ADS in desalination and cooling applications. The study also compares the elevated adsorption desalination cycle with the conventional adsorption desalination cycle and reveals that the elevated cycle increases water uptake by 45 %.

Experimental study on optimum performance of two-stage air-heated bubble-column humidification–dehumidification system

An experimental investigation of a small-scale air-heated humidification–dehumidification (HDH) desalination system with bubble-column humidification and dehumidification units was conducted. The study addressed the performance of the multistage air-heated bubble-column HDH system, which has limited coverage in the literature, by operating two bubble-column humidifiers in series for the air humidification process with air reheating. The effect of operating parameters such as airflow rate, air temperature, and saline water levels in both humidifiers on the performance metrics of the system were investigated. The product distillate rate, energy consumption, gain output ratio (GOR), and specific energy consumption (SEC) are the main indicators of performance for the proposed desalination system. Response surface methodology (RSM) was applied to the current system using the design of experiment (DoE) for the prediction of variables that greatlyaffect productivity and energy input. The airflow rate, air temperature, and water level of the second humidifier have a favourable effect on the distillate rate and GOR of the system. In contrast, the effect of the water level inside the first humidifier is insignificant. Furthermore, the RSM optimization approach was used to obtain the optimum distillate productivity. An optimized distillate rate of 0.45 L/h and a GOR of 0.4 are achieved at 1.5 SCFM (standard cubic feet per minute) of airflow rate, and 6.5 cm of water level in the second humidifier with 140°C air inlet temperature. The numerical optimization reveals the optimal operating parameters, that correspond to maximum distillate production of 0.3 L/h with minimum input energy of 0.71 kW, to be 139°C air temperature, 1.13 SCFM of airflow rate, 6.5 cm and 3 cm water levels of second and first humidifier, respectively.

Biocompatible Polymer for Self-Humidification.

Lung supportive devices (LSDs) have been extensively utilized in treating patients diagnosed with various respiratory disorders. However, these devices can cause moisture depletion in the upper airway by interfering with the natural lubrication and air conditioning process. To remedy this, current technologies implement heated humidification processes, which are bulky, costly, and nonfriendly. However, it has been demonstrated that in a breath cycle, the amount of water vapor in the exhaled air is of a similar quantity to the amount needed to humidify the inhaled air. This research proposes to trap the moisture from exhaled air and reuse it during inhalation by developing a state-of-the-art hydrophilic/hydrophobic polymer tuned to deliver this purpose. Using the atom transfer radical polymerization (ATRP) method, a substrate was successfully created by incorporating poly (N-isopropyl acrylamide) (PNIPAM) onto cotton. The fabricated material exhibited a water vapor release rate of 24.2 ± 1.054%/min at 32 °C, indicating its ability to humidify the inhaled air effectively. These findings highlight the potential of the developed material as a promising solution for applications requiring rapid moisture recovery.

Chemical composition-dependent hygroscopic behavior of individual ambient aerosol particles collected at a coastal site

Abstract. This study investigated the hygroscopic behavior of individual ambient aerosol particles collected at a coastal site of Jeju Island, South Korea. The size of the particles changes along with the phase transitions during humidification and dehydration processes, and the chemical compositions of the particles were determined by optical microscopy and scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX), respectively. Of the 39 particles analyzed, 24 were aged sea spray aerosols (SSAs), with diverse mixing ratios of Cl− and NO3-. The ambient SSAs exhibited multiple deliquescence and efflorescence transitions that were dominantly influenced by NaCl, NaNO3, MgCl2, Mg(NO3)2, and organic species covering the surface of the aged SSAs. For Cl-rich SSAs with X(Na,Mg)Cl>0.4, although some particles showed very slow water uptake at low relative humidity levels (RH ≃30 %), two major transitions were observed during the humidification process. The first was at RH ≃63.8 %, regardless of their chemical compositions, which is the mutual deliquescence relative humidity (MDRH) level; and the second was at RH 67.5 % to 73.5 %, depending on their chemical compositions, which are the final deliquescence relative humidity (DRH) levels. During the dehydration process, the Cl-rich SSAs showed single-stage efflorescence at RH 33.0 % to 50.5 %, due to simultaneous heterogeneous crystallization of inorganic salts. For Cl-depleted SSAs with X(Na,Mg)Cl<0.4, two prompt deliquescence transitions were observed during the humidification process. The first was at MDRH 63.8 %, and the second was at RH 65.4 % to 72.9 %. The mutual deliquescence transition was more distinguishable for Cl-depleted SSAs. During the dehydration process, step-wise transitions were observed at efflorescence RH levels (ERH 24.6 % to 46.0 % and 17.9 % to 30.5 %), depending on their chemical compositions. Additionally, aged mineral particles showed partial or complete phase changes with varying RH due to the presence of SSAs and/or NO3- species. In contrast, non-reacted mineral and Fe-rich particles maintained their size during the entire hygroscopic process. The mixture particles of organic and ammonium sulfate (AS) exhibited lower deliquescence and efflorescence RH levels compared to pure AS salt, highlighting the impact of organic species on the hygroscopic behavior of AS. These findings emphasize the complexity of atmospheric aerosols and the importance of considering their composition and mixing state when modeling their hygroscopic behavior and subsequent atmospheric impacts.

A study on the collapse characteristics of loess based on energy spectrum superposition method

Mineral types form the basis for studying the structural stability of loess, and identifying mineral types at the microscopic scale has always been a difficult task. Identifying mineral types at the microscopic scale is very helpful in understanding the differential role that different minerals play in the structural stability of loess, and it can also clarify the specific mineral changes that occur during the process of humidification and dehumidification. Using an innovative energy spectrum superposition method, this article combines backscattered electron imaging and X-ray energy spectrum analysis results to achieve direct identification of the eight main minerals in loess, including quartz, illite, and chlorite, within SEM images. The mineral identification results provide a basis for statistical analysis of mineral water sensitivity and morphological changes under wetting conditions. The results demonstrate that chlorite and hematite, which account for no more than 23% of the loess composition, play a crucial role in binding. Furthermore, these minerals exhibit significant hydrolysis phenomena. Particularly, the intense decomposition of chlorite leads to the displacement of non-binding quartz and feldspar particles, thereby altering the pore structure of loess. These findings are of great significance in understanding the multi-level collapsibility of loess.

Study of the numerical model and humidification strategy of wet-membrane humidifier

Despite the fact that wet-membrane humidifiers are commonly used, their designs and forecasts of humid air are generally based on very simple experimental data, which has resulted in certain design errors. Though some numerical models have been developed in the literature, these models make some idealized assumptions about the fluid flow inside the wet-membrane medium in order to solve the momentum conservation equation. Besides, these models had not been validated using accurate experimental data. Thus, based on a thorough examination of the physical procedure of wet-membrane humidification, a new numerical model for the wet-membrane humidification process is developed that can precisely predict the outlet air temperature and Relative Humidity (RH) under a variety of conditions. To verify the model's correctness, the authors built a wet-membrane humidification test-bed and carried out orthogonal experiments with various inlet factors. The numerical model was validated using the experimental data, and it was then utilized to compare various humidifier design strategies. It is found that the ability of the wet-membrane humidifier to humidify the air under the same heat gain increases when the inlet water is heated rather than the inlet air. While using this method, the inlet water parameters and wet-membrane size must be properly set in order to prevent humid air supersaturation.