Search

Approximately two billion people worldwide lack access to clean drinking water, negatively impacting national security, hygiene, and agriculture. Atmospheric water harvesting (AWH) is the conversion of ambient humidity into clean water; however, conventional dehumidification is energy-intensive. Improvement in AWH may be achieved with elastocaloric cooling, using temperature-sensitive materials in active thermoregulation. Potential benefits, compared to conventional desiccant wheel designs, include substantial reductions in energy use, size, and complexity. A nickel–titanium (NiTi) elastocaloric water harvester was designed and compared with a desiccant wheel design under controlled conditions of relative humidity, air volume, and power. In a 30 min interval, the NiTi device harvested more water on average at 0.18 ± 0.027 mL/WH, compared to the 0.1567 ± 0.023 mL/WH of the desiccant wheel harvester. Moreover, the NiTi harvester required half the power input and was thermoregulated more efficiently. Future work will focus on mechanical design parameter optimization. Elastocaloric cooling is a promising advancement in dehumidification, making AWH more economical and feasible. [ABSTRACT FROM AUTHOR]

The perfect combination of renewable energy and desalination technologies is the key to meeting water demands in a cost-effective, efficient and environmentally friendly way. The desalination technique by humidification-dehumidification is non-conventional approach suitable for areas with low infrastructure (such as rural and decentralized regions) since it does not require permanent maintenance. In this study, this technology is implemented by using solar energy as a source of thermal power. A seawater desalination unit is considered, which consists of a chamber with two evaporators (humidifiers), a wetted porous material made of a corrugated cellulose cardboard and a condenser (dehumidifier). The evaporation system is tested with dry bulb temperature and relative air humidity data. The results of numerical simulations indicate that higher inlet air velocities (from 0.75 to 3 m/s) lead to a decrease in the ΔT, ΔRH, and effectiveness. With the air remaining within the evaporator for 30 cm, the temperature differential increases to 5.7°C, accompanied by a 39% rise in relative humidity contrast. These changes result in a significant enhancement in humidification efficiency, achieving a remarkable efficiency level of 78%. However, a wettability value of 630 m2/m3 leads to a smaller reduction of these parameters. Increasing the pad thickness, particularly to 0.3 m, improves performance by boosting ΔT, ΔRH, and effectiveness, especially for pads with a wettability of 630 m2/m3, for which superior performances are predicted by the numerical tests. [ABSTRACT FROM AUTHOR]

A solid desiccant-based novel dehumidification technique in indoor cooling is a viable substitute for a traditional dehumidification system in regions with high humidity levels. The ozone layer is being steadily destroyed by vapour compression-based conventional dehumidification systems, which also have a number of other disadvantages such as excessive power consumption and a rise in the amount of chlorofluorocarbons type refrigerant leakage in the atmosphere. As compared to traditionally used vapour compression type refrigeration air conditioners, solid desiccant-integrated novel cooling may be more advantageous as it provides more easily accessible, cost-effective, and ecologically sound cooling. It can be more competitive when it is reactivated by freely available renewable heat available from solar power and industrial waste heat. Not only marginally saving energy, but it can also help in drastically lower operational costs. Recently, many studies have been carried out with aim of ameliorating desiccant air conditioners' overall performance through the development of novel system configurations, enhanced system designs and better controls, and the integration of hybrid energy sources for desiccant reactivation as well as sub-systems technological advancements. By this means, the present study offers a thorough analysis of the previously described investigations. This offers detailed study on possible suggestions and recommendations for possible future work direction based on the most recent investigations in the field of the desiccant-powered novel cooling techniques. These recommendations can help to amplify the efforts to find better solutions to concurrent technological issues, which will definitely ameliorate the overall performance of desiccant-integrated dehumidification and hybrid cooling in the field of heating, ventilation and air conditioning. [ABSTRACT FROM AUTHOR]

The objective of this paper is to provide the reliable calculation procedure for determining heat and mass flow rates for plate finned tube heat exchangers in dehumidification regimes that can be used easily in engineering practice. For this purpose, the experiments are conducted on two heat exchangers, and datasets for six more heat exchangers are used from literature. Comprehensive database is established with total of 637 sets of data, and it gathers 365 new measurement sets and 272 sets from open literature. The new calculation procedure predicts heat transfer rate and condensate flow rate where new methodology approach (based on the porous velocity, the ratio of characteristic surfaces and hydraulic diameter) is used. Predicted results show 5–10 % deviation for heat duty and up to 20 % for mass flow rate from experimental results, which is of importance to industrial practice. [ABSTRACT FROM AUTHOR]

In this study, to increase the heat and mass transfer coefficients in the system, a combination of liquid desiccant such as lithium chloride (LiCl) and hybrid nanoparticles of multi-walled carbon nanotubes (CNT-MW) Aluminum Oxide (Al2O3) and silicon oxide (SiO2) has been used. Poly-Vinyl Pyrrolidone (PVP) surface activator or surfactant has been used for complete stability of hybrid nanoparticles in lithium chloride (LiCl) desiccant solution and liquid water. By the experimental data, heat and mass transfer coefficients in the system have been determined in a relational way for different combinations of nanoparticles and adsorbents. The effect of important parameters such as air flow intensity and desiccant liquid, air temperature and humidity, temperature and composition of incoming desiccant liquid nanofluid on the efficiency of the system has been studied. And from there the exergy analysis of the system has been done. In this way, the best operating conditions for the better performance of the system containing liquid desiccant nanofluid have been determined.The results of this research have clearly shown that, changes in the air humidity and temperature have been increased by adding the hybrid nanoparticles to LiCl/H2O liquid desiccant. In this regard, the mass transfer rate has been improved from 3.41% to 28.3% and the heat transfer rate has been improved from 4.18% to 29.11%. So, the average improvement has been 23.23% and 22.22%, respectively. Adding hybrid nanoparticles to LiCl/H2O liquid desiccant has increased the mass transfer coefficient from 17.42% to 29.26% and the heat transfer coefficient from 19.83% to 33.55%. Therefore, according to these results, the average value of improvement in mass and heat transfer coefficients has been about 22.73% and 26.51%, respectively.

As global temperatures rise, droughts are becoming more frequent and severe. To predict how drought might affect plant communities, ecologists have traditionally designed drought experiments with controlled watering regimes and rainout shelters. Both treatments have proven effective for simulating soil drought. However, neither are designed to directly modify atmospheric drought. Here, we detail the efficacy of a silica gel atmospheric drought treatment in outdoor mesocosms with and without a co‐occurring soil drought treatment. At California State University, Los Angeles, we monitored relative humidity, temperature, and vapor pressure deficit every 10 min for 5 months in bare‐ground, open‐top mesocosms treated with soil drought (reduced watering) and/or atmospheric drought (silica dehumidification packets suspended 12 cm above soil). We found that silica packets dehumidified these mesocosm microclimates most effectively (−5% RH) when combined with reduced soil water, regardless of the ambient humidity levels of the surrounding air. Further, packets increased microclimate vapor pressure deficit most effectively (+0.4 kPa) when combined with reduced soil water and ambient air temperatures above 20°C. Finally, packets simulated atmospheric drought most consistently when replaced within 3 days of deployment. Our results demonstrate the use of silica packets as effective dehumidification agents in outdoor drought experiments. We emphasize that incorporating atmospheric drought in existing soil drought experiments can improve our understandings of the ecological impacts of drought. [ABSTRACT FROM AUTHOR]

The radiant systems come to the fore due to energy saving potential and good integration. The effect of different forms of cold surfaces on human thermal comfort is focused on its application. A novel natural convection-radiant evaporator for heat pumps was developed and its influence on thermal comfort was investigated. A numerical model of the chamber with the evaporator was established and verified with experimental results. Thermal comfort experiments were conducted in a climate chamber and the influence of its asymmetric and uneven cold radiation on the thermal comfort was investigated. Due to the limitation of PMV in uneven radiation situations, the revised predicted mean vote (RPMV) was proposed to assess the thermal comfort in asymmetric and uneven radiation environments based on experimental results. Based on RPMV, the influence of the surface area and temperature of the evaporator on thermal comfort was numerically analyzed. The results indicate that indoor air temperature and relative humidity, RPMV increase with the increase of plate temperature, but decrease with an increase in plate area. The most favourable indoor thermal comfort environment was obtained at an indoor air temperature of 28°C and relative humidity of 50%, which is 2°C higher than traditional air conditioning system. [ABSTRACT FROM AUTHOR]

In comfort, air-conditioning control over the humidity is essential in applications such as pharmaceutical industries, electronic gadgets manufacturing units, the food sector, paper industries, etc. Relative humidity of nearly 50% can effectively prevent the growth and abidance of biological pollutants. There are several methods using which dehumidification can be achieved. The most common method is subcooling air up to the condensation temperature of the moisture trapped and then cooling again, and the condensate is collected. This method is time-consuming and needs to be more effective. On the other hand, desiccants' dehumidification process is suitable for maintaining humidity in air-conditioning systems and producing dry air. Desiccants with economical materials, high moisture removal rate, low regeneration temperature, and steadiness after many years make a desiccant system more successful in its performance and cost. The effect of change in process air temperature, process air humidity ratio, and regeneration temperature on the system's performance is studied. This research focuses on the functioning of various desiccant dehumidification systems and their applications. A comparative study of the different dehumidification systems found efficiency, low maintenance cost, and high sustainability. [ABSTRACT FROM AUTHOR]

A double layer membrane humidity sensor was designed with a synergistic effect of force and hygroscopic expansion, capitalizing on the high sensitivity demonstrated by MXene material. This sensitivity was achieved through the modulation of resistance change associated with layer spacing of MXene. The double layer structure of sensor was made by vacuum filtration, with an inner layer of MXene for conductivity and an outer layer of cellulose nanofibers (CNF) for moisture absorption, which is rooted in the MXene through the CNFs, similar to the biomimetic structure of hairs rooted in the skin. The synergistic effect of humidity sensitivity is achieved by trapping and dissociating water molecules through the CNF layer generating a change in MXene stress and disrupting the conductive pathway of MXene upon swelling. The CNF/MXene humidity sensor showed a resistance change rate of 117.93 % from 11 % RH to 98 % RH, accompanied by a response time of 319s and a recovery time of 132s. Stable sensing performance is maintained even after 5 times adsorption and desorption cycling, prolonged exposure (7 days) or bending and folding. CNF/MXene bilayer membrane also has good electrical heating performance, reaching about 80 °C at 7V and maintaining stable performance under 5 cycles of heating and 10 min of long heating, respectively. The CNF/MXene membrane humidity sensor can monitor human respiration monitoring, fingertip humidity, pipeline leakage and artifact dehumidification, and combined with the function of electric heating can realize the cycle of dehumidification and humidity monitoring, which has a wide range of application prospects in flexible equipment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating loads. Solid desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed recently. To improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process, in this paper, the application of composite silica gel in a heat pump fresh air unit was investigated. The comparison between silica gel coating (SGC) and composite silica gel coating (CSGC) shows that the adsorption rate and water uptake capacity of CSGC are more than two times higher than those of SGC. An experimental setup for the solid desiccant heat pump fresh air unit was established. The performance of SGC and CSGC was tested in the setup successively. Results show that under summer conditions, compared with the solid desiccant heat pump fresh air unit using silica gel (SGFU), the average moisture removal and COP of the one using composite silica gel (CSGFU) increased by 15% and 30%, respectively. Under winter conditions, compared with SGFU, the average humidification and COP of CSGFU increased by 42% and 17%. With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency, the COP of CSGFU under summer conditions can reach 7.6. Results also show that the CSGFU and SGFU have higher COP and dehumidification rate under higher outdoor temperature and humidity ratio. [ABSTRACT FROM AUTHOR]

In this study, to increase the heat and mass transfer coefficients in the system, a combination of liquid desiccant such as lithium chloride (LiCl) and hybrid nanoparticles of multi-walled carbon nanotubes (CNT-MW) Aluminum Oxide (Al2O3) and silicon oxide (SiO2) has been used. Poly-Vinyl Pyrrolidone (PVP) surface activator or surfactant has been used for complete stability of hybrid nanoparticles in lithium chloride (LiCl) desiccant solution and liquid water. By the experimental data, heat and mass transfer coefficients in the system have been determined in a relational way for different combinations of nanoparticles and adsorbents. The effect of important parameters such as air flow intensity and desiccant liquid, air temperature and humidity, temperature and composition of incoming desiccant liquid nanofluid on the efficiency of the system has been studied. And from there the exergy analysis of the system has been done. In this way, the best operating conditions for the better performance of the system containing liquid desiccant nanofluid have been determined. The results of this research have clearly shown that, changes in the air humidity and temperature have been increased by adding the hybrid nanoparticles to LiCl/H2O liquid desiccant. In this regard, the mass transfer rate has been improved from 3.41% to 28.3% and the heat transfer rate has been improved from 4.18% to 29.11%. So, the average improvement has been 23.23% and 22.22%, respectively. Adding hybrid nanoparticles to LiCl/H2O liquid desiccant has increased the mass transfer coefficient from 17.42% to 29.26% and the heat transfer coefficient from 19.83% to 33.55%. Therefore, according to these results, the average value of improvement in mass and heat transfer coefficients has been about 22.73% and 26.51%, respectively. [ABSTRACT FROM AUTHOR]

In addressing the practical application of direct air capture (DAC) technology to achieve net-zero greenhouse gas emissions by 2050, the intricate climatic environment presents a significant challenge in selecting capture adsorbents with excellent adsorption performance, high moisture tolerance and stability. This study seeks to assess the efficacy of a temperature vacuum swing adsorption (TVSA) system for DAC, integrated with two distinct pre-dehumidification methods: condensation dehumidification and solid desiccant dehumidification. Initially, to balance enhanced adsorption capacity with the energy required for regeneration in the presence of water vapor, the optimal techno-economic performance is achieved at a 40 % relative humidity (RH). This corresponds to 15.49 GJ/t of heat consumption and 194.08 $/tonCO2 of CO2 the levelized cost of DAC (LCOD). Following dynamic simulation, the dehumidification system effectively controlled the outlet RH. Furthermore, economic analysis indicates that reducing environmental air to 40 % RH is more suitable and cost-efficient for both integrated systems. The optimal LCODs are 200.29 $/tonCO2 for the solid desiccant dehumidification system and 197.16 $/tonCO2 for the condensation dehumidification system, which could effectively save 7.09 % and 5.61 % of LCOD, respectively, compared to systems without a dehumidification process.

Abstract Objective Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause recalcitrant lung disease. Prior reports have demonstrated links between shower use and infections, yet the aerosolization of NTM from showerheads, as well as the humidity levels that may modulate NTM aerosolization from showerheads is less studied. The objective of the current study was to investigate the role of humidity in NTM aerosolization among showers in homes located in a geographic area with high lung disease incidence, Hawai’i, and test whether deployment of a dehumidifier in well-ventilated bathrooms reduce NTM exposure. Results Across two sampling events and five showers, existing NTM showerhead biofilms along with shower air were sampled at three points: pre-shower, post-shower, and post-dehumidification. In each of the sampling events, respiratory relevant NTM species were identified from shower biofilms, which were also detected in aerosolized shower air after showering events, but not after the shower was dehumidified and bathrooms vented. While sample size was small, these data suggest running a shower is a possible source of NTM aerosolization and using a commercial household dehumidifier in conjunction with opening bathroom doors and windows may be simple, cost-effective interventions to reduce environmental NTM exposures.

The latest research progress of water vapor separation membrane technology is summarized, first introduces the classification of water vapor separation membrane materials, and the characteristics and research progress of different membrane materials are described・ Besides, the three categories and working principles of water vapor separation membranes with different structures in gas dehumidification and humidification are described systematically, and discusses the application and research status of water vapor separation membrane in the field of gas dehumidification at home and abroad・ The future research and development direction of membrane separation technology in the field of gas dehumidification and humidification are prospected. [ABSTRACT FROM AUTHOR]

To effectively reduce building energy consumption, a novel full fresh air system with a heat source tower (HST) and a borehole heat exchanger (BHE) was proposed for space cooling and dehumidification in this paper. The cooling system only adopts geothermal energy to produce dry and cold fresh air for space cooling and dehumidification through the BHE and HST, which has the advantage of non-condensate water compared to BHE systems integrated with a fan coil or chilled beam. Based on the established mathematical model of the cooling system, this paper analyzed the system characteristics, feasibility, operation strategy, energy performance, and cost-effectiveness of the proposed model in detail. The results show that the mathematical model has less than 10% error in estimating the system performance compared to the practical HST–BHE experimental set up. Under the specific boundary conditions, the cooling and dehumidification capacity of this system increases with the decrease in the air temperature, air moisture content, and inlet water temperature of the HST. The optimal cooling capacity and the system COP can be achieved when the air–water flow ratio is at 4:3. A case study was conducted in a residential building in Shenyang with an area of about 1800 m2. It was found that this system can fully meet the cooling and dehumidification demand in such a residential building. The operation strategy of the cooling system can be optimized by adjusting the air–water flow ratio from 4:3 to 3:2 during the early cooling season (7 June–1 July) and end cooling season (3 August–1 September). As a result, the average COP of the cooling system during the whole cooling season can be improved from 6.1 to 8.7. Compared with the air source heat pump (ASHP) and the ground source heat pump (GSHP) for space cooling, the proposed cooling system can achieve an energy saving rate of 123% and 26%, respectively. Considering that the BHE of the GSHP can be part of the proposed HST–BHE cooling system, the integration of the HST and GHSP for space cooling (and heating) is strongly recommended in actual applications. [ABSTRACT FROM AUTHOR]

Photovoltaic thermal (PVT) systems are attracting a significant amount of attention in research because they can generate electricity outside of daytime hours, unlike photovoltaic (PV) systems, and can increase efficiency and collect additional energy by reducing the temperature of PVT panels. However, a somewhat lower amount of collected energy is used in the summer than in the winter, and research on this issue is lacking. In this study, first, we experimentally evaluated the performance of PV and PVT systems by season and verified the improvement in the performance of the PVT system. Second, experiments were conducted to verify the enthalpy reduction via mist cooling and dehumidification, and the temperature and humidity control effect via mist cooling and dehumidification was verified. Based on our research findings, we propose a model that can be integrated with indoor ventilation systems to increase the solar energy utilization of PVT systems. Using the PVT system, we improved the panel power generation efficiency by up to 5.89% and generated up to a 38.0% higher collection efficiency than that of the PV system. The air that passed through the PVT system was then subjected to mist cooling and dehumidification to reduce its temperature and increase its humidity, resulting in a 23.2% reduction in enthalpy. [ABSTRACT FROM AUTHOR]

The condenser's rejected heat in a vapour compression refrigeration system when thrown into the surrounding air results in its thermal pollution and gets wasted, while it has the potential to be recovered. Another major targeted concern is freshwater scarcity which is faced by the population in many areas. Addressing these difficulties, a double-stage integrated humidification-dehumidification and air conditioning system that recovers the condenser's waste heat and is assembled in a novel duct architecture is proposed. The obtained results of the developed model are established using the experimental data. The analysis explores the outcomes of the integrated system and investigates the influences of saline water temperature, humidifier efficiency, ambient temperature, and relative humidity on the output and performance metrics. The system provides air conditioning of 31.410 kJ and desalination of 65.020 mL from a unit volume of air using 0.661 kW of power and mitigates the environmental impact of existing technology. The coefficient of energy performance, cooling performance, gained output ratio, and exergy efficiency at the specified working situations are 0.958, 1.320, 6.809, and 2.701 %, respectively. A litre of freshwater costs $ 0.0068486. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause recalcitrant lung disease. Prior reports have demonstrated links between shower use and infections, yet the aerosolization of NTM from showerheads, as well as the humidity levels that may modulate NTM aerosolization from showerheads is less studied. The objective of the current study was to investigate the role of humidity in NTM aerosolization among showers in homes located in a geographic area with high lung disease incidence, Hawai'i, and test whether deployment of a dehumidifier in well-ventilated bathrooms reduce NTM exposure. Results: Across two sampling events and five showers, existing NTM showerhead biofilms along with shower air were sampled at three points: pre-shower, post-shower, and post-dehumidification. In each of the sampling events, respiratory relevant NTM species were identified from shower biofilms, which were also detected in aerosolized shower air after showering events, but not after the shower was dehumidified and bathrooms vented. While sample size was small, these data suggest running a shower is a possible source of NTM aerosolization and using a commercial household dehumidifier in conjunction with opening bathroom doors and windows may be simple, cost-effective interventions to reduce environmental NTM exposures. [ABSTRACT FROM AUTHOR]

Abstract As global temperatures rise, droughts are becoming more frequent and severe. To predict how drought might affect plant communities, ecologists have traditionally designed drought experiments with controlled watering regimes and rainout shelters. Both treatments have proven effective for simulating soil drought. However, neither are designed to directly modify atmospheric drought. Here, we detail the efficacy of a silica gel atmospheric drought treatment in outdoor mesocosms with and without a co‐occurring soil drought treatment. At California State University, Los Angeles, we monitored relative humidity, temperature, and vapor pressure deficit every 10 min for 5 months in bare‐ground, open‐top mesocosms treated with soil drought (reduced watering) and/or atmospheric drought (silica dehumidification packets suspended 12 cm above soil). We found that silica packets dehumidified these mesocosm microclimates most effectively (−5% RH) when combined with reduced soil water, regardless of the ambient humidity levels of the surrounding air. Further, packets increased microclimate vapor pressure deficit most effectively (+0.4 kPa) when combined with reduced soil water and ambient air temperatures above 20°C. Finally, packets simulated atmospheric drought most consistently when replaced within 3 days of deployment. Our results demonstrate the use of silica packets as effective dehumidification agents in outdoor drought experiments. We emphasize that incorporating atmospheric drought in existing soil drought experiments can improve our understandings of the ecological impacts of drought.

Approximately two billion people worldwide lack access to clean drinking water, negatively impacting national security, hygiene, and agriculture. Atmospheric water harvesting (AWH) is the conversion of ambient humidity into clean water; however, conventional dehumidification is energy-intensive. Improvement in AWH may be achieved with elastocaloric cooling, using temperature-sensitive materials in active thermoregulation. Potential benefits, compared to conventional desiccant wheel designs, include substantial reductions in energy use, size, and complexity. A nickel–titanium (NiTi) elastocaloric water harvester was designed and compared with a desiccant wheel design under controlled conditions of relative humidity, air volume, and power. In a 30 min interval, the NiTi device harvested more water on average at 0.18 ± 0.027 mL/WH, compared to the 0.1567 ± 0.023 mL/WH of the desiccant wheel harvester. Moreover, the NiTi harvester required half the power input and was thermoregulated more efficiently. Future work will focus on mechanical design parameter optimization. Elastocaloric cooling is a promising advancement in dehumidification, making AWH more economical and feasible.

The cable room, located at the base of the ring main unit, is prone to water vapor due to its proximity to damp cable holes and its relatively enclosed structure. This may penetrate internally and ultimately affect operational safety. Therefore, a dehumidifier was introduced to utilize dry air for internal circulation. To enhance the dehumidification in the cable room, the cable room device was designed for experimental research. Meanwhile, computational fluid dynamics (CFD)-electromagnetic (EMAG) coupling simulation is used to calculate the power loss of heat sources and their influence on multiple physical fields in numerical simulations. The feasibility of this study was confirmed by comparing the relative humidity, temperature, and velocity values between the experimental and numerical approaches. Furthermore, the layout of the ventilation pipes was modified to a vertical distribution, with upward supply and downward suction, to improve the airflow. The results indicate that the maximum relative errors in temperature, relative humidity, and velocity are only 3.61%, 7.14%, and 7.14%, respectively, which fall within an acceptable range. On this basis, additional simulation analysis was conducted on the humidity, dew point temperature, and airflow within the cable room, using an optimized model with a more comprehensive internal structure and cables. After implementing an optimized ventilation pipe layout, the relative humidity at the corresponding measuring points can decrease by up to 10.6%. The dew point temperature has decreased by 2.61 °C and the airflow has become more stable. [ABSTRACT FROM AUTHOR]

• Polymer desiccant wheel with high water uptake and low regeneration temperature is studied. • Polymer's adsorption capacity of 1.15 g kg−1 at 90 %RH is five times that of silica gel. • Polymer's desorption rate coefficient is 1.32–1.64 times that of silica gel at 40–70 °C heat sources. • The maximum ∆ Y and DCOP of the polymer desiccant wheel are 4.0 g kg−1 and 0.66, respectively. • Polymer desiccant wheel offers a promising measure for ultra-low dew point humidity control. Desiccant wheels have been widely used in humidity control, particularly under conditions with ultra-low dew point temperatures. However, traditional desiccants such as silica gel and zeolites are subject to relatively low adsorption capacity and high regeneration temperature. To address these challenges, a type of polymer material with high water uptake and low regeneration temperature is investigated in this paper. Firstly, the adsorption/desorption capacity of this polymer is thoroughly tested. Results reveal that its remarkable equilibrium adsorption capacity and desorption rate coefficients k LDF,de are 350% and 32–64% higher than that of silica gel, respectively. Moreover, its required regeneration temperature is just about 40–70 °C. The performance of the desiccant wheel using this polymer is simulated by a model validated by experiments tests. Parameter analysis demonstrates that the desiccant wheel is suitable for cool and humid conditions, reaching the maximum moisture removal (∆ Y) and dehumidification coefficient of performance (DCOP) of 4.0 g kg−1 and 0.66, respectively. Furthermore, the corresponding relationship between other parameters and the optimal rotation speed is discussed in detail. The ω opt is around 18 rph, enabling the attainment of the highest ∆ Y. Finally, the performance comparison with a traditional silica gel desiccant wheel is carried out. The results indicate that the polymer one performs 17–53.9% higher in terms of both ∆ Y and DCOP than the silica gel counterpart. And the most significant improvement is observed in low relative humidity conditions (45%RH), where ∆ Y and DCOP are 1.25–1.53 times that of the silica gel's, highlighting the advantageous utilization of the polymer material. [ABSTRACT FROM AUTHOR]

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. • Osmotic distillation (OD) was used for air dehumidification. • Direct contact membrane distillation (DCMD) was used for desiccant regeneration. • PVDF HF membrane was applied to OD and DCMD systems. • Operating parameters of the OD system were studied for air dehumidification. • Regeneration performance of calcium chloride liquid desiccant was examined. [ABSTRACT FROM AUTHOR]

The main goal of this research is to use zeolite TiO2 nanocomposite membranes in order to remove moisture from gas. For this reason, a certain TiZ-V membrane was selected and manufactured as a standard membrane, which was the result of the initial assessment of a suitable membrane for gas dehumidification, and this membrane was used as a standard to measure the effect of manufacturing parameters. The findings showed that increasing the concentration of SiO2 had greatest effect on increasing the water flux of the membrane due to the effect of increasing the reaction time of the vapor phase carrier and reducing the selectivity drop at higher pressures. Also, the experiments of changing the relative humidity of the feed have shown the improving efficiency of the membrane in relative humidities lower than 80%, so that under the conditions of lower relative humidity, the selectivity of the membrane has increased. Another positive point found is a slight change in the selectivity efficiency of the membrane with respect to different relative humidities. This case showed the stability of membrane performance under the different conditions of humidity of the feed gas. Next, in order to increase the performance of membrane as much as possible, the sweeper gas was added from the inside of membrane. Increase in the sweeper gas, which increases the water concentration gradient and decreases the gas concentration gradient on the sides of membrane wall, increases the selectivity of membrane to the highest level of 543. [ABSTRACT FROM AUTHOR]

The main goal of this research is to use zeolite TiO2 nanocomposite membranes in order to remove moisture from gas. For this reason, a certain TiZ-V membrane was selected and manufactured as a standard membrane, which was the result of the initial assessment of a suitable membrane for gas dehumidification, and this membrane was used as a standard to measure the effect of manufacturing parameters. The findings showed that increasing the concentration of SiO2 had greatest effect on increasing the water flux of the membrane due to the effect of increasing the reaction time of the vapor phase carrier and reducing the selectivity drop at higher pressures. Also, the experiments of changing the relative humidity of the feed have shown the improving efficiency of the membrane in relative humidities lower than 80%, so that under the conditions of lower relative humidity, the selectivity of the membrane has increased. Another positive point found is a slight change in the selectivity efficiency of the membrane with respect to different relative humidities. This case showed the stability of membrane performance under the different conditions of humidity of the feed gas. Next, in order to increase the performance of membrane as much as possible, the sweeper gas was added from the inside of membrane. Increase in the sweeper gas, which increases the water concentration gradient and decreases the gas concentration gradient on the sides of membrane wall, increases the selectivity of membrane to the highest level of 543. [ABSTRACT FROM AUTHOR]

• Spherical membrane-based micro-absorbers were produced using microfluidics setup. • The proposed micro-absorbers offer surface-to-volume ratios up to 12,000 m2/m3. • The design overcomes challenges such as solution carryover and crystallization. In this work, a novel design concept for absorbers used in dehumidification systems is proposed to overcome the practical challenges of the conventional packed-column absorbers. In the proposed design, spherical micro-absorbers (microcapsules) that contain a liquid LiBr desiccant inside a semi-permeable polymeric membrane shell are produced by using a custom-built microfluidic technique. The produced microcapsules are capable of containing the salt during crystallization. The X-ray diffraction analysis has confirmed that the observed crystals in the microscopes images were indeed for the encapsulated (LiBr) salt. Due to the indirect contact between the liquid desiccant and the process air, problems such as solution carryover and corrosion associated with packed-column absorbers can be eliminated. The collected sorption data show that the spherical microcapsules offer a high sorption capacity of 1 g w /g dry under 80% relative humidity. The proposed microcapsules offer surface-to-volume ratios between 6,000–12,000 m2/m3, which is up to two orders of magnitude higher than the conventional packed-column absorbers (200–600 m2/m3). The produced micro-absorbers can withstand a compression force up to 2 × 105 their weight, elastically expanded during the absorption process without rupture, and did not show a leakage or a reduction in capacity even after an accelerated test of 200 sorption-desorption cycles. [ABSTRACT FROM AUTHOR]

In this study, a new polymer membrane was developed for natural gas dehumidification using the combination of hydrophilic silica nanoparticles in the Pebax polymer matrix. The membranes were characterized using various analytical methods including FTIR, XRD, SEM, and TGA. The results indicated that adding nanoparticles increased the porosity and thermal stability of the membranes. Also, the enhancement of copolymer hydrophilicity was confirmed by reducing contact angles. The study found that increasing the nanoparticle content from 0 w% to 3 w% at 15 bar pressure resulted in a 33% increase in water permeability and a 12% increase in methane permeability. Adding of silica also increased the H2O/CH4 selectivity from 24.17 to 27.34. Moreover, at higher temperatures (from 25 to 55°C), the permeability of H2O and CH4 reached 171.3 and 10.71 bar, respectively. The findings of this study show that the inclusion of hydrophilic silica nanoparticles in the Pebax matrix can enhance the efficiency of membranes for natural gas dehumidification. Additionally, the study highlights the significance of temperature in the design and implementation of such membranes [ABSTRACT FROM AUTHOR]

Efficient dehumidification has been one of the technical problems to restrict the high-quality development of the greenhouse industry in China. It is a high demand to dehumidify and recover the heat energy in the process of dehumidification during winter. Among them, the airside heat and moisture transfer properties of finned-tube evaporators have had direct impacts on the performance of the entire dehumidification system in the greenhouse. In this study, the heat transfer models were established for the evaporators under both low temperatures and high relative humidity. Four hydrophilic finned-tube evaporators were taken with the plain fin, the plain fin with vortex generator, wavy fin, and slit fin. The numerical simulation was verified to compare the experimental data. The heat and moisture transfer properties of four evaporators were assessed for the refrigeration dehumidification systems in the greenhouse using various parameters, including the heat transfer capacity, Nusselt number, friction factor, dehumidification capacity per area, and the enhanced heat-transfer factor. The results showed that average relative errors of less than 3% were achieved in the Nusselt number and friction factor of the models for the grid system. There were the higher Nusselt number, heat transfer capacity, friction factor of the air side in the plain fin with vortex generator, the wavy fin, and the slit fin, compared with the plain fin. The largest heat-transfer capacity and friction factor of the slit fin were achieved under the same inlet air velocity and relative humidity conditions. The friction factor also decreased significantly with the increase of inlet air velocity, with an average decrease of 26.06%, 24.87%, 21.10%, and 29.06%, respectively. By contrast, there was a relatively small effect of the relative humidity on the friction factor. The slit fin exhibited the highest heat transfer capacity and friction factor, whereas, the plain fin displayed the lowest under the same conditions. The other three types of fins improved the convection heat transfer on the air side of the evaporator, due to their unique structure. The dehumidification capacity was augmented with the rise in the inlet air velocity and relative humidity. The wavy fin shared the greatest average increase in the dehumidification capacity per area, with 8.68% and 7.60%, respectively, at inlet air velocity and relative humidity. The wavy fin-tube evaporator presented the highest average enhanced heat transfer factor of 1.084 and 1.041, respectively, under the conditions of inlet air velocity and relative humidity, indicating the most favorable heat and moisture transfer properties. Hence, the wavy fin-tube evaporator was recommended for dehumidification at low temperatures and high relative humidity in the winter of cold regions, when the inlet air velocity exceeded 2 m/s and the relative humidity was over 80% in the greenhouse environment. The findings can provide a strong reference for the design and application of the hydrophilic finned-tube evaporators in the refrigeration dehumidification systems in the greenhouse. [ABSTRACT FROM AUTHOR]

The majority of household energy is consumed in heating and air conditioning. Desiccant disks are a way to harvest renewable solar energy or waste heat for air conditioning. In the literature there is a gap in the investigation of start-up of desiccant dehumidifiers, which this paper attempts to covers. For this work, a desiccant disk was designed, manufactured, and tested. To reduce the cost, off-the-shelf components were used as structure materials. And as adsorption material, widely available materials were used. Input heat was simulated by an electrical heater and power to auxiliary motors was provided in the form of DC power. Temperature and humidity were recorded at various locations using DHT11 sensors. The system was turned off and tested at a start of operation mode. The performance of the desiccant disk was quantified by the coefficient of performance and the dehumidification efficiency. Results showed gradual increase of the desiccant disk efficiency with a maximum COP value of 0.4 reached within 10 min of the start of operation. Time delays were attributed to heating of the disk. Further work is required to fully understand the transient operation.

The polymer desiccant cooling system (PDCS) efficiently reduces energy consumption compared to the vapor compression system (VCS). In this paper, a PDCS integrated heat pump is proposed. Experimental and simulation are used to analyze the performance of the PDCS. The control strategy is optimized with the NSGA Ⅱ algorithm. A case study in Shanghai illustrates the practical application of the PDCS optimization strategy. The calculation results based on the thermal comfort requirement show the maximum energy consumption of optimized PDCS, routine PDCS, and VCS are 549.9 kW, 597.7 kW, and 1327.7 kW. About 62.7 % and 72.3 % of energy can be saved in routine PDCS and optimized PDCS compared to VCS. Moreover, the maximum moisture removal efficiency of the above scenarios is 10.67 kW/(g·s), 11.56 kW/(g·s), and 25.42 kW/(g·s), separately. Additionally, the maximum coefficient of performance is 0.530, 0.457, and 0.182, respectively.

To effectively reduce building energy consumption, a novel full fresh air system with a heat source tower (HST) and a borehole heat exchanger (BHE) was proposed for space cooling and dehumidification in this paper. The cooling system only adopts geothermal energy to produce dry and cold fresh air for space cooling and dehumidification through the BHE and HST, which has the advantage of non-condensate water compared to BHE systems integrated with a fan coil or chilled beam. Based on the established mathematical model of the cooling system, this paper analyzed the system characteristics, feasibility, operation strategy, energy performance, and cost-effectiveness of the proposed model in detail. The results show that the mathematical model has less than 10% error in estimating the system performance compared to the practical HST–BHE experimental set up. Under the specific boundary conditions, the cooling and dehumidification capacity of this system increases with the decrease in the air temperature, air moisture content, and inlet water temperature of the HST. The optimal cooling capacity and the system COP can be achieved when the air–water flow ratio is at 4:3. A case study was conducted in a residential building in Shenyang with an area of about 1800 m2. It was found that this system can fully meet the cooling and dehumidification demand in such a residential building. The operation strategy of the cooling system can be optimized by adjusting the air–water flow ratio from 4:3 to 3:2 during the early cooling season (7 June–1 July) and end cooling season (3 August–1 September). As a result, the average COP of the cooling system during the whole cooling season can be improved from 6.1 to 8.7. Compared with the air source heat pump (ASHP) and the ground source heat pump (GSHP) for space cooling, the proposed cooling system can achieve an energy saving rate of 123% and 26%, respectively. Considering that the BHE of the GSHP can be part of the proposed HST–BHE cooling system, the integration of the HST and GHSP for space cooling (and heating) is strongly recommended in actual applications.

Photovoltaic thermal (PVT) systems are attracting a significant amount of attention in research because they can generate electricity outside of daytime hours, unlike photovoltaic (PV) systems, and can increase efficiency and collect additional energy by reducing the temperature of PVT panels. However, a somewhat lower amount of collected energy is used in the summer than in the winter, and research on this issue is lacking. In this study, first, we experimentally evaluated the performance of PV and PVT systems by season and verified the improvement in the performance of the PVT system. Second, experiments were conducted to verify the enthalpy reduction via mist cooling and dehumidification, and the temperature and humidity control effect via mist cooling and dehumidification was verified. Based on our research findings, we propose a model that can be integrated with indoor ventilation systems to increase the solar energy utilization of PVT systems. Using the PVT system, we improved the panel power generation efficiency by up to 5.89% and generated up to a 38.0% higher collection efficiency than that of the PV system. The air that passed through the PVT system was then subjected to mist cooling and dehumidification to reduce its temperature and increase its humidity, resulting in a 23.2% reduction in enthalpy.

The cable room, located at the base of the ring main unit, is prone to water vapor due to its proximity to damp cable holes and its relatively enclosed structure. This may penetrate internally and ultimately affect operational safety. Therefore, a dehumidifier was introduced to utilize dry air for internal circulation. To enhance the dehumidification in the cable room, the cable room device was designed for experimental research. Meanwhile, computational fluid dynamics (CFD)-electromagnetic (EMAG) coupling simulation is used to calculate the power loss of heat sources and their influence on multiple physical fields in numerical simulations. The feasibility of this study was confirmed by comparing the relative humidity, temperature, and velocity values between the experimental and numerical approaches. Furthermore, the layout of the ventilation pipes was modified to a vertical distribution, with upward supply and downward suction, to improve the airflow. The results indicate that the maximum relative errors in temperature, relative humidity, and velocity are only 3.61%, 7.14%, and 7.14%, respectively, which fall within an acceptable range. On this basis, additional simulation analysis was conducted on the humidity, dew point temperature, and airflow within the cable room, using an optimized model with a more comprehensive internal structure and cables. After implementing an optimized ventilation pipe layout, the relative humidity at the corresponding measuring points can decrease by up to 10.6%. The dew point temperature has decreased by 2.61 °C and the airflow has become more stable.

Desiccant materials have an important impact on the dehumidification performance of desiccant-coated heat exchanger (DCHE). In this paper, a desiccant-coated heat exchanger based on a composite desiccant material of metal organic frameworks (MOFs) and silica gel was proposed. The coating was experimentally prepared and tested for its hygroscopic performance under different binder types (PVP, PVA, and PVB), different binder mass concentrations, and different MOF mass concentrations in the composite adsorbent. Further simulations were performed to investigate the effects of key structural and operational parameters on the performance of DCHE. Experimentally, the optimal hygroscopic performance of the composite adsorbent was obtained at 15 wt% PVP and 20 wt% MOF, which was 51.71 % higher than that of silica coating, and the cost of the composite adsorbent drops 78.04 % by comparing to the pure MOF for laboratory fabrication, and based on the novel economic efficiency index proposed in this paper, the mass concentration of the MOF should not exceed 32.8 wt%. Simulation results showed that under the conditions as follows: 1.2 mm (fin spacing), 25 mm (fin height), 0.28 mm (coating thickness), 25 °C (cooling water temperature), and 0 % (initial moisture content), the corresponding moisture removal capacity (MRC) and of DCHE was 6.740 g/kg, which was 149.63 % higher than that of silica coating. • A composite coating is fabricated using silica/Mil-100(Fe). • The fabrication method and mixture percentage are optimal selected. • Multiple evaluation indexes are introduced to estimate the comprehensive performance. • The effects of structural and operation related parameters are clarified. [ABSTRACT FROM AUTHOR]

This study focuses on the application of desiccant coated heat exchangers (DCHEs) in conditions where condensation occurs below the dew point temperature. Previous experimental studies on DCHEs and DCHPs have predominantly examined the sorption mechanism above the dew point, leaving a gap regarding material selection and system design in the presence of condensation. To address this, a guide is introduced that combines the understanding of condensation and sorption processes for desiccant applications. The guide is applied to evaluate the suitability of a superabsorbent-LiCl (SAP-LiCl) composite desiccant for desiccant coated heat pump (DCHP) applications. The stability of the desiccant in the presence of condensed water droplets is validated. Additionally, an experimental investigation explores the relationship between sorption and condensation mechanisms, identifying the transitional coolant temperature at which dehumidification shifts from condensation-dominant to sorption-dominant. By incrementally adjusting the coolant temperature in 5 °C steps, the transitional temperature of the SAP-LiCl based DCHE is determined to be approximately 15 °C under the target operation scenario, rendering its suitability for additional below-dew-point applications. The study reveals optimal operational parameters for DCHE, demonstrating a potential energy saving of 20 %. Based on these findings, a DCHP prototype is constructed to assess the feasibility of DCHE in real-world applications. The transient behaviors of this prototype are analyzed during each operating cycle, yielding a coefficient of performance of 4.97 and a cooling capacity of 1.5 kW under baseline operating conditions. • A desiccant application guidance for DCHPs under condensation conditions is proposed. • The combined effects of sorption and condensation are comprehensively studied. • The transition coolant temperature is found crucial to desiccant selection. • DCHE achieves 3.6 latent cooling effectiveness. • DCHP provides a 1.5 kW cooling capacity with a COP of 4.97. [ABSTRACT FROM AUTHOR]

Indoor mold exposure in hot-humid regions poses considerable risks to public health and food security. Ensuring safe, durable, and energy-efficient air disinfection is crucial for the air-conditioning field. While liquid desiccant air-conditioning (LDAC) systems eliminate condensation-related mold proliferation, their capability to combat airborne mold spores is limited due to the spores' robust resistance. This paper explores a novel airborne ultrasound-assisted liquid desiccant air-conditioning (US-LDAC) system. Experiments were conducted using culture-based methods to compare the system's disinfection capacities against Aspergillus niger spores, a desiccant-resistant species, under ventilation, liquid desiccation dehumidification, and airborne ultrasound-assisted liquid desiccant dehumidification modes. Moreover, the viability and morphological changes of mold spores exposed to airborne ultrasound, with and without liquid desiccants, were analyzed to verify the disinfection effectiveness and extrapolate the improving mechanisms. The results show that irradiating low-intensity airborne ultrasound (∼127 W, harmless mechanical waves) into the dehumidifier significantly increased the disinfection efficiency by 50 % and the dehumidification rate by over 90 % when airflow passed through the dehumidifier (∼0.4 s). The enhanced disinfection is attributed to ultrasonic cavitation, which facilitates the rupture of the desiccant-captured spores through microstreaming-induced shear forces. Notably, the improvements were more pronounced in humid air and with dilute desiccant solutions, suggesting that efficiency can be maintained with lowered desiccant concentrations. The US-LDAC system was particularly adept at removing mold aerosols (2.1–3.3 μm) which are easily inhaled. These findings propose a promising avenue for retrofitting existing LDAC systems to effectively reduce airborne molds and enhance dehumidification, thereby protecting indoor air quality. • Ultrasound boosted liquid desiccant in reducing mold aerosols by 50 % in 0.4 s. • Dehumidification performance increased simultaneously by over 90 %. • The reduction of small mold aerosols was more pronounced. • Lower concentration desiccant maintained sufficient efficiency. • Primary improvement mechanisms were identified. [ABSTRACT FROM AUTHOR]

Many industrial environments have low-humidity requirements. However, most research focuses on dehumidification systems in civil buildings, while research on industrial low humidity environments is extremely limited. This paper aims to summarize the research of dehumidification systems in low-humidity industrial environments, and provide some suggestions for the selection and improvement of dehumidification systems. Firstly, the environmental control requirements of industrial plants are reviewed and categorized into low humidity and extremely low humidity based on a relative humidity of 45 %. Then, the performance and applicability of condensation dehumidification systems, desiccant wheel (rotary dehumidifier) dehumidification systems and liquid desiccant dehumidification systems in typical industrial environments are summarized. Several preliminary system selection and configuration methods are presented. It is shown that the traditional condensation system is only suitable for low humidity plants. The desiccant wheel-based system is more capable of deep dehumidification, with a humidity ratio of less than 4 g/kg of supply air, while the liquid desiccant-based system can achieve high air volume operation of 10000 m3/h. Furthermore, their ranking under different scenarios is still outstanding issues. Evaluation indicators that weigh factors such as initial investment, operating costs, and control effectiveness need to be urgently proposed. Long term on-site testing is strongly recommended. [Display omitted] • Categorize production to low and extremely low humidity by 45 % relative humidity. • Desiccant wheel systems are recommended for supply air humidity less than 4 g/kg. • Liquid desiccant systems are preferred for air flowrate higher than 10000 m3/h. • Design and improvement methods of dehumidification systems in plants are presented. • Configuration and operation for year-round heating, cooling, dehumidification mode. [ABSTRACT FROM AUTHOR]

Desiccant dehumidification can realize decoupling of latent and sensible heat loads in dehumidified air conditioning, thereby reducing energy consumption. This paper proposes a solar regenerated carbon-based composite desiccant coated heat exchangers (DCHE) for air dehumidification. Carbon-based composite desiccant is electrostatically sprayed onto the surface of the heat exchanger to form a dehumidification coating. An experimental system for evaluating the dehumidification and regeneration performance of DCHE is established. The Taguchi method is employed to evaluate the impact of operating parameters such as air velocity, water flow rate, and regeneration temperature on the dehumidification and regeneration efficiency of DCHE. The result shows that air velocity is the primary factor impacting the dehumidification performance of DCHE, with regeneration temperature and cooling water flow rate following in importance. With the faster air velocity and the lower cooling water flow rate, DCHE shows the better dehumidification performance. Moreover, excessively both high and low regeneration temperatures can result in a degradation in the dehumidification performance of DCHE. Under optimal operating conditions, the dehumidification rate (EDE) and thermal coefficient of performance (COPth) of DCHE can reach 7.5 kg/h and 2.3, respectively. The moisture content of the air reduces from 19.6 g/kg to 8.0 g/kg. • A solar regenerated carbon-based composite desiccant coated heat exchanger (DCHE) is proposed. • Dehumidification process of DCHE can reduce the influence of adsorption heat of desiccant. • DCHE solve the high humidity problem in direct evaporative cooling supply air. • Equilibrium adsorption capacity of carbon-based composite desiccant is 6.8 times than activated carbon. [ABSTRACT FROM AUTHOR]

The development of efficient energy systems and renewable alternative energy sources has attracted substantial attention owing to the rise in environmental deterioration and energy usage. A combined cooling, heating, and power (CCHP) system can fully use different types of energy with low emissions and offers a viable solution to address these issues. Demand flexibility is a key issue in collaborating with different types of supplies and demands for optimal system operation. In this study, a proton-exchange membrane fuel cell driven CCHP system with humidity control is proposed to fully investigate the impact of demand flexibility on system operation. A novel flexible load regulation strategy was designed for the proposed system. The results show that flexible load regulation can reduce the thermal storage capacity by 25 %. Supplement heating and cooling do not need operate in winter and summer. With flexible regulation, the heating load can be reduced by 15.69 % in winter, and the cooling and dehumidification loads can be reduced by 30.71 % and 6.09 % in summer. The reductions in hydrogen consumption can reach 1.98 % and 7.51 % during winter and summer. The proposed method can simultaneously increase the exergy efficiency and reduce carbon emission, as well as the economy cost. [ABSTRACT FROM AUTHOR]

The conventional desiccant coated heat exchangers (DCHEs) suffer from the inefficient utilization of regenerative energy and the inadequate dehumidification capacity of a single desiccant. In this study, a concept of dual-desiccants cross-flow DCHE with staged adsorption-desorption process was proposed to strengthen dehumidification capacity and energy efficiency simultaneously. In order to guide the construction of proposed DCHE, the steady-state dehumidification capacity of single-desiccant (specifically, silica gel, FAM Z01, FAM Z05 and EMM-8) cross-flow DCHE was investigated by thermodynamic analysis. The dual-desiccants cross-flow DCHE was thus constructed, and its numerical model was established to investigate the dehumidification characteristics. Theoretical analysis revealed that single-desiccant cross-flow DCHEs exhibit different optimal relative humidity ranges for dehumidification. The minimum regeneration temperature driving dehumidification cycle increases as the lower supply air humidity is required. Numerical results demonstrated that the staged adsorption process ensures a large dehumidification capacity across a wide humidity range, including low humidity conditions. Meanwhile, the staged desorption process facilitates the cascade utilization of energy and the direct recovery of regenerative waste heat. For dual-desiccants cross-flow DCHE utilizing silica gel and EMM-8, the moisture removal capacity and dehumidification coefficient of performance can reach 0.012 kg/kg and 0.41, respectively. • Thermodynamic analysis on dehumidification cycle of single-desiccant cross-flow DCHEs was conducted. • Dual-desiccants cross-flow DCHE with staged adsorption-desorption process was proposed. • Single-desiccant cross-flow DCHEs have different optimal relative humidity ranges for dehumidification. • Minimum regeneration temperature increases as the lower supply air humidity is required. • Strengthening dehumidification capacity and energy efficiency are achieved in dual-desiccants DCHE. [ABSTRACT FROM AUTHOR]

Sorption-based atmospheric water harvesting (SAWH) is a promising way to address global water shortage. However, there still lacks further study to demonstrate the potential of simultaneous water production and humidity regulation broadening its applications. Here, a metal–organic framework-based humidity pump was proposed to realize both the two functions in a wide humidity range. Double sorption bed with Ni 2 Cl 2 (BTDD) coating was integrated to switch alternately between adsorption (dehumidification) and desorption (water production) states throughout the day. The device produced 2510 mL water ·kg−1 MOF ·day−1 indoors superior to the existing researches. Even at arid condition (35 % RH), it still exhibited high yield of 1780 mL water ·kg−1 MOF ·day−1 benefiting from enhanced heat and mass transfer. Besides, the device effectively dehumidified a space with 20.5-time volume below 60 % RH under variable high-humidity environments (75 %-90 % RH). This device is a feasible way to water scarcity and a functional product for multi-scenario utilization, promoting SAWH a further step to practical applications. [Display omitted] • A MOF-based interconnected porous sorption layer was fabricated with enhanced property. • A high-yield integrated continuous humidity pump with dual functions was proposed. • The daily water production reached 1780 and 2510 mL·kg−1 MOF ·day−1 at 35% and 70% RH. • The MOF-based sorbent bed exhibited durable dehumidification effect under variable RHs. [ABSTRACT FROM AUTHOR]

Fresh air system is getting more and more important nowadays. The heat pump fresh air system based on the desiccant coated heat exchanger (DCHE) that can handle the latent and sensible load of fresh air efficiently has a large energy saving potential. To improve the performance of the heat pump fresh air system based on DCHE, in this paper, a control system based on PLC is established and the operation strategies of the system are investigated. An operation strategy including automatic control of the opening of the electronic expansion valve based on the suction superheat of the compressor, control of the switchover period based on the relative humidity of supply air, and control of compressor frequency based on evaporation and condensation temperature is established. By using the optimal operation strategies, the dehumidification rate and COP of the system can reach 4.42 kg/h and 6.2 in summer, compared with the unoptimized strategy it increased 8% and 25%, respectively. The two performance indices can reach to 3.04 kg/h and 6.98, with an increase of 89% and 78%. • A control system for Heat pump fresh air system based on DCHE is established. • The optimal operation strategy of the system is proposed. • The dehumidification rate and COP of the system reach 4.42 kg/h and 6.2 in summer. • The humidification rate and COP of the system reach 3.04 kg/h and 6.98 in winter. [ABSTRACT FROM AUTHOR]

Present study aimed at the fabrication of a counter flow dehumidifier unit using biomass-based organic materials like coconut coir and wood shave as packing alternatives. The wettability of these packings is evaluated by arranging them structurally and their influence on the dehumidification performance has been experimentally studied. A prediction-based mathematical model is constructed to simulate the performance of biomass packing materials. Theoretical and experimental results were very close, with an average deviation of 8.33% for wood shaving and 5.79% for coconut coir packings. Overall, this unit gave the rate of moisture removal (MRR), dehumidification effectiveness (DE), coefficient of mass transfer (MTC) and specific humidity ratio equal to 0.70 g/s, 76%, 37 kg/m2-s and 0.78 respectively. A packing life study and its influence on dehumidification performance is checked. After the third week of continuous usage, results revealed that air contamination CO 2 , TVOC, and HCHO levels increased by 14.60%, 34.48%, and 38.46%, and the moisture removal rate decreased by 29%, for wood shaving packing. After the third week, the performance deteriorated since the packing fragments became brittle due to the salt interaction. This fibre breakage affected the wettability significantly. [Display omitted] • Locally available biomass materials were tested as alternative packing for dehumidification. • Maximum values of MRR, DE, and MTC are found to be 0.70 g/s, 76% & 37 kg/m2-s, respectively. • Mathematical model deviation of 8.33% and 5.79% is observed wood shaving & coconut packing. • Performance for packing was raised till 3 weeks & then it deteriorated due to salt deposition. • Wood shaving packing with wettability 500 m2/m3 gave high performance compared to coconut packing. [ABSTRACT FROM AUTHOR]

There is a growing interest in desiccant coated heat exchanger (DCHE)-based systems due to characteristics of isothermal dehumidification and compact structure. To enhance the dehumidification efficiency and reduce the regeneration temperature of DCHE-based systems, a thermo-responsive composite desiccant coated heat exchanger (PSLCHE) was developed. This study focuses on investigating the influence of operating parameters (such as air temperature, relative humidity, regeneration temperature and adsorption/desorption time ratio) on the dynamic performance, average dehumidification capacity (D avg) and thermal coefficient of performance (COP th) of the system. Under the air condition of 30 °C & 60% RH, the PSLCHE demonstrates remarkable performance with the D avg of 7.3 g·kg−1 and COP th of 0.93 at 40 °C. This study provides a route to the design of highly efficient air conditioning systems using thermo-responsive composite for ultra-low grade thermal energy at 40 °C. • A thermo-responsive composite coated heat exchanger PSLCHE was developed. • The average dehumidification capacity (D avg) of PSLCHE can be up to 9.87 g kg−1. • The thermal coefficient of performance (COP th) of PSLCHE can be as high as 1.15. • PSLCHE can be regenerated at ultra-low temperatures (40 °C). [ABSTRACT FROM AUTHOR]

A CNF-based dehumidifying foam is prepared by a facile ambient drying method, which possesses advantageous water vapor sorption properties, excellent dehumidification performance, and good cyclic stability. The foam shows an open pore structure and porosity of 92.3%. Its water uptake reaches 0.71 g/g within 8h at 50% RH and remains stable after 10 cycles, indicating a great potential application for indoor air dehumidification. [Display omitted] • Moisture-absorbing cellulose nanofibril foam is prepared by facile ambient drying. • Synergistic effect of LiCl and CNFs network is critical for air dehumidification. • Porous foam acts as a reservoir for the storage of adsorbed water to avoid leakage. • CNF-based foam achieves high moisture sorption and excellent cyclic stability. Hygroscopic salt is often used as an important functional component of moisture-absorbing materials because of its excellent capability of capturing water from the air. However, hygroscopic salt cannot store large amounts of condensed water and has poor structural stability, as it dissolves easily in the condensate. The droplets leak from porous composites, resulting in hygroscopic salt consumption and poor water uptake. Herein, we aimed to develop a porous moisture-absorbing foam, which consists of a hydrophilic cellulose nanofibril (CNF)/4A molecular sieve network functionalized by hygroscopic lithium chloride (LiCl), using an ambient drying method. The hygroscopic LiCl considerably enhanced the moisture absorption of the porous foam, while strong hydrophilic CNFs captured the adjacent water molecules via hydrogen bonding and transported the condensed water to the inner part of the foam. The synergistic effect of LiCl and the CNF/4A molecular sieve network was critical for the air dehumidification performance, conferring the foam with excellent water uptake ability of 0.74 g/g within 8 h at 50 % relative humidity (RH). The liquefied water was confined completely in the porous foam during the moisture sorption process, thereby achieving good cyclic stability (10 cycles). Even when the volume was equivalent to 120 × of the volume of one foam, the RH was reduced by the foam from 55 to 58 % to 28–31 % (within 23 min) and then maintained stably up to 8 h. The foam possessed better dehumidification ability than desiccant wheel and silica gel, indicating that it may be used for air dehumidification and environmental humidity management. [ABSTRACT FROM AUTHOR]