Mass Flux Divergence Research Articles

Transient features of mass diffusion of MHD slip flow over an unsteady permeable stretching sheet in the presence of a moving free stream, destructive/constructive chemical reaction and variable mass flux

Transient features of mass diffusion of MHD slip flow over an unsteady permeable stretching sheet in the presence of a moving free stream, destructive/constructive chemical reaction and variable mass flux

GNSS reflectometry from low-cost sensors for continuous in situ contemporaneous glacier mass balance and flux divergence

Abstract Recent advances in remote sensing have produced global glacier surface elevation change data. Parsing these elevation change signals into contributions from the climate (i.e. climatic mass balance) and glacier dynamics (i.e. flux divergence) is critical to enhance our process-based understanding of glacier change. In this study, we evaluate three approaches for direct, continuous measurements of the climatic mass balance, flux divergence and elevation change at a site on Gulkana Glacier in Alaska using low-cost global navigation satellite system (GNSS) sensors, GNSS interferometric reflectometry (GNSS-IR), banded ablation stakes with time-lapse cameras and combinations thereof. Cumulative climatic mass balance over the season was 4.85 m and the three approaches were within 0.08 m through early July before the snowpack melted, and within 0.28 m through mid-August. The flux divergence increased from 0.52 ± 0.03 cm d−1 before June 3 to about 0.73 cm d−1 after June 27. We demonstrate a single GNSS system fixed atop an ablation stake can measure contemporaneous climatic mass balance, flux divergence and elevation change based on the antenna's position and GNSS-IR techniques. The ability of these systems to measure glacier mass balance and flux divergence offers unique opportunities for year-round observations on mountain glaciers in the future.

Investigating subcooled flow boiling heat transfer and fluid dynamics within a shell-and-plate heat exchanger

The study experimentally investigates subcooled flow boiling in a single channel of a shell-and-plate heat exchanger. Experiments on single-phase and boiling heat transfer were conducted under varying mass flux (61.442 to 199.326 kg/m2·s), preheating (20 to 42℃), and heating temperatures (30 to 60℃), using the refrigerant R365mfc. Key findings include that microscale boiling is the dominant heat transfer mechanism, with macroscale boiling occurring at high mass flux and preheating temperatures. The boiling heat transfer coefficient and friction pressure drop increase with mass flux, while optimal heat transfer occurs with an inlet subcooling of 4–6 °C. Flow patterns—bubbly, bubbly-slug, and churn flows—were identified, with bubbly flow offering superior heat transfer performance at the cost of higher pressure drop. The prediction model for friction pressure drop and heat transfer coefficient, using the Weber and boiling numbers, shows a prediction error within ±20 % of experimental data.

Experimental investigation of heat transfer coefficient and frictional pressure drop in flow boiling of R513A: Comparative analysis of micro-fin and smooth tubes

The heat transfer coefficient (HTC) and frictional pressure drop (FPD) of R513A in flow boiling conditions experimentally investigated in the present article. The study employed micro-fin tubes (MFT1 and MFT2) and smooth tubes (ST1 and ST2) as testing tubes under various operational parameters. The test sections featured standardized tube lengths (1000 mm) and outer diameter (9.52 mm) across all tubes, with variations in mass flux (50–300 kg·m−2·s−1), vapor quality (0.02–0.96), saturation temperature (12°C, 17°C, and 22 °C) and heat flux (6, 18, and 30 kW·m−2). Research focused on evaluating influence of micro-fin enhancement on flow boiling characteristics, specifically comparing HTC and FPD between micro-fin and smooth tubes. Results indicate significant improvement on HTC within micro-fin tubes compared to smooth tubes, accompanied by reasonable increase in FPD. Additionally, the study validated experimental data against established correlations and conducted sensitivity analysis to understand influence of key parameters on HTC and FPD. Overall, findings contribute valuable insights for optimizing heat exchanger design and thermal system efficiency in flow boiling applications.

Dynamic heat transfer characteristics of printed circuit precooler in supercritical CO2 Brayton cycle

The dynamic characteristics of heat exchangers are critical in supercritical CO2 Brayton cycle, especially in the precooler where significant thermophysical property variations occur. However, few studies have comprehensively analyzed the dynamic heat transfer characteristics in precooler, particularly with respect to the detailed flow and thermal field evolution. A three-dimensional numerical model was developed to study the dynamic performance of a printed circuit precooler, with an emphasis on the impact of thermophysical properties. The study examines responses to abrupt changes in CO2 and water inlet temperature, as well as mass flux variations. Results show that the precooler exhibits rapid response characteristics with mild fluctuations in heat transfer parameters and flow structure. Notably, the large specific heat near the critical point results in minimal variation in CO2 outlet temperature despite abrupt increases in CO2 inlet temperature, thereby enhancing system stability. Conversely, a decrease in CO2 mass flux causes a transition from forced convection to mixed flow, with strengthened buoyancy effects and decreased entropy production. These variations lead to significant changes in CO2 outlet temperature, posing potential challenges to system stability under CO2 mass flux step change conditions. The heat transfer shows a relatively lower response rate to parameter changes of water compared to CO2. Although variations in water parameters have a negligible effect on CO2 heat transfer, they influence the overall heat transfer coefficient. The dynamic heat transfer characteristics of the precooler presented in this paper address research gaps left by 1D numerical and experimental studies, which have provided limited information on flow and thermal fields during dynamic processes. These insights are essential for understanding the dynamic behavior of the entire system.

Effects of adding micro/nano-scale surface roughness on upward flow boiling of R-134a through annular tubes

The enhancement of heat transfer efficiency is crucial for development of high-performance thermal systems in various industrial applications. This study investigates heat transfer and pressure drop during upward saturated flow boiling of R-134a in annular tubes featuring smooth and micro/nano-scale roughened copper surfaces achieved through sandblasting and chemical etching. A high-pressure chamber with a glass side is designed to observe surface wettability and measure contact angles of R-134a on both surfaces. The annular tubes, with inner and outer diameters of 28.6 and 42 mm respectively, and a total heated length of 1000 mm, undergo varying mass flux, vapor quality, and saturation pressure within ranges of 6.73–20.19 kg m−2 s−1, 0.14–0.95, and 530–1000 kPa, alongside heat flux variations from 608 to 2432 W m−2. Results indicate that the application of micro/nano-scale roughness to copper surfaces minimally reduces the contact angle of R-134a which slightly improves its wettability. However, this modification significantly increases the heat transfer coefficient by 256 % compared to the smooth tube, albeit with an associated increase in pressure drop. Additionally, increasing mass flux and vapor quality increases both the heat transfer coefficient and pressure drop. Furthermore, higher heat flux results in a higher heat transfer coefficient with a small increase in pressure drop. Also, the experimental results are compared with some of the available correlations in the literature. The novelty and significance of this work advances our understanding of effect of surface roughness on flow boiling characteristics. Understanding these phenomena is crucial for optimizing the design and performance of heat exchangers and other thermal systems used in various industries, including refrigeration, air conditioning, and power generation.

Evaluation of innovative thermal performance augmentation techniques in heat sinks & heat pipes: Electronics & renewable energy applications

Heat sinks and heat pipes have vast applications including industrial domains requiring high heat flux. Due to numerous uses of these heat transfer devices, there have been great advancement in this area through innovation. This study focuses use of nanofluids and hybrid nanofluids for thermal performance enhancement of heat pipes and heat sinks. There are five different arrangements finless sintered copper wicked heat pipe, water based TiO2 filled heat pipe, TiO2 and SiO2 based hybrid nanofluid filled heat pipe, water cooled cylindrical pin finned heat sink and Fe2O3 and TiO2 hybrid nanofluid cooled heat sink. There are two test rigs one for testing heat pipe configurations and other for heat sinks. All the five elements are tested at constant heat flux ranging from 900 W/m2 to 3600 W/m2, in four equal steps. It’s observed that nanofluids play a very significant role in thermal performance augmentation, the affect is even more significant in heat pipes compared to heat sinks. Interestingly, nanofluids based heat pipes are proved more significant for high heat flux applications, although, nanofluid cooled heat sinks have slight better performance compared to the said but at a higher expense of weight, auxiliaries, space and cost. At 3600 W/m2 nanofluid based heat pipes have 33 % lower thermal resistance compared to water cooled heat sink. Therefore, nanofluid based heat pipes are primarily significant unless use of heat sink deemed dire. Nusselt number of heat sink is calculated at various heat flux and at variable mass flux conditions and found increasing with both parameter.

Heat transfer enhancement of different ribbing pitched semi-closed microstructure tube bundles fabricated by deformational cutting method

The study investigates the limitations posed by low-value heat transfer coefficients and higher wall superheat in conventional tube bundles, which adversely impact the performance of heat exchangers. To address this challenge, semi-closed microstructure tubes, created via deformational cutting at ribbing pitches of 300 µm and 400 µm, are proposed as a potential solution. The research centers on analyzing the two-phase boiling heat transfer performance of these microstructure tubes arranged in 2 × 3 staggered tube bundles. A comparative analysis is conducted, evaluating the thermal effectiveness of the microstructure tube bundles against a 2 × 3 smooth tube bundle and a copper-coated tube bundle under varying mass flux, heat flux, and pitch-to-diameter ratios. The experimental findings indicate the superior heat transfer performance of both microstructure tube bundles, with reduced wall superheat compared to other tube bundles. The findings further indicate that the 2 × 3 semi-closed microstructure tube bundle with a higher ribbing pitch outperforms the microstructure with a lower ribbing pitch. The 2 × 3 high-pitched microstructure tube bundle exhibits a maximum enhancement of 420 % over the 5 × 3 smooth tube bundle and 340 % over the 2 × 3 smooth tube bundle. Moreover, it surpasses the performance of copper-coated tube bundles by 230 % and outperforms its lower-pitch counterpart by 70 %. Particularly, the use of microstructure tube bundles allows for a reduction in the number of tubes required in the heat exchanger configuration without compromising its performance, promoting compactness and cost-effectiveness. Overall, the study highlights the feasibility of implementing these tubes in the two-phase heat exchanger owing to their superior performance compared to conventional tubes.

Numerical investigation of flow boiling characteristics of R134A in a smooth horizontal tube

Three-dimensional transient simulations using ANSYS Fluentʼs mixture multiphase model was conducted to investigate the impact of heat flux, mass flux, and saturation temperature variations on pressure drop behaviour and heat transfer characteristics during flow boiling of R134a refrigerant in smooth horizontal tubes of different diameters. The simulations employ an implicit numerical method to solve the governing equations, with relevant source terms for mass and energy transfer, incorporating the continuum surface force (CSF) and shear stress transport (SST) κ-ω models to account for surface tension and flow turbulence respectively. The results are presented in both dimensional (heat transfer coefficient and pressure drop) and non-dimensional (Nusselt number and two-phase frictional factor) forms. The Nusselt number shows a direct relationship with the Reynolds number, while the two-phase friction factor exhibits different behaviour. At higher vapor quality, mass flux significantly affects heat transfer performance and pressure drop. Heat flux plays a crucial role in heat transfer, but its impact on pressure drop is negligible. Higher saturation temperatures enhance heat transfer while reducing pressure gradients. The obtained results demonstrate good agreement with existing correlations, with mean absolute deviations (MAD) as low as 1.2 % for the heat transfer coefficient and 23.7 % for the pressure drop behaviour. This highlights the model's accuracy in predicting flow boiling behaviour of R134a in smooth horizontal channels, providing valuable insights for thermal analysis. The findings contribute to the understanding of flow boiling processes and aid in designing and optimizing efficient heat exchangers for various engineering applications.

Coupling haze and cloud microphysics in WASP-39b’s atmosphere based on JWST observations

ABSTRACT We present a study on the coupling of haze and clouds in the atmosphere of WASP-39b. We developed a cloud microphysics model simulating the formation of Na2S and MgSiO3 condensates over photochemical hazes in gas giant atmospheres. We apply this model to WASP-39b, recently observed with the JWST to study how these heterogeneous components may affect the transit spectrum. We simulate both morning and evening terminators independently and average their transit spectra. While MgSiO3 formation has negligible impact on the spectrum, Na2S condensates produce grey opacities in the water band, in agreement with Hubble Space Telescope (HST) and JWST observations. Moreover, the formation of Na2S on the morning side depletes the atmosphere of its sodium content, decreasing the strength of the Na line. Combining morning and evening profiles results in a good fit of the Na observations. These nominal results assume a small Na2S/haze contact angle (5.7°). Using a larger value (61°) reduces the cloud density and opacity, but the effect on the Na profile and spectral line remains identical. In addition, the presence of haze in the upper atmosphere reproduces the ultraviolet (UV)-visible slope observed in the HST and Very Large Telescope data and contributes to the opacity between the water bands at wavelengths below 2 μm. The averaged spectra are rather insensitive to the variation of eddy diffusion and haze mass flux tested in this study, though the UV-visible slope, probing the haze layer above the clouds, is affected. Finally, our disequilibrium chemistry model, including photochemistry, reproduces the SO2 and CO2 absorption features observed.

Prediction of heat and mass transfer inside 3D frost microstructure

In the present study, a CFD model based on 3D frost microstructure is developed. The desublimation phase change coupled with mass transfer of water vapor to ice surface and heat conduction through the tortuous ice crystals are calculated to predict accurate heat transfer process inside the frost microstructure. Air velocity and temperature inside the frost structure after 30 min operation are significantly lower than those inside 10 min operation, which are influenced by the structural change of the ice crystals. Vertical variations in ice crystal surface temperature and ice surface mass flux are also calculated, which varied between the frost structures operated for different periods. At 70 μm height of the frost, the mass flux at the ice crystal surface shows significant decrease from 7.48 × 10−5 kg/m2s for the frost structure at 10 min to 1.82 × 10−5 kg/m2s for that at 30 min. This study provides new and fundamental information to understand the mechanism of frost growth which is very important in refrigeration, cryogenics, and aerospace industry, etc.

Heat transfer characteristics of R134a flow boiling in a microfin tube under typical ORC pressures based on comparison with a smooth tube

The experimental investigation on the flow boiling heat transfer of an organic working fluid under typical organic Rankine cycle (ORC) operating conditions is insufficient, which directly affects the performance of the ORC system. In this paper, the flow boiling characteristics of R134a in a horizontal microfin tube were experimentally investigated in the reduced pressure range 0.6 ∼ 0.9. The general convection heat transfer characteristics of R134a flow boiling, along with the effects of heat flux, mass flux, pressure, and rewetting conditions, were investigated in a microfin tube and compared with that in a smooth tube. Results show that the main flow regime in the microfin tube under typical ORC operating pressures is the stratified flow with dry-out occurring at the top surface. The microfin effectively enhances the heat transfer and restrains the wall temperature separation through inducing strong helical flow due to buoyancy and centrifugal forces. With the heat flux increasing, the micro-fin strengthens the nucleate boiling by enhancing the vaporization cores, leading to more pronounced heat transfer enhancement compared with that in the smooth tube. The heat transfer on the bottom surface shows almost negligible sensitivity to variations in mass flux. However, in regions of high vapor quality, an increase in mass flux results in higher heat transfer coefficients on the top surface. Due to the interaction between intensified nucleate boiling and weakened gas convection when pressure is increased, it slightly affects the heat transfer coefficient. Unlike the smooth tube, the rewetting in the microfin tube can be maintained within a larger range of vapor quality due to the spiral flow caused by the micro-fin.

Two-phase flow condensation heat transfer characteristics of R-134a inside three-dimensional cylindrical micropillar enhanced tube

This paper presents an experimental investigation for evaluation of heat transfer coefficient, frictional pressure drops and flow regimes with their transitions during the condensation of R-134a inside a smooth, two microfins (MF1 and MF2) and a newly developed micropillar (MP) tubes. The experiments are carried out for a range of mass flux at an average saturation temperature of 35°C. Micropillar tube has produced the maximum heat transfer coefficient, while the microfin (MF1) tube resulted the highest frictional pressure gradient compared to other tubes. The experimental observations of microfin and micropillar tubes are plotted on the mass flux versus vapor quality flow map and Taitel and Duckler flow map to discuss the transitions within different flow patterns achieved. Visual inspection of the flow regimes with varying mass flux and vapor quality showed stratified-wavy, intermittent, and annular flow regimes. The occurrence of annular flow is found to be more in MF1 and MP tube. A performance evaluation factor (PEF) is defined to evaluate the thermal-hydraulic performance of the tubes. Using the same, it has been observed that the newly developed MP tube has a PEF value greater than unity which suggest augmentation of heat transfer coefficient at the expense of lesser pressure drop penalty.

Experimental investigation on condensation heat transfer coefficient and frictional pressure drop of low GWP refrigerant R1234yf on a wavy fin surface

Refrigerant R1234yf is an ideal substitute to replace R134a due to its lower value of global warming potential (GWP). The thermophysical properties of R1234yf are similar with R134a and thus it is considered as a potential replacement for R134a in thermal fluid systems. Further, it was noticed that there is a lack of analysis on the condensation of R1234yf in a brazed plate fin compact heat exchanger (CHE) employing wavy fins. In the present work, condensation heat transfer coefficient and frictional pressure drop of refrigerant R1234yf are investigated in a brazed plate fin compact heat exchanger with wavy fin surfaces. The test condenser with wavy fin surface was selected to examine the condensation heat transfer coefficient and frictional pressure drop using refrigerants R134a and R1234yf for varying mass flux and saturation temperatures. The present study also discusses the dependency of specific kinetic energy of refrigerant on frictional pressure drop. Further, using the experimental data of wavy fin surfaces, suitable correlations for the condensation heat transfer coefficient and frictional pressure drop of R1234yf were proposed. The present paper also reports the comparison made between refrigerants R134a and R1234yf. Comparison between R1234yf and R134a shows that condensation heat transfer coefficient and frictional pressure drop of R1234yf is 9–16 % and 10–17 %, respectively, lower than of R134a in the mass flux range 15–44 kg/m2s.

Heat transfer in a fluidized bed tubular solar receiver. On-sun experimental investigation

Using particles as heat transfer fluid in a solar receiver is an attractive way to increase the global efficiency of solar power plants. In the case of the particle-in-tube solar receiver concept, the fluidized particles circulate vertically in tubes thanks to a controlled pressure gradient and an additional air injection. Experiments are conducted with olivine particles in a one-tube mock-up at the 1 MW CNRS solar furnace (France). The tube of high aspect ratio (more than 3 m height over 48 mm internal diameter) is irradiated along a 1-m height with several solar flux configurations that correspond to realistic operation conditions of a solar thermal power plant. The novelties of this paper lie in extending the operating parameters compared to earlier studies and in linking the fluidization regimes to wall heat transfer. Slugging, turbulent fluidization and fast fluidization regimes are detected within the receiver tube. It is shown that the system can tolerate high solar flux densities, up to 800 kW/m2. The system proves to be highly controllable and flexible with respect to particle mass flux variation and transient operations. Particle temperature increase ranges from 100 to 650 °C depending on the particle mass flux. Maximum thermal efficiency and particle outlet temperature of respectively ∼ 60 % and 680 °C are obtained, proving that this technology can be combined with highly efficient thermodynamic cycles. Global wall-to-particle heat transfer coefficient varies strongly with particle mass flux. It reaches a quasi-plateau above 15 kg/(m2s) with a mean value of 1000 ± 200 W/(m2K) and peaks data up to 1500 W/(m2K). A dimensionless heat transfer index is derived to account for the effects of the particle mass flux on the experimental results. It highlights that both increasing the temperature and working in the turbulent fluidization regime result in the increase of the heat transfer between the tube walls and the particles.

Reynolds-Number Effects on the Acoustic Disturbance Environment in a Mach 6 Nozzle

To understand the impact of the Reynolds number on the disturbance field inside a high-speed wind tunnel, we use direct numerical simulations to model turbulent boundary layers along the walls of a quasi-two-dimensional nozzle configuration. These simulations are performed at four different unit Reynolds numbers, ranging from to . The predominantly hydrodynamic fluctuations inside the boundary layer are nearly unaffected by the freestream forcing of the impinging acoustic radiation from the opposite wall. Within the nozzle-core region, the disturbance environment is found to be spatially uniform and solely acoustic in character. Comparisons with tunnel noise measurements are made using the numerical data. For the first time, comparisons of fluctuations in the same physical quantity (the streamwise mass flux) have been published, as opposed to earlier comparisons involving static-pressure fluctuations based on the simulations and pitot-pressure fluctuations recorded in the wind tunnel. The NASA 20 in. Mach 6 wind tunnel observations corroborate the predicted trend of decreased root-mean-square variations in pressure and mass flux as the Reynolds number rises. Additional details of the acoustic radiation field are quantified and should be useful toward a digital synthesis of the tunnel disturbance environment that would enable realistic simulations of the natural transition process.

Three-dimensional flow simulation and cavitation erosion modeling for the assessment of incubation time and erosion rate

A compressible three-dimensional in-house flow solver is employed for the assessment of cavitation erosion. The flow solution method provides the wall load, which is coupled to a one-dimensional ductile material model and which yields the incubation time and erosion rate. Due to the assumption of a homogeneous mixture in the flow solver, details of collapsing wall adjacent single bubbles cannot be resolved, so that two different wall load models are presented. In the first method, a collapse detection algorithm based on the mass flux divergence is applied, load collectives are statistically evaluated by the multitude of detected collapses, and a spectrum of distinct loads is passed on to the material model. Since the physical simulation time is much shorter than the real exposure time, a method for the time extrapolation of the wall load to capture realistic time scales is presented. In the second method, a sub grid scale micro jet model is applied, and the wall load is approximated by mean values, so that a time extrapolation is dispensable. Both methods require calibration to e.g. experimentally measured incubation time. An application to the widely used Grenoble axisymmetric impinging jet test case reveals, that the first method fails to capture the location of maximum wear. Due to the inclusion of an erosion probability for the detection of prospectively erosive collapse events in the second method, a good match with data is obtained. Beyond a validation for a broad range of erosive flow conditions, the use of alternative material models including high cycle fatigue as important wear mechanism is planned in future studies.

The flow of non‐Newtonian fluid in an inclined channel through variable permeability

AbstractA non‐Newtonian fluid's Poiseuille flow in a porous medium with variable inclination and permeability is investigated. Let us assume for the sake of simplification that permeability varies as a quadratic parabolic function form. The porous medium is used by the Brinkman methodology to control the flow. The equations for velocity distribution and mass flow that result from this are evaluated using different input values. This problem describes the effect of inclination, Jeffrey parameter, and variable permeability on the classical Poiseuille flow between parallel plates. This problem can also be treated as an extension of the work of Hamdan and Kamel for non‐Newtonian fluid flow in an inclined channel. Also, the effects of these variables on the variation of mass flux with Jeffrey parameter λ1 is analyzed through graphs, and the skin friction coefficient is analyzed through table values. It is observed that the maximum permeability of the porous medium affects both the mass flow rate and the velocity, which increase with rising λ1 and decrease with rising Ha, respectively.

CFD simulation of circumferential crack in low pressure water pipelines

Detection of the pipeline leakage and its repair at an early stage is very crucial as leaks can cause significant destruction to the surrounding infrastructures. This paper demonstrates the change in flow characteristics of a low-pressure water pipeline with the existence of a narrow circumferential crack of three different sizes. The steady state simulations have shown clear indications in the velocity and mass flux variations along the pipe and at the crack surface. These results show that the crack causes measurable differences in fluid flow properties at different inlet pressure. Predicted results were analysed to assess the effect of leakage on the pressure field and maximum mass flux. The study intends to contribute in the development of pipe crack leakage detection in various industrial and commercial purposes.

Numerical study on the heat and mass transfer in charging and discharging processes of a triangular honeycomb thermochemical energy storage reactor

• A triangular honeycomb reactor has been designed and experimentally investigated. • A 3-D numerical model of this reactor has been developed and validated. • Relationships between heat transfer and mass diffusion are determined. • The thermal efficiency of triangular honeycomb reactor can achieve around 20% Adsorption heat storage based on porous adsorbents attracts considerable attention for the high energy storage density and long storage duration compared to sensible and latent heat storage methods. However, one of the critical challenges is the poor heat and mass transfer performance of thermochemical reactors. This study presents a triangular honeycomb reactor using zeolite 13X-H 2 O working pair and investigates the heat and mass transfer performance. To do this, a three-dimensional transient heat and mass transfer model has been built in COMSOL to simulate the adsorption and desorption processes of the new reactor. A detailed numerical model and the corresponding modelling methods are critical to the investigation while most of the recent studies are based on one-dimensional and two-dimensional models. The model has been experimentally validated thoroughly to a close agreement in both adsorption and desorption processes (mean sum of percent errors of 0.6% to 8.91% for air temperature and relative humidity). The reactor thermal efficiency from the simulation and experiment are 19.57% and 21.93%, respectively, which are achieved by the fast and controllable charging and discharging performance along with the reduced air pressure drop benefited from the reactor design. To add value of the charging and discharging details, this study also presents the contour diagrams with detail discussions for the air velocity, temperature, water concentration, and heat and mass flux variations of the triangular honeycomb channel during desorption and adsorption processes. The results show that the side of triangle channel has larger and stronger moisture desorption in a charging process and stronger moisture adsorption in a discharging process than that of the triangle corner areas.