Pall Rings Research Articles

Evaluation of the performance of new plastic packing materials from plastic waste in biotrickling filters for odour removal

The gas emissions from wastewater treatment plants (WWTPs) contain multiple chemical compounds, such as H2S, NH3 and volatile organic compounds (VOCs), which can cause odour nuisance and health hazards. Biological technologies, such as biotrickling filters (BTFs), are preferred due to their cost-effectiveness and eco-friendliness. The selection of the packing materials in these bioreactors is crucial due to their high purchase cost, frequent replacement and impact on the gas-liquid mass transfer. This research aims at evaluating the NH3, H2S and VOC abatement performance of novel packing materials from plastic byproducts from the water cycle at different gas residence times (EBRT). The experimental set-up consisted of three BTFs of 2 L of working volume constructed with three different packing materials: commercial Pall rings (control), recycled plastic (from bottle caps), and extruded recycled plastic materials in the form of an optimised 3D-printed carrier. The three BTFs supported a complete removal of H2S and NH3 at EBRTs of 30, 15, 10 and 6 s, and VOCs removal above 90 % at EBRTs of 30 and 15 s. The extruded recycled plastic materials in the form of optimised 3D-printed carrier supported toluene and α-pinene removals of 100 % at EBRTs of 30 and 15 s. The genus Thiobacillus was identified in the three BTFs. This research confirmed the potential of reused and recycled plastics from the integral water cycle as a packing material in BTFs devoted to odour treatment.

Wastewater treatment using black soldier fly larvae: Influence of larval density and solid support

The use of Black Soldier Fly larvae for wastewater treatment has emerged as a promising alternative, coupling high removal efficiency with recovery of high-value products. To overcome the critical issue of larvae mortality in a liquid environment, a patented solution employs a physical porous support to be saturated by liquid, allowing larvae mobility. In view of process optimisation, a knowledge gap persists regarding both the optimal supporting material and larval density. The optimum supporting material and larval density should maximise the porosity (i.e. active volume of the reactor) and the removal efficiencies respectively, without compromising the survival rate. In the present study, three different plastic products (granules, pall rings and geomat) were tested at four different larval densities (4, 8, 16 and 32 larvae/cm2). Process performance was compared in terms of larval growth and substrate removal. An increase in larval density only impairs process once threshold density is exceeded. The threshold depended on the supporting material: higher porosity materials allow the use of higher larval densities, and therefore higher organic loads, with reduced reactor volumes.The best performance was achieved at larval density of 16 larvae/cm2 with pall rings, resulting in a survival rate and carbon removal efficiency of approx. 92 % and 97 % respectively.

Development and Performance Evaluation Experiment of a Device for Simultaneous Reduction of SOx and PM

Mitigating air pollutants such as SOx and PM emitted from ships is an important task for marine environmental protection and improving air quality. To address this, exhaust gas after-treatment devices have been introduced, but treating pollutants like SOx and PM individually poses challenges due to spatial constraints on ships. Consequently, a Total Gas Cleaning System (TGCS) capable of simultaneously reducing sulfur oxides and particulate matter has been developed. The TGCS combines a cyclone dust collector and a wet scrubber system. The cyclone dust collector is designed to maintain a certain distance from the bottom of the wet scrubber, allowing exhaust gases entering from the bottom to rise as sulfur oxides are adsorbed. Additionally, the exhaust gases descending through the space between the cyclone dust collector and the wet scrubber collide with the scrubbing solution before entering the bottom of the wet scrubber, facilitating the absorption of SOx. In this study, the efficiency of the developed TGCS was evaluated, and the reduction effects based on design parameters were investigated. Furthermore, the impact of this device on ship engines was analyzed to assess its practical applicability. Experimental results showed that increasing the volume flow rate of the cleaning solution enhanced the PM reduction effect. Particularly, when the height of the Pall ring was 1000 mm and the volume flow rate was 35 L/min, the sulfur oxide reduction effect met the standards for Sulfur Emission Control Areas (SECA). Based on these findings, suggestions for effectively controlling atmospheric pollutants from ships were made, with the expectation of contributing to the development of systems combining various after-treatment devices.

Assessing the efficiency and microbial diversity of H2S-removing biotrickling filters at various pH conditions

This study aimed to investigate the operation of three parallel biotrickling filters (BTFs) in removing H2S at different pH conditions (haloalkaliphilic, neutrophilic, and acidophilic) and their associated microbial population in the biodesulfurization process. BTF columns were inoculated with enriched inoculum and experiments were performed by gradually reducing Empty Bed Retention Time (EBRT) and increasing inlet concentration in which the maximum removal efficiency and maximum elimination capacity in EBRT 60 s reached their maximum level in haloalkaline condition (91% and 179.5 g S-H2S m−3 h−1). For visualizing the attached microbial biofilms on pall rings, Scanning Electron Microscopy (SEM) was used and microbial community structure analysis by NGS showed that the most abundant phyla in haBTF, nBTF, and aBTF belong to Gammaproteobacteria, Betaproteobacteria, and Acidithiobacillia, respectively. Shannon and Simpson indexes evaluation showed a lower diversity of bacteria in the aBTF reactor than that of nBTF and haBTF and beta analysis indicated a different composition of bacteria in haBTF compared to the other two filters. These results indicated that the proper performance of BTF under haloalkaliphilic conditions is the most effective way for H2S removal from air pollutants of different industries.Graphical

Experimental investigation and modeling of the impact of random packings on mass transfer in fluidized beds

This study investigates the impact of two novel settings of bubbling fluidized beds equipped with random metal packings on the mass transfer. To do this, a comprehensive approach is applied that integrates experiments and modeling and explores the relevance of the different underlying mechanisms involved in interphase mass transfer in fluidized beds. Firstly, the mass transfer of water from moisturized silica gel particles to dry air is studied in both a packed-fluidized bed and a freely bubbling bed with no packing. The experimental set-up consists of a cylindrical bubbling fluidized-bed column with an inner diameter of 22 cm. Silica-gel particles with a mean particle diameter of 797 μm are used as bed material. The total bed amount ranges from 4 to 8 kg, while the fluidization number (F) varies between 1.7 and 2.3. Two types of packing, RMSR (stainless steel thread saddle rings) and Hiflow (stainless steel pall rings) are examined and compared to the reference case of a bubbling bed with no packing. The height of the packed section is maintained at 60 cm. The results show that, at all operating conditions, the use of packings enhances the amount of desorbed water in the fluidized bed. The increase is up to 17%, as compared to the bed without packing. The effect is believed to be inhibition of bubble growth in the packed-fluidized bed. To study this further, a mass-transfer model is introduced to analyze the different mass-transfer steps (intra-particle, particle surface to emulsion gas, and emulsion gas to bubble gas) in packed-fluidized beds compared to beds with no packing. TGA experiments are applied to describe the intra-particle mass transfer through a desorption kinetic model. Model analysis shows that the main resistance for mass transfer occurs across the bubble-emulsion boundary. The calculated value of the mass transfer coefficient for this, Kb, at reference conditions (6 kg of silica gel and F = 2.3) is 7.6e-5 s−1 with packings (in average) and 6.2e-5 s−1 without packings, i.e. a 23% improvement in the governing mass-transfer coefficient.

Hydrodynamic Insights on Floating Bubbling Fluidized Beds: Dynamic Solutions for Mitigating Gas Maldistribution

This study examined bubbling fluidized beds as an alternative to fixed-bed dry scrubbers on ships for reducing pollutants from marine fuels. It focused on overcoming the challenges of gas maldistribution/slug formation, especially under rough sea conditions. This research departed from traditional methods by introducing mobile internal elements into the bed emulsion phase and investigating their effectiveness in various settings, such as vertical, inclined, and rolling beds. A specialized hexapod-driven bubbling fluidized bed was developed to mimic marine operating conditions and to study the behavior of shipboard fluidized beds. Techniques such as digital image analysis (DIA) and particle image velocimetry (PIV) were used to observe bubble dynamics and granular phases, measuring local void fractions and particle velocities. A key finding is the effectiveness of moving internals in preventing bubble coalescence, which is critical for avoiding wall slugs, at different inclinations. Three types of packing were used as mobile internals: Super Raschig, Pall, and square rings. Super Raschig rings, which are characterized by high porosity, were the most efficient in reducing bubble coalescence, making them a preferred choice for offshore fluidized bed applications. This research contributes to the advancement of fluidized bed technology in marine applications and provides insight for future improvements.

Advances in design, scale and operability of the Rotating Liquid Sheet (RLS) contactor: Pressure drop, flood-point and mass transfer – Comparison to random packing

The Rotating Liquid Sheet (RLS) contactor is a novel packing-less gas-liquid contactor where multiple continuous liquid sheets form at the outlet of helical slots in a rotating central feed tube. Each liquid sheet is auger-shaped, and the rotation of the feed tube transfers momentum from the sheets to the gas. Multiple sheets travel in parallel to arrive unbroken at the column wall. The gas travels through the space between adjacent sheets providing close contact between the gas and liquid. Careful design ensures that liquid sheets travel in parallel arcs, enabling scale-up from 150–600 mm diameter column, a size suitable for the speciality chemical or pharmaceutical industries. Pressure drop and flooding measurements using an air/water system compared the RLS contactor with 25 mm Pall Rings. Results for the Pall Rings matched expected performance, while RLS contactor pressure drop was 10% of that measured for the Pall Rings. Mass transfer experiments using an air+CO2/NaOH solution system showed measured mass transfer coefficients using the RLS contactor were comparable to a packed bed (25 mm Pall Rings) of similar specific surface area, while foaming in the packed bed did not occur in the RLS contactor using the same liquid sample. The RLS contactor also displayed minimal entrainment.

Recovery of acetoin from Bacillus subtilis fermentation broth by supercritical CO2 extraction

AbstractComponent enrichment from fermentation broths by solvent extraction using supercritical carbon dioxide (sCO2) has been demonstrated in the literature. This work investigates for the first time the feasibility of the enrichment of an acetoin fraction from a real fermentation broth at a pilot plant scale using sCO2. A 4-m-tall, 28-mm-diameter, counter-current column packed with pall rings was used. The ranges of process pressure and temperature investigated were 100 to 300 bar, and 37 to 80 °C respectively. The optimum recovery of acetoin was 77.8%, with little difference between the simulated and actual broths. A modest two-fold concentration of acetoin was obtained in the extract. The results show that where a modest enrichment of the targeted product makes a significant difference in subsequent separation processes, and where the purity of the product, particularly from harmful solvents, is important, sCO2 fluid separation is a credible option for the enrichment of such products of fermentation.

Investigations on a solar humidification dehumidification desalination system equipped with various packing materials and multi-stage bubble column dehumidifier.

This work presents the theoretical and experimental investigation of a solar-powered humidification dehumidification desalination (HDD) system with different humidifier packing materials and a two-stage bubble column dehumidifier (BCD). Naturally available coconut shells (CS) and coconut shells with drilled holes (CSH) on the surface to improve water permeability were used as packing materials in the humidifier, and their performance was compared with that of commercial-type pall ring (PR) and raschig ring (RR) packings. An in-house developed numerical model of the HDD system in conjunction with a flat plate solar water collector was used in this study. Steady-state experimental results showed that CSH packing exhibited the highest volumetric mass transfer coefficient (0.00852kg/s), resulting in maximum humidifier efficiency (96%) and freshwater yield (2.16kg/hr), followed by PR (0.00841kg/s, 94%, and 2.137kg/hr), CS (0.00831kg/s, 90%, and 2.127kg/hr), and RR (0.0081kg/s, 81%, and 2.087kg/hr) at feedwater mass flow rate of 1.5kg/min and humidifier inlet temperature of 75 [Formula: see text]. Furthermore, transient outdoor test results showed that using a two-stage configuration in a BCD increased the daily average effectiveness to 0.93, as against 0.79 for a single-stage BCD. Employing CSH instead of PR and RR packings in the humidifier reduced freshwater costs by 6.2% and 7.6%, respectively.

Greywater treatment performance of a pilot-scale membrane bioreactor and characteristics of bacterial biofilm signatures in permeate effluent

Treated greywater has a high potential for water reuse. However, the post-treatment processes of reclaimed greywater may face biofouling problems due to biofilm formation. In the present study, the greywater treatment performance of a pilot-scale membrane bioreactor (MBR) was evaluated, and the effect of a dominant bacterial biofilm growing on the Pall ring media placed in the permeate pipeline was investigated. The MBR was operated for 125 days with a constant hydraulic retention time of 2 days under complete sludge retention. The treatment performance in terms of the levels of organic compounds, ammonium nitrogen, suspended solids, total coliforms, and Escherichia coli was >90 %. During the operation, a high relative abundance (>70 %) of the following bacterial phyla was observed within the MBR and the bacterial biofilm: Proteobacteria, Chloroflexi, Actinobacteria, and Planctomycetes. Furthermore, the following bacterial orders were predominantly observed in the biofilm: Sphingomonadales, Burkholderiales, and Planctomycetes. Acidovorax, Methylibium, Blastomonas, and Planctomyces were the important genera identified in the biofilm. Interestingly, the present study revealed that these bacterial species were predominant and well adapted in treated greywater containing various surfactant and detergent components. Knowledge of the predominant bacterial species in the biofilm could enable to select the appropriate disinfection method and prevent the biofouling of the reverse osmosis (RO) membrane, which can facilitate further application of the MBR-RO process for water reuse.

Study of axial dispersion on several modern structured and random packings

The study investigates the phenomenon of axial dispersion in a packed absorption column, which is known to reduce the efficiency of separation equipment by reducing the mass transfer driving force. The aim of the study is to determine the Bodenstein number, which represents axial dispersion, for five types of modern packings used in the column. The packings used in the study were random packings (NeXRing0.7 and NeXRing1.2) and structured packings (MellaPak350Y, 452Y, and 500Y). The data obtained from dynamic experiments in the form of a response to a step change in tracer substance concentration were compared to a diffusion-type differential equation, which was solved with boundary conditions for a closed system. By measuring the responses at two different packed bed heights and using convolution, the influence of the end effects was eliminated. The lowest axial dispersion was obtained for M452Y, and it is almost twice as low as for M250Y. It was found that the values of the Bodenstein number for standard series of Mellapak type packing (M250Y, M350Y and M500Y) have comparable axial dispersion, especially at low liquid rates. The axial dispersion obtained for random packings is generally higher compared to structured packings. However, compared to other random packings such as Pall rings (25 mm) and Intalox saddles (25 mm), NXR0.7 and NXR1.2 exhibit up to a two-fold reduction in axial dispersion.

스크러버 내 충진층에서의 압력강하 특성에 관한 실험적 연구

According to the regulation on the pollution of the marine environment, SOx emission from ships has to be reduced. A SOx scrubbing system installed in a funnel of a ship is considered in order to reduce SOx emission. A scrubbing layer with a porous material is present in the funnel to increase the contact area between exhaust gas and water. In this study, experiments on the pressure drop characteristics in the scrubbing layer are conducted to investigate the effect of the scrubber on the engine load. The pressure drop according to flow rate of air instead of exhaust gas was measured for fillers such as sphere, pall ring and saddle in the scrubbing layer. First of all, porosity is experimentally measured for the three types of filler and it is confirmed that the porosity of the saddle-type filler was the largest. The pressure drop according to the change in air flow rate was measured for the three types of fillers in the scrubbing layer. As a result, the pressure drop was the smallest in the scrubbing layer with the saddle-type filler which has the largest porosity. In addition, the effect of spraying water flowing counter flow against air flow is experimentally examined. It is known that the pressure drop is increased because the air flow space is reduced when water is sprayed. In the case of the saddle, the pressure drop is about 1.5 to 2 times greater than that when only air flows at the optimum exhaust gas-water injection ratio.

Optimasi Laju Alir Tri-Ethylene Glycol terhadap Efisiensi Penyerapan Air pada Kolom Absorbsi Di PT. Pertamina Hulu Energi

Absorption was a separation process between gas fluids using liquid fluid media. The glycol contactor aims to separate the water content contained in the gas using tri-ethylene glycol media with process conditions at a pressure of 795-810 psi and a temperature of 85-110 o F . The contact process between fluids is assisted by the I ntalox S addle type packing which aims to maximize the contact process between fluids and it is hoped that the absorption process that occurs can be maximized. Tri-ethylene glycol which has absorbed the water content in the gas is regenerated in the glycol burner. This analysis used 4 packing variables (Raschig Rings, Pall Rings Plastic, Berl Saddles Ceramic, and Intalox Saddles Ceramic), 5 flow rate variables (1600, 1800, 2000, 2200, and 2400 BPD) and this analysis use the Hysys simulation program. Based on these variables, the absorption efficiency analysis results are obtained in the range of 93-94%, and the flooding percentage is 21-36%. It can be concluded that the type of packing is very influential on the percentage of flooding. Pall Ring Plastic was the type of packing with the lowest flooding percentage. According to research, lower flow rates increase the efficiency of H 2 O absorption.

Optimization of dry anaerobic co-fermentation of sludge and corn straw with magnetite (Fe3O4)

In this study, an Optimized addition amount of magnetite (Fe3O4) and the combination of Pall ring with Fe3O4 were investigated to scrutinize the concentration of short-chain fatty acids during the dry anaerobic co-fermentation of corn straw and waste sludge for the first time. Experimental results revealed that the production of SCFAs was significantly promoted in the presence of 0.16 g/g TS magnetite. Under these conditions, the maximum SCFA concentration was 283.4 ± 11.1 mg COD·L-1, which was 1.35 times that without magnetite (Fe3O4) (210.1 ± 4.8 mg COD·L-1) and 1.23 times that with 0.08 g/g TS (229.6 ± 24.5 mg COD·L-1). Meanwhile, 0.16 g/g TS Fe3O4 could significantly enhance the release of soluble organic matter, and NH4+-N removal efficiency was considerably accelerated. Consequently, the removal rate of TS and VS were significantly enhanced to 1.01 ± 0.10 g·d-1 and 0.84 ± 0.04 g·d-1 with the addition of 0.16 g/g TS Fe3O4, which were 1.53-folds and 1.31-folds than that of the control. Microbial community analysis revealed that 0.16 g/g TS Fe3O4 improved microbial activity, microbial community richness and the relative abundance of hydrolyzed acid-producing microbes such as Firmicutes, Synergistota, Bacteroidetes and Chloroflexi. The relative abundance of Proteobacteria (SCFA consumer) was highly enriched and reached 41.39% in the control group. The combination of Pall ring with 0.16 g/g TS Fe3O4 had no obvious synergistic effect on promoting acid production, but exhibited high microbial activity and lower concentration of NH4+-N. Collectively, this work will provide suggestions to boost SCFA yield from corn straw and waste sludge via anaerobic co-digestion.

Research and development of advanced structured packing in a rotating packed bed

As the core component of the rotating packing bed, packing is a place for efficient gas–liquid mixing and mass transfer. In this paper, a 3D structured packing composed of a mesh structure and a support structure was designed. The mesh structure is a ring-shaped mesh surrounded by triangular meshes, which is stable in structure and can achieve a high degree of dispersion and aggregation of the liquid phase. The support structure is composed of ring-shaped structural units arranged at a certain angle along the axial direction, which can enhance the turbulence of the airflow while constructing regular gas-phase channels. Circumferential steel meshes of different diameters and supporting structures are alternately combined to form 3D packing, which is loaded in a layered cross-flow rotating packing bed. The results show that under the same operating conditions, the mass transfer performance of 3D packing and wire mesh packing are equivalent, and both are better than pall ring packing. Moreover, the pressure drop of 3D packing is significantly lower than that of pall ring packing and wire mesh packing. The design and implementation of packing the development presented in this paper can be used to develop special structured packing for rotating bed, which can further improve the performance of rotating packed bed (RPB).

Prediction of separation efficiency of structured and stacked packings under low and normal pressure

This work presents a model for the prediction of the separation efficiency of packed columns filled with structured metal sheet packings and stacked packings of different materials and types for distillation and absorption processes. For model validation, packings of sheet metal, ceramic and plastic of various shapes and sizes such as Mellapak, Montz-Pack, Gempak, Ralu-Pak, metal and ceramic Impulse packing IP50 and IP100 and various other types of regularly arranged packings such as 50 mm ceramic Pall rings, 25 and 50 mm metallic Białecki rings, 50 mm PSL rings made of metal and 50 mm plastic Hiflow were investigated using absorption and distillation test systems under low pressure and atmospheric conditions in columns with diameters ranging between 0.15 and 0.60 m. The model was validated in the operating range below the flooding line for FV 0.90 FV,Fl and for turbulent liquid flow ReL ≥ 2. The comparison of the predicted values with measured data presented in this work has confirmed that the presented model is suitable for determining the separation efficiency not only for sheet metal structured packing, but also for regularly arranged stacked packings filled with packing commonly used as random packing for absorption and distillation systems under vacuum and normal pressure. The calculation example shows also the application of the presented model for predicting the separation efficiency nt/H of sheet metal packings and stacked packings with a specific packing area a from 60 up to 500 (750) m²/m³ for distillation processes under low and normal pressure.

Development of a new technological scheme for water purification from iron

Drinking water is the most valuable resource for human life and for the existence of all life on Earth. Scientists predict that about half of the world's population will experience water shortages by 2030. Purification of fresh water from contamination to the required quality standards is one of the most demanded engineering tasks. Taking into account the prevailing hydrogeological conditions, the removal of dissolved iron from the water of underground horizons is more in demand. Iron removal technology includes the use of oxidizing agents: oxygen, chlorine, potassium permanganate and ozone. It is ozone, due to its high oxidizing potential - 2.07 V, that has become worldwide in industrial water treatment systems, where it is generated using a corona discharge. But in water purification systems of low productivity, up to 1000 l / h, ozone is practically not used, due to the high cost of such generators. The Sterlight S8Q-OZ lamp was proposed as an alternative for ozone generation. According to the manufacturer's data, the lamp can produce ozone in a concentration of 1.59 to 2.82 mg / l when an air flow of 141.5 to 28.3 liters per hour passes through it. A new technological scheme was developed for deferrization of water in a stream using ozone generated by an ultraviolet lamp or a block of lamps. The installation contains an injector, an improved mixing chamber with a bottom inlet of the ozone-air mixture with Pall rings, a sand-gravel filter, an ultraviolet sterilizer lamp. The design feature was that small doses of ozone produced from the air under the influence of ultraviolet radiation with a length of 185 nm oxidized the iron dissolved in water. As a result of the tests carried out, the iron content in the source water was reduced from 2.58 mg / l to 0.02 mg / l, which is 10.0 times lower than the maximum permissible values of the EU sanitary requirements and 15.0 times lower than the maximum permissible values of sanitary requirements of the Russian Federation and the USA. It has also been noted that iron oxidation is significantly improved in the presence of 10% STIROX catalyst based on total backfill.

Chemical Looping Combustion in a Packed Fluidized Bed Reactor─Fundamental Modeling and Batch Experiments with Random Metal Packings

The conversion of gaseous fuels during chemical looping combustion (CLC) was investigated in a packed fluidized reactor. The experimental setup consisted of a cylindrical laboratory-scale bubbling fluidized bed reactor with an inner diameter of 78 mm and a height of 1.27 m. Two types of fuel, syngas (50:50% H2/CO) and carbon monoxide (100% CO), were used. Two different types of packings were assessed and compared to the reference case, which was a bubbling bed with no packings. The investigated packings were 25 mm stainless-steel thread saddle rings (RMSR) with a bulk density of 195 kg/m3 and 25 mm stainless-steel pall rings (Hiflow) with a bulk density of 271 kg/m3. The height of the packed reactor section was kept constant at 1 m. Ilmenite concentrate particles in the size range of 90–212 μm was used as an oxygen carrier. The unfluidized bed height was varied between 10 and 60 cm. The results show that the fuel conversion increases as the bed height increases and that the use of packings have a positive effect on fuel conversion. For RMSR packings, the syngas conversion at 840 °C improves from 0.84 (for 10 cm bed height) to 1.00 (for 60 cm bed height). This should be compared to the bed with no packings, for which the corresponding improvement was from 0.69 to 0.98. The general pattern is consistent for all fuels, packings, and bed heights. The results are interpreted as an improvement in gas–solid mass transfer when packings are used, mainly as a result of the reduced bubble size. A fundamental analysis of the variance in the pressure drop over the bed to estimate the bubble diameter supports this interpretation. It is also shown that the mass-based first-order effective reaction contact factor kf improves up to 109% in the bed with RMSR packings compared to the bed without packings.

Performance evaluation and optimization of humidification–dehumidification desalination system for low-grade waste heat energy applications

A humidification–dehumidification desalination system powered by low-grade waste heat energy (45 °C–70 °C) was experimentally investigated. The seawater directly utilized as coolant (25 °C) for the dehumidifier was preheated by latent heat recovery from the water vapor produced by the humidifier. The effect of key performance-contributing factors such as the mass flow rate and temperature of the air and feed at the inlets of the humidifier and dehumidifier were evaluated and optimized. For a constant volume, the effect of the humidifier's surface area was evaluated comparatively considering different novel packing materials such as tri-pack rings, pall rings (diameter = 16 mm and 25 mm), saddle rings, and snowflake rings. It was determined that compared to other factors, air-related and water-related parameters influenced the humidifier and dehumidifier performance respectively. Maximum freshwater productivity of 1398 mL/h was achieved with 16 mm pall ring humidifier, owing to its improved wet area (188,000 m2/m3) under optimal conditions of air flow rate, feed flow rate, humidifier air inlet temperature, humidifier, and dehumidifier water inlet temperatures of 3.5 kg/min, 0.9 L/min, 70 °C, 55 °C, and 25 °C, respectively, with a dual-fluid preheating mechanism. Detailed chemical analysis revealed that the generated freshwater is potable.

Performance analysis of humidifier packing for humidification dehumidification desalination system

The Humidification Dehumidification (HDH) desalination system is a promising method for production of potable water in isolated locations. Among different component constituting the HDH desalination system, humidifier and its packing are paramount factors in determining system productivity. Several experimental investigations were conducted to study the influence of packing on humidifier performance. However, numerical analysis dealing with performance of humidifier packing is still not available. Such an investigation will be useful to select the optimized packing for a humidifier. In the present work, performance analysis of 15 different types of random packing have been carried out using Scilab software. From this study, it is concluded that metal packing with highest surface area to volume ratio, lowest packing factor and smallest packing diameter functions as the best humidifier packing. Experimental study was also conducted in a pilot plant of open air open water HDH cycle using pall ring 25 mm diameter metal packing, which has shown the highest performance index in the numerical study. Experimental results obtained were found to be in agreement with the numerical results. Present work is a useful tool in designing new packing material of desired properties since the packing performance is a strong function of its geometrical properties.