Water Misting Research Articles

Dynamic wetting characteristics of two droplets impacting a spherical dust particle

The removal of dust based on water misting is one of the most effective measures for dust control, and the basis of this method lies in the liquid–solid impact behavior. To further improve the dust removal efficiency, in this work, the removal mechanism was studied at the microscopic level, and the dynamic impact between two water droplets and a spherical dust particle was simulated using the coupled level-set/volume-of-fluid (CLSVOF) method. The optimal parameter ranges for micron-level dust removal were determined through the method of variable control, and the reliability of the obtained results was experimentally verified. When two droplets continuously or simultaneously impact a spherical particle, the liquid film formed undergoes deformation phenomena such as fusion, rupture, stretching, contraction, and fragmentation. The liquid film is more likely to break at higher droplet velocities, leading to the filling of the gas film and hindering the wetting process. The optimum contact angle and velocity range of the liquid droplets to completely encapsulate the dust particles were found to be θ = 2 and V = 10–20 m/s, respectively. The experimental results also showed that for the same dust particle size, the dust removal efficiency initially increased but then decreased with increasing dust concentration. The optimum dust removal efficiency of 98.1 % was achieved for θ = 2 and V = 10 m/s. This study sheds new light on the dust removal mechanism of water mist-based dust removal technologies and can aid in the design and parameter optimization of more effective dust suppression systems.

Respons Fisiologis Sapi Pedaging terhadap Pengabutan Air Menggunakan Sprinkler Water

Indonesia is facing the problem of low productivity of cattle. To increase the productivity of cattle producer, it can actually be done by relocating the cattle to the comfort zone by observing the physiological response. The purpose of this research is to evaluate the effects of misting cattle’s environment by using water sprinkler on the physiological response and the microclimate of the cattle’s shed. The design used was a paired T-test for physiological and microclimate response variables with 5 replications and a completely randomized design to determine the difference between body surface temperatures. The observations were conducted before water misting and after water misting. The results showed that treatment of misting water in the afternoon significantly decreased (P<0.05) the variables of cage temperature, humidity, temperature humidity index, rectal temperature, respiratory rate, and heart rate. Water misting in the afternoon in cattle produced a good effect on all physiological response variables.
 
 Keywords: beef cattle, pen microclimate, physiological responses, water sprinkler

Annual performance assessment of an off‐grid and self‐sufficient sustainable climate refuge for hot arid climates

AbstractTo overcome the problem of walking in the scorching heat and to encourage people to use more public transport (ie, trams and metros), the idea of sustainable climate refuge shelter is highly needed. In this study, the proposed shelter includes semi‐transparent photovoltaic cells located on the roof integrated with batteries to keep the system running at nighttime and in unfavorable irradiation conditions. An atmospheric water generator for freshwater production is employed for drinking and water misting in addition to a vapor compression cooling system with a fan. Freshwater is collected by extracting water from humid air through cooling with dehumidification. The system is analyzed thermodynamically through energy and exergy efficiencies. The overall energy and exergy efficiencies of the system are 19.45% and 9.58%, respectively. The electrical efficiency of the photovoltaic cells decreases from 16.87% to 15.24% with an increase in cell temperature from 309 K to 315 K. Hourly analysis of the proposed system for the whole year is performed to evaluate the energy profile. The proposed system generates electricity in winters that is sufficient to keep the system operational for 2 days (only for drinking water requirement), but in the summers, only 24 h due to extensive cooling load. The effects of several parameters such as irradiance, ambient temperature, relative humidity, transmittance, and occupancy rate are studied.

Post‐mortem indications of poor welfare—an hypothesis upon supine broilers: stress and efforts to ameliorate suffering in a low throughput abattoir

Broilers at slaughterhouses are prone to heat stress. They should be checked for panting, which occurs above an ambient temperature of 17°C. Fan cooling, water misting, cooling by evaporation on module roofs, cascading water down the lattice of drawers, and cold drinks all help to reduce heat stress. Drawer opening by 4–6 cm and stocking reduction also facilitate heat escape. Removing live or dead supine, or trapped prone broilers, with broken legs or wings, wedged toes or with rubbed upper wing joints, improves the welfare of the remaining broilers. Indications of stressed broilers, for example, pale soft exudative and dark, firm, dry pectoral muscles, should be sought in untreated dead on arrival birds and in postmortem rejects.

Preparation and performance characteristics of an environmentally-friendly agglomerant to improve the dry dust removal effect for filter material

The incomplete and uneven dust removal of a pulse filter greatly reduces the dust removal efficiency, which affects the efficiency, service life, and running resistance of dust removers. Therefore, due to improve the pulse cleaning effect, an agglomerant developed by free radical polymerization was added during dust removal. The optimal process conditions were determined by measuring the viscosity, surface tension, and atomization effect of the agglomerant solution. The phases, chemical composition, surface morphology, and morphology of the agglomerant and coal dust were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Molecular dynamics simulations were used to study the interaction mechanism between the agglomerant and coal dust. Finally, the dust removal performance under water mist conditions and agglomerate solution atomization was tested using a pulse filter. The results showed that a 0.3 % agglomerant solution effectively reduced the surface tension of the solution and displayed good wetting and bonding properties. Compared with water misting, the agglomerant solution subjected to an atomization rate of 2400 m3/h prolonged the filtration period, reduced the filtration resistance, and reduced the dust emission concentration. These results have important theoretical and practical significance for improving the dust removal effect of pulse filters.

The Evaluation of Short-Term Water Misting of Room Air in Reducing Airborne Dust after Renovation Work.

To shorten the time for airborne dust concentration to be reduced to a lower level after a renovation task has been completed, a short-term water misting method was assessed. A short-term water misting method is based on low water consumption to avoid harmful wetting of materials. The method is considered similar to a general ventilation method that dilutes work-generated airborne dust concentrations. Thus, short-term misting is not intended to replace the source control measures. Airborne dust removal by the short-term water misting performed after dust generation was evaluated in a controlled laboratory settings by comparing PM10 decay and inhalable dust concentrations between a control and misting tests (average water flow = 0.22 l min-1) of 2 and 4 min. A portable handheld misting device was used. The practicability and effectiveness of the misting technique as a supplementary control measure was verified in the three field cases. In laboratory tests, reductions in airborne PM10 and inhalable dust were 30% and 28%, avoiding condensation of water to surfaces. In the field, inhalable dust concentrations were reduced by 86-95% after an hour from the misting, whereas ventilation alone was calculated to dilute dust concentrations by 18-39%. Average clean air delivery rates varied from 0.03 to 0.07 m3 s-1. Short-term misting after a dust-generating task is an effective measure to control the airborne dust after dust-producing tasks in environments where an effective air exchange for dust removal is not a feasible alternative. The information obtained from the study is beneficial to construction and renovation project management personnel and field practitioners.

Application of a ventilation fan-misting bank on pigs kept in a stationary trailer before unloading: Effects on trailer microclimate, and pig behaviour and physiological response

The aim of this study was to evaluate the effectiveness of water misting with forced ventilation on a stationary trailer on internal vehicle ambient conditions, and behavioural and physiological response of market pigs. During 6 shipments, two identical 2-axle pot-belly trailers transported 191 pigs each (126 ± 5 kg BW) to the same slaughter plant (135 km). On arrival, trailers were kept stationary in the yard for 30 min before unloading. One trailer was positioned along a fan-misting bank (PBVM), while the other trailer had no access to this cooling system (PBC). The PBVM treatment consisted of 10 min of fan-assisted ventilation (phase 1, P1) followed by 10 min of ventilation and water misting (phase 2, P2) and a final 10 min of ventilation (phase 3, P3). Within each trailer, 4 compartments (rear-top [C4], front-middle [C5], center-middle [C7], and front-bottom [C9]) were chosen for data collection. The air temperature (T) and relative humidity (RH) were monitored using data loggers. The percentage of lying pigs during each phase, and the latency to lie down and the frequency of drinking during lairage were calculated. Gastrointestinal tract temperature (GTT) and exsanguination blood lactate, hematocrit, creatine kinase and cortisol concentrations were assessed. Data from the last 5 min of P1 (wait 1), P2 (wait 2), and P3 (wait 3) were analysed. In wait 1, the application of the fan-assisted ventilation resulted in lower (P ≤ 0.05) T and temperature-humidity index (THI) in the PBVM compared to the PBC. A greater (P ≤ 0.05) drop in RH was recorded in C5 and C7 of the PBVM compared to the same compartments in the PBC. In wait 3, T and THI were lower (P < 0.001) in PBVM compared to PBC, but the RH was higher (P < 0.01). Pigs from C4 in the PBVM had a greater (P < 0.001) activity during phases 2 and 3, and a reduced latency to lie down in the lairage pen compared to the same compartment in the PBC (P ≤ 0.05). A higher (P ≤ 0.05) GTT drop was recorded until 1 h after lairage in pigs located in PBC compared to those transported in PBVM. Although the efficiency of the fan-misting bank varied by compartment location, this cooling system appears to be effective in improving the trailer internal thermal environment and thermal comfort of pigs kept in a stationary trailer.

Productive losses on broiler preslaughter operations: effects of the distance from farms to abattoirs and of lairage time in a climatized holding area

This work aimed to assess the effects of preslaughter lairage time on the welfare and mortality of broilers transported in different farm-abattoir distances. It was evaluated 215 poultry transport trucks from a commercial poultry slaughterhouse from 2006 to 2007. Data were obtained from the holding area acclimatized through fans and water misting in the mornings, afternoons and at night. The thermal variables (temperature and relative humidity), distance, lairage time and density of birds per cage were considered in the analysis. The effects of distance and lairage time were important in the variation of rectal temperature of the animals and on the number of dead animals per truck. Two models were developed (mean and dispersion), for each response variable in function of the interaction between lairage time and distance. As the lairage time in the holding area increased, the rectal temperature of the birds was reduced for all the studied distances. In farm-abattoir distances higher than 25 km, mortality was low when lairage time was lower than 1 hour. However, for distances below 25 km, in the same time interval, the number of dead birds was two-fold higher than in the first situation. The adjustment of lairage time has to be done accordingly to the distance provided that the lairage environment is correctly climatized.

Attenuation of solar radiation by a water mist from the ultraviolet to the infrared range

A model is developed for the hemispherical transmittance of direct and scattered solar radiation from a cloudless atmosphere by a mist layer of water droplets in order to investigate the potential of water misting systems to serve as a protection from solar irradiation with particular emphasis on harmful UV radiation. The proposed model is based on published spectral experimental data for solar irradiation, Mie theory for interaction of the radiation with single spherical droplets, and radiative transfer theory. Known limiting solutions are employed to simplify the Mie calculations. The modified two-flux approximation is used to account for both direct and diffuse irradiation in lieu of a numerical solution for the full radiative transfer equation in anisotropically scattering media. The role of the governing parameters of a disperse water curtain of water droplets, water content, and droplet size for sample conditions is studied in some detail, particularly in the near-ultraviolet part of the spectrum where radiation can result in human tissue damage.

On the shrinking and hardening of EPDM rubber membranes in water sanitation filtration tanks

A water reclamation plant (WRP) uses a fine bubble-diffuser system to treat biological sewage waste. The process involves pumping air through slits in rubber membranes to feed bacteria in the waste stream. This case study deals with problems encountered with shrinking and hardening of the EPDM rubber membranes. Several factors affecting the performance of the rubber were investigated, including “leaching” of plasticizers, accelerated cross-linking due to the effects of temperature, and vulcanization effects on rubber flexibility. Different rubber materials were evaluated (i.e. silicone, Hypalon, Viton, neoprene, and a different formulation of the EPDM rubber). The investigation found that EPDM compound 7195 provided superior performance and met the required parameters for the wastewater treatment application. Additional investigations revolved around improving pumping losses in membrane through optimized perforation sizes and the inclusion of a cooling system (water misting or heat-exchanger) to cool the air before it reaches the membrane.

The Development of a CFD Based Simulator for Water Mist Suppression Systems: The Development of the Fire Submodel

The FIRE Detection and Suppression Simulation (FIREDASS) project was concerned with the development of water misting systems as a possible replacement for halon based fire suppression systems currently used in aircraft cargo holds and ship engine rooms. As part of this program of work, a computational model was developed to assist engineers optimize the design of water mist suppression systems. The model is based on Computational Fluid Dynamics (CFD) and comprised of the following components: fire model; mist model; two-phase radiation model; suppression model; detector/activation model. In this paper the FIREDASS software package is described and the theory behind the fire and radiation sub-models is detailed. The fire model uses prescribed release rates for heat and gaseous combustion products to represent the fire load. Typical release rates have been determined through experimentation. The radiation model is a six-flux model coupled to the gas (and mist) phase. As part of the FIREDASS project, a detailed series of fire experiments were conducted in order to validate the fire model. Model predictions are compared with data from these experiments and good agreement is found.

Responses of the Mosses Brachythecium rutabulum and Pseudoscleropodium purum to a Mineral Nutrient Pulse

The mosses Brachythecium rutabulum and Pseudoscleropodium purum were subjected to a nutrient'pulse'consisting of eight daily additions of a solution of KH 2 PO 4 and NH 4 NO 3 at a concentration of 5 mm, and then grown for 10 weeks with daily distilled water misting but no further nutrient application. Biomass increase and tissue contents of N, P, K, Ca and Mg were determined during the experiment. Relative growth rate in the nutrient-deficient environment was higher in Pseudoscleropodium than in Brachythecium. The nutrient pulse significantly stimulated subsequent growth of Pseudoscheropodium but not of Brachythecium (...)

Cold Water Mist Humidification to Preserve the Quality of Fresh Vegetables During Retail Sale

The effects of water misting on the maintenance of quality of field-lettuce, head-lettuce, broccoli, chicory and carrots, under retail trade storage conditions were analysed. The results were compared with samples which were stored without misting. Water misted crops (e.g. spraying time of 6s, interval of 20 min) have far lower weight losses and a lower increase of dry matter. The texture (firmness and crispness) of the raw material was preserved for much longer. Thereby an evidently slower decrease in the ascorbic acid content was found. An impact on colour was not observed. Misted as well as non-misted vegetables showed an increase in the number of microorganisms/g within the same log cycle only.

Effects of Filtered Air and Misting Treatments on Cuticles of Red Spruce Needles on Whiteface Mountain, N.Y.

wo sets of large (8-20 m tall) red spruce (Picea rubens Sarg.) trees growing on Whiteface Mountain, N.Y., were used in branch chamber experiments. In the summer of 1988, the treatments were made on four healthy trees and consisted of: (1) open branches (N), and in chambers that were supplied with either: (2) ambient air (A); (3) charcoal-filtered air (T); or (4) charcoalfiltered air and deionized water misting when the forest was immersed in ambient cloud water (M). Each tree had all of the treatments. The treatments for the second year (summer of 1989) were made on four declining trees and consisted of: (1) open branches (NC) and chambers supplied with either (2) ambient air and mist (AA), (3) synthetic acid mist and ambient air (SA), (4) distilled water mist and ambient air (DA), (5) synthetic acid mist with filtered air (SF), and (6) distilled water mist with filtered air (DF). Foliar properties measurcd included: (1) microreflectivity, a measure of surface wax properties; (2) cuticle thickness; (3) cutinized cell wall thickness; (4) total cuticular layer thickness: (5) the mass of surface wax extracted from needle samples; and (6) contact angles, a measure of surface wetting. In addition, needles were collected and measured from healthy trees at lower and higher elevations. In the first experiment, reflectance from the wax in the stomata1 antechambers in treatment M was statistically significantly greater than all the other treatments. The cuticles of needles in treatment M were also statistically significantly thicker than the cuticles measured in all the other treatments (40% thicker than for the open branches). A plot of cuticular layer against elevation showed that the two filtered chambers (M and T) provided environments for cuticle development that mimic lower elevations. In 1989 the weather was cooler and more moist, and although the trees used in 1989 were declining, the results were similar to those of 1988. However, the additional treatments with synthetic acid mist resulted in reduced cuticle thickness. While the cuticles of the chamber trees growing at 1,170 m were, except for treatment M and T, generally thicker in 1989 than in 1988, they were still considerably thinner than those of spruce trees growing at the lower elevations. These results suggest regional scale air and precipitation quality have detrimental effects on red spruce needles at Whiteface Mountain.

The use of contingent water misting in the treatment of self-choking

A 25-year-old, deaf-blind, mentally retarded male was treated for chronic self-choking using water mist treatment and positive reinforcement. During pre-treatment baseline, self-chokes occured at a rate of 2.09 per minute. During treatment sessions each self-choke was followed by water misting of the subject's face paired with a forceful “No!”. Periods of 20 sec absent of self-chokes were positively reinforced with liquids and/or social contacts. Treatment procedures were generalized from the initial therapists, location, and absence of other clients and staff to other locations, and the presence of other clients and staff. Water mist treatment was associated with at least a 10-fold and as much as a 100-fold reduction of self-choking (i.e. to 0.02–0.20 self-chokes per min) across treatment and generalization phases. Eight-month follow-up observations showed that self-choke rates were at zero.

Bactericidal Activity, Eggshell Conductance, and Hatchability Effects of Ozone Versus Formaldehyde Disinfection ,

Ozone and formaldehyde were evaluated as disinfectants in a prototype laboratory setter against microorganisms that are naturally present on fertile, freshly laid, broiler hatching eggs. Significantly lower microbial counts of over 2.5 log10 (P<.05) were observed for water-misted and ozonated (2.83% by weight) eggs or formaldehyde-fumigated (triple strength) eggs than for control and water-misted eggs. Eggshell conductance studies as measured by egg moisture losses in a desiccator showed no significant differences (P>.05) among untreated, water misted, ozonated (3.06% by weight) with water mist, or formaldehyde (triple strength)-fumigated eggs. Hatchability was significantly reduced (26.5 to 37.5%) following ozonation (3.03% ozone by weight, 2 h) in comparison with effects of no treatment or water misting. Misting with ozonation was equally as effective as formaldehyde fumigation in reducing microbial counts. However, ozone treatment at the concentrations tested significantly reduced hatchability when compared with results of either no treatment, water misting, or an average hatchability figure for formaldehyde fumigation. These findings indicate that ozone is a good disinfectant yet may adversely affect embryo development when given in the gaseous form.

Water Misting: Treating Self-Injurious Behavior in a Multiply Handicapped, Visually Impaired Child

A water mist was employed as a punisher to reduce head hitting in a multiply handicapped, visually impaired child. A multiple baseline across four situations (lunch, breakfast, industrial arts class, and residential hall) was used to evaluate the effects of water misting on head hitting as well as on appropriate behaviors. The results indicated that water mist alone was effective in reducing the frequency of head hits during meals, but that the other two situations required the addition of primary reinforcers or stimulus control or both to reduce the frequency of head hitting. These results suggest a need to consider the setting and task requirements in evaluating a mild punisher to reduce self-injurious behavior.

The effects of contingent water mist on the stereotypic responding of a severely handicapped adolescent

The reductive effects of the water misting procedure on the stereotypic responding of a severely handicapped adolescent were investigated by using a variation of the multiple baseline design across settings, with sequential interventions across settings and simultaneous interventions across teachers. The results indicated that the intervention was related to reduced rates of stereotypic responding in each setting. The effects of the intervention were also maintained across multiple administrators of the procedure and during follow-up. Instructional implications are discussed. Further research is suggested.