Wick Material Research Articles

A Solid-matrix, Liquid Hybrid Hydroponic System for Establishing Small-seeded Crop Species

A solid-matrix-over-liquid (hybrid) growth system was developed for direct sowing of small-seeded crop species into hydroponic culture and compared for performance with a standard solid-matrix, capillary-wick hydroponic system. Seeds were sown directly onto a 3-cm (1.2-inch) deep soilless seed bed occupying 0.147 m2 (1.582 ft2) within a tray. The planted seed bed was moistened by wicking up nutrient solution through polyester wicking material from a 7.0-L (6.6-qt) reservoir just below the matrix seed bed. The hybrid system successfully grew dense [435 plants/m2 (40.4 plants/ft2)], uniform canopies of dwarf Brassica napus L. in a controlled-environment growth room. Seed yield using the hybrid system was twice that achieved with the matrix-based system. Both systems eliminated the labor needed to transplant many small seedlings from a separate nurse bed into a standard bulk liquid hydroponic system. Root-zone pH extremes caused by ion uptake and exchange between roots and unrinsed soilless media were avoided for the hybrid system by the short dwell time of roots in the thin matrix before they grew through the matrix and an intervening headspace into the bulk solution below, where pH was easily managed. Once roots grew into the bulk solution, its level was lowered, thereby cutting off further capillary wicking action and drying out the upper medium. Beyond early seedling establishment, water and nutrients were provided to the crop stand only by the bulk nutrient solution. This hybrid hydroponic system serves as a prototype for largerscale soilless growth systems that could be developed for production of smallseeded crops in greenhouses or controlled environments.

New chill-block melt spinning relations to predict ribbon thickness

References Chi, S. W., Heat Pipe Theory and Practice, McGraw-Hill, New York, 1976, pp. 213-226. Maxwell, J. C., A Treatise on Electricity and Magnetism, Vol. 1, 3rd ed., Oxford Univ. Press, Oxford, England, UK, 1954. Alexander, E. G., Jr., Structure-Property Relationships in Heat Pipe Wicking Materials, Ph.D. Dissertation, Dept. of Chemical Engineering, North Carolina State Univ., Raleigh, NC, 1972. Van Sant, J. H., and Malet, J. R., *'Thermal Conductivity of Some Heat Pipe Wicks,'* Letters in Heat and Mass Transfer, Vol. 2, 1975, pp. 199-206. Chang, W. S., Porosity and Effective Thermal Conductivity of Wire Screens, Journal of Heat Transfer, Vol. 112, No. 5, 1990, pp. 5-9. Hsu, C. T., Cheng, P., and Wong, K. W., A Lumped Parameter Model for Stagnant Thermal Conductivity of Spatially Periodic Porous Media, Journal of Heat Transfer, Vol. 117, 1995, pp. 264-269. Hsu, C. T., Cheng, P., and Wong, K. W, Modified ZehnerSchlunder Models for Stagnant Thermal Conductivity of Porous Medium, International Journal of Heat and Mass Transfer, Vol. 37, No. 17, 1994, pp. 2751-2759.

An Experimental Study on the Permeability of Screen Wicks.

Several kinds of test screens, which have a large mesh number similar to the wick material of heat pipes conventionally employed, were prepared to examine the influence of wick characteristics on permeability. From the experimental results, an expression of fRe (the product of friction factor and Reynolds number) correlating to the ratio of the wick thickness per single layer and the wire diameter was proposed

Ant Association with Parinari excelsa (Chrysobalanaceae) in Marajo, Brazil

The field notes in herbaria for many species of Patinari often state that these trees are full of ants or ant nests. For example, ants make nests by weaving together the curved margins of the leaves of Parinari alvimii Prance (fide S. Mori, F. Benton & I. White collecton N? 10243) in Bahia, Brazil. On a recent trip to Marajo Island in the Amazon delta, I observed that about 150 trees (almost every tree) of Parinari excelsa Sabine, growing along the banks of the Rios Anajas and Moco6es, were inhabited by ants and full of unusual looking ant nests made of a brown, woolly substance. An examination of the nests and observations of the tree leaves showed that the nests are constructed out of a brown, woolly indumentum that covers the lower surfaces of the young leaves of P. excelsa. In heavily ant-infested trees most of the new leaves had been harvested by these ants, identified as Hypoclinea sp. in the subfamily Dolichoderinae by Dr. Roy Snelling. They gather the hair by scraping it from the leaves and then carting it off in large bundles, using their mandibles. The older nests are up to 1.5 m in size, and most trees also have smaller nests along the branches (Fig. 1). Ant nests were not observed in species other than P. excelsa. A brief note by Sefer (1957) refers to ant nests made of an unknown cottony substance being collected from trees of Parinari montana Aubl. in the Tembe Indian reservation on the Rio Guama in Para. He observes that: "The branches and leaves were impregnated with a spongy substance that is much used by the Indians and which is called, inappropriately by some people, ant cotton (algodao de formiga)." The ants in this case were identified as Dolichoderus mucronifer Roger, also in the subfamily Dolichoderinae. Sefer thought that the spongy nest material was secreted by the ants. He observed that the nest material is difficult to wet and easily flammable so the Indians use it as a wick material. They also use it as a starting material when they light fires by the heat of friction in the traditional manner of spinning one

A Wick Tensiometer to Measure Low Tensions in Coarse Soils

AbstractA wick tensiometer was constructed to measure soil water pressures or tensions in coarse sands and gravelly soils. The tensiometer is similar in design to a conventional tensiometer except that a flexible wick material is used instead of a ceramic cup. Soil matric potential (reported as tension) or water pressure is sensed by the wick and monitored with a pressure transducer or hanging water column. Several wick materials were tested. Absorbent toweling, rolled to form a tight cylinder and sealed into a tensiometer body by a compression fitting, measured tensions up to 90 cm successfully. Glass‐fiber filter paper and wettable plastic sheeting were also tested successfully. Initial tests indicated that the wick sensor was as responsive to tension changes in gravelly soil as ceramic cup units and was less likely to break during placement.

Experimental investigation of a cornstalk wick heat pipe

This paper describes a heat pipe constructed with cornstalks as a wick material in an aluminum tube tested in a temperature range of 22 to 62C. It used water as the fluid for heat transfer operating in a vacuum state. The heat transferred was computed based on the measurement of parameters of the heat pipe.

The effective thermal conductivity of screen wicks.

An experimental study was performed on the effective thermal conductivity of screen wicks saturated with a liquid. A planar heat pipe was employed to determine the effective thermal conductivity, and its value was calculated from the heat transfer coefficient in the condenser of the heat pipe positioned horizontally. A comparison of the existing correlations with the present experimental data indicated that the effective thermal conductivity of screen wicks could be predicted by Maxwell's equation derived for the case where wick materials (or screens) were dispersed in working liquids. It was also found that, in predicting the effective thermal conductivity by Maxwell's equation, the thickness and porosity of multilayer screen wicks had to be estimated accurately by taking account of the intermeshing between screen layers.

A sampling method to determine insecticide residues on surfaces and its application to food-handling establishments

Known amounts of acephate, chlorpyrifos, and diazinon were applied to Formica, unfinished plywood, stainless steel, and vinyl tile. Cotton-ball and dental wick materials were dipped in 2-propanol and "swiped" over the treated surface area two time. More acephate was found on the second swipe compared to the first from vinyl tile, similar amounts on both swipes from plywood, and less on the second swipe from formica and stainless steel. The ratio of chlorpyrifos on Swipe 1 compared to Swipe 2 found with cotton-ball on both formica and stainless steel surfaces was equivalent (6:1), but a considerable difference was seen when two dental wick swipes were used. Residues of diazinon removed from formica and stainless steel were equivalent, regardless of the swiping material used. Residues of chlorpyrifos were detected by taking swipes of surfaces in two restaurants and a supermarket up to 6 mo after a prescribed application by a commercial pest control firm. The data show that measurable amounts of chloropyrifos can be detected on surfaces not treated with the insecticide for at least 6 mo.

Improved Double-Vial Radiorespirometric Technique for Mineralization of 14 C-Labeled Substrates

New procedures which simplify sample preparation and improve counting efficiency were developed for double-vial radiorespirometry. Under certain conditions, efficiency of fluor-NaOH-impregnated wicks was not stable, but was adversely affected by water vapor, NaOH concentration, and CO(2) loading. Glass fiber wick material treated with a methanolic fluor-NaOH solution showed improved C counting efficiency (58%) compared with previous methods.

Capture of Diaprepes abbreviatus (Coleoptera: Curculionidae) in Traps: Effects of Location in a Citrus Tree and Wick Materials for Release of the Attractant

In replicated field tests made in Florida in October and November 1982 to develop a survey for Diaprepes abbreviatus L., we devised a trap, obtained an attractant from the weevil colony, and then used the trap and attractant to determine the best trap location in a citrus tree as well as to identify a wick material for release of the attractant. Traps were constructed with a cage attached to an inverted funnel. An attractant used in the traps was from a chloroform extract of weevil frass. Trap location was a highly significant factor in weevil capture in a 4-m-high citrus tree. Traps in the top (4.3 m above ground) captured 349 weevils, those in the middle captured 138, and those at a low level (0.3 m above ground) captured 19 weevils. Top and middle traps also captured significantly more male than female weevils (2.8:1). Presence of the attractant significantly increased weevil capture per trap compared with traps with no attractant. Significantly more weevils were captured in traps when glass wool rather than cotton or rubber was used as the wick material for release of the attractant.

Study on life of sodium heat pipe

Life tests of stainless steel heat pipes containing sodium working fluid were carried out at evaporator surface temperatures of 600, 650 and 700°C for 1200 h of operation in ambient environments. After the finish of each test, the containers were cut open and were examined through an X-ray micro-analyzer, a metallurgical microscope etc. Heat pipes were fabricated from sus 316L stainless steel with 2 layers of 50-mesh screen wick of the same material. The total length of the heat pipe was 1000 mm with 25 mm diameter and the length of heating zone by ultra-gold furnace is 265 mm. The adiabatic zone is 235 mm and the remaining part is the condenser zone. The following became clear after the examinations. 1. (1) Cr crystal substance is deposited on the inner surfaces of the containers and the wick surfaces due to elution or precipitation of some Cr from the containers and wick materials. 2. (2) Selective crystal boundary corrosion is observed at wicks. However, it is clear that such a small amount of corrosion will not affect the life of the heat pipes.

Apparatus for high-voltage thin-layer electrophoresis: Application to amino acid analysis

An apparatus for high-voltage thin-layer electrophoresis designed to operate at a load of 5.0 kV and 50 mA and characterized by simplicity of construction and operation is described. The analysis of the relative contribution and interdependence of the following factors as they affect the operation and resolution ability of this unit was made: current-voltage relationships, electrical field gradients, solvent transport, heat exchange, wick material, salts, buffer type, and concentration. The relative mobilities of the majority of amino acids in a pH 2.5 formic acid buffer and in a pH 10.2 ammonium buffer are sufficiently characteristic to provide a basis for tentative identification. The mobility of the amino acids exhibits a striking functional dependence on the ionic charge, molecular weight, type of hetero atoms in the side chain, and type and concentration of electrolytes employed. The resolution ability of this technique is equivalent or superior to that obtained by high-voltage paper electrophoresis.

High Altitude and Space Simulation Testing

drogen, NASA News Release 61-12, and zero g fuel studies to aid centaur, Rover and Saturn propulsion programs, Western Aviation, Missiles and Space 41, 12-13 (February 1961). 58 Adelberg, M. and Forster, H. K., Discussion of Ref. 16, J. Heat Transfer 83, 251-253 (1961). 59 Forster, H. K., Private communication (1960). 60 Allingham, W. D. and McEntire, J. A., Determination of boiling film coefficient for a heated horizontal tube in a water-saturated wick material, Am. Soc. Mech. Engrs., J. Heat Transfer 83, Series C, 71-76 (February 1961). 61 Ginwala, K. (ed.), study of vapor cycle cooling equipment for zero gravity environment, Wright Air Dev. Div. TR 60-776 (January 1961). 62 Costello, C. P. and Tuthill, W. E., Effects of acceleration on nucleate pool boiling, Am. Inst. Chem. Engrs., Chemical Engineering Progress Symposium Series 57, no. 32, p. 189 (1961). 63 Costello, C. P. and Adams, J. M,, Burnout heat fluxes in pool boiling at high accelerations, 1961 International Heat Transfer Conference (American Society of Mechanical Engineers, New York, 1961), Part I I , pp. 255261. 64 Silvern, D. H., Collins, J. L., Hays, L., and Haire, A., Design of a surface radiator-condenser for use in a space environment, ElectroOptical Systems Rept. 310-DR (October 1959). 65 Koestel, A., Hydrodynamic problem areas in zero gravity, TapcoTRW Tech. Memo 1488 (November 1959). 66 Payne, J., Private communication (1960). 67 Reitz, J. G., Zero gravity mercury condensing research, Aerospace Eng. 19, 18-23 (September 1960). 68 Cummings, R. L., Grevstad, P. E., and Reitz, J. G., Orbital force field boiling and condensing experiment, Weightlessness-Physical Phenomena and Biological Effects, edited by E. T. Benedikt (Plenum Press, New York, 1961), pp. 121-132. 69 Jaenke, C. T., Koestel, A., and Reitz, J. G., Snap II power conversion system topical report no. 13—OFFBACE testing, ThompsonRamo Wooldridge Rept. ER-4670 (November 1961). 70 Lieblein, S. (ed.), Government-industry conference on mercury condensing, April 18, 1961, Pasadena, California, NASA TN D-1188 (February 1962). 71 Grevstad, P. E., TAPCO Group, New Devices Laboratories, Thompson-Ramo Wooldridge, Private communication (1960). 72 Weatherston, R. C. and Smith, W. E., A method for heat rejection from space power plants, ARS J. 30, 268 (1960). 73 Rocketdyne develops space heat radiator, Aviation Week 73, 65 (October 10, 1960). 74 Hays, L., Collins, J., and Neustein, J., Investigation of spray type condensers with mercury and water, Proceedings of the 1961 Heat Transfer and Fluid Mechanics Institute (Stanford University Press, Stanford, Calif., 1961), pp. 114-129. 75 Kittinger, J. W., The long, lonely leap, Natl. Geographic Mag. 118, 854(1960).

Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material

Using an absorbent wick material saturated with a coolant has become attractive from a design standpoint for some missile-cooling applications. However, published data for predicting film coefficients are very limited. In this study, boiling film coefficients for a 1.0-in. OD horizontal copper tube embedded in water-saturated ceramic fiber-wick material were correlated over a heat-flux range from 1000 to 10,000 Btu per hr sq ft by the dimensionless equation hCG′CμK0.6ρLσP20.21=0.072DeG′μ−0.77 where G′=QAελ The presence of wick material next to a heat-transfer surface decreases turbulence in the region near the surface, increases the effective surface area, and provides active sites for bubble formation. This produces a higher film coefficient at low heat flux than occurs with pool boiling. At higher heat flux, the wick-boiling film coefficient was lower than for pool boiling.

Discussion: “Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material” (Allingham, William D., and McEntire, Jack A., 1961, ASME J. Heat Transfer, 83, pp. 71–75)

Discussion: “Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material” (Allingham, William D., and McEntire, Jack A., 1961, ASME J. Heat Transfer, 83, pp. 71–75)

Closure to “Discussion of ‘Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material’” (1961, ASME J. Heat Transfer, 83, p. 76)

Closure to “Discussion of ‘Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material’” (1961, ASME J. Heat Transfer, 83, p. 76)