Search results

The purpose of this paper is to use numerical simulations to investigate the energy conversion performance and the flow and temperature structures inside horizontal tubes connected to a vertical manifold channel.

The simulations are performed for different flow rates and inlet temperatures using CFD.

In both the “flowing wind mode” and “upwind mode,” the inlet velocity is not infinitely small under the influence of natural convection; however, such small inlet velocities cannot be achieved in practice and are of no practical significance. In the “flowing wind mode,” the appropriate velocity for achieving high efficiency is 0.01-0.02 m/s. In the “upwind mode,” the appropriate velocity for obtaining high efficiency is 0.1-0.2 m/s. A high inlet temperature can lead to high efficiency; therefore, a large temperature difference and a small flow can be used in actual designs.

The energy conversion performance and flow structures inside evacuated tubular collectors were investigated using CFD for different operating conditions, notably in the “following wind mode” and the “upwind mode.”

The purpose of this paper is to describe a method for the prompt intervention and remediation of tanker wrecks, for recovering the fuel trapped in their tanks.

The environmental conditions, the functional specifications, the conceptual and preliminary design, the computational methods (fluid/structure interaction, computational fluid dynamics analysis and finite element analysis), the hydrodynamic scale model tests and the dynamic response analysis are included in this research paper.

The paper provides analytical and numerical tools for the response of subsea structures. These tools were calibrated by hydrodynamic scale model tests and extrapolated for different depths (shallow, deep water and ultra deep water).

The method is applicable as long as the trapped pollutant does not dissolve and is of lower density than the sea water.

This paper presents a new structure for the oil recovery from shipwrecks, which is simple and quickly deployed.

This paper investigates how to design traditional ready-to-eat food packaging by manipulating its shape, font and slogan to promote consumer buying intention and willingness to pay (WTP).

Two package designs, interplaying the square shapes (vertical vs horizontal), font formality (formal vs less formal/casual) and slogans (ethno-positioning vs short and catchy), were created and tested in an online experiment with 483 participants.

The results revealed that the differed package designs elicited relatively equal levels of attractiveness to consumers and their buying intentions. However, the designs significantly differentiated consumers' WTP. The results further show the significant direct and indirect effects on WTP of packaging attractiveness when it is moderated by package designs and mediated by buying intention. However, the varied package designs did not have significant direct or indirect impacts on WTP when mediated by packaging attractiveness and buying intention.

The vertical square-shaped packaging, written in a less formal font and highlighting a short and catchy slogan, is more financially promising for marketers to get a better price for local food products perceived as hedonic and bought impulsively on casual occasions. Furthermore, besides prominent package design elements such as font, color, size, material and picture, packaging designers or marketing practitioners should consider other supporting factors, such as shelf efficiency.

This study complements existing studies of “cue utilization theory” and “packaging design theory” by demonstrating the importance of extrinsic packaging cues, such as shape, font style and slogan, in improving consumers' WTP for traditional food products. The study also fills some gaps in the literature by exploring the direct, mediating and moderating relationships between package design, packaging attractiveness, buying intention and WTP, especially in an emerging market such as Indonesia.

The Gemini is a four‐seater wooden aeroplane designed for service on personal, club or taxi duties. Dual controls can be fitted and glider‐towing equipment can also be installed. The data which follow are for the standard model, but various alternative installations and equipment are listed at the end.

The preliminary figures for the production of fruit in the United States of America for the year 1930 issued by the Department of Commerce, Washington, are as follows:—Apples, 163,543,000 bushel; grapes, 2,368,557 tons; peaches, 53,286,000 bushel; pears, 25,703,000 bushel; strawberries, 59,996,000 quarts; cranberries, 570,000 barrels. Assuming the bushel to be equal to fifty pounds weight (Av.), the weights of apples, peaches and pears produced are 3,650,000 tons, 1,189,000 tons, 574,000 tons respectively. The Department of Commerce has no means of intimating the proportions of fruits used for the raw, canning and preserve markets. The production of canned fruits is, however, high in the United States, a much larger proportion of the total crop of fruit being used for this purpose than is the case in this country. In the United States the fruit that is preserved is marketed either as jam, the fruit for this purpose being more or less in the form of pulp; or as preserved fruit when the fruit is whole or unbroken; or as fruit butter, which is fruit juice and fruit pulp evaporated till they form a semi‐solid homogeneous mass with or without the addition of sugar, spices, or vinegar; or as fruit jelly, which is the juice or water extract of fruit concentrated to a suitable consistency with the addition of sugar. In 1929, according to the Bureau of Census figures, the total value of the four products above named amounted to $44,073,809, or in round figures about £9,000,000. It appears that some two hundred firms are mainly engaged in the manufacture of these, a small and unknown amount being made as a kind of side line by certain wholesale grocers. It may be observed that (1) the fruit used is home grown; (2) the product, whether it be preserved fruit, jam, fruit butter or fruit jelly, has to be made in accordance with Federal or State definitions of these products; (3) the label on the pot or tin must truly describe the contents as to nature, quality and quantity; (4) that misleading statements or designs on such labels are forbidden by law. At the request of the National Preservers' Association the Bureau of Foreign and Domestic Commerce recently completed a survey of the preserving industry. The results are incomplete, as many firms did not make returns, but the figures obtained would appear to cover about 40 per cent. of those relating to the industry for the year 1929. These figures are at least useful for comparative purposes, and multiplication by 2½ is probably justifiable under the circumstances as affording some guide to the total amount. Thus the actual figures obtained by the Department for production by “major classification” are as follows:—Preserves and jams, 62,490,389 lbs.; jellies, 32,301,654 lbs.; fruit butters, 40,019,560 lbs.; citrus marmalade, 1,849,104 lbs. Total, 136,660,707 lbs. This total when multiplied by 2½ shows that something over 150,000 tons, of 2,240 lbs. to the ton, of the products mentioned above were made in 1929. If the population of the United States be 125 millions, it is certainly near that figure, the output is low compared with the output in this country; for preserves and jams very low. The deficiency in this item is offset by the high percentage compared with our figures of fruit jelly (235), and of fruit butters (30) produced. Much fruit grown in the United States is, however, absorbed by the canning industry which has been long established and has reached enormous dimensions; and also in the production of fruit juices as beverages. Again, anything but a numerical comparison, even if that be directly permissible, is to our disadvantage. For while the fruit grower in the United States finds a ready market for his crops in the markets for jam and its associated products, our fruit growers would seem to receive no such measure of encouragement from our jam makers, who purchase large quantities of cheap imported fruit pulp of questionable wholesomeness in many cases. As to the quality of the material it is safe to say that much of the jam made in the country at the present time would be refused entry into the United States. As to the kind of jam and preserve made in the United States, there are three kinds: Standard, Compound, and Imitation. In round figures 75 per cent. of the jam is of standard grade, 19 per cent. is compound, and 6 per cent. imitation. For jellies the figures are: 45·45 per cent. standard, 27 per cent. pectin and apple base, imitation 27 per cent. As to the kinds of fruit used in making jam, strawberry jam heads the list with 39 per cent. of the total; raspberry with 19 per cent. No other percentages run into double figures. The next highest is peach 8·74 per cent., the lowest is gooseberry 0·13 per cent. 78·5 per cent. by weight of the strawberry jam is of standard quality, 19 per cent. compound, 2·3 imitation; 75·5 per cent. of the raspberry jam is standard, 21 per cent. compound, 1·6 imitation. The average invoice values of these jams are as follows:—Standard strawberry jam, 17.64 cents per lb., say 9d. per lb.; compound strawberry, 7d.; imitation strawberry, 5d. The corresponding figures for raspberry being 7½d., 6½d., 5¼d. These figures being about the average invoice prices for all kinds of jams of the three qualities named. From these figures it would appear that it is possible in the United States to market strawberry and raspberry jam of a nature conforming to Dr. Johnson's definition at a fairly low price. In the United States of America there are two laws which govern the purity of the food supply. One is the Federal Law of 30th June, 1906. The Federal Law applies to the Federal District of Columbia and to Inter‐State Commerce, that is to say to goods which may be sent from one State of the Union to another State of the Union. The other laws are the State laws which have been passed by the legislatures of the various States. Before these laws were passed, manufacturers of adulterated food products were at liberty to make and sell such products in their State. These State laws are applicable only to the particular States for which they have been passed. As a general rule they are founded on the Federal Law or follow the wording of this law closely as a matter of expediency, but the various States responsible for these enactments are not bound in any way by the wording of the Federal enactments. The State Laws, however, are complementary to the Federal Law. The power of a State to protect itself against the ill‐effects of unsatisfactory food products manufactured in another and imported within its boundaries is extremely limited. This is a matter for the Federal authorities in the enforcement of the Federal Law. On the other hand the Federal Law has no power over goods manufactured in any given State for sale in that State. It is only when such goods pass from one State to another and thus become part of Inter‐State Commerce that the Federal Law has authority. Nevertheless the Federal and State officials are in close co‐operation, and a network of protective legislation covers the United States, and the laws and regulations are administered by keen and experienced legal and technical officers.

Several small assembly systems based on robots were in evidence at Tokyo's Assembly Automation Show. John Hartley reports.

Inhibition of corrosion is a specialised division of the science of water treatment. The necessity for treatment of industrial waters for the prevention of scale deposits and to adjust the dissolved constituents to suit a particular manufacturing process is clearly recognised, but the conditioning of the pretreated water to prevent corrosion is often not considered at all or at least given only superficial attention. It is usually not until the incidence of corrosion poses maintenance problems and affects the manufacturing process that the corrosion aspect of water treatment is looked at seriously.

In the present work, a theoretical model based on the full Navier-Stokes and energy equations for transient mixed convection in a vertical tube is extended to nanofluids with nanoparticle volume fraction up to 5 percent to ensure a Newtonian fluid behaviour. The paper aims to discuss these issues.

The nanofluids considered, alumina/water and CuO/water, flow inside a vertical tube of circular cross-section, which is subjected to convective heat exchange at the outer surface. The transient regime is caused by a sudden change of nanofluid temperature at the tube inlet. The range of the Richardson number (1.6=Ri=2.5) investigated in this study corresponds to classic cases of mixed convection flow.

Results have shown a significant reduction in the size of the recirculation zone near the wall when the particle volume fraction increases. This may be attributed to the viscosity increase with the volume fraction. Moreover, the flow structure clearly changes when the convective heat transfer coefficient is modified. A decrease of the wall temperature along the tube was found when increasing the convective heat transfer coefficient imposed at the tube external surface.

The problem formulation in 2D axisymmetric geometry includes the continuity, the Navier-Stokes and energy equations and is based on the stream function and vorticity; the numerical solution of equations is carried out using a finite difference method.

From an economic point of view, this research paper is innovative in the sense that it considers nanofluids as a new and more efficient way to transfer heat. This paper could find applications for heat exchange purposes of compact systems with high thermal loads.

Across the world, a still growing number of research teams are investigating nanofluids and their properties. Investigations concern several aspects such as the preparation of the nanofluids, as well as the applications of these nanofluids for convective heat transfer purposes. The dynamical study will consist in the instantaneous and spatial characterization of the dynamic flow field for different nanoparticle volume fractions.

The effects of tube inclination and Grashof number on the fully developed hydrodynamic and thermal fields are investigated numerically for laminar ascending flow of air and water in uniformly heated circular tubes. The effects of the buoyancy induced secondary flow on the hydrodynamic and thermal fields are complex and strongly dependent on the Grashof number, the Prandtl number and the tube inclination. The influence of these parameters on the intensity of the secondary flow, on the distortion of the axial velocity profile and of the temperature field from the corresponding distributions for pure forced flow, as well as on the circumferential variation of the local shear stress and of the local Nusselt number are analysed. The average shear stress is higher than for pure forced flow and it increases with both the tube inclination and with the Grashof number. The average Nusselt number is higher than for pure forced flow and increases with the Grashof number. For a given fluid and Grashof number there exists an optimum tube inclination which maximizes the average Nusselt number. Correlations for the average Nusselt number in terms of Gr and Pr are presented for four different tube inclinations.

The fully developed laminar mixed convection flow in inclined tubes subject to axially and circumferentially uniform heat flux has been studied numerically for a Boussinesq fluid. Dual solutions characterized by a two‐ and a four‐vortex secondary flow structure in a cross‐section normal to the tube’s longitudinal axis have been found for different combinations of the Grashof number Gr and of the tube inclination α for all Prandtl numbers between 0.7 and 7. In the two‐parameter space defined by Gr and α dual solutions occur: at a given α, if the Grashof number exceeds a critical value Gr_ℓ (for horizontal tubes Gr_ℓ is approximately 5.5 × 10⁵, 1.7 × 10⁵ and 1.7 × 10⁴ respectively for Pr = 0.7, 7 and 70); at a given Gr, if the tube inclination is below a critical value α_c (for Gr = 10⁶ this critical angle is approximately 62.5° and 83.5° respectively for Pr = 0.7 and 7). Numerical experiments carried out for developing flows indicate that the two‐vortex solution is the only stable flow structure.