Infrared Heating Research Articles

Modelling of the One-Sided Infra-Red Heating of Polyurethane

Modelling of the One-Sided Infra-Red Heating of Polyurethane

The effects of hydroxide gel drying on the characteristics of co-precipitated zirconia-hafnia powders

Mixed zirconia-hafnia (Hf0.25Zr0.75O2) powders of fine particle size and narrow particle-size distribution can be prepared via co-precipitation routes using mixed zirconium and hafnium salts as the starting materials. The characteristics of the resultant zirconia-hafnia powders are dependent strongly on the dehydration route by which the co-precipitated hydroxide gels are dried. Zirconium-hafnium hydroxide gels are formed when zirconium and hafnium oxynitrates are co-precipitated in an ammonia solution of pH 10.5. The co-precipitated hydrous gels were dried by three very different routes including organic solvent dehydration, microwave drying, and conventional infrared heating lamp drying. The dried hydroxides were then calcined at various temperatures in the temperature range 550–1150 °C, followed by ball milling to remove large soft-particle agglomerates. The resultant zirconia-hafnia powders were characterized for crystallite size, particle size, particle-size distribution, particle morphology, and the degree of powder agglomeration, using experimental techniques such as X-ray diffraction, BET surface area, differential thermal analysis, thermo-gravimetric analysis, sedigraph, scanning and transmission electron microscopy. Hard particle aggregates, which cannot be effectively eliminated using ball milling, occur in the zirconia-hafnia powders processed via either the microwave drying or conventional infrared heating lamp drying routes. In contrast, the organic solvent dehydration route resulted in an almost aggregate-free powder of fine crystallite and particle sizes. Therefore, the zirconia-hafnia powder processed via the organic solvent dehydration route exhibited high sinterability on sintering at 1300 °C.

Innovatory developments in infra-red process heating

Infra-red heating has been in existence for many years, but there are still many areas in which innovations can be made

食品産業における遠赤外線利用の現状と問題点

食品産業における遠赤外線利用の現状と問題点

Oxygen and carbon incorporation during infra-red assisted Czochralski growth of silicon crystals

In silicon crystal growth by the Czochralski technique, the diameter of the crystal is always maintained at a predetermined value by changes in the pull rate. In this investigation a new technique for diameter control has been applied. The technique involves the use of fast, adjustable infra-red (IR) heaters directed towards the melt surface and facilitates growth at constant pull rate. Using this method, two crystals were grown and compared to a reference crystal grown with normal CZ technique. The axial oxygen distribution in the reference crystal could be understood reasonably well by application of a steady state model of the dynamic oxygen equilibrium in the melt. The other two crystals showed a more even oxygen concentration than predicted, and it was clear that power adjustment of the IR heaters was followed by variations that could not be accounted for by the steady state model. By the application of a new time dependent model emphasizing the kinetics at the interfaces towards the crucible and the atmosphere, it became evident that a dynamic oxygen equilibrium in the melt was never reached. The deviations from the steady state model could thus be explained, and so also could the short range oxygen variations. The axial carbon distributions showed higher levels in the crystal grown using IR heating. Radial carbon and oxygen measurements did not reveal any significant differences between the reference crystal and the two crystals grown by the new technique.

近, 中赤外放射に対する水の滲透深さと屈折率の分光特性

Absorption and penetration depth of infra-red radiation covering 0.8-2.5 micro-meter wave length has been established successfully in spectrographic way for city water at room temperature by means of transmittance measurements and precise analysis formulae concerned already etsablished by one of the authors. The view point of this paper is based on infra-red radiation heating of water.Special references are made to interference effects caused by forward going and successively reflected backward waves in the measured thin water film.Taking advantage of the above interference effects, water refraction index spectrum covering 0.8-2.5 micro-meter wave length has been found, and also the approximate one for 2.5-25. micro-meter has been given by means of a special reflection measurement.

Electronic control system infrared heating applied to surface cooking

Resistive heating units made from materials such as molybdenum disilicide (MoSi/sub 2/) and tungsten (W) can generate short-wavelength infrared (IR) energy, which can pass through IR transmissive glass-ceramic to heat up cooking utensils. Cooktops made with IR heating units provide for smooth-top cooking surfaces that are highly efficient with fast response times. However, these materials have unique characteristics that create severe control problems. An electronic control system that solves problems such as the nonlinearity between on-time and power output, the high inrush currents, the RFI/light-flicker interference, and the complexity of controlling four heating units in a cooktop versus one heating unit is described. The IR heater control portion is combined with standard electronic functions, such as input and display, to produce a low-cost microprocessor-based control. >

Stomatal Resistance and Water Potential of Calceolaria Grown Under Two Different Heating Systems

Abstract Calceolaria × herbeohybrida cv. Multiflora Mix was sown on five dates in the 1984 and 1985 winter seasons and grown in greenhouses heated with forced hot-air or infrared heating systems. Neither stomatal resistance nor water potential was significantly different between plants grown in the two heating systems.

Variability of heating and cooling rates during radiant heating in a scincid lizard, Egernia cunninghami

1. 1. Heating rates were significantly greater than cooling rates in Egernia cunninghami. 2. 2. Male lizards had significantly slower cooling rates than females, while heating rates of both sexes were similar. 3. 3. Faster heating and cooling rates were recorded in the earlier months of the 32-week experiment than during the winter season. 4. 4. The effect of infra-red heat intensity on heating and cooling rates was apparent only in the winter months. 5. 5. Painting the animals black retarded the radiant heating rates, rather than enhancing them.

Snail numbers, biomass and respiratory metabolism in a beech woodland ? Wytham Woods, Oxford

Two methods of extraction were used in the estimation of snail population densities in woodland litter. The time-consuming-Vágvölgyi technique proved to be 6.25 times more efficient than infra-red heat extraction but it was shown that the results obtained by the latter method could be easily corrected to conform with those of the former.Snail density varied with season (Winter, 1,000-1,250 m-2, Summer, 50-600 m-2), the annual mean density being 645 m-2. The annual mean ash-free dry weight biomass was 176 mg m-2 while annual population metabolism equalled 0.8941 O2 (=17.84 kJ m-2 yr-1).Two independent estimates of the energy equivalent of food consumption gave rise to values of 25.37 and 57.98 kJ m-2 yr-1, these respectively account for 0.54 and 1.23% of the known ground litter disappearance of 4,716.58 kJ (=235 g dry wt. m-2 yr-1).

Intravenous cholecystokinin octapeptide in pigs reduces operant responding for food, water, sucrose solution or radiant heat

The effect of intravenous injections of 0 (Saline vehicle), 10, 20 or 40 units of CCK was studied in pigs performing operant responses for food, water, sucrose solution or radiant heat. In hungry pigs working for food, thirsty pigs responding for water, and non-deprived pigs working for sucrose, 20 and 40 units CCK produced significant dose-related decreases in response rates lasting for about 5 min. In pigs responding for 10 sec bursts of infra-red heat at an ambient temperature of 5°C, 40 units CCK significantly reduced the response rate during the 5 min period following injection.

Evaluation of Infrared Heating in a Michigan Greenhouse

ABSTRACT INFRARED heating has been found to be a practical heating system for a 2790 m^ greenhouse in Michigan. It provided a 31 percent reduction in gas consumption and a 17 percent reduction in costs when compared to a gas boiler system. Uniform temperatures can be main-tained and high quality crops can be grown under the alternative infrared heating system

Simulation of Energy Used by Foodservice Infrared Heating Equipment with Bentonite Models of Menu Items

Bentonite-water dispersions were used to simulate 10 menu items heat processed to various degrees of doneness in a foodservice infrared conveyorized oven. Bentonite is an absorptive and colloidal clay with several industrial uses, including simulation of heat transfer mechanisms within the canning industry. Ratios of bentonite to water ranging from 60–78.5% were used and several trends were revealed. First, differences in evaporation losses between the menu items and the bentonite models were least when steaks were simulated to a medium stage of doneness (40–41 C). Second, the mean product yields for the bentonite models tended to be greater than for the menu items, largely because drip loss was not stimulated. Third, when energy usage was monitored during heat processing of three kinds of steak menu items and bentonite models, no significant differences in energy usage were revealed between the menu items and the models. A potential use for models of bentonite-water dispersions during energy studies of foodservice heating equipment was identified.

The effects of ambient temperature on urinary flow and composition in the fowl.

1. Urine flow and compositions were determined in normally hydrated, waterloaded and hypotonic saline infused hens under various ambient temperatures (Ta). 2. At Ta 29 and 32 degrees C normal urine flow was reduced and osmolality increased; at Ta 0 and -5 degrees C urine flow increased and osmolality decreased. 3. In hydrated hens at Ta 32 degrees C antidiuresis occurred within 10 min and persisted for 2 hr without any significant change in rectal temperature (Tr). 4. At Ta 40 degrees C there was no antidiuresis but a tendency for urine flow to increase; Tr also rose. The antidiuresis shown by water-restricted hens at Ta 20 degrees C was abolished at Ta 40 degrees C. 5. An antidiuresis, similar to that seen at Ta 32 degrees C, could be produced at Ta 20 degrees C by moderate haemorrhage, exposure to infra-red heating or by vasopressin or vasotocin. Adrenaline and noradrenaline provoked a diuresis. 6. Hypothalamic heating failed to elicit an antidiuresis but hypothalamic cooling increased urine flow at Ta 20 degrees C and abolished the antidiuretic response at Ta 32 degrees C. 7. It is concluded that the antidiuresis seen at warm ambient temperatures is caused by the release of antidiuretic hormone possibly as a response to a rise in skin temperature.

Infra-red heating source and associated apparatus for the study of contaminants in inert gases

Vacuum microbalance methods using radiant heating of the sample, a flow type of reaction system and a sensitive monitoring system for water vapor were used to study the reactivity of metal powders with contaminants in inert gases. Kinetic and capacity studies were made on zirconium and aluminum powders in argon atmospheres containing H 2, O 2, H 2O and CO 2 at the 5 to 50 ppm level at 400°C.

Emploi de la télédétection pour l'étude de l'humidité des sols

Soil is an important item of information for the agronomist in that it determines the plants' water supply. Determination of surface moisture, however, is insufficient for giving advice to a farmer; one has to reason in terms of volume. In addition, one must determine the dynamics of the content of the considered volume in order to establish whether the plant will find water when it needs it. Teledetection provides data on and associated factors. Some of the latter can be detected directly. Micro-waves are required to obtain data for the top 15 cm of soil. Indications are also obtainable by infra-red heat measurement. The following can be ascertained by visible and close infra-red range measurement : 1. organic matter content (Fig. 1), 2. roughness (Fig. 1) and 3. (Fig. 2). The 950 nm and 1150 nm bands should supply interesting results. Other factors can be detected by indirect methods. Factors connected with for example can be determined from morphology, surface and vegetation data. To understand the soil moisture dynamic system, one has to consider the following: a) Soil water supply b) Soil water losses c) Water retention by the Having carefully studied the above, one then considerations what teledetection could contribute for each. Soil stoniness, roughness and other factors also have to be taken into account. Soil can be interpreted in four stages related to the following : a) Soil water dynamics b) Estimated water storage c) Internal water circulation d) Soil water balance A partial model is constructed at each stage, the elements of which are questions which can almost invariably be answered by interpretation of relevant pictures and photographs. The models are run one after the other in order to successively integrate the static and dynamic aspects (models 1 and 2 respectively), then the spatial and temporal aspects (model 3 and water balance respectively). Using simple models, various states can be assessed in both time and space. To run such models, one requires the full set of teledetection data and a certain number of ground-based measurement data.

Intake of hay by cattle given supplements of barley subjected to various forms of physical treatment or treatment with alkali

SummaryVoluntary intake of hay by steers was measured when supplements of barley were given: (1) whole unprocessed, (2) NaOH treated, (3) torrified (infra-red heat treatment), (4) crimped, (5) rolled, (6) ground and (7) ground and pelleted. The cereal supplements were given at 50 g/kg live weight0·75/day. The voluntary intakes of hay dry matter were 42·1, 43·0, 38·1, 35·1, 34·9, 34·4 and 30·5 g/kg W0·75/day respectively.Dry-matter digestibilities of barley given without hay were (g/kg): whole, 672; NaOH treated, 807; torrified, 813 and rolled, 834.Incubation of feed samples in the rumen in polyester bags showed that rolled barley disappeared much more rapidly than NaOH treated and torrified barley.It is concluded that the deleterious effect of a cereal based supplement on rate of digestion of cellulose and consequently voluntary intake can be largely overcome by use of processing methods which reduce the rate of release of starch and yet ensure complete digestion. Treatment with NaOH looks promising in this respect.

Patient comfort and radiant ceiling heating in a hospital ward

An experimental survey of the limitations placed by patient comfort considerations on the size and surface temperature of infra-red ceiling heating panels in a hospital ward is described. It was found that at ceiling surface temperatures of up to 50°C patients suffered no additional discomfort with angle factors, based on a parallel planes measure, of up to 0.31 to the heated surface, and that at ceiling surface temperatures of up to 60°C angle factors of up to 0.12, where the air temperature was limited to 23°C, and of up to 0.31, where the air temperature was limited to 21°C, were permissible.

The thermoreculatory responses of the galago (Galago crassicaudatus), the baboon (Papio cynocephalus) and the chimpanzee (Pan stayrus) to heat stress.

1. The thermoregulatory response of the galago, the baboon and the chimpanzee were studied on exposure to dry bulb temperatures of up to 40 degrees C in a temperature controlled room. 2. Heat exposure caused an elevation in the respiratory frequency of all three species. The increase in the galago was significantly greater than that in the baboon and the chimpanzee. 3. Heat exposure also caused an increase in the cutaneous moisture loss of the baboon and the chimpanzee but not in the galago. 4. Rectal temperatures always rose on heat exposure but the animals never become hypethermic. 5. Sweat gland activity in the baboon and the chimpanzee was stimulated by the administration of acetylcholine and was blocked by the administration of atropine. Sympathetic and parasympathetic drugs had no stimulatory effect on the sueat glands of the galago. 6. Local, infra-red heating of the skin of the galago and the baboon did not stimulate any sweat gland activity. 7. The sweat glands in the galago and the baboon were found to be epitrichial. 8. These findings are discussed in relation to the habitat of each species. They are also compared to thermoregulation in other primate species, especially in relation to the unique nature of thermoregulation in man.

Gold reflectors in infra-red heating

Heating by means of medium wave or short wave infra-red radiation is an essential feature of a wide variety of industrial processes. Its applications are to be found, for example, in the textile and papermaking industries, in printing, in the manufacture of plastics and of laminated glass, and in cooking and the drying of foodstuffs. Generally it is used with most effect in conveyor type ovens where continuous processing is involved and where poorly conducting materials are to be heated rapidly. The high temperature source employed is either a tungsten filament operating at around 2200°C—for short wave—or a nickel-chromium spiral filament running at 800°C or over for medium wave heating. In either case the filament is enclosed in a tubular envelope of quartz glass, a material which will withstand the high temperature and which is also transparent to infra-red. The envelope thus remains relatively cool and so minimises the loss of radiant heat to the surrounding atmosphere. This type of construction provides a simple and compact unit giving rapid heating and cooling times with ease of maintenance. In many cases these infra-red units are located above the material to be heated, and an efficient means of reflecting the heat must be employed. While external reflectors can be arranged, an improved technique recently developed involves applying a conventional gold coating to the reverse side of the quartz glass envelope. This gives a highly efficient reflector for infra-red, more than 99 per cent, particularly when employed in the form of twin tubes. Improved performance and of course the permanent maintenance of the high reflecting gold surface are ensured since it is not directly exposed to possibly unclean environments. For a more detailed account of the fundamentals of infra-red heating and of the types of equipment available an earlier paper by the writer may be found useful (Electrical Review, 1974, 194, (22), 681-684).