OPTIMIZATION OF THE DRYING PROCESS GRAIN CROP IN A TUMBLE DRYER WITH HEAT PUMP

Рассмотрена возможность автоматической оптимизации процесса сушки зернобобовых культур в барабанной сушилке с парокомпрессионным тепловым насосом по технико-экономическому показателю при выполнении ограничений на качество готового продукта. В качестве критерия оптимизации использованы суммарные энергетические затраты, приходящиеся на единицу массы испаряемой влаги. Определены три составляющие числителя критерия оптимизации: затраты на преодоление аэродинамического сопротивления слоя продукта в барабанной сушилке, затраты электроэнергии на привод компрессора парокомпрессионного теплового насоса (ТНУ), привод вращения барабана. Затраты электроэнергии на привод компрессора рассчитывали через холодопроизводительность ТНУ. Установлена зависимость разности влагосодержаний сушильного агента до сушки и после нее от степени заполнения сушильного барабана зернистым продуктом при различных значениях его начальной влажности. Получена однозначная функциональная связь суммарных энергетических затрат, приходящихся на единицу массы испаряемой влаги от степени заполнения барабана. На примере сушки зерна пшеницы в барабанной сушилке с профильной канальной насадкой, укомплектованной парокомпрессионным тепловым насосом, показана возможность управления степенью заполнения барабана по минимальной величине удельных энергетических затрат. Сочетанием экспериментальных и аналитических методов исследования разработана система экстремального управления процессом сушки зерна в барабанной сушилке с тепловым насосом, позволяющая с помощью микропроцессора осуществлять оперативный поиск оптимального значения степени заполнения барабана, что существенно снизит удельные энергозатраты на процесс сушки. При этом по текущей информации, получаемой с датчиков, микропроцессор непрерывно вырабатывает сигнал отклонения текущего значения степени заполнения от оптимального и посредством исполнительного механизма воздействует на расход влажного зерна, а следовательно, и на степень заполнения барабана продуктом, так чтобы суммарная удельная мощность энергооборудования для выбранного режима сушки была бы минимальной. Для многозонной барабанной сушилки предложенный алгоритм управления необходимо повторять для каждой из зон, в которых степень заполнения регулируется с помощью секторных заслонок. The possibility of automatic optimization of the drying process of legumes in a tumble dryer with a steam compression heat pump according to the technical and economic indicator when the quality of the finished product is limited. As an optimization criterion, the total energy costs per unit mass of evaporated moisture. Three components of the numerator of the optimization criterion are determined: the costs of overcoming the aerodynamic resistance of the product layer in the drum dryer, power consumption for the compressor drive of a steam compression heat pump (HPI), drum rotation drive. The energy costs for the compressor drive were calculated through the cooling capacity of the HPI. The dependence the difference in the moisture content of the drying agent before and after drying on the degree of filling the drying drum with a granular product is established for different values its initial humidity. An unambiguous functional relationship between the total energy costs per unit mass of evaporated moisture, the degree filling the drum. On the example wheat grain drying in a drum drier with a profile channel nozzle equipped with a steam compression heat pump, it is shown that it is possible to control the degree of filling of the drum by the minimum value of the specific energy costs. A combination experimental and analytical research methods developed a system for extreme control of the drying process grain in a drum dryer with a heat pump, allowing using the microprocessor to perform an operative search for the optimal degree of filling of the drum, which will significantly reduce the specific energy consumption for the drying process. At the same time, according to the current information received from the sensors, the microprocessor continuously generates a signal of deviation of the current value the filling degree from the optimal one and by means of the actuator it affects the consumption wet grain, and consequently, the degree of filling of the drum with the product, so that the total specific power of the power equipment for the selected drying regime would be minimal. For a multi-zone drum dryer, the proposed control algorithm must be repeated for each zone in which the degree of filling is controlled by sectoral dampers.

Researches about the Dynamic Behavior of Green Composites Reinforced with Rush and Bulrush

The paper presents some researches about the dynamic mechanical properties for some green composites made as follows: the reinforcement is made from rush and bulrush and the matrix is from epoxy resin Resoltech 1050 with its hardener Resoltech 1055. The dynamic parameters were determined from the bars free vibrations. In the first part of the paper, there are presented the mathematical calculus formulas used for the dynamic parameters determination based on the experimental recordings for the free vibrations. The next experimental montage was used: the bars were clamped at one end and were left free at the other end. At the free end, a Bruel&Kjaer accelerometer with 0.04 pC/ms-2 sensitivity was placed in order to record the beams dynamic response. A force was applied at the free end to bend the beams and after bending, the force was cancelled and the beams were left to freely vibrate. The accelerometer was connected to a signal conditioner Nexus and the signal conditioner was connected to a data acquisition system SPIDER 8 made by Hottinger Baldwin Messtec. The acquisition system was connected to a notebook ant the experimental parameters were obtained through CATMAN EASY software. From the free vibrations recording, the following mechanical parameters were determined: the eigenfrequency of the first eigenmode and the damping factors per unit mass. With these values, we have determined some direct calculus formulas for the damping factor per unit mass.

Pengaruh Suhu dan Kelembaban Terhadap Rasio Kelembaban dan Entalpi (Studi Kasus: Gedung UNIFA Makassar)

Temperature affects humidity. The interaction of temperature and humidity also directly affects the health and well-being of humans. The relative humidity (RH) of the air is an indication of how much water vapor is in the air at a particular temperature compared with how much water vapor the air could actually hold at that temperature. Air at 100 % relative humidity holds the maximum amount of water possible at that particular temperature and is said to be saturated. Therefore, air at 50% relative humidity, regardless of temperature, is holding half of its total possible water capacity. In essence, cold air cannot hold as much water vapor as warm air. In a closed environment such as a display case, there will be a fixed amount of water vapor, referred to as the absolute humidity. If the temperature inside the case falls then the relative humidity will rise. If the temperature rises the relative humidity will fall. Such changes in relative humidity could be caused by many factors including direct sunlight, spotlights and air-conditioning failures. Research carried out by experimental studies that we can get the humidity ratio and specific enthalpy in a kind of rooms either using The Psychrometric Chart and The formula. The specific humidity or humidity ratio of an air sample is the ratio of the weight of water vapor contained in the sample compared to the weight of the dry air in the same sample. Enthalpy is the amount of heat (energy) in the air per unit mass. Enthalpy is the total amount of energy present in the air, both from air and water vapor contained therein. And, Specific enthalpy of moist air is defined as the total enthalpy of the dry air and the water vapor mixture - per unit mass of dry air. Keywords: Temperature; Relative Humidity; Humidity Ratio; Specific Enthalpy.

Some physical properties of kariya (Hildegardia barteri) nut/ kernel relevant to the design of its processing equipment

Kariya kernel is very rich in essential fats, oils and other valuable nutrients which may find applications in many food formulations. To harness these nutrients, processing equipment and machines are to be used. In order to effectively design these machines, the values of some physical properties of kariya nut and kernel are needed. In this study, some physical properties of the kariya nut and kernel were investigated. Results showed that mean major diameter, intermediate diameter, minor diameter and unit mass obtained at the nut moisture content of 19.83 ± 3.71 (w.b.) were 14.16 ± 0.79 mm, 10.17 ± 0.36 mm, 9.78 ± 0.28 mm and 0.503 ± 0.05g, respectively while the corresponding values obtained at the kernel moisture content of 8.89 ± 2.22% (w.b.) were 9.07 ±0.72 mm, 7.32 ±0.49 mm, 7.08 ± 0.41 mm and 0.328 ± 0.03 g, respectively. The values of calculated geometric mean diameter were 11.20 ±mm and 7.77 ± 0.36 mm, for the kariya nut and kernel, respectively. The skewness value of the sample distribution of 0.08 and -0.24 were recorded for the kariya nut and kernel, respectively. The sphericity, surface area, volume, density, bulk density and porosity were 79.27 ± 3.07%, 394.75 23.13 mm2, 738.37 ± 64.96 mm3 , 681.1 ± 20 kg/m3, 440.24 ± 0.04 kg/m3 and 36.65 ± 0.74% ; and 85.97 ± 5.27%, 189.85 ± 17.34 mm2, 246.71 ± 33.60 mm3, 1342.1 ± 136.23 kg/m3, 773.06 ± 0.06 kg/m3 and 42.28 ± 4.10% for the kariya nut and kernel respectively.

Black liquor evaporator upgrades— life cycle cost analysis

Black liquor evaporation is generally the most energy intensive unit operation in a pulp and paper manufacturing facility. The black liquor evaporators can represent a third or more of the total mill steam usage, followed by the paper machine and digester. Evaporator steam economy is defined as the unit mass of steam required to evaporate a unit mass of water from black liquor (i.e., lb/lb or kg/kg.) The economy is determined by the number of effects in an evaporator train and the system configuration. Older systems use four to six effects, most of which are the long tube vertical rising film type. Newer systems may be designed with seven or even eight effects using falling film and forced circulation crystallization technology for high product solids. The median age of all North American evaporator systems is 44 years. Roughly 25% of the current North American operating systems are 54 years or older. Older systems require more periodic maintenance and have a higher risk of unplanned downtime. Also, older systems have chronic issues with persistent liquor and vapor leaks, shell wall thinning, corrosion, and plugged tubes. Often these issues worsen to the point of requiring rebuild or replacement. When considering the age, technology, and lower efficiency of older systems, a major rebuild or new system may be warranted. The intent of this paper is to review the current state of black liquor evaporator systems in North America and present a basic method for determining whether a major rebuild or new installation is warranted using total life cycle cost analysis (LCCA).

Quantitative Characterization of Shale Porosities of Different Origins by Integrating Pore Genesis and Logging Analysis

In this paper, a new and pragmatic technique has been developed to identify pore types and characterize porosities of shales with various origins. By comparing the genesis of pore types (i.e., organic, brittle, and clay mineral porosities) in shales, the corresponding pore volumes per unit mass are determined as a function of the total porosity, density and the content of each pore type from core samples. Subsequently, a new inverse framework was proposed and successfully applied to quantify different types of porosities in the Silurian Longmaxi formation shale in the Zhaotong area. The pore volume per unit mass of organic matter is calculated to be around 0.185-0.190 cm3/g, which is 10-21 and 8-19 times more than that of brittle mineral and clay mineral, respectively, indicating that pore space of organic matter contributes greater to the total porosity than that of the clay and brittle minerals. Using single well data, the porosity in organic matter is found to follow the same pattern as the total porosity in the vertical direction. Such an identified porosity type leads to more accurate sweet spots as well as more appropriate drilling locations for horizontal wells in shale reservoirs.

Heat of Combustion of Coffee Pulp and Husks as Alternative Sources of Renewable Energy

The study determined the amount of heat energy (heat of combustion) produced per unit mass from coffee pulp and coffee husks to see if these can be used as alternative sources of energy. The samples were obtained from Mount Elgon areas in Eastern Uganda. The objectives determined the amount of heat produced per unit mass from coffee husk and pulp and compared the amount of heat produced per unit mass from the coffee husk and coffee pulp. The coffee husk and pulp were dried, ground and sieved using a 150 microns diameter sieve. The resultant powder was analyzed using IKA C200 bomb calorimeter. The Heat values produced per unit mass from coffee husk and pulp were 15.389KJg-1 and 13.755KJg-1 respectively. Further analysis showed that both coffee pulp and coffee husks could be used as fuels for renewable energy. However, from the findings, it is recommended that coffee husks should be preferred as a better source of fuel since it generated 1.634KJg-1 more energy than the coffee pulp. Comprehensive study should be carried out on the two samples to obtain a complete fuel description of the samples.

Small nutation of a symmetic gyroscope: two viewpoints

The paper is devoted to the small nutation of an axisymmetric gyroscope in the field of gravity. The expansion of the known solution of the nutation equation as a function of time in powers of the amplitude is obtained. In this case, the frequencies of third order Raman oscillations are both the tripled frequency and the frequency coinciding with the initial one. A formula is found for the nutation amplitude as a function of the integrals of the gyroscope motion. The frequency of zero nutation is also calculated. Another way to obtain the decomposition is to use the results of the general theory of free one-dimensional oscillations. This method is based on the ability to represent the gyro nutation as the movement of a material point of unit mass in a field that cubically-quadratically depends on the coordinate. In this case the only frequency of the third-order Raman oscillation is a triple of the original frequency. Thus, both methods give the same result only for oscillations no higher than second order. In the third approximation, the existing theory of oscillations is insufficient.

Comparative Exergy Analysis of Units for the Porous Ammonium Nitrate Granulation

The article deals with the study on the efficiency of units for porous ammonium nitrate production. The ways which increase the effective implementation of energy resources are determined by including the ejector recycling module, heat and mass exchangers that utilize principles of regenerative indirect evaporative cooling, and the sub-atmospheric inverse Brayton cycle. Mixed exergy analysis evaluates all flows of the system contour as those of the same value. The target parameter for determining the efficiency of both systems is the ratio of the unit’s productivity to the exergy expenditures to produce the unit mass of the product. As a result, it is found that the mentioned devices and units enable to increase the efficiency of the basic scheme by 87%.

Total, average and marginal rates of basal heat production during human growth

<abstract> <p>Our goal was to examine how total, average (heat production rate per unit mass) and marginal (the increase in the heat production rate per unit increase in mass) rates of basal heat production changed as mass increased in growing humans. Specifically, our hypotheses were that the marginal basal heat production rate did not decrease monotonically as humans grew; and that an energetically optimal mass, one at which the average basal heat production rate of a growing human was minimal, existed. Marginal rates of heat production were estimated and six potential models to describe the effect of mass during human growth on basal heat production rate were evaluated using a large, meticulously curated, dataset from the literature. Marginal rates of heat production were quadratically related to body mass during growth; they declined initially, reached a minimum, and then increased. This suggested that the relationship between basal heat production rate and mass was cubic. Of the six potential models evaluated, a three-parameter cubic polynomial best described the data. Marginal rates of heat production were minimal for 56-kg females and 62-kg males. Basal heat production rates per unit mass of a growing human were minimal (i.e., energetically optimal) for 83-kg females and 93-kg males; the average masses of U.S. adults have been increasing and approaching these optima over the last 60 yr.</p> </abstract>