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The main working media in adsorption refrigerators are the adsorbent (carbon) and the coolant. In connection with this, it is necessary to know the physical characteristics of adsorbents to determine the operating parameters of such refrigerators. A method of determining the physical characteristics of adsorbents was presented in [1 ].An adsorbent is fully characterized by the following physical parameters: the true and apparent unit masses, porosity, the total volume of the pores [1]. These parameters must be known in order to correctly choose an adsorbent and to calculate the amount of adsorbent needed to absorb a given substance. Here, we propose a method of determining the apparent unit mass of an adsorbent.By the true unit mass d of an adsorbent, we mean the mass of a unit of volume of the dense (nonporous) material comprising the adsorbent. The value of d is determined pycnometrically. A pycnometer with a capacity of 25-100 ml is weighed on an analytical balance (m t is the mass of the pycnometer when it is empty). Then the pycnometer is filled to the mark with distilled water (it is preferable to use distilled water that has just cooled after being thoroughly boiled) and weighed (m 2 is the mass of the pycnometer with the water). The water is then poured out and the pycnometer is dried and again weighed: its mass should be equal to m 1.The adsorbent (1-5 g) is poured into the pycnometer and weighed (m 3 is the mass of the pycnometer with the adsorbent). The pycnometer is filled with water to roughly half its volume and the contents of the pycnometer are boiled for 1 h to remove air from the pores. The boiled water is allowed to cool, and then distilled water is poured in to a point slightly above the mark. The pycnometer is placed in a thermostat with a temperature of 20~ and kept there for 30--40 rain. Without removing the pycnometer from the thermostat, the water level is brought up to the mark and the weight is determined (m4).The volume v I of the weighed quantity of adsorbent is equal to the volume of the displaced water:where (m 2 -m 1) is the mass of the water in the pycnometer, g (kg); (m 4 -m 3) is the mass of the water in the pycnometer without the adsorbent, g (kg); p is the density of the water at the test temperature, ffcm 3 (k~m3).The true unit mass is calculated from the formula d = (m 3-ml)/V 1, where (m 3 -ml) is the mass of the adsorbent in the pycnometer.The apparent unit mass of the adsorbent ~ is the mass of a unit of volume of the porous material comprising the adsorbent.To determine 5, a weighed quantity of adsorbent having the mass m 5 is placed on a wire grid and lowered into melted paraffin. To remove excess paraffin from the outside surface, the grid is extracted from the paraffin and placed in a funnel for hot filtration. After the adsorbent and paraffin have cooled, they are placed in the pycnometer and the pycnometer is weighed (the mass m6). The remaining paraffin completely obstructs the pores of the adsorbent. It is assumed that the volume of the grains of the adsorbent rem...

Рассматривается распределенная система контроля технологических объектов нефтегазо-вой промышленности на базе беспроводной сенсорной сети. Проведено исследование суще-ствующих систем мониторинга. Отмечается, что ввиду ряда недостатков эти системы не обеспечивают должного уровня надежности. Приведены принципы проектирования структуры сенсорной телекоммуникационной системы, которая является оптимальным ва-риантом для предприятий газотранспортной отрасли. Предложены варианты построения распределенных систем контроля утечек газа линейных участков магистрали на базе раз-личных технологий беспроводных сенсорных сетей. Рассматривается сенсорная сеть на базе технологии ZigBee. Для расчета затухания сигнала беспроводной сенсорной сети при разном значении высоты подвеса (подъема) антенны использовалась модель Окамуры. Определено количество датчиков, необходимых для построения надежной сенсорной сети.Ключевые слова: магистральный газопровод, датчик, беспроводная сенсорная сеть, за-тухание сигнала, антенна, распределенная система контроля.

Performance of solar refrigerating units using ammonia, methylamine, ethylamine, dimethylamine, methanol, and ethanol as refrigerants (adsorbates) and activated carbon as adsorbents has been studied. A mathematical model has been built to determine the level of thermodynamic perfection based on simplified theoretical operation cycle and gradual integration of experimental and calculated values of daily variation of the key parameters of the refrigerating unit. A solar power unit where horizontal insolating tubes and plane mirror concentrators are used has been built and successfully tested.One way of utilizing solar energy (radiation) for refrigeration is to use ecologically safe solar adsorption refrigerating units (SARU).Operation of such units is based on the physical adsorption process in which the molecules of a gaseous refrigerant cluster up over the solid surface of the sorbent, followed by condensation, upon cooling, of the vapor of the refrigerant in the porous structure of the sorbent. This process is reversible, i.e., when heat energy is supplied, the refrigerant (adsorbate) is desorbed from the adsorbent.The flow diagram of the SARU does not differ from that of "dry" solar sorption units [1]. The presence of the solid sorbent predetermines the periodicity (cyclicity) of operation of such a unit. During the day, due to solar heating in the generator, the refrigerant is released (desorbed) from the saturated adsorbent and is accumulated in a receiver upon liquefaction in a condenser. During the night, the refrigerant is adsorbed as the adsorber cools off, whereupon cooling effect is produced in the evaporator.In the SARU, ammonia (NH 3 ), methylamine (CH 3 NH 2 ), ethylamine (C 2 H 5 NH 2 ), dimethylamine (CH 3 ) 2 NH, methanol (CH 3 OH), and ethanol (C 2 H 5 OH) can be used as refrigerants-adsorbates and activated carbon, as adsorbents.In the process of producing activated carbon, hydroxyl (-OH) and carboxyl (-COOH) groups may form on its surface, so the carbon may be both nonpolar and polar and exhibit properties of cations, anions, or ampholytes.The adsorbates containing electronegative elements (oxygen, nitrogen, etc.) may form associates (micelle) owing to formation of hydrogen bonds and the amine and alcohol molecules may exhibit diphilic properties due to polar functional groups (-NH 2 and -OH) and nonpolar radical (-R); the molecules of the surface-active substances may form associates depending on the polarity of the surrounding phase. Having dipole moments, the adsorbates also may form associates on account of electrostatic interaction of the dipoles [2].Based on their basicity strength, the adorbates can be arranged in the following order: C 2 H 5 NH 2 > (CH 3 ) 2 NH > > CH 3 NH 2 > NH 3 > C 2 H 5 OH > CH 3 OH.The base is an electron donor (nucleophile) [3]. Presence of carboxyl groups (-COOH) on the carbon surface facilitates formation of stronger bonds with strong bases.

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