Electrolytic refining of lead in molten chloride electrolytes

Three types of antimony and bismuth electrolytic cells to be used for lead electrorefining were developed and tested. The electrolytic cell with the bipolar metallic electrode, the electrolytic cell with two anodes and one cathode, and the electrolytic cell with the porous diaphragm were studied. The tests demonstrated that lead is effectively separated from the metallic impurities in all constructions. Grade lead may be obtained at the cathode, and lead-antimony and lead-bismuth alloys may be produced at the anode. The electrolytic cell with a porous diaphragm was found to double the production rate and greatly decrease the electrical potential of the cell as compared to the other two constructions. © IJTech 2017

Interaction between UN and CdCl2 in molten LiCl-KCl eutectic. I. Experiment at 773 K

The interaction between UN and CdCl2 in the LiCl-KCl molten eutectic was studied at 773 K. The reaction was controlled by sampling the melt, as well as by analysis of the resulting precipitate. The process was shown to proceed according to several parallel reactions. The summary reaction was determined to have two stages: a fast one and a slow one. The 19–53% UN → UCl3 conversion was obtained for the molar ratio of CdCl2/UN = 1.22–14.9. The rest of UN converts into the precipitate of complex composition (UNCl + U2N3 + U4N7 + UN2). The increase in the CdCl2/UN molar ratio from 1.22 to 14.9 resulted in the decrease in duration of the first “fast” stage of the process from 18 h to 1 h. © 201

Interaction between UN and CdCl2 in Molten LiCl–KCl Eutectic. II. Experiment at 1023 K

The interaction between UN and CdCl2 in the LiCl–KCl molten eutectic was studied at 1023 K. The chlorination was monitored by sampling and recording the redox potential of the medium. At 1023 K the chlorination of UN with cadmium chloride in the molten LiCl–KCl eutectic proceeds completely and results in the formation of uranium chlorides. The melts of the LiCl–KCl–UCl3 or LiCl–KCl–UCl4 compositions can be obtained by the end of experiment depending on the presence of metallic cadmium in the reaction zone. The higher the concentration of the chlorinating agent, the faster the reaction rate. At [CdCl2]/[UN] = 1.65 (10% excess) the reaction proceeds to completion in about 7.5 h. At [CdCl2]/[UN] = 7 the complete chlorination takes 2.5–3 h. © 2021.The authors gratefully acknowledge for analytical support of the Shared Access Centre "Composition of Compounds" of the Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences. The present research was partially performed within the Proryv (Breakthrough) project of State Atomic Energy Corporation Rosatom

Analysis of Relationship Between the Dynamics of a Thermoelectric Cooler and Its Design and Modes of Operation

We examined a dynamic model of the relationship between basic parameters and indicators of reliability, taking into consideration the structural and technological elements, for a single-stage cooling device under various current modes of operation, thermal load at a temperature difference of 40 K. The ratios derived allow us to define the time required for a single-stage of thermoelectric cooling device to enter a stationary mode of operation, and the temperature of a heat-absorbing junction. The dependences take into consideration values of a thermal load, the number of thermoelements, current mode of operation, with respect to both the mass and heat capacity of the object, and the mass and heat capacity of structural and technological elements at heat-absorbing junctions of the module. It was found that the heat capacity and mass of structural and technological elements of the module affect not only the time required to enter a stationary mode, but the device's reliability indicators, reducing them by 2‒3 times. The results of analysis of dynamic characteristics and energy indicators of a single-stage thermoelectric cooler demonstrated the possibility to control the time required to enter a stationary mode. Structural control, enabled by selecting the number and geometry of the cooler's thermoelements, and the mass and heat capacity of the load, makes it possible to reduce the time required for a thermoelectric cooling device to enter a stationary mode by up to 2.5 times. Operational control, executed by changing working current of the cooler, makes it possible to reduce the time required to enter a stationary mode by up to 3 times

Determination of the Maximum Cooling Capacities of Two-stage Coolers with a Variation in the Geometry of Branches in Stages

A model of the relationship between the reliability indices of two-stage TECs of various designs with the geometry of the branches of thermoelements in cascades in the ΔTmax mode with electrical series of cascades (stages) is proposed and analyzed. Relations are obtained for determining the optimal geometry of the branches of thermoelements in cascades corresponding to the maximum temperature difference. The expression allows to estimate both the maximum cooling capacities and the reliability indices of two-stage thermoelectric cooling devices of various designs. The possibility of increasing the maximum temperature drop to 4 % is shown by choosing the optimal geometry of the branches of thermoelements in cascades (stages). This is achieved under the condition that the ratio of the length to the cross-sectional area of the elements of the first stage is greater than the ratio of the length to the cross-sectional area of the second stage, which differs from the traditional equality of these ratios for a given working current. The proposed approach makes it possible to estimate the maximum temperature drop and to predict the reliability indices of two-stage thermoelectric coolers of various designs for various operating conditions and to conduct an optimized design of radio electronic equipment using cascade thermoelectric cooling devices

Developing A Model to Control the Thermal Mode of Thermoelectric Cooling Devices by Minimizing the Set of Three Basic Parameters

The systems maintaining thermal regimes are a necessary component of thermally-loaded radio-electronic equipment, without which its operation is impossible. The uneven distribution of heat emitted by components such as semiconductor lasers, receivers of intense infrared radiation predetermines the preference of thermoelectric coolers for them. The joint application of a cooler and a heat-loaded element significantly tightens the requirements for the reliability indicators and the dynamic characteristics of the cooler. The cause is the influence exerted by the temperature gradients in the soldered joints between different materials of thermoelements and the electrode of the substrate. The main parameters of thermoelectric coolers are the number of thermoelements and the value of the working current. When targeting the design of thermoelectric systems for ensuring thermal regimes based on reliability indicators, the optimization of the problem for the following set has been proposed: the number of thermoelements, the working current, and the relative intensity of failures. At the fixed branches' geometry, decreasing the number of thermoelements leads to a decrease in the heat load, which can be compensated for by increasing the working current of the thermoelectric cooler. A ratio has been derived for the relative working current corresponding to the minimum size of the set. Using the set makes it possible to choose the required working current, for which there is an extremum, which optimizes the process of control over the cooler. The win in the refrigeration factor, compared to the mode of maximum cooling capacity, is 15 %. This demonstrates the advantage of a comprehensive indicator, which allows the development of systems enabling thermal modes for practical application, in particular, on-board systems for which energy consumption is critical. The originality of the results obtained is related to a comprehensive criterion for the basic performance indicators, which has a minimu

Developing A Model to Control the Thermal Mode of Thermoelectric Cooling Devices by Minimizing the Set of Three Basic Parameters

The systems maintaining thermal regimes are a necessary component of thermally-loaded radio-electronic equipment, without which its operation is impossible. The uneven distribution of heat emitted by components such as semiconductor lasers, receivers of intense infrared radiation predetermines the preference of thermoelectric coolers for them. The joint application of a cooler and a heat-loaded element significantly tightens the requirements for the reliability indicators and the dynamic characteristics of the cooler. The cause is the influence exerted by the temperature gradients in the soldered joints between different materials of thermoelements and the electrode of the substrate. The main parameters of thermoelectric coolers are the number of thermoelements and the value of the working current. When targeting the design of thermoelectric systems for ensuring thermal regimes based on reliability indicators, the optimization of the problem for the following set has been proposed: the number of thermoelements, the working current, and the relative intensity of failures. At the fixed branches' geometry, decreasing the number of thermoelements leads to a decrease in the heat load, which can be compensated for by increasing the working current of the thermoelectric cooler. A ratio has been derived for the relative working current corresponding to the minimum size of the set. Using the set makes it possible to choose the required working current, for which there is an extremum, which optimizes the process of control over the cooler. The win in the refrigeration factor, compared to the mode of maximum cooling capacity, is 15 %. This demonstrates the advantage of a comprehensive indicator, which allows the development of systems enabling thermal modes for practical application, in particular, on-board systems for which energy consumption is critical. The originality of the results obtained is related to a comprehensive criterion for the basic performance indicators, which has a minimu