Гибридные режимы работы термоэлектрических модулей

It is suggested that thermoelectric coolers designing should not be limited to the extreme modes of their operation. In some cases, it is convenient to use the so called hybrid modes - a combination of the extreme mode of maximum coefficient of performance for large temperature differences and a general cooling mode for small ones. The proposed hybrid mode makes it possible to control the cooling capacity of the module and not to confine this value to that under the extreme operating conditions, the maximum coefficient of performance in particular.

Method for increasing the dynamic characteristics of thermoelectric coolers

The influence of the efficiency of the initial thermoelectric materials on the dynamics of the functioning of the thermoelectric cooling device for various characteristic current modes of operation in the range of operating temperature drops and heat load at a given geometry of thermoelement legs is considered. The parameters of thermoelectric materials of thermoelements are conventionally divided into three groups: used for batch production, laboratory research and maximum values. The criterion for choosing the operating mode of the thermoelectric cooler takes into account the mutual influence and weight of each of the limiting factors. Since the design conditions can be very diverse, simultaneously varying several limiting factors (constructive, energy and reliability), you can choose the most rational mode of operation. The analysis was carried out for typical current modes of operation of thermoelectric coolers: maximum cooling capacity, maximum cooling capacity at a given current, maximum coefficient of performance, minimum failure rate. It is shown that with an increase in the efficiency of the initial thermoelectric materials, the time for reaching the stationary operating mode of the thermoelectric cooler, the required number of thermoelements, and the maximum temperature difference increase. A method is proposed for reducing the time constant of thermoelectric coolers due to the revealed relationship between the efficiency of thermoelectric materials and the dynamic characteristics of thermoelements. It is shown that an increase in the dynamic characteristics of thermoelectric coolers is achieved without changing the design documentation, manufacturing technology and additional climatic and mechanical testing of products.

Control of thermal regime of thermoelectric coolers in uniform temperature field

The comparative analysis of means of control of a thermal mode at minimization of a complex of the basic parameters in various combinations with indicators of reliability and dynamics of functioning of one-stage thermoelectric cooler is resulted. The study was conducted for the operating range of temperature differences, standard heat load and different geometry of the branches of thermocouples. According to the results of research to minimize the sets of basic parameters in interaction with the indicators of reliability and dynamics of work, a number of current modes of operation have been developed. The developed mathematical models for the optimal operating current from the relative temperature difference and heat transfer of the radiator for the proposed operating modes are analyzed. The results of calculations of the main parameters, reliability indicators, and time of transition to stationary mode of operation for different current modes of operation in the range of temperature differences for different geometry of branches of thermoelements are given. The extremes of dependences of the cooling coefficient, heat dissipation capacity of the radiator, the amount of energy consumed on the relative operating current are determined, which is essential for the implementation of the control function. The possibility of choosing the current mode of operation for optimal control of the thermal regime of single-stage thermoelectric devices manufactured by the same technology, taking into account mass, size, energy, reliability and dynamic characteristics. The developed method of optimal regulation of the thermal regime of a single-stage thermoelectric cooler based on minimizing the set of basic parameters allows finding and choosing compromise solutions taking into account the importance of each of the limiting factors.

Improving Heat Transfer from Peltier Devices Used in an Atmospheric Water Generation

Present Atmospheric Water Generation (AWG) systems are useful for providing water in areas with limited water supplies. Many industrial AWG systems use VCR (vapor-compression refrigeration) to achieve a large amount of cooling to extract liquid water out of the air. These systems require large amounts of energy to operate, usually in the form of diesel or AC-powered generators. The systems also have many moving parts that require maintenance and use refrigerants that can leak and cause problems with the environment. An alternative AWG solution is to use DC-powered Peltier devices (thermoelectric coolers) to reduce the temperature of condensation plates to extract water from the air. This solution eliminates the issues with traditional industrial AWG systems since the Peltier devices are solid-state, have very long mean-time between failure (MTBF) performance, and can be powered by solar panels that eliminate the need to burn hydrocarbon-based fuels or have access to a reliable power grid. Also eliminated is the need to use chlorofluorocarbon (CFC) or hydrochlorofluorocarbons (HCFC) refrigerants that have been shown to deplete the ozone layer. This paper will present methods to improve the efficiency of the thermoelectric coolers by more efficiently extracting heat from the hot side of the device. This efficiency will be quantified by evaluating the coefficient of performance (COP) of the thermoelectric cooler under the various operating conditions. Different combinations of conductive heat transfer using aluminium heatsinks, convection heat transfer using forced airflow, and phase change heat transfer using copper heat pipes filled with distilled water will be investigated and evaluated.

Features of Designing Computer Control Systems for Precision Thermoelectric Coolers

An effective electrical circuit and an operating algorithm have been developed, and a working sample of a thermoelectric precision thermostat has been designed with the possibility of autonomous operation, continuous monitoring and recording of the temperature log using a computer or smartphone. It is shown that the developed algorithm provides effective shockless control and an accuracy of maintaining the temperature of 0.03°C, with a power consumption of 3-7 W. A design and a specialized computer control system for a multistage cryogenic thermoelectric cooler have been developed.