Solar cooling has a good seasonal match, that is, the hotter the weather, the better the solar radiation, the greater the cooling capacity of the system. This feature has made solar refrigeration technology a priority and development. The realization of solar cooling has "light-heat-cold", "light-electric-cold", "light-heat-electric-cold" and other ways. Solar semiconductor refrigeration is a special refrigeration method that uses the electric energy generated by solar cells to drive a semiconductor refrigeration device to realize thermal energy transfer. The working principle is mainly photovoltaic effect and Peltier effect. The solar-powered semiconductor refrigeration system is compact and easy to carry, and can be made into a miniaturized special refrigeration device according to user needs. It has the characteristics of simple use and maintenance, good safety performance, distributable power supply, convenient storage and no environmental pollution. In addition, the semiconductor refrigeration system using the Peltier effect does not require moving parts such as pumps and compressors as compared with general mechanical refrigeration, so there is no wear and noise. It does not require a refrigerant, so it does not cause environmental pollution, and it also eliminates complicated transmission lines. It simply switches the current direction to change the system from a cooling state to a heating state. These unparalleled advantages have led to a strong interest in solar semiconductor refrigeration technology. At present, the efficiency of solar semiconductor refrigeration systems is still relatively low, and some important technical problems of the system have yet to be further studied. 1 Working principle and basic structure of solar semiconductor refrigeration Semiconductor refrigeration is a kind of refrigeration method that utilizes the thermoelectric refrigeration effect, so it is also called thermoelectric refrigeration or thermoelectric cooling. The basic component of a semiconductor refrigerator is a thermocouple pair, that is, a thermocouple in which a p-type semiconductor element and an n-type semiconductor element are connected. When the DC power is turned on, the current direction of the upper connector is np, the temperature is lowered, and the heat is absorbed to form a cold end; the current direction of the lower joint is pn, the temperature rises, and the heat is released to form a hot end. Connecting a number of pairs of thermocouples constitutes a common thermopile. With the help of various heat transfer devices, the hot end of the thermopile is continuously dissipated and maintained at a certain temperature, and the cold end of the thermopile is placed in the working environment to be sucked. Heat, low temperature, this is the working principle of semiconductor refrigeration. The solar semiconductor refrigeration system utilizes the thermoelectric cooling effect of the semiconductor, and directly supplies the required direct current from the solar cell to achieve the effect of cooling and heating. The solar semiconductor refrigeration system consists of a solar photoelectric converter, a numerical control matcher, an energy storage device, and a semiconductor refrigeration device. The solar-to-electrical converter outputs DC power, one part is directly supplied to the semiconductor refrigeration unit, and the other part is stored in an energy storage device for use on a cloudy day or night, so that the system can operate normally around the clock. The solar photovoltaic converter can select a crystalline silicon solar cell or a nanocrystalline solar cell, and select the type of the solar cell according to the capacity of the refrigeration device. On a sunny day, a solar-to-electrical photoelectric converter converts solar radiant energy that illuminates its surface into electrical energy for use by the entire system. The CNC matcher keeps the energy transfer of the entire system in an optimal match. At the same time, the overcharge and overdischarge of the energy storage equipment are controlled. Energy storage equipment generally uses a battery, which stores some or all of the energy output from the photoelectric converter for use when the solar photoelectric converter has no output, thereby enabling the solar semiconductor refrigeration system to operate around the clock. 2 Key issues in solar semiconductor refrigeration The biggest shortcoming of solar refrigeration systems is the low cooling efficiency and high cost. This has seriously affected the promotion and application of solar refrigeration systems. If you improve and improve the performance of solar refrigeration systems, you should start with the following key issues. (1) Improve the performance of semiconductor refrigeration materials The core of the solar semiconductor refrigeration system lies in the semiconductor refrigeration material. The main reason for the low efficiency of the semiconductor refrigeration system is that the thermoelectric conversion efficiency of the semiconductor refrigeration material is not high. The final decision on the performance of thermoelectric materials is the figure of merit Z. Where: the Seebeck coefficient of the α-semiconductor refrigeration element; R—the resistance of the refrigeration component; Kt—The thermal conductivity of the cooling element. The product ZT of the figure of merit Z and the temperature T is a common parameter for evaluating the properties of a material. As far as semiconductor refrigeration is concerned, if its refrigeration performance is comparable to that of mechanical refrigeration, the dimensionless parameter ZT should reach 3 or more. At present, semiconductor materials commonly used in various countries are far from this level. The most commonly used thermoelectric material (Bi-Sb-Te-Se series solid solution) at room temperature has a ZT value of about 1. Therefore, how to improve the performance of materials and find more ideal materials has become an important issue in solar semiconductor refrigeration. (2) Energy optimization of the system The solar semiconductor refrigeration system itself has energy loss. How to reduce these losses and ensure the stable and reliable operation of the system is an important issue. Photoelectric conversion efficiency and refrigeration efficiency are the main indicators for measuring energy loss. The higher the photoelectric efficiency, the smaller the area of ​​the solar cell required in the case of the same power output, which contributes to the miniaturization of the solar semiconductor refrigeration system. The solar cells currently in common use have a photoelectric efficiency of up to 17%. The cooling efficiency COP is the most important operating parameter for any refrigeration system. At present, the COP of a semiconductor refrigeration device is generally about 0.2 to 0.3, which is much lower than that of compression refrigeration. The experimental study found that the temperature difference between the cold and the hot end has a great influence on the efficiency of semiconductor refrigeration. The performance of the semiconductor refrigeration system can be greatly improved by strengthening the heat dissipation method at the hot end. Hall Voltage Sensor,Hall Effect Voltage Sensor,Open Loop Voltage Sensor,Open Loop Hall Voltage Sensor Zibo Tongyue Electronics Co., Ltd , https://www.tongyueelectron.com