Working principle of semiconductor refrigeration sheet
In principle, the semiconductor chip is a heat transfer tool. When an electric current flows through a thermocouple formed by an N-type semiconductor material and a P-type semiconductor material, heat transfer occurs between the two ends. Heat is transferred from one end to the other, resulting in a temperature difference forming the hot and cold ends. But the semiconductor itself has resistance and when current passes through the semiconductor it creates heat, which affects heat transfer. The heat between the plates is also transferred in reverse through the air and the semiconductor material itself. When the cold and hot ends reach a certain temperature difference and the amount of the two kinds of heat transfer is equal, a balance point will be reached, and the forward and reverse heat transfer cancel each other. At this point, the temperature of the hot and cold ends will not continue to change. In order to achieve lower temperature, heat dissipation and other ways to reduce the temperature of the hot end to achieve.
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The function of fans and heat sink is mainly to cool the hot end of the cooling plate. Usually the temperature difference between the hot and cold end of the semiconductor refrigeration sheet can reach 40 to 65 degrees, if the way to reduce the hot end temperature through active heat dissipation, the cold end temperature will decrease accordingly, so as to achieve a lower temperature.
When a piece of N-type semiconductor material and a piece of P-type semiconductor material connected into a pair, in this circuit after the DC current, can produce the transfer of energy, current from the N-type element to the p-type element of the joint to absorb heat, become a cold end; Heat is released from the p-type element to the joint of the N-type element and becomes the hot end. The magnitude of endothermic and exothermic heat is determined by the magnitude of the current and the logarithm of the semiconductor material N and P. The following three points are the thermoelectric effects of thermoelectric refrigeration.
In 1822, German Sebeck discovered that when two different conductors are connected, if the two connecting points maintain different temperature differences, a temperature difference electromotive force is generated in the conductor: ES=S.△T in the formula: ES is the temperature difference electromotive force, S is the temperature difference electromotive force rate (Sebeck coefficient), △T is the temperature difference between the contacts.
The Peltier effect
In 1834, The French polter discovered the opposite effect of seebeck effect, that is, when a current flows through a junction formed by two different conductors, there will be exothermic and endothermic phenomena at the junction. The exothermic or endothermic phenomena are determined by the size of the current.
Q л л. = I л = aTc
Where Qπ is the exothermic or endothermic power, π is the proportional coefficient, known as the Pelter coefficient, I is the operating current, A is the electromotive force rate of the temperature difference, Tc is the temperature of the cold contact.
When a current flows through a conductor with a temperature gradient, in addition to the joule heat generated by the resistance of the conductor, the conductor also emits or absorbs heat. Between two points of the conductor with a temperature difference of △T, the heat released or absorbed is: Qτ=τ
Advantages and disadvantages of semiconductor refrigeration chip radiator
When the current flows from N through P, the electric field causes the electrons in N and the holes in P to flow in opposite directions. The energy they generate comes from the thermal energy of the crystal tube, thus absorbing heat on the guide plate and releasing heat at the other end, resulting in a temperature difference "-- this is the principle of semiconductor refrigeration.
Advantages: can make the temperature to a very ideal room temperature below; And the temperature can be accurately adjusted by using closed-loop temperature control circuit, the highest temperature can be accurate to 0.1 degree; High reliability, the use of solid device cooling, CPU will not wear; Long service life.
Disadvantages: There may be condensation around the CPU, which may cause a short circuit on the mainboard. Installation is difficult and requires some knowledge of electronics. The safer method is to make the cold side of the semiconductor cooler work at about 20℃
Semiconductor refrigeration chip power
The power of a single refrigeration component of a semiconductor refrigeration piece is very small, but combined into a pile, with the same type of pile series, parallel method combined into a refrigeration system, the power can be done very large, so the refrigeration power can be done in the range of several milliwatts to tens of thousands of watts.