Introduce the principle of refrigeration tablets:
Thermoelectric cooling thermoelectric effect is the Peltier effect is mainly used in refrigeration technology. Practical thermoelectric cooling device is a thermoelectric effect more significant, more efficient thermoelectric cooling semiconductor thermocouple composition.
Semiconductor thermocouple by the N -type semiconductor and P -type semiconductor components. N-type material has excess electrons have a negative thermoelectric power . P-type material electron deficiency , there are thermoelectric power ; When electrons pass through the junction from the P -type to N -type , its energy will increase, and the increase in energy corresponds to the energy consumed by the node . This can be used to justify lowering the temperature difference .
At the cold end of the thermopile , the following is the hot end . With a variety of heat exchanger means , so that the thermopile
In contrast, when electrons flow from the N-type to P -type material , the junction temperature will rise. Thermocouple circuit in direct contact with the actual references are not available , so the connection method instead of on the map , experiments show that the introduction of a third material ( copper sheet and wire connection ) will not change in the temperature difference between the circuit characteristics of the circuit .
Thus , the semiconductor device can meet the various requirements of users connected to the method . A P -type semiconductor and the N -type semiconductor junction to a thermocouple, connected to the DC power is generated at the joint and heat transfer temperature difference in the joints , the current direction at the N to P, the temperature drop and endothermic , which is the cold side . In the following a joint , to the current direction is P N, and the exothermic temperature rise , and therefore the hot end .
According to the figure on the number of semiconductor thermocouples connected in series to the circuit together , and in terms of the heat transfer in parallel , which constitutes a common cooling thermopile . Illustrated by the DC power supply is connected , the end of the continuous heat and cooling to maintain a certain temperature of the thermopile cold end into the working environment to the endothermic cooling, which is the working principle of thermoelectric cooling .
Refrigeration piece Precautions:
1 , do not know when the cold surface of the refrigerator , we can use this method, the positive power supply red and black wire to negative , and in the absence of cooling conditions, the instantaneous power test , the cooling touch two end devices , and will feel the heat on one side , one side slightly cold sensation, heat one side of the hot side and cold side is feeling cold . But time is not more than 5 seconds , otherwise due to the hot end of the temperature is too high , can easily cause the device to burn out .
2 , under normal conditions, the red lead is usually expressed as positive : usually in black is negative , which is wiring thermoelectric cooler at work. To take the heat . As long as the current polarity can be changed . Refrigeration work must be using switching power supply, power supply ripple factor should be less than 10%.
3 , the number of identification methods and limit voltage , thermocouple refers to the number of P, the number of nodes N thermocouples cooler . For example: refrigerator models for TEC1-12706, the 127 is cooler on the number of thermocouples , 06 to allow current value : A, cooler ≈ thermocouple voltage limit on the number of × 0.12, for example : TECI- 12706 limit voltage V = 127 × 0.12 = 15.4 (V). 78% of normal operating pressure of the threshold voltage , such as TEC1-12706 operating voltage of 15.4 * 0.78 = 12.01V.
4 , the use of various refrigerating or whether the test , the temperature of the refrigerant caused by such cold heat exchange surface should be brought to room temperature ( usually 15 minutes or more ) . It will cause damage to the refrigerator .
5 , in order to prolong the life of thermoelectric cooler , refrigeration components four weeks to respond to seal deal . Our method has two kinds , one is using 704 silicone seals ; another one is mining epoxy seal, seal is designed to make cooler thermocouple completely isolated from the outside air . Plays a role in moisture proof , and can extend the life of the refrigerator .
6 , during the installation , first refrigeration components on both sides Wipe clean and evenly coated with a thin layer of thermal grease in the refrigerator were hot and cold surfaces . Aluminum radiator cold storage or surface contact with the cooler should be leveled and wipe clean, and also the surface evenly coated with thermal grease ; cooler in the installation process and must be stored cold good contact with cold , hot surfaces should be fully in contact with the surface of the aluminum radiator ( such as with screws , a few screws should be a uniform force , not excessive force , or uneven ) . To achieve the best cooling effect between cold storage applications and the aluminum heat sink material filling , the thickness is generally 25-30mm is appropriate.
7 , install the recommended pressure refrigeration piece between 150PSI to 300PSI, the pressure is too low will cause poor contact chip cooling contact surfaces , too much pressure can damage the chip cooling .
8 users in the absence of a dedicated instrument cases, cooler or not qualified to judge , mainly to test its resistance. You can use the data bridge or ohmmeter , measure the resistance of the refrigerator with compensation . Static cooling components with a multimeter to test the resistance is not accurate, just for reference.
9, in the handling and installation process of the refrigerator , the operator should be gently strictly prohibited refrigeration piece fell from a height , even at 10-20cm height will cause the refrigerator produce significant internal resistance changes , resulting in damage to the chiller .
10 , the semiconductor chip cooling used in the following situations , a significant reduction of its life will be possible : A, frequent use of alternating hot and cold use B, using C under vibration , hot side heat sink temperature exceeds 65 degrees D, the working voltage of excess pressure ( no more than 70% of the recommended limit voltage ) heating surface E, refrigeration piece of bad F, surrounded by pieces without refrigeration sealant for use in wet environments
11 , the semiconductor chip cooling for use in the following cases , there will be the possibility of damage quickly : A, heating surface chip cooling is not in contact with any heat objects B, refrigeration piece using voltage exceeds the limit operating voltage C, cooling sheets under pressure over 500PSI
