Among the factors affecting the quality of electric defrost heating element, the quality of the material is an important reason. Reasonable selection of raw materials for defrost heating tube is the premise of ensuring the quality of defrost heater.
1, the selection principle of pipe: temperature resistance, corrosion resistance.
For low temperature pipes, BUNDY, aluminum pipes, copper pipes are generally used, and high temperature pipes are generally stainless steel pipes and Ingle pipes. Ingle 800 heatig tube can be used in the condition of poor water quality, Ingle 840 electric heating tube can be used in high temperature working condition has a good oxidation resistance, has a good corrosion resistance.
2, the selection of resistance wire
The resistance wire materials commonly used in electric defrost heating element are Fe-Cr-Al and Cr20Ni80 resistance wire. The main difference between the two resistance wires is that the melting point of 0Cr25Al5 is higher than that of Cr20Ni80, but at higher temperatures, 0Cr25Al5 is easier to oxidize, and Cr20Ni80 can also maintain stable performance at high temperatures. Therefore, the resistance wire used at high temperature is generally Cr20Ni80.
3, the selection of MgO powder
The MgO powder is located between the resistance wire and the wall of the tube and is used for insulation between the resistance wire and the wall of the tube. At the same time, MgO powder has good thermal conductivity. However, MgO powder has strong hygroscopic properties, so it should be treated with moisture resistance (modified MgO powder or sealed with electric heat pipe) when used.
MgO powder can be divided into low temperature powder and high temperature powder according to the temperature range used. Low temperature powder can only be used below 400 ° C, generally modified MgO powder.
The MgO powder used in the electric heat pipe is composed of different thickness MgO powder particles in accordance with a certain proportion (mesh ratio).
4, the selection of sealing materials
The role of the sealing material is to prevent the atmospheric moisture from entering the MgO powder by the pipe mouth, so that the MgO powder is damp, the insulation performance is reduced, and the electric heat pipe leakage and failure. The modified magnesia powder can not be sealed.
The main materials used for sealing electric heating tube (moisture-proof) are glass, epoxy resin, silicone oil and so on. In the electric heat pipe sealed with silicone oil, after heating, the silicone oil at the mouth of the pipe will be volatilized by heat, and the insulation of the electric heat pipe will decrease. The temperature resistance of epoxy resin material is not high, and it can not be used in high-temperature electric tubes such as barbecue and microwave oven with high temperature at the pipe mouth. Glass has higher temperature resistance, but the price is higher, and it is more used for sealing high temperature pipes.
In addition, there will be silicone tubes, silicone sleeves, porcelain beads, plastic insulators and other parts in the pipe mouth, mainly to increase the electrical gap and creepage distance between the lead rod and the metal wall of the pipe mouth. Silicone rubber can play the role of filling and bonding.
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Post time: May-16-2024