Compatibility is of great significance in cast aluminum heaters, and the life of cast aluminum heaters mainly depends on compatibility.
First, discuss the impact of incompatibility between working fluid and material. A common incompatibility phenomenon in cast aluminum heaters is the chemical reaction between the working fluid and the tube core or tube shell material to produce non-condensable gas. When the cast aluminum heater is working, the gas is swept by the steam flow to the end of the condensation section to accumulate, forming a gas lock, blocking a part of the steam space, reducing the effective condensation area, increasing the thermal resistance, and the temperature difference of the cast aluminum heater. If it is enlarged, the condensing section can even be completely blocked and unable to work. The non-condensable gas has a more serious impact on the linear cast aluminum heater, which has been mentioned before and will not be repeated. In the gas-controlled variable thermal conductivity cast aluminum heater, the non-condensable gas produced will cause the working temperature of the cast aluminum heater to exceed the design value. Even if the product of the reaction is not a gas, but a solid and a liquid, it will affect the physical properties of the working fluid or the structure of the tube core, thereby deteriorating the performance of the cast aluminum heater.
The mechanisms that cause incompatibility are also diverse. Generally speaking, non-condensable gas generated by electrochemical process is often encountered in medium and low ju cast aluminum heaters, which leads to performance degradation or failure. In high-temperature cast aluminum heaters, it is often because the tube core or tube shell material is dissolved in the working fluid, which causes the tube core to be damaged or the tube shell to corrode and perforate. The general corrosion research results can only be used as a guide for selecting the combination of working fluid materials. As for the compatibility of cast aluminum heater materials, it must be proved by compatibility test (or life test).