When using thermal bimetallic coils in heat exchangers, how do you choose the right metal combination?

When using heat-matching bimetallic coil components in heat exchangers, it is crucial to choose the right metal combination, and the following factors should be considered:

1. Thermal conductivity matching
Purpose: The main function of a Thermal Bimetal Strip Roll Part is to efficiently exchange heat, so when choosing metals, it is necessary to ensure that the combination can provide good thermal conductivity.
Selection: Metals with higher thermal conductivity (such as copper and aluminum) are usually selected to be combined with metals with better corrosion resistance (such as stainless steel and titanium alloy). Copper and aluminum are often used for parts with strong heat conduction, while stainless steel and titanium alloys are used for parts with strong corrosion resistance.
Consideration: Copper has high thermal conductivity but is easy to corrode, so it is often combined with metals with strong corrosion resistance (such as stainless steel) to form a composite material to take into account both heat exchange efficiency and long-term stability.

2. Thermal expansion coefficient matching
Purpose: Different metals have different expansion behaviors when heated or cooled. If the thermal expansion coefficients of two metals differ too much, it may cause stress at the joint between the materials, or even fall off or deform, affecting the stability and durability of the equipment.
Selection: Generally, metal materials with smaller differences in thermal expansion coefficients are selected. For example, the expansion coefficients of stainless steel and copper are less different, and they can better maintain stability in high temperature environments.
Consideration: When making actual selections, consider the operating temperature range of the application to avoid potential problems caused by expansion mismatches between metals.

3. Corrosion resistance
Purpose: Heat exchangers often work in high temperature, high pressure, and corrosive environments, so it is necessary to select metals with good corrosion resistance.
Selection: Metals such as stainless steel and titanium alloys are often used to resist corrosive environments, especially in the flow of chemical media. For heat exchangers that handle acidic or alkaline media, it is crucial to select alloys with strong corrosion resistance.
Consideration: If there are strong corrosive substances or salt water in the working environment, titanium alloys may be a better choice.

4. Mechanical strength and high temperature resistance
Purpose: Heat exchangers usually need to withstand high temperature and high pressure conditions, so it is necessary to select a metal combination with sufficient mechanical strength and high temperature resistance.
Selection: High-strength and high-temperature resistant metals such as stainless steel, titanium alloys or nickel-based alloys are often used to withstand high temperature operating environments.
Consideration: When selecting, attention should be paid to the tensile strength, yield strength and stability of metal materials in high temperature environments to avoid softening or loss of original properties of materials at high temperatures.

5. Weldability and processability
Purpose: The combination of bimetallic materials is usually carried out by welding, diffusion bonding or other processes, so it is necessary to select a metal combination with good weldability and processability.
Selection: When selecting, it is necessary to consider whether the two metals are easy to combine effectively to avoid problems such as brittleness and cracks in the joint area after welding. The combination of aluminum and copper is usually carried out by cold welding or brazing, while the combination of stainless steel and aluminum can be carried out by laser welding or brazing technology.
Consideration: Metal combinations with good processability can improve production efficiency and reduce manufacturing costs.

6. Cost-effectiveness
Purpose: The design of heat exchangers should not only consider the performance of materials, but also the overall cost, especially in large-scale production.
Selection: Under the premise of meeting technical requirements, try to choose metal combinations with moderate costs. For example, the combination of aluminum and copper is often low in cost, while titanium alloy has excellent performance but high in cost.
Consideration: For some standard applications, choosing relatively low-priced but suitable materials (such as aluminum and stainless steel combination) can effectively control costs while ensuring long-term operation of the equipment.

Comprehensive consideration:
Application example: If the heat exchanger is mainly used in industrial waste gas treatment or chemical reaction system, a combination of stainless steel and aluminum may be selected to take into account heat exchange performance and corrosion resistance; while in the oil and gas field, under high temperature and high pressure environment, a combination of nickel-based alloy and titanium alloy may be selected to obtain better high temperature resistance and corrosion resistance.
By comprehensively considering the above factors, the best metal combination can be selected to ensure that the hot bimetallic coil works efficiently in the heat exchanger for a long time.