Abstract: The ground source heat pump tube heat exchangers require high corrosion resistance and wear resistance for their internal pipelines. Studied the corrosion rate of T2 copper tubes and B10 copper-nickel alloy tubes in a mixed solution of 0.0598 mol/L NaCl and 0.1 mol/ L NaHSO₃ primarily, analyzed the corrosion behavior and resistance of the two alloy tubes, and comprehensively considered the mechanical properties, processing technology, and material cost of both alloys in order to optimize material selection. The results indicate that in a 3.5% NaCl and 0.1 mol/ L NaHSO₃ solution, T2 copper tubes mainly experience uniform corrosion with a maximum depth of approximately 0.121 mm, while B10 copper-nickel alloy surfaces exhibit slight corrosion with local pitting pits and a maximum depth of 0.041 mm, thus demonstrating significantly better corrosion resistance than copper tubes. The tensile strength and hardness of B10 copper-nickel alloy are measured at 450 MPa and 140 HV respectively, indicating superior mechanical properties compared to copper. Taking into account corrosion resistance, mechanical properties, processing technology, and material cost considerations lead to the conclusion that B10 copper-nickel alloy is more suitable for use as pipe inside heat exchangers for ground source heat pumps.

Key words: Double pipe heat exchanger, T2 copper alloy, B10 copper-nickel, Mechanical property, Corrosion behavior