A comprehensive geometric investigation of non-circular cross section spring-wire turbulator through the spiral-tube based heat exchangers

Non-circular cross section spring wire has not been investigated before as a turbulator through the spiral-tube based heat exchangers. Generally, spring diameter, springe pitch and wire diameter can impact the thermal performance of the spring wire employed as a turbulator through the heat exchangers. However, the impact level of these parameters becomes more severer and important when its cross section is non-circular shape such as triangular, rectangular, square, and hexagonal which are investigated in this research from thermal, exergetic and frictional viewpoints. According to the results, the general order of the highest to the lowest enhanced Nu number is triangular, rectangular, hexagonal, square, and circular. However, variation of the mentioned geometries significantly impacts the gap between the cases so that sometimes, the above order changes which are interesting. For instance, for smaller size of spring diameter there is no difference between the cross-section shapes so that all of them almost provides the same value of Nu number. However, by increasing spring diameter, different cross sections make completely different Nu number.