Numerical study and geometric structure optimization on casing tube for R290 using response surface method

Three types of casing tube heat exchangers for R290 are studied in this paper. The corrugated tube with grooves is a novel heat exchange tube and its heat transfer and pressure drop characteristics have not been studied. Based on CFD, an investigation is conducted into heat transfer and pressure drop of R290 during flow boiling, and performance evaluation criteria (PEC) serves to assess performance of tube. The results show that PEC value of corrugated tube with grooves is higher than that of both smooth tube and circular corrugated tube. The performance of corrugated tube with grooves is further studied in this paper, and influence of three geometric structure parameters on heat transfer and pressure drop is explored. By using response surface method (RSM), the significance of the three parameters is obtained. The results reveal that groove number has the most significant impact on PEC of corrugated tube with grooves. Under given working conditions, with constant tube diameter, tube length, corrugation width and wall thickness, the optimal geometric parameters are obtained: groove number A = 10, corrugation height B = 0.3 mm, and corrugation spacing C = 5 mm. And PEC value of the optimized tube can be up to 1.848.