Thermohydraulic performance evaluation of multi-start spirally corrugated tubes

摘要

Spirally corrugated tubes are widely used in thermal engineering, such as airconditionings and heat pumps due to their advantages like extended surfaces for heat transfer enhancement and easy fabrication with low economic costs. In this paper, the numerical simulation is carried out to analyze the thermohydraulic performances of multi-start spirally corrugated tubes with the equivalent inner diameter. The pitches are divided by number of starts, and the corrugation depths are identical in a gesture to exclude their influences. The axial velocity distributions in fully developed region are analyzed with different corrugation structures. Meanwhile, the temperature field and secondary flow velocity distributions are both investigated to make a preliminary assessment of thermal performances. In order to find out the most functional starts value of multi-start spirally corrugated tubes, the heat transfer enhancement of six different spirally corrugated tubes are evaluated, by means of the first law of thermodynamics and the second law of thermodynamics correspondingly. According to Performance evaluation criteria (PEC), as well as the entropy production theorem, eight-start spirally corrugated tube is of functional and economical value in comparison with other multi-start spirally corrugated tubes studied, and the PEC value is around 1.10 times as that of six-start spirally corrugated tube, while the Ns of it is about 0.73-0.85 times as that of six-start spirally corrugated tube.