Development of a new high performance heat exchanger using a surfactant water solution

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12650199
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Gifu University
• Principal Investigator: KUMADA Masaya Gifu Univ., Fac. of Engineering, Professor, 工学部, 教授 (30021603)
• Co-Investigator(Kenkyū-buntansha): MIMATSU Junji Gifu Univ., Fac. of Engineering, Associate Professor, 工学部, 助教授 (20202351)
• Project Period (FY): 2000 – 2001
• Keywords: Tom's effect / Drag redaction / Heat transfer enhancement / Turbulence promoter / Performance evaluation based on a constant pump power / Surfactant solution / Heat exchanger

Research Abstract

An experiment was conducted to investigate the drag-reduction and the heat transfer characteristics in a surfactant water solution flow. It was confirmed that the percentage of the drag-reduction was more than 70 % and simultaneously, the heat transfer coefficient was reduced at the same rate. In order to promote the heat transfer for the surfactant water solution flow, an enhancement method using a triangular rib was proposed. Comparing with the case without rib, it was found that the dependence of the drag-reduction and the heat transfer characteristics on Re and C was similar, but the critical Reynolds number at which the drag reduction reaches a maximum was smaller. Further, by the performance evaluation based on a constant pump power, it was verified that the compound method by the surfactant and the triangular rib is effective to improve the performance of heat exchangers.
To investigate the temperature dependence of the Tom's effect, measurements of velocity and temperature profi les in a two-dimensional channel were done as parameters of inlet velocity, temperature of the working fluid and wall surface. It was found that the velocity profiles vary clearly with temperature of the wall surface as comparing with the temperature profiles. However, the Tom's effect does not stop working, when the temperature in the thermal boundary layer is that it stops working. The Tom's effect is very sensitive for the temperature, on the other hand it is suggested that the varying process is complex.
The rate of drag reduction of a single pipe with, roughness surface using the air-conditioner was measured, because the triangle rib as mentioned above is too expensive to apply to a real-product heat exchanger. It was found that the appearance of the Toms effect is observed as similar with previous results. As concerning the heat exchanger, the rate of drag reduction of the radiator on the market with using roughness pipe is measured. It is decreased by the header part of the radiator, however the roughness pipe is still useful for the drag reduction.