管内流が急加速・急減速する時の熱伝達と圧力損失の変動

抄録

In this paper, we examined the heat transfer enhancement of a pulsating pipe flow generated by opening and closing the electric valve. The temporal variation of the pressure loss was evaluated by measuring temporal variations of the pressure difference and the flow rate in the pipe. The pressure loss defined here means the loss caused by viscous dissipation, which can be calculated by subtracting the power required for acceleration/deceleration from the power required to drive the flow. As a result of the pulsation between Re = 900 and 9000, heat transfer was enhanced by 16-42% by applying the pulsation under the condition at the same average Reynolds number. Also, under the condition of the same average pressure loss, the heat transfer enhancement due to the pulsation was small, but there was a tendency to enhance the heat transfer by 3-10% at the longest valve opening time of 3.4 s in this pulsation condition.