Experimental Study On Heat Transfer Enhancement By Laminar Pulsating Flow

With the continuous development of science and technology, many problems have been emerged, especially in energy and environment. How to make better use of energy and improve the energy utilization have attracted more and more attention. Heat transfer enhancement as a major method of improving heat efficiency plays an important role in energy saving, which has been investigated by the researches all over the world. Pulsating flow as a main way of heat transfer enhancement has numerically and experimentally confirmed.Heat transfer enhancement by laminar pulsating flow in triangular grooved channels was experimentally investigated by taking various factors into consideration, such as, Reynolds number, Strouhal number, pulsation amplitude and groove depth (6mm,9mm and12mm).The results show that pulsating flow agitation promotes the heat transfer in triangular grooved channels. In steady flow case, Nusselt number increases as the Reynolds number increases, and it increases at first and then decrease with the increase of groove depth. In pulsating flow case, the heat transfer enhancement factor is improved with the increase of Reynolds number and pulsation amplitude. And the heat transfer enhancement factor increases firstly and then decreases with the increase of Strouhal number. There exists an optimal Strouhal number corresponding to the maximum heat transfer enhancement factor. The Reynolds number and pulsation amplitude have no effect on the optimal pulsation frequency. The heat transfer enhancement factor gets the maximum value when the groove channel depth is12mm and reaches the minimum value when the depth is9mm. And the groove channel depth has no influence on the optimum Strouhal number. The amplitude of pressure gradient increases with the increase of Reynolds number and pulsation amplitude, and decreases with the increase of pulsation frequency.