Experimental research on heat transfer enhancement and associated bubble characteristics under high-frequency reciprocating flow

•High-frequency flow reciprocation can enhance both forced convection and nucleate boiling heat transfer.•The CHF can be improved upto 42.3%.•A correlation between the CHF, Reynolds number and Strouhal number is obtained.•Bubbles under reciprocating flow are much smaller than that under steady flow.•Reciprocating flow limits the growth time of bubbles and brakes the stability of flow field.