A Printed Circuit Heat Exchanger(PCHE)

with straight channels and semi-circle cross section

was fabricated and experimental studies on heat transfer and fluid flow were conducted

during which the flow regime was transition flow

water was working fluid

and flow rate of water was various. The results obtained from correlations of macro circular tubes had obvious deviations from the experimental results. Specifically

the f factor obtained from experiments are larger

and the changes of the overall heat transfer coefficient were more complex with various Reynolds number. The heat transfer and flow correlations in transition zone of PCHE was calibrated within corresponding application ranges. In order to obtain the heat transfer correlations

a numerical method was introduced to obtain one-sided average convective heat transfer coefficients under transition flow. The results showed that the average deviations of the overall heat transfer coefficient obtained from average convective heat transfer coefficients was 8.5% comparing to experimental results

while the maximum deviation reached 17.2%.However

in spite of that

a correlation to predicted the overall heat transfer coefficients through average convective ones still can be obtained

and the deviations comparing with experimental results was within 10%. It is recommended that obtaining one-sided average convective heat transfer coefficient with numerical method is feasible especially when it was transition flow in PCHE.