Verification of pressure loss evaluation method for high temperature and high pressure evaporator tubes including subcooled boiling region

To confirm the accuracy of predicting the pressure loss of an evaporator tube with a diameter used in boilers and under high heat flux conditions, the pressure loss in the tube was calculated using representative prediction equations and compared with experimental values. the test was conducted under the condition that water was used as the working fluid and the pressure was 8 -16 MPa. As a result, it was confirmed that the predicted value of pressure loss obtained by Thoms method agreed well with the experimental value even under the condition of high heat flux below CHF. On the other hand, to predict the friction loss under the condition of high heat flux and the regions from sub-cool to low steam quality, it is necessary to consider liquid temperature rise near the wall and subcooled flow boiling as previously reported. For subcooled flow boiling, it was confirmed that the prediction accuracy of friction loss was improved by using the simple calculation method of Sekoguchi. (author)