Mixture loss coefficient of safety valves used in nuclear plants

Theoretical and experimental investigations on the loss coefficient of gas–liquid mixture across safety relief valves have been carried out. Experiments were performed for three different types of safety valves and under different flow conditions. Using the Darcy equation and based on the presented experimental results, a new empirical correlation has been developed to calculate the loss coefficient and hence pressure loss. By consideration of flow contraction, high viscous fluids, Reynolds number and safety valve geometry, the model includes therefore the relevant primary influencing parameters. The reproductive accuracy of the proposed model and the statistical comparison, based on about 2000 measured data in the literature, demonstrated that the proposed model is the best overall agreement with the data. The standard deviation of the data is less than 27%. The model fits the data well and is sufficiently accurate for engineering purposes. The reported results of the tested safety relief valve are very important to improve the practical and safety design of the nuclear plants.