Investigation of the Thermal Characteristics of a Circular Fusible-Type Sprinkler Using the Energy Transport Equation

Abstract

In this study, we investigate the thermal characteristics of a circular fusible-type sprinkler. Analytic solutions regarding the radial-temperature distribution are obtained by using the energy-transport equation for the heat-responsive element of the sprinkler. When solving the equation, the fitted curves of the measured temperatures derived from the previous correlation of the heat-transfer coefficient are used as the boundary conditions at the element surface. To verify the accuracy of the present approach, the predictions from the use of the analytic solution are compared with the operation-time measurements of the sprinkler; the bulk temperature of the element is then estimated based on these results for the quantification of the operation time of the sprinkler. To verify the present analytic model, we systematically compare the operation time of the sprinkler with those of the response time index (RTI) and modified response time index (RTIv) models. The results show that the present model can be used for an estimation of both the temperature distribution inside the element and the operation time of the sprinkler.