Thermostatic mixing valves - A method for non-disturbing intra-valve heat transfer estimation

摘要

The time dependent control characteristics of thermostatic mixing valves are determined by the steep velocity, pressure and temperature gradients present inside the valve. The aim of this study is to investigate how these parameters affect the heat flux from the flowing water to the thermostat which both senses and realizes the control of the valve. A newly developed method for non-disturbing intra-valve measurement is used to determine the convective heat transfer coefficient (h) at the surface of the thermostat, Despite the steep gradients inside the valve, the method manages to dissolve the axial and azimuthal dependence of h. The variations are of such a magnitude that they should be accounted for when analyzing this type of valve.