Single-phase natural circulation flow in a short rectangular loop.

Abstract

The characteristics of the steady single-phase natural circulation flow of water were experimentally studied in a short rectangular loop from the point of view of residual heat removal in a reactor core. The loop is made of Pyrex glass tubes and has a height of 2.03m and a width of 0.81m, and is equipped with a heater and three coolers. For each type of cooler arrangement, the experimental values of the circulation mass flow rate are proportional to the square root of the heat input and agree well with the calculated values from the momentum and energy balance assuming one-dimensional flow. The circulation flow rate increases with the equivalent height defined as the distance between the heater and the coolers except for the case that the cooler is set in the riser. In this case, the water also circulates at a little lower mass flow rate than others.