Reserve Circulation Phenomena of a Cooling System with Natural-Circulation Loop using CO₂ and Control Method of the Reverse Circulation

Abstract

The experiments and calculations were carried out to evaluate the transient operation characteristics of a cooling system with natural circulation loop using CO₂. The characteristics of the reverse circulation observed under the supercritical state were analyzed from a point of the air intake temperature profile in the inlet of the heat exchangers. As a result, the air intake temperature profile causes the driving head difference for the reverse circulation. In addition, the driving head difference for the reverse circulation depends on the density change to temperature under the supercritical state. Also, a new fan control method has been developed to convert the reverse circulation into the normal circulation. The effect of the developed fan control method was confirmed from the experimental results.