In Part I, the flow model which was set in Chap. 2 explained the process of heat storage and heatrelease in the heat storage water tank based on the water flow inside the tank. With this model,the water flow inside the tank and the dynamic characteristics of heat storage and heat releasecould be estimated from three parameters: dimension1ess dead time L/k, dimensionless time constantT/k, and dead water region ratio D.

The good correspondence was obtained between the result of the fundamental experiment in Chap.3 and the result of model analysis. Also, the observation on water flow in Chap. 4 proved that the water flow inside the water vessel was coexisting water flow of forced convection (circulating water flow) and natural convection (density difference water flow).

In this paper, Part II, authors established a law of similarity comparing the actual test andthe model test. The case study on a heat storage system was made, and authors found a method ofan approximate realization of the ideal water flow.