Investigation of Fluid Dynamics in the Case of Two Higher-temperature Fluid Inputs to Effectively Heat the Vessels

Abstract

When higher-temperature fluid is supplied to a vessel filled by the lower-temperature fluid from the top, the supplied one often can hardly reach the bottom immediately due to the buoyancy, leading to a long time to make a uniform temperature in the vessel. This situation commonly happens during room heating, bathing, and so on. However, it is usually necessary to make a uniform temperature distribution as quickly as possible to save energy or control the product quality. To address this issue, a dual inputs system was proposed in this research in which the heat fluids were fed. The fluids from the two inputs have different temperatures. Experiments of examining local temperatures and fluid dynamics visualization were conducted using water in a vessel to observe the heating effect of this proposed system. The vessel was initially filled with 10 °C water, and the 50 °C and 30 °C waters were supplied from two inlets with different flow rate ratios. It is found that the bottom temperature can rise immediately by increasing the supply ratio of 30 °C water from 1/2 to 4/5 of an unvaried total flow rate, albeit at the cost of temperatures decreases of approximately 6 °C on the top layer and 2 °C on the middle and bottom layers. The findings of this research suggest a promising approach to achieving uniform temperature distribution rapidly, contributing to the energy efficiency enhancement of heating vessels.