Principle

At the ice–water interface in a steady-state condition, the heat flux transferred from water to the ice–water interface is equal to that conducted from the ice–water interface to ice. By measuring the coordinates of the ice–water interface, the heat flux from the interface to ice is calculated by the boundaryelement method. The local heat-transfer coefficient on the ice–water interface is, then, estimated by Newton's law of cooling.

Object

Ice formation around tubes in a water flow relates to many practical problems such as lowering thermal efficiency or increasing pressure drop in a water-cooled heat exchanger in a refrigeration system. It also relates to many other applications such as the ice-bank method in a low-temperature heatstorage system. In those cases, the local heat-transfer coefficient on the ice surface is an important factor in predicting the ice amount around the tubes and also the thermal efficiency of the heat exchanger. The measurement of the local heat-transfer coefficient, therefore, presents essential information for practical designs.

Apparatus

The experimental apparatus consists of a calming section, a test section, a flow meter, a refrigeration unit, and two circulation systems of water and a coolant as shown in Fig. 13.1. In Fig. 13.2, a schematic illustration of the test section is shown. The test section has a 0.15-m × 0.04-m cross-sectional area and has a 1.0-m length. The walls are made of transparent acrylic resin plates in order to observe the growth of the ice layer, and are installed in the vertical position to minimize the effect of the natural convection of water.