Tube vibrations in heat exchangers are being systematically investigated in a series of tests performed with an industrial-size test exchanger. Results from water-flow tests of eleven different tube bundles, in six- and eight-cross-pass configurations on a 90 degree square layout with a pitch-to-diameter ratio of 1.25 are reported. The test cases include full tube bundles, no-tubes-in-window bundles, finned tube bundles, and proposed field and design fixes. The testing focused on identification of the lowest critical flow-rate to initiate fluid-elastic instability (large amplitude tube motion) and the location within the bundle of the tubes which first experience instability. The test results are tabulated to permit comparison with results obtained from previous tests with a 30 degree triangular layout tube bundle. Instability criteria are evaluated preliminarily. Pressure drop data are also generated and reported.

Tests are conducted for tubes conveying fluid for six types of support conditions. The objectives are to understand the dynamic characteristics of such systems for different support conditions and to explore the methods to control tube stability. Transition from one instability mechanism to another is examined, and the feasibility of using feedback control to increase the critical flow velocity is demonstrated.

ASHRAE Standard 94-77, Method of Testing Thermal Storage Devices Based on Thermal Performance, was developed to allow manufacturers of thermal energy storage devices to compare their products in a meaningful way. When Standard 94-77 was used for thermal energy storage products based on latent heat storage, the Standard was found to be inadequate for comparison of these devices. Standard Project Committee SPC 94.1 was established to devise a Standard that would be adequate for comparing latent heat systems. The purpose of this report is to describe several alternatives to Standard 94-77 and discuss the advantages and disadvantages of each alternative. The discussion focuses on two proposed replacement standards and includes experimental results for each. The experimental results are from tests conducted on a PCM storage tank that uses sodium thiosulfate as the PCM and water as the heat transfer fluid. The experimental arrangement is discussed in detail.