Masters Theses

Date of Award

6-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

R. V. Arimilli

Abstract

The transient thermal performance of an experimental packed bed thermal energy storage system, (TES), installed in the two-phase flow laboratory of the Mechanical and Aerospace Engineering Department of the University of Tennessee at Knoxville, was determined. In this study the working fluids used were refrigerants-12 and -113. Two types of packings were used; single solid phase 5/8" diameter glass spheres, and 1/2" diameter 5/16" thick encapsulated pellets of phase-change material. The phase-change thermal energy storage materials tested were of two types: PWC-73, which is a eutectic mixture of Glauber's salt that has a specified phase-change temperature in the range of 71-75 °F, and PWC-89 which is Glauber's salt and has a specified phase-change temperature of 89 °F. Both single-and two-phase working fluid results are presented.

The storage unit used consists of a randomly packed 5" diameter 4' long tube. In the case of single-phase working fluid runs with glass packing, an energy balance was carried out and was found to agree with theoretical calculations to within 10 percent. The measured heat-transfer coefficient for single-phase liquid working fluid runs showed good agreement with published literature on gas-solid packed bed systems. Single-phase working fluid data were obtained for a working fluid Prandtl number in the range of 6 to 8, and a modified Reynolds number in the range of 30 to 1200. Two-phase working fluid data were obtained for a bed inlet quality ranging from 0.3 to 0.9 at a refrigerant mass velocity of 23.5 pounds mass per minute per square foot.

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