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Title: Identification of mixing effects in stratified chilled-water storage tanks by analysis of time series temperature data

Abstract

Several one-dimensional models of mixing in stratified chilled-water thermal energy storage tanks have been proposed. In the simplest models, mixing is assumed to be uniform throughout the tank. Other models permit spatial variation of mixing intensity. Published models were developed by adjusting model parameters to achieve qualitative agreement with measured profiles. The literature does not describe quantitative criteria for evaluating the performance of mixing models. This paper describes a method that can be used to determine the relative spatial distribution of mixing effects directly from experimental data. It also illustrates a method for quantitative comparison of experimental and modeled temperature profiles. The mixing calculation procedure may be applied to instantaneous spatial temperature data if temperature sensor spacing is sufficiently small. When sensors are widely spaced, time series data taken at individual sensors provide better accuracy. A criterion for maximum sensor spacing is proposed. The application of these procedures to time series charge-cycle operating data from a full-scale chilled-water thermal storage system serving a large medical center is described. Results of this analysis indicate that mixing is localized near the inlet diffuser and that one-dimensional flow with streamwise conduction predominates in most of the tank.

Authors:
 [1];  [2]
  1. James Posey Associates, Inc., Baltimore, MD (United States)
  2. Pennsylvania State Univ., University Park, PA (United States). Dept. of Architectural Engineering
Publication Date:
OSTI Identifier:
687606
Report Number(s):
CONF-980650-
Journal ID: ISSN 0001-2505; TRN: IM9944%%271
Resource Type:
Conference
Resource Relation:
Conference: 1998 ASHRAE summer annual meeting, Toronto (Canada), 20 Jun 1998; Other Information: PBD: 1998; Related Information: Is Part Of ASHRAE transactions 1998: Technical and symposium papers. Volume 104, Part 2; PB: 1511 p.
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 25 ENERGY STORAGE; THERMAL ENERGY STORAGE EQUIPMENT; SENSIBLE HEAT STORAGE; MIXING; SPATIAL DISTRIBUTION; TIME-SERIES ANALYSIS; TEMPERATURE DISTRIBUTION; DISTRICT COOLING; MEDICAL ESTABLISHMENTS

Citation Formats

Caldwell, J S, and Bahnfleth, W P. Identification of mixing effects in stratified chilled-water storage tanks by analysis of time series temperature data. United States: N. p., 1998. Web.
Caldwell, J S, & Bahnfleth, W P. Identification of mixing effects in stratified chilled-water storage tanks by analysis of time series temperature data. United States.
Caldwell, J S, and Bahnfleth, W P. 1998. "Identification of mixing effects in stratified chilled-water storage tanks by analysis of time series temperature data". United States.
@article{osti_687606,
title = {Identification of mixing effects in stratified chilled-water storage tanks by analysis of time series temperature data},
author = {Caldwell, J S and Bahnfleth, W P},
abstractNote = {Several one-dimensional models of mixing in stratified chilled-water thermal energy storage tanks have been proposed. In the simplest models, mixing is assumed to be uniform throughout the tank. Other models permit spatial variation of mixing intensity. Published models were developed by adjusting model parameters to achieve qualitative agreement with measured profiles. The literature does not describe quantitative criteria for evaluating the performance of mixing models. This paper describes a method that can be used to determine the relative spatial distribution of mixing effects directly from experimental data. It also illustrates a method for quantitative comparison of experimental and modeled temperature profiles. The mixing calculation procedure may be applied to instantaneous spatial temperature data if temperature sensor spacing is sufficiently small. When sensors are widely spaced, time series data taken at individual sensors provide better accuracy. A criterion for maximum sensor spacing is proposed. The application of these procedures to time series charge-cycle operating data from a full-scale chilled-water thermal storage system serving a large medical center is described. Results of this analysis indicate that mixing is localized near the inlet diffuser and that one-dimensional flow with streamwise conduction predominates in most of the tank.},
doi = {},
url = {https://www.osti.gov/biblio/687606}, journal = {},
issn = {0001-2505},
number = ,
volume = ,
place = {United States},
year = {Thu Dec 31 00:00:00 EST 1998},
month = {Thu Dec 31 00:00:00 EST 1998}
}

Conference:
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