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Title: THERMAL REGAIN FROM DISPLACEMENT OF DUCT LEAKAGE WITHIN INSULATION.

Abstract

In one type of duct efficiency retrofit, additional insulation is added to a duct system that is already insulated. For example, a layer of R-4 insulation might be: added to a duct system that already has R-4 installed. It is possible that--either by chance or by design--the add-on layer, while not stopping duct leaks, might cause the leakage air to flow longitudinally for a distance, parallel to the duct, before it finds a way out of the newly added outer layer. This could happen by chance if the outer and inner layers of insulation have seams at different locations. Perhaps more usefully, if such longitudinal displacement of the leakage air turned out to be useful, it might be designed into the makeup of the outer insulation layer intended to be used in the retrofit. It is plausible that this leakage air might serve a useful function in keeping the insulation layer warmer (or, in the air-conditioning mode, cooler) than it would be in the absence of the leakage. By being held close to the ducts for a while, it might establish an artificially warmer (or cooler, in air conditioning) zone around the ducts. To the extent that this effect wouldmore » reduce the heat losses from the ducts, the leakage should be credited with a ''thermal regain'' in the same way that leakage into buffer zones is credited with thermal regain when the leakage air warms (or cools) the buffer zone relative to the temperature it would have in the absence of such duct leakage. The purpose of this report is to investigate whether and to what extent such thermal regain exists. The model developed below applies to a situation where there are two distinct layers of insulation around the duct, with leakage air moving between them in a longitudinal direction for a distance before it finds its way out from the outer insulation layer. It may also apply approximately where there is a single insulation layer with an air barrier on the outside. Leakage air may pass into the insulation itself and thence longitudinally through the insulation material until it finds an opening in the air barrier through which it can escape.« less

Authors:
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
806193
Report Number(s):
BNL-69412
R&D Project: EST112NEDA; EC0904000; TRN: US200303%%444
DOE Contract Number:  
AC02-98CH10886
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 May 2002
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; AIR; AIR CONDITIONING; BUFFERS; DUCTS; EFFICIENCY; OPENINGS

Citation Formats

ANDREWS, J W. THERMAL REGAIN FROM DISPLACEMENT OF DUCT LEAKAGE WITHIN INSULATION.. United States: N. p., 2002. Web. doi:10.2172/806193.
ANDREWS, J W. THERMAL REGAIN FROM DISPLACEMENT OF DUCT LEAKAGE WITHIN INSULATION.. United States. https://doi.org/10.2172/806193
ANDREWS, J W. 2002. "THERMAL REGAIN FROM DISPLACEMENT OF DUCT LEAKAGE WITHIN INSULATION.". United States. https://doi.org/10.2172/806193. https://www.osti.gov/servlets/purl/806193.
@article{osti_806193,
title = {THERMAL REGAIN FROM DISPLACEMENT OF DUCT LEAKAGE WITHIN INSULATION.},
author = {ANDREWS, J W},
abstractNote = {In one type of duct efficiency retrofit, additional insulation is added to a duct system that is already insulated. For example, a layer of R-4 insulation might be: added to a duct system that already has R-4 installed. It is possible that--either by chance or by design--the add-on layer, while not stopping duct leaks, might cause the leakage air to flow longitudinally for a distance, parallel to the duct, before it finds a way out of the newly added outer layer. This could happen by chance if the outer and inner layers of insulation have seams at different locations. Perhaps more usefully, if such longitudinal displacement of the leakage air turned out to be useful, it might be designed into the makeup of the outer insulation layer intended to be used in the retrofit. It is plausible that this leakage air might serve a useful function in keeping the insulation layer warmer (or, in the air-conditioning mode, cooler) than it would be in the absence of the leakage. By being held close to the ducts for a while, it might establish an artificially warmer (or cooler, in air conditioning) zone around the ducts. To the extent that this effect would reduce the heat losses from the ducts, the leakage should be credited with a ''thermal regain'' in the same way that leakage into buffer zones is credited with thermal regain when the leakage air warms (or cools) the buffer zone relative to the temperature it would have in the absence of such duct leakage. The purpose of this report is to investigate whether and to what extent such thermal regain exists. The model developed below applies to a situation where there are two distinct layers of insulation around the duct, with leakage air moving between them in a longitudinal direction for a distance before it finds its way out from the outer insulation layer. It may also apply approximately where there is a single insulation layer with an air barrier on the outside. Leakage air may pass into the insulation itself and thence longitudinally through the insulation material until it finds an opening in the air barrier through which it can escape.},
doi = {10.2172/806193},
url = {https://www.osti.gov/biblio/806193}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed May 01 00:00:00 EDT 2002},
month = {Wed May 01 00:00:00 EDT 2002}
}