Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments

The drain water heat recovery device (DWHR) is a vertical, counter-flow heat exchanger, which is designed to recover heat from warm grey water in buildings. In this study, the transient characteristics of a DWHR device is experimentally and analytically investigated. A transient model is developed t...

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Main Authors: Ezra Ovadia, Mostafa H. Sharqawy
Format: Article
Language:English
Published: Elsevier 2023-08-01
Series:Case Studies in Thermal Engineering
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2214157X23004021
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author Ezra Ovadia
Mostafa H. Sharqawy
author_facet Ezra Ovadia
Mostafa H. Sharqawy
author_sort Ezra Ovadia
collection DOAJ
description The drain water heat recovery device (DWHR) is a vertical, counter-flow heat exchanger, which is designed to recover heat from warm grey water in buildings. In this study, the transient characteristics of a DWHR device is experimentally and analytically investigated. A transient model is developed to predict the response time of the DWHR device under different flow conditions. The thermal performance of the system is evaluated with the transient and steady state effectiveness. The effect of system operating conditions and geometry on the response time was investigated experimentally and well predicted analytically. It was found that the response time increases with the volume of water in the system and decreases with the water flow rate. In addition, a large decrease in the effectiveness is observed when short and frequent use of hot water occurs. An economic analysis concluded that there is a 37% overall reduction in annual savings when the device transient performance is taken into consideration, where individually the sink and shower usage annual saving decreases by 56% and 13% respectively.
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spelling doaj.art-c45e003e17bb49aab0fd5ad9713cdd562023-06-15T04:56:04ZengElsevierCase Studies in Thermal Engineering2214-157X2023-08-0148103096Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessmentsEzra Ovadia0Mostafa H. Sharqawy1School of Engineering, College of Engineering and Physical Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, CanadaCorresponding author.; School of Engineering, College of Engineering and Physical Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, CanadaThe drain water heat recovery device (DWHR) is a vertical, counter-flow heat exchanger, which is designed to recover heat from warm grey water in buildings. In this study, the transient characteristics of a DWHR device is experimentally and analytically investigated. A transient model is developed to predict the response time of the DWHR device under different flow conditions. The thermal performance of the system is evaluated with the transient and steady state effectiveness. The effect of system operating conditions and geometry on the response time was investigated experimentally and well predicted analytically. It was found that the response time increases with the volume of water in the system and decreases with the water flow rate. In addition, a large decrease in the effectiveness is observed when short and frequent use of hot water occurs. An economic analysis concluded that there is a 37% overall reduction in annual savings when the device transient performance is taken into consideration, where individually the sink and shower usage annual saving decreases by 56% and 13% respectively.http://www.sciencedirect.com/science/article/pii/S2214157X23004021Transient analysisDrain water heat recoveryGreywaterHeat exchangerExperimental
spellingShingle Ezra Ovadia
Mostafa H. Sharqawy
Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
Case Studies in Thermal Engineering
Transient analysis
Drain water heat recovery
Greywater
Heat exchanger
Experimental
title Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
title_full Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
title_fullStr Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
title_full_unstemmed Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
title_short Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments
title_sort transient behavior of a falling film drain water heat recovery device thermal and economic performance assessments
topic Transient analysis
Drain water heat recovery
Greywater
Heat exchanger
Experimental
url http://www.sciencedirect.com/science/article/pii/S2214157X23004021
work_keys_str_mv AT ezraovadia transientbehaviorofafallingfilmdrainwaterheatrecoverydevicethermalandeconomicperformanceassessments
AT mostafahsharqawy transientbehaviorofafallingfilmdrainwaterheatrecoverydevicethermalandeconomicperformanceassessments