Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study

Heat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing syst...

Full description

Saved in:
Bibliographic Details
Main Authors: Ahmed Elatar, Joseph Rendall, Jian Sun, Jamieson Brechtl, Kashif Nawaz
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/18/14/3661
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1839616058507395072
author Ahmed Elatar
Joseph Rendall
Jian Sun
Jamieson Brechtl
Kashif Nawaz
author_facet Ahmed Elatar
Joseph Rendall
Jian Sun
Jamieson Brechtl
Kashif Nawaz
author_sort Ahmed Elatar
collection DOAJ
description Heat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing systems use R-134a as a working refrigerant, R290 has gained major attention owing to its superior thermodynamic properties. The goal of the current study is to assess the performance of residential HPWH with R290 as a direct refrigerant replacement for R134a. Two units of a 50 gal HPWH were used in this experimental study. A baseline unit contained R134a refrigerant, and a prototype unit contained R290 refrigerant. The prototype unit was developed through the modification of a commercially available HPWH unit to achieve a low charge of R290 refrigerant. Another major modification was the replacement of the baseline compressor with a compressor designed for R290. Tests were conducted in a field environment (a research and demonstration house) using programmed drawn profiles daily. The prototype that reduced the charge by 43–47% provided displayed performance comparable to the baseline unit regarding first-hour rating (FHR) and the uniform energy factor (UEF).
format Article
id doaj-art-1ac85e5e8a8e4a43b4f23c181a434cbc
institution Matheson Library
issn 1996-1073
language English
publishDate 2025-07-01
publisher MDPI AG
record_format Article
series Energies
spelling doaj-art-1ac85e5e8a8e4a43b4f23c181a434cbc2025-07-25T13:21:12ZengMDPI AGEnergies1996-10732025-07-011814366110.3390/en18143661Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field StudyAhmed Elatar0Joseph Rendall1Jian Sun2Jamieson Brechtl3Kashif Nawaz4Oak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge, TN 37831, USAOak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge, TN 37831, USAOak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge, TN 37831, USAOak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge, TN 37831, USAOak Ridge National Laboratory, Energy and Transportation Science Division, Oak Ridge, TN 37831, USAHeat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing systems use R-134a as a working refrigerant, R290 has gained major attention owing to its superior thermodynamic properties. The goal of the current study is to assess the performance of residential HPWH with R290 as a direct refrigerant replacement for R134a. Two units of a 50 gal HPWH were used in this experimental study. A baseline unit contained R134a refrigerant, and a prototype unit contained R290 refrigerant. The prototype unit was developed through the modification of a commercially available HPWH unit to achieve a low charge of R290 refrigerant. Another major modification was the replacement of the baseline compressor with a compressor designed for R290. Tests were conducted in a field environment (a research and demonstration house) using programmed drawn profiles daily. The prototype that reduced the charge by 43–47% provided displayed performance comparable to the baseline unit regarding first-hour rating (FHR) and the uniform energy factor (UEF).https://www.mdpi.com/1996-1073/18/14/3661HPWHR290drop-in-replacement
spellingShingle Ahmed Elatar
Joseph Rendall
Jian Sun
Jamieson Brechtl
Kashif Nawaz
Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
Energies
HPWH
R290
drop-in-replacement
title Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
title_full Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
title_fullStr Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
title_full_unstemmed Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
title_short Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study
title_sort charge reduction and performance analysis of a heat pump water heater using r290 as a refrigerant a field study
topic HPWH
R290
drop-in-replacement
url https://www.mdpi.com/1996-1073/18/14/3661
work_keys_str_mv AT ahmedelatar chargereductionandperformanceanalysisofaheatpumpwaterheaterusingr290asarefrigerantafieldstudy
AT josephrendall chargereductionandperformanceanalysisofaheatpumpwaterheaterusingr290asarefrigerantafieldstudy
AT jiansun chargereductionandperformanceanalysisofaheatpumpwaterheaterusingr290asarefrigerantafieldstudy
AT jamiesonbrechtl chargereductionandperformanceanalysisofaheatpumpwaterheaterusingr290asarefrigerantafieldstudy
AT kashifnawaz chargereductionandperformanceanalysisofaheatpumpwaterheaterusingr290asarefrigerantafieldstudy