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Title: Performance optimization of CO 2 heat pump water heater

Abstract

A preliminary analysis was conducted to analyze the performance of a heat pump water heater (HPWH) that uses CO 2 as the refrigerant. A model to predict the performance was developed and calibrated based on the experimental data for an existing HPWH using a CO 2 refrigerant. The calibrated model was then used to run a parametric analysis in which factors such as water supply temperature, water circulation rate, tank stratification, and condenser configuration were considered. The performance of a commercial CO 2 system was compared with that of a similar system using R-134a as the refrigerant. It was found that CO 2 HPWH performance was comparable to that of an R-134a HPWH, more so for a separated gas cooler configuration. For comparable performance, the compressor size and the tube-in-tube heat exchanger (condenser/gas cooler) size were compared for CO 2- and R-134a-based systems. Finally, the impact of the water circulation rate on the water temperature stratification in the tank, an essential requirement for higher performance for CO 2 HPWH systems was also investigated.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1414698
Alternate Identifier(s):
OSTI ID: 1549396
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
International Journal of Refrigeration
Additional Journal Information:
Journal Volume: 85; Journal Issue: C; Journal ID: ISSN 0140-7007
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Heat pump; Water heater; Carbon dioxide; Alternative refrigerants

Citation Formats

Nawaz, Kashif, Shen, Bo, Elatar, Ahmed, Baxter, Van D., and Abdelaziz, Omar. Performance optimization of CO2 heat pump water heater. United States: N. p., 2017. Web. doi:10.1016/j.ijrefrig.2017.09.027.
Nawaz, Kashif, Shen, Bo, Elatar, Ahmed, Baxter, Van D., & Abdelaziz, Omar. Performance optimization of CO2 heat pump water heater. United States. doi:10.1016/j.ijrefrig.2017.09.027.
Nawaz, Kashif, Shen, Bo, Elatar, Ahmed, Baxter, Van D., and Abdelaziz, Omar. Sat . "Performance optimization of CO2 heat pump water heater". United States. doi:10.1016/j.ijrefrig.2017.09.027. https://www.osti.gov/servlets/purl/1414698.
@article{osti_1414698,
title = {Performance optimization of CO2 heat pump water heater},
author = {Nawaz, Kashif and Shen, Bo and Elatar, Ahmed and Baxter, Van D. and Abdelaziz, Omar},
abstractNote = {A preliminary analysis was conducted to analyze the performance of a heat pump water heater (HPWH) that uses CO2 as the refrigerant. A model to predict the performance was developed and calibrated based on the experimental data for an existing HPWH using a CO2 refrigerant. The calibrated model was then used to run a parametric analysis in which factors such as water supply temperature, water circulation rate, tank stratification, and condenser configuration were considered. The performance of a commercial CO2 system was compared with that of a similar system using R-134a as the refrigerant. It was found that CO2 HPWH performance was comparable to that of an R-134a HPWH, more so for a separated gas cooler configuration. For comparable performance, the compressor size and the tube-in-tube heat exchanger (condenser/gas cooler) size were compared for CO2- and R-134a-based systems. Finally, the impact of the water circulation rate on the water temperature stratification in the tank, an essential requirement for higher performance for CO2 HPWH systems was also investigated.},
doi = {10.1016/j.ijrefrig.2017.09.027},
journal = {International Journal of Refrigeration},
number = C,
volume = 85,
place = {United States},
year = {2017},
month = {10}
}

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Cited by: 4 works
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Works referencing / citing this record:

Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications
journal, February 2019

  • Paniagua, Ignacio; Álvaro, Ángel; Martín, Javier
  • Energies, Vol. 12, Issue 3
  • DOI: 10.3390/en12030479