Feasibility analysis of a Commercial HPWH with CO₂ Refrigerant

Technical Report · Sun Feb 12 00:00:00 EST 2017

DOI:https://doi.org/10.2172/1366408· OSTI ID:1366408

Nawaz, Kashif ^[1]; Shen, Bo ^[1]; Elatar, Ahmed F. ^[1]; Baxter, Van D. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

A scoping-level analysis has conducted to establish the feasibility of using CO₂ as refrigerant for a commercial heat pump water heater (HPWH) for U.S. applications. The DOE/ORNL Heat Pump Design Model (HPDM) modeling tool was used for the assessment with data from a Japanese heat pump water heater (Sanden) using CO₂ as refrigerant for calibration. A CFD modeling tool was used to further refine the HPDM tank model. After calibration, the model was used to simulate the performance of commercial HPWHs using CO₂ and R-134a (baseline). The parametric analysis concluded that compressor discharge pressure and water temperature stratification are critical parameters for the system. For comparable performance the compressor size and water-heater size can be significantly different for R-134 and CO₂ HPWHs. The proposed design deploying a gas-cooler configuration not only exceeds the Energy Star Energy Factor criteria i.e. 2.20, but is also comparable to some of the most efficient products in the market using conventional refrigerants.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Building Technologies Research and Integration Center (BTRIC)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1366408
• Report Number(s): ORNL/TM-2017/127; BT0400000; CEBT002
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION