Development and validation of quasi-steady-state heat pump water heater model having stratified water tank and wrapped-tank condenser. (March 2018)

• Record Type: Journal Article
• Authors: Shen, Bo; Nawaz, Kashif; Baxter, Van; Elatar, Ahmed
• Is Part Of: International journal of refrigeration. Volume 87(2018)
• Page Start: 78
• Page End: 90
• Publication Date: 2018-03
• Subjects: Heat pump water heater -- Wrap-tank condenser coil -- Modeling -- Stratified water tank -- Energy factor; Chauffe-eau à pompe à chaleur -- Condenseur enveloppant la cuve -- Modélisation -- Réservoir d'eau stratifié -- Facteur énergétique; Refrigeration and refrigerating machinery -- Periodicals; 621.56
• DOI: 10.1016/j.ijrefrig.2017.10.023
• Languages: English
• ISSNs: 0140-7007

Abstract

Highlights: Calibration method to match water stratification. Couple a detailed vapor compression system model with a stratified water tank. Simulate varied condenser heat distribution to water nodes. Abstract: Heat pump water heater systems (HPWH) introduce new challenges for design and modeling tools, because they require vapor compression system balanced with a water storage tank. In addition, a wrapped-tank condenser coil has strong coupling with a stratified water tank, which leads HPWH simulation to a transient process. To tackle these challenges and deliver an effective, hardware-based HPWH equipment design tool, a quasi-steady-state HPWH model was developed based on the DOE/ORNL Heat Pump Design Model (HPDM). Two new component models were added via this study. One is a one-dimensional stratified water tank model, an improvement to the open-source EnergyPlus water tank model, by introducing a calibration factor to account for bulk mixing effect due to water draws, circulations, etc. The other is a wrapped-tank condenser coil model, using a segment-to-segment modeling approach. The HPWH system model was validated against available experimental data. After that, the model was used for parametric simulations to determine the effects of various design factors.