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## A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle

#### Yasuaki Bando [1] , Hironori Hattori [2] , Yoshiharu Amano [3]

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Energy management is a systematic activity for improving energy performances of a target system, and an energy management system is expected to solve operational planning problems and report or suggest opportunities for performance improvement. An equipment model is required to reflect the characteristics of the actual equipment’s performance and to have a simple structure to apply to operational planning problems. The model should be able to diagnose changes with performance degradation over time. In this study, we proposed a thermodynamically-sound model of a CO2 heat pump water heater, suitable for solving operational planning problems and diagnosing degradation of equipment. The proposed model consists of a heat pump unit (HP) and a hot water storage tank (ST). The HP model is a status-transition model, constructed based on the Lorentz efficiency, which is identified by experimental values and a theoretical maximum coefficient of performance (COP) for a trans-critical heat pump cycle. The ST model is simplified and can describe temperature distribution in the ST because the unit COP of the HP influences the thermal stratification of the ST. The proposed model is preferable in its simplicity and robust performance for a wide temperature range by comparison with a conventional statistical regression model.

energy management system, heat pump water heater, Lorentz cycle, operational planning
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Primary Language en Engineering Regular Original Research Article Author: Yasuaki Bando (Primary Author)Institution: Waseda UniversityCountry: Japan Author: Hironori HattoriInstitution: Waseda UniversityCountry: Japan Author: Yoshiharu AmanoInstitution: Waseda UniversityCountry: Japan
 Bibtex @research article { ijot499185, journal = {International Journal of Thermodynamics}, issn = {1301-9724}, eissn = {2146-1511}, address = {Yaşar DEMİREL}, year = {2019}, volume = {22}, pages = {26 - 33}, doi = {10.5541/ijot.499185}, title = {A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle}, key = {cite}, author = {Bando, Yasuaki and Hattori, Hironori and Amano, Yoshiharu} } APA Bando, Y , Hattori, H , Amano, Y . (2019). A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle. International Journal of Thermodynamics, 22 (1), 26-33. DOI: 10.5541/ijot.499185 MLA Bando, Y , Hattori, H , Amano, Y . "A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle". International Journal of Thermodynamics 22 (2019): 26-33 Chicago Bando, Y , Hattori, H , Amano, Y . "A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle". International Journal of Thermodynamics 22 (2019): 26-33 RIS TY - JOUR T1 - A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle AU - Yasuaki Bando , Hironori Hattori , Yoshiharu Amano Y1 - 2019 PY - 2019 N1 - doi: 10.5541/ijot.499185 DO - 10.5541/ijot.499185 T2 - International Journal of Thermodynamics JF - Journal JO - JOR SP - 26 EP - 33 VL - 22 IS - 1 SN - 1301-9724-2146-1511 M3 - doi: 10.5541/ijot.499185 UR - https://doi.org/10.5541/ijot.499185 Y2 - 2019 ER - EndNote %0 International Journal of Thermodynamics A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle %A Yasuaki Bando , Hironori Hattori , Yoshiharu Amano %T A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle %D 2019 %J International Journal of Thermodynamics %P 1301-9724-2146-1511 %V 22 %N 1 %R doi: 10.5541/ijot.499185 %U 10.5541/ijot.499185 ISNAD Bando, Yasuaki , Hattori, Hironori , Amano, Yoshiharu . "A Status-transition Model for CO2 Heat Pump Water Heater Based on Modified Lorentz cycle". International Journal of Thermodynamics 22 / 1 (March 2019): 26-33. https://doi.org/10.5541/ijot.499185