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3. Achieving Energy Self-Sufficiency in a Dormitory Building: An Experimental Analysis of a PV–AWHP-ERV Integrated System.

Author

Yang, Su-Kwang, Kang, Yul-Ho, and Ahn, Young-Chull

Subjects
ENERGY consumption, BUILDING-integrated photovoltaic systems, SELF-reliant living, ELECTRIC power consumption, HEAT pumps, ENERGY security, ELECTRICAL energy
Abstract

In this study, we investigated the performance of air-to-water heat pump (AWHP) and energy recovery ventilator (ERV) systems combined with photovoltaics (PV) to achieve the energy independence of a dormitory building and conducted an analysis of the energy independence rate and economic feasibility by using energy storage devices. Our data were collected for 5 months from July to November, and the building energy load, energy consumption, and system performance were derived by measuring the PV power generation, purchase, sales volume, AWHP inlet and outlet water temperature, and ERV outdoor, supply, and exhaust temperature. When analyzing representative days, the PV–AWHP integrated system achieved an energy efficiency ratio (EER) of 4.49 and a coefficient of performance (COP) of 2.27. Even when the generated electrical energy exceeds 100% of the electricity consumption, the energy self-sufficiency rate remains at 24% due to the imbalance between energy consumption and production. The monthly average energy self-sufficiency rate changed significantly during the measurement period, from 20.27% in November to 57.95% in September, highlighting the importance of energy storage for self-reliance. When using a 4 kWp solar power system and 4 kWh and 8 kWh batteries, the annual energy self-sufficiency rate would increase to 67.43% and 86.98%, respectively, and our economic analysis showed it would take 16.5 years and more than 20 years, respectively, to become profitable compared to the operation of an AWHP system alone. [ABSTRACT FROM AUTHOR]

Published
2024
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7. An Analytical Study on Thermal Management of Battery for Air Flow in ESS Cooling Rack

Author

Lee Jin Kyung, Kang Yul-Ho, and Lee Joon-Hyun

Subjects
Rack, Tray, Volume (thermodynamics), Air changes per hour, Nuclear engineering, Airflow, Battery (vacuum tube), Environmental science, Energy storage, Lithium-ion battery
Abstract

In this study, a thermal analysis of cells in a battery rack with multiple batteries is performed for large-scale energy storage system. For this analysis rack consisting of 18 trays and 12 batteries are arranged in each tray. Cold air is supplied through the air supply of the rack, and each tray is also analyzed for a general-purpose battery rack with individual fans. The cooling efficiency inside the rack is analysed due to change of temperature condition at the cell and air inside the rack. In this paper, the temperature of the main air supply is 298.15 K, and the number of air changes per hour (ACH), which is the volume of the rack divided by the air flow rate per hour, is 50-2,500. As the ACH of the rack increases, it is assumed that the momentum source of the tray exit also increases linearly and the ACH range of the tray is 214.8-1,578.5. In the rack"s ACH range from 50 to 500, the cooling rate of the battery drastically increased as the ACH increased. The cooling rate converged from the section where rack"s ACH exceeded about 1,000. It was found in this study that the thermal analysis could be predicted effectively in the condition that the air supply air volume of the rack was 2,000 or more ACH.

Published
2020

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