| Abstract | To achieve carbon neutrality, the trend in building design is to retrofit HVAC systems from
using fossil fuels to reducing carbon emissions and saving energy in buildings. Air-source heat
pumps, which use outdoor air as a heat source, have limited performance at low
temperatures in winter. To deal with performance degradation, hybrid heat pump systems
with auxiliary heaters are considered essential in cold climates. Typically, heat pump systems
use thermal storage tanks for instant hot water supply. However, in urban residential
buildings, such as apartments, minimizing system size is highly recommended due to limited
space and high land costs. To address the limitation, a previous study proposed a tankless
hybrid heat pump system, which replaces the storage tank with a heat exchanger to reduce
system size. However, in that system, there was a problem that the water flow rate of the
system was over-designed. In this study, the configuration of the hybrid heat pump system
was modified, and the total flow rate was reduced to further minimize system size and
improve performance. The proposed tankless hybrid heat pump system was evaluated
through energy simulation and compared with a reference system in terms of total water flow
rate and primary energy consumption. As a result, the proposed system reduced the total
flow rate by 70%, and also reduced the primary energy consumption. |
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