Performance Analysis of an Air-Source Heat Pump andSolid Thermal Energy Storage Staged Series HeatingSystem in Severe Cold Regions

Abstract

In regions with severe cold, both air-source heat pumps (ASHP) and
solid thermal energy storage (STES) systems have performance limitations when
used for heating in isolation. This paper addresses MW-scale heating demands
by developing a model for the series-connected, coordinated operation of ASHPs
and STES, and analyses system performance under different ambient and
intermediate temperatures. The results indicate that a decrease in ambient
temperature leads to a significant drop in the ASHP’s coefficient of performance
(COP), with a particularly marked decline below–15 ℃. The ASHP-STES
system optimizes heat pump operating conditions through staged heating; under
conditions of–20 ℃ to–25 ℃, total energy consumption is reduced by
approximately 1.05% and 10.78% compared with ASHP and STES-ASHP
systems, respectively. Its total power consumption exhibits a U-shaped variation
with intermediate temperature, reaching an optimum in the 80–85 ℃ range,
resulting in energy savings of 1.4% to 5.1% compared with the ASHP system. In
contrast, the STES-ASHP system consistently fails to demonstrate any energy
efficiency advantage. When the ambient temperature exceeds–10 ℃, standalone
ASHP heating is optimal; when it falls below–15 ℃, the ASHP-STES system
offers greater energy-saving benefits.