THERMAL SCIENCE

International Scientific Journal

Suola Shao

,

Chengcheng Xu

,

Bicui Ye

,

Wenjian Wei

,

Wenjuan Li

,

Yonghui Liu

THERMAL CHARACTERISTICS OF AN ALUMINUM FANLESS RADIANT PANEL HEAT EXCHANGER ASSISTED HEAT PUMP: EXPERIMENTAL INVESTIGATION ACROSS DIVERSE OPERATING REGIMES

ABSTRACT
This study experimentally investigates a novel air source heat pump (ASHP) system integrated with an aluminum fanless radiant panel heat exchanger (AHE) incorporating thermal storage for cold climate applications. The system’s thermal performance was evaluated under the normal (7°C), typical (–7°C), and ex¬treme (–12°C) winter conditions, with condensation temperatures varying from 34.1-60.7°C. Results demonstrate that the ASHP-AHE system maintains stable operation with consistent COP values of 2.19 ±0.03 at 7°C, 2.07 ±0.05 at –7°C, and 1.80 ±0.03 at –12°C, and with heat dissipation fluctuations remaining below ±1.8%. The integrated thermal storage effectively buffers temperature variations while maintaining a characteristic 15.8% radiant heat transfer proportion at the condensation temperature of 46.0°C. Comparative analysis reveals that the average COP is 4.1%-7.7% higher than conventional systems, particularly at medium temperatures below 40 °C. Pressure drop analysis shows minimal impact on heat dissipation. The flow resistance accounts for merely 3.1%-4.4% of the total pressure. The system exhibits superior performance stability at lower ambient temperatures, with heat flux remaining constant (2260.3 ±14.5 W/m2 at 46.0 ±0.3°C condensation temperature) regardless of outdoor conditions. These findings validate the technical feasibility of thermal storage-integrated radiant terminals for ASHP systems in cold climates, providing design guidelines for efficient heating solutions in severe winter regions. The study contributes empirical evidence for advancing low carbon heating technologies while addressing performance limitations under extreme cold conditions.
KEYWORDS
Air source heat pump, Radiant terminal, thermal performance, thermal storage, Extreme cold conditions
PAPER SUBMITTED: 2025-08-15
PAPER REVISED: 2025-11-10
PAPER ACCEPTED: 2025-11-14
PUBLISHED ONLINE: 2026-01-17
DOI REFERENCE: https://doi.org/10.2298/TSCI250815235S
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2026, VOLUME 30, ISSUE No. 3, PAGES [2101 - 2115]
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Thermal characteristics of an aluminum fanless radiant panel heat exchanger assisted heat pump: Experimental investigation across diverse operating regimes

© 2026 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence