Experimental investigation of a heat pump recovering waste heat from mobile network stations for building heating applications

The worldwide growth of 5G networks is increasing energy consumption in the technology sector, turning telecommunication base stations (TBS) into significant sources of low-temperature waste heat. This presents a major, yet largely untapped, opportunity to recover this energy, especially in cities where the heat could be recovered to produce domestic hot water (DHW). The primary challenge lies in upgrading this low-temperature (30-45°C) heat to the 55-60°C required for DHW systems. This paper presents the design, prototyping, and comprehensive experimental evaluation of a novel solution: a compact "heat pump door" designed for direct integration into TBS cabinets. The prototype employs a miniaturized vapor-compression cycle using the low-GWP natural refrigerant R600a (isobutane) with a charge under 150 g. A systematic experimental campaign was conducted in the laboratory with a dedicated test rig to quantify the system's performance under emulated real-world conditions. The results demonstrate the system's viability, successfully producing DHW at 55°C with a heating COP of 3.1 and a heat recovery ratio (HRR) reaching up to 85%. A detailed experimental investigation has also been conducted into key parameters like compressor speed, fan power, and internal airflow management to evaluate the system's performance for evaluating the optimal operating strategies. This work provides the first experimental validation of novel miniaturized heat pump prototype. This technology offers a scalable solution through mass deployment across widespread TBS waste heat sources, contributing to the decarbonization of both the telecommunication and building sectors.