Techno-economic and environmental assessment of an ammonia-water absorption refrigeration system driven by waste heat recovery for frozen warehouse

Refrigeration and deep-freezing are essential for preserving perishable food products but represent a major share of energy use in the food industry, accounting for approximately 30-60 % of electricity consumption in commercial facilities. The growing demand for frozen food has further increased the need for low-temperature storage. Currently, most systems rely on vapor compression refrigeration (VCR), which is highly electricity-intensive and leads to a significant carbon footprint, particularly in regions such as Southeast Asia where power generation is largely fossil-based. In this context, alternative technologies with reduced electricity consumption are receiving increasing attention. Absorption refrigeration systems, which can be driven by industrial waste heat, represent a solution. For sub-zero cooling, the Generator-Absorber heat exchange (GAX) cycle using ammonia-water working pair offers improved thermodynamic efficiency compared to conventional single-effect systems. However, the application of this technology for low-temperature refrigeration, as required in cold storage (around -18 °C), has not yet been explored. This study develops and assesses a waste-heat-driven GAX absorption refrigeration system for cold storage by comparison with a conventional VCR system. The analysis focuses on evaluating techno-economic, and environmental performance using different indicators, including an electrical coefficient of performance (ECOP), thermal coefficient of performance (COPth), payback period (PBP), net present value (NPV), levelized cost of cooling (LCOC), and CO2 emission reduction potential. The preliminary results show that the VCR system achieves the ECOP of about 1.6 in weather conditions of Vietnam, reflecting reduced efficiency at low evaporating temperatures (-27 °C). The GAX system, operating under the same conditions and using pressurized water at 150 °C supplied from waste heat, attains the COPth of approximately 0.25. This value is lower than that typically obtained under normal operating conditions for a conventional single-effect system (0.5–0.7). However, when accounting for all auxiliary electrical consumptions (cooling, heating, and solution pumps), the GAX system reaches the ECOP of around 11.5, significantly outperforming the VCR system and demonstrating strong potential for electricity savings. Future work will focus on detailed techno-economic and sensitivity analysis to assess the impact of key parameters such as capital cost and energy prices. This will provide further insight into the conditions under which waste heat-driven absorption systems can become economically viable and contribute to industrial decarbonization and net-zero emission targets.

Work In Progress