What is it about?
This review dives into absorption heat transformers (AHTs)—clever devices that recycle low-grade waste heat from factories or solar sources, turning it into higher-temperature useful heat without burning extra fuel. Imagine capturing the warmth from an industrial process at 80°C and boosting it to 120°C for steam generation or drying, saving energy and cutting costs. AHTs work like a heat pump but use heat instead of electricity: a mixture (often water and lithium bromide salt) absorbs and releases heat in a cycle of evaporator, absorber, generator, and condenser components. The paper surveys nearly 170 studies since 1986, comparing single-stage AHTs (simple setups yielding up to 50% efficiency, or COP of 0.5, with 50°C temperature lifts) to advanced ones like two-stage or double-absorption systems (higher lifts up to 140°C but lower efficiency around 0.2-0.3). It spotlights water-lithium bromide as the go-to fluid but explores greener alternatives like water-Carrol (less corrosive, higher lifts) or ionic liquids (for 200°C ops). Applications shine: in desalination, AHTs purify seawater using waste heat, producing up to 1 kg/h distilled water per kW while boosting efficiency 120%; in industries like paper mills or refineries, they slash steam use by 25-60%, with payback in 2-5 years. Experimental prototypes (500W-5MW) confirm real-world viability, though challenges like corrosion persist. Overall, AHTs could transform energy waste into savings, reducing CO2 by millions of tons yearly—perfect for sunny, industrial regions facing fuel hikes.
Featured Image
Photo by Pawel Czerwinski on Unsplash
Why is it important?
This 2015 review uniquely compiles 168 studies on AHTs by configuration and fluid, exposing gaps like limited high-temp alternatives (e.g., TFE/NMP for 200°C vs. LiBr's 150°C limit) and real efficiencies (0.45 lab vs. 0.2 industrial). Timely amid 2020s energy crises—fossil fuels still 90% of supply, waste heat untapped in 20-50% processes—it shows AHTs could recover 4.5MW/site, cutting emissions 10-20% in desalination or cogeneration. Unlike vague overviews, it quantifies paybacks (2-5 years at $5-11/MMBtu gas) and scalability, guiding prototypes for renewables integration. Impact: Accelerates adoption in emerging markets (e.g., Mexico's refineries), saving billions in fuel while hitting SDGs on clean energy—potentially offsetting 1-2% global industrial CO2 if scaled.
Perspectives
In thermal engineering, this review synthesizes AHT evolution from niche 1980s prototypes to viable waste-heat tech, emphasizing hybrids (e.g., solar ponds + AHT for 100°C boosts) over vapor-compression's electricity hunger. It critiques LiBr dominance amid corrosion woes, spotlighting ionic liquids for eco-upgrades, and ties to broader sustainability: beyond desalination (120% COP gains), it enables circular economies in chemicals/paper. Future: AI-optimized cycles or nanomaterials for 0.6+ COP; integrate with carbon capture for net-zero industries. As renewables surge, AHTs bridge low-grade heat gaps, aligning with Paris goals—vital for equitable cooling in a 2°C world.
Professor Rosenberg J Romero
Universidad Autonoma del Estado de Morelos
Read the Original
This page is a summary of: A review of absorption heat transformers, Applied Thermal Engineering, December 2015, Elsevier,
DOI: 10.1016/j.applthermaleng.2015.08.021.
You can read the full text:
Contributors
The following have contributed to this page
