Bio‐waste‐derived adsorbents in vapor adsorption refrigeration and cold storage: A statistical and analytical review

Abstract Vapor adsorption refrigeration (VAR) systems employing renewable heat sources are becoming more popular worldwide due to the requirement for low‐carbon refrigeration, notably in off‐grid agricultural and food‐preservation businesses for different scenarios. Adsorbents with sufficient vapor capacity; good thermal conductivity; adequate regeneration energy and reasonable cyclic life are required. Therefore, this statistical and analytical review provides an evaluation of over 100 research articles concerning bio‐waste derived adsorbents; thermal management composite materials; photothermal materials and related performance characteristics for VAR. The results show that BET surface areas for bio‐waste derived activated carbons typically fall in the range of 900–1500 m 2 /g and vapor uptake ranges of 0.32–0.45 g/g. As such, these surface areas exceed those typically obtained using silica gel (i.e., 0.20–0.30 g/g) and approach or equal those obtainable with commercial activated carbons (i.e., 0.30–0.35 g/g). Phase‐change materials made from bio‐wastes have been shown to possess latent heat values of 165–192 J/g and can withstand up to 1200 thermal cycles. Additionally, thermal conductivities as low as 0.038 W/mK have been achieved using insulating materials produced from natural fibers. Therefore, the review concludes that optimized bio‐waste derived adsorbent materials should contain BET surface areas >900 m 2 /g; micropore volumes of 0.50–0.70 cm 3 /g; vapor uptakes >0.35 g/g; adsorption heats of 40–55 kJ/mol and thermal conductivity >0.5 W/mK when included in packed bed configurations. By combining material physics, adsorption thermodynamics, and thermal‐management advancements, this study prepares bio‐waste‐based VAR systems for realistic, scalable cold storage.