Proceedings of the International scientific and practical conference ―Science, technology and art in global context (July 8-10, 2025) / OP website: www.naukainfo.com. – Dresden, Germany, 2025. - 140 p.

119 LITERATURE REVIEW Various technologies have been developed to recover low-grade heat from exhaust streams. Common solutions include recuperative heat exchangers—such as crossflow and counterflow plate designs—which separate warm and cold streams with thin walls. These systems typically achieve 55–70% heat recovery, with top units reaching ~80% efficiency [4]. Rotary heat exchangers (thermal wheels) offer another approach. These rotating elements, made of porous materials like metallic honeycombs or polymer fibers, alternately absorb heat from exhaust air and transfer it to intake air. Operating as rotating regenerators, they achieve 65–80% recovery, with optimized systems reaching up to ~85% efficiency [4, 5].The diagram below illustrates the basic principle of such a rotary regenerator: a rotating porous disk sequentially contacts the hot (red arrow) and cold (blue arrow) streams, storing heat in its mass and transferring it to the opposite flow. Fig. 1 [5]. Operating principle of a rotary regenerator (thermal wheel). Other solutions include heat pipes, dual-circuit systems with remote heat exchangers (run-around coils), and heat pumps that boost low-grade heat to higher temperatures [4]. However, these systems require electricity and complex equipment. As a simpler alternative, static regenerators using solid thermal storage media—such as sand, gravel, or ceramic granules—are gaining interest.