Reducing the environmental impacts of tobacco factories

Reducing industrial waste is key to lowering pollution and mitigating energy shortages. In tobacco factories, air compressors are a major culprit, operating at only 10% to 15% efficiency. Without effective systems to capture and repurpose the excess heat they generate, much of it is lost as waste.

Zeotropic refrigerants are mixtures of multiple liquids that allow for adjustable boiling points. They are safer and more sustainable than traditional refrigerants, offering a promising alternative in factory air compression. To reduce the heat waste in tobacco manufacturing, Ruan et al. compared heat transfer models to optimize heat pump parameters and zeotropic mixture flows.

“Addressing this issue poses several challenges: the technical complexity of designing and integrating heat pump systems that can efficiently recover this waste heat, the need to optimize refrigerant mixtures and operating conditions, and the economic hurdle of ensuring that the initial investment in such systems is offset by long-term energy savings,” said author Liqiang Guo. “These factors complicate efforts to improve compressor efficiency.”

The authors analyzed the effects of four zeotropic fluids for tobacco heat pump waste on evaporation and heat pump performance, according to four common models. A few key relationships were clear: As the refrigerant inlet temperature rises and its flow rate increases, its performance and efficiency decrease, and the cost rises.

Guo says the findings underscore the importance of tailored approaches for energy recovery, which can lead to greener, more efficient industrial practices all around.

“The principles outlined — particularly the optimization of refrigerant mixtures and heat transfer models — are not limited to tobacco manufacturing,” said Guo. “They can be adapted to other industries with comparable waste heat sources, such as food processing or chemical manufacturing.”

Source: “Comparative analysis on evaporator design and heat pump system performance under different zeotropic mixture flow boiling corrections: Waste heat recovery for tobacco factory air compressor,” by Wang Ruan, Jing Wang, Xu Xu, Liqiang Guo, and Xudong Hu, Journal or Renewable and Sustainable Energy (2025). The article can be accessed at https://doi.org/10.1063/5.0254640 .