Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Last modified date:2021.04.05

Assistant Professor / Department of Aeronautics and Astronautics / Faculty of Engineering


Papers
1. Xiaoyue Zhang, Zhenying Wang, Zhen Li, A novel flue gas heat recovery system based on low-pressure regeneration liquid desiccant cycle, INTERNATIONAL JOURNAL OF LOW-CARBON TECHNOLOGIES, 10.1093/ijlct/ctx013, 13, 1, 1-5, 2018.03, Flue gas from natural gas boilers contains much water vapor, so the latent heat occupies a large proportion of the total waste heat. This paper introduces a flue gas driven absorption system based on low-pressure regeneration liquid cycle to recover water and waste heat, especially the latent heat. The concentrated liquid desiccant is sprayed into the packed tower to absorb the vapor from the low-temperature flue gas and gets diluted itself. Then the diluted desiccant is heated and concentrated by the high-temperature flue gas in the vacuum regenerator. The evaporated water from the regenerator then releases condensation heat to the return water of the heating network. Based on the thermodynamic model of the new system, the simulation results show that the flue gas (200 degrees C, 120 g/kg) is eventually released to the atmosphere at 53 degrees C with a humidity ratio of 46 g/kg, which means considerable heat is recovered by the system. The heat and water recovery of the new system is not constrained by the dew point of the flue gas. It also lowers the requirement of the generation temperature due to vacuum regeneration. So in terms of heat recovery, the new system outperforms the traditional condensing system and the open-cycle absorption system by 28.3% and 23.1%, respectively. The new system also helps to reduce particulate emissions and recover water, with a recovery of 0.36 tons of water per hour according to the simulation result based on the boiler with a power of 2.8 MW..
2. Zhenying Wang, Daniel Orejon, Khellil Sefiane, Yasuyuki Takata, Effect of Substrate Conductivity on the Transient Thermal Transport of Hygroscopic Droplets during Vapor Absorption, Micromachines, 10.3390/mi11020193, 2020.02, In all kinds of liquid desiccant dehumidification systems, the temperature increase of the desiccant solution due to the effect of absorptive heating is one of the main reasons of performance deterioration. In this study, we look into the thermal effects during vapor absorption into single hygroscopic liquid desiccant droplets. Specifically, the effect of substrate conductivity on the transient heat and mass transfer process is analyzed in detail. The relative strength of the thermal effect and the solutal effect on the rate of vapor absorption is investigated and compared to the thermal effect by evaporative cooling taking place in pure water droplets. In the case of liquid desiccants, results indicate that the high thermal conductivity of copper substrates ensures more efficient heat removal, and the temperature at the droplet surface decreases more rapidly than that on Polytetrafluoroethylene (PTFE) substrates. As a result, the initial rate of vapor absorption on copper substrates slightly outweighs that on PTFE substrates. Further analysis by decomposing the vapor pressure difference indicates that the variation of vapor pressure caused by the temperature change during vapor absorption is much weaker than that induced by the concentration change. The conclusions demonstrate that a simplified isothermal model can be applied to capture the main mechanisms during vapor absorption into hygroscopic droplets even though it is evidenced to be unreliable for droplet evaporation..