Acoustic agglomeration is employed as a precursor technique that modifies the sound field of fine particles to increase their size, thereby facilitating more efficient emission control. This paper reviews progress in the field of acoustic agglomeration technology, clarifies the mechanisms at play within the acoustic agglomeration process, and outlines its applicability in both gas-liquid and gas-solid phases. Furthermore, it analyzes the factors impacting the efficacy of acoustic agglomeration, summarizes the numerical simulation research of acoustic agglomeration, and proposes directions for technological enhancement.
1 November 2022 in International Journal of Heat and Mass Transfer
Electrochemical energy storage stations serve as an important means of load regulation, and their proportion has been increasing year by year. The temperature monitoring of lithium batteries necessitates heightened criteria. Ultrasonic thermometry, based on its noncontact measurement characteristics, is an ideal method for monitoring the internal temperature of lithium batteries. In this study, temperature and ultrasonic time delay measurement experiments were conducted on 18650 lithium batteries and laminated and wound lithium batteries to obtain the corresponding relationship between temperature and time delay and validate the temperature measurement for the same type of battery. The experimental results show that (1) the ultrasonic temperature measurement technique exhibits a relatively large error when used for 18650 Li-ion batteries under experimental conditions; (2) in the experiments on laminated and wound soft-pack lithium batteries, the relationship between temperature and time delay exhibits a nonlinear characteristic; and (3) under the experimental conditions, the ultrasonic temperature measurement errors were ±1.1 °C for stacked Li-ion batteries and ±1.4 °C for wound Li-ion batteries.
The direct discharge of wet saturated flue gas from a coal-fired power plant boiler causes a lot of water and waste heat loss. An inorganic ceramic membrane condenser recovers water and waste heat from the flue gas, which has great significance to improve energy utilization efficiency and reduce water consumption. However, the flue gas temperature is relatively low; thus, it is difficult to effectively utilize waste heat. In this paper, it is attempted to use the boiler secondary air as the cooling medium of the ceramic membrane condenser to realize the flue gas waste heat reuse. Based on the above ideas, a purge gas ceramic membrane condenser experimental platform was built for the water and waste heat recovery from the flue gas, and the water and waste heat recovery characteristics and the purge gas outlet parameters were discussed. Simultaneously, the heat transfer resistance and water recovery power consumption are also analyzed. The experimental results show that the water and waste heat recovery characteristics are enhanced with the purge gas flow increases. Increasing the flue gas temperature will increase the water recovery rate and heat recovery power. The ceramic membrane transmission efficiency is a key factor in restricting the actual water recovery efficiency. The purge gas absorbs the water and waste heat from the flue gas, the purge gas temperature and moisture content are significantly increased, and the purge gas relative humidity is also close to saturation. The Biot number of the ceramic membrane condenser is about 3.2 × 10–3 to 1.9 × 10–2; thus, the ceramic membrane tube wall thermal resistance can be neglected. There is a temperature difference between the flue gas and the purge gas, and the entropy production value of the ceramic membrane condenser increases with the flue gas temperature increases by the irreversible process.
The typical flue gas exhaust temperature of coal-fired boilers is up to 150 °C. There is a considerable amount of waste heat that cannot be efficiently recovered. This study describes a zero-energy consumption absorption heat pump system that can improve the thermal efficiency and recover moisture. In the proposed system, lithium bromide solution serves as the recyclable heat-transfer medium, which absorbs sensible heat at the outlet of the air preheater by a generator. The latent heat of the flue gas is absorbed by an evaporator, and the condensate water appears. Theoretical investigation and mathematical models are built. Meanwhile, the operating parameters of the system are displayed. The results showed that the acid dew point of flue gas is related to the water content. The sorption heat pump efficiency (coefficient of performance) increased to 1.64. Compared with the two-stage heat exchanger system, 24.4 t/h condensate water and 47.21 MW waste heat were recovered. The flue gas temperature at the chimney entrance was reduced by 4.18 °C.