Xin-Rong Zhang

As the global freshwater crisis intensifies, desalination has emerged as a reliable method for water supply worldwide. However, the high energy consumption and operating costs associated with conventional steam-driven seawater desalination remain significant challenges. This study proposes a low-temperature multi-effect distillation (LT-MED) model driven by waste heat to replace conventional steam and reduce the cost of distillation. A case study was conducted on the 15,000 m³/day Hengli Petrochemical hybrid system in Dalian, China, which integrates distillation desalination with hot-water flashing. The thermodynamic model of the hybrid system, based on energy and mass balance equations, demonstrates that a seven-effect evaporator setup offers the most cost-effective and energy-efficient solution. The study explores four methods to enhance the Gain Output Ratio (GOR) and identifies optimal parameters and configurations for improved overall system performance. The findings provide valuable insights for designing innovative hybrid distillation systems powered by low-grade waste heat.

Improving the pool boiling heat transfer by changing the properties of the heating surface has been experimentally studied by many researchers. In this paper, two novel microstructured surfaces with open channels were simulated and investigated. The two microstructured surfaces had different cavity positions and different groove widths of open channels. At the same time, a pool boiling experiment on the plain-heated surface was carried out to verify the reliability and accuracy of the CFD model. The results showed the relationship between the heat flux and wall superheat. Moreover, the bubble dynamic behaviors of different surfaces were obtained. It was found that both microstructured surfaces could enhance the pool boiling heat transfer coefficient (HTC) and critical heat flux (CHF). Enlarging the length of the groove gap can not only increase the heat transfer area, but also increase the bubble nucleation rate. However, constantly increasing the groove width will cause the horizontal coalescence of bubbles on the heating surface at low heat flux. When the negative effect of bubble coalescence is higher than the enhancement effect, the boiling heat transfer capacity of the heating surface will decrease unless the heat flux is high enough to delay bubble coalescence.

BTES is an important seasonal thermal energy storage technology that effectively addresses the uneven temporal and spatial distribution of energy. However, the complex and time-consuming thermal analysis of BTES poses challenges to its development. This paper presents a simplified analytical algorithm based on the FLS model, integrating convective heat transfer within the borehole fluid and transient thermal conductivity of the surrounding soil to establish an analytical model. The model is simplified based on its geometric symmetry, and a numerical model is established for validation. The results show that the relative errors between 0.54% and 5.76% were associated with temperature variations ranging from 0.21°C to 0.58°C.