The relationship between population growth and precipitation change in some regions across Vietnam: implications for urbanization effect.

According to a review of numerous publications and scientific reports, the effects of urbanization on urban climate are of greatest concern. This study aims to evaluate the impact of urbanization focusing on population growth on precipitation trends in 11 provinces across Vietnam during the period 2008-2018 by identifying the relationship between population growth and precipitation change. Regression analysis is used to determine the trends of precipitation and population growth. Precipitation maps and graphs show the overall precipitation trends, changes, and patterns in past decades. Overall, population growth tends to correlate with precipitation change trends. Furthermore, the type of region groups (countryside region, small city, or medium city) also plays a crucial role in determining the magnitude of the change in precipitation trends for each region. This further lends credibility to the notion that urbanization contributes to changes in precipitation trends.

Assessment of pilot direct contact membrane distillation regeneration of lithium chloride solution in liquid desiccant air-conditioning systems using computer simulation.

Membrane distillation (MD) has been increasingly explored for treatment of various hyper saline waters, including lithium chloride (LiCl) solutions used in liquid desiccant air-conditioning (LDAC) systems. In this study, the regeneration of liquid desiccant LiCl solution by a pilot direct contact membrane distillation (DCMD) process is assessed using computer simulation. Unlike previous experimental investigations, the simulation allows to incorporate both temperature and concentration polarisation effects in the analysis of heat and mass transfer through the membrane, thus enabling the systematic assessment of the pilot DCMD regeneration of the LiCl solution. The simulation results demonstrate distinctive profiles of water flux, thermal efficiency, and LiCl concentration along the membrane under cocurrent and counter-current flow modes, and the pilot DCMD process under counter-current flow is superior to that under cocurrent flow regarding the process thermal efficiency and LiCl concentration enrichment. Moreover, for the pilot DCMD regeneration of LiCl solution under the counter-current flow, the feed inlet temperature, LiCl concentration, and especially the membrane leaf length exert profound impacts on the process performance: the process water flux halves from 12 to 6 L/(m2·h) whilst thermal efficiency decreases by 20% from 0.46 to 0.37 when the membrane leaf length increases from 0.5 to 1.5 m.