Study on Cultivation Way with Desalination of the Brackish Water

由于森林砍伐，泰国东北部的生态系统遭到破坏。超过150万公顷的面积受到盐分积累的影响。在该地区，池塘水和地下水中也含有大量的盐分，这类水的农业利用存在许多困难。本研究探讨了泰国东北部盐碱地池塘水和地下水的有效利用方法。对于苦咸水的淡化，介绍了太阳能蒸馏等多种方法。在本研究中，提出了一种新型的太阳能蒸馏器。该系统分为两部分，一部分是蒸发器，另一部分是冷凝器，迫使蒸汽空气直接凝结到土壤中。这种强制冷凝过程被称为“蒸汽灌溉”。为了评价这种新型太阳能蒸馏器的性能，我们进行了一些蒸发和冷凝实验。在强制冷凝过程中，增大水蒸气与冷凝面的温差是非常重要的。为此目的，减少装置的热损失，使用集热器来提高水蒸气温度，使用Peltier元件等冷却装置来降低冷凝物表面的温度可能是有效的。结合光伏排水泵控制地面植被，本研究将有助于泰国东北部盐碱地植被的恢复。

Because of deforestation, ecosystem has been devastated in Northeast of Thailand. More than 1.5million ha of area is nos affected by salt accumulation. In such area, water in ponds and groundwater are also including much salt, and there are many difficulties to use such water for agriculture.In this study, methods for effective utilization of the water in ponds and groundwater on saline land such as Northeast of Thailand were discussed.For desalination of the brackish water, a lot of ways as solar distillation methods were introduced. In this research, a new type of solar still was proposed. The system is separated ito two parts, one is evaporator and another is condenser, which forced to make vapor air condensed dirctly into the soil. This forced condensing process is called as the "Vapor irrigation".Some experiments of evaporation and condensation were carried out to evaluate the performance of the new type of solar still. In forced condensing process, it is important to increase the difference of temperature between water vapor and condensing surface. For that purpose, it might be effective to decrease heat losses of devices, to use heat collectors for increasing temperature of water vapor and to use the cooling devices like peltier element for decreasing temperature of condensign surface.With combining with PV drainage pump for groundwarer control, this study will be useful for recovering vegetalion on the saline land as Northeast of Thailand.