This study aims to design a portable desalination device and discusses the feasibility of the device for overcoming a shortage of safe drinking water. A low-energy, self-supporting, and portable desalination device is designed based on forward osmosis (FO) using an ammonium bicarbonate solution. Experiments with various concentrations of ammonium bicarbonate solution and sodium chloride solution showed that the portable desalination device's performance such as volume and flow rate of desalting water and time required satisfied drinking water standards. The device performance is controlled by varying the concentration and temperature of the solution.

Design and Evaluation of Portable Forward Osmosis Desalination Device

* Dept. of Mechanical Engineering Chungnam Nat’l Univ.** COAVIS, *** Korea Automotive Technology Institute, (Received July 29, 2014 ; Revised September 25, 2014 ; Accepted October 30, 2014)Key Words: Nonpower-Pump(무동력펌프), Ejector(이젝터), Cavitation(공동현상), CFD Analysis(CFD 해석), Flux Ratio(유량비)초록: 무동력펌프의 일종인 이젝터는 압력을 갖는 유체를 노즐에서 분사하여 주위의 유체를 흡입 후 혼합유체를 외부 동력 없이 송출하는 장치이다. 구조가 간단하고 고장이 적어 여러 산업분야에서 이용되고 있으며, 자동차 산업에서는 연료주입용으로도 이용되고 있다. 대부분 이젝터는 가스상을 사용하기 때문에, 가스상 이젝터는 오래전부터 연구되어 왔다. 액체상 이젝터는 그 용도에 비해 아직 연구가 활발하지 못하다. 가스상 이젝터와 달리, 액체상 이젝터는 노즐목에서 부분적인 압력강하에의한 공동현상이 발생되고 이러한 공동현상은 부품파손을 유발하며, 소음을 발생시키는 원인이 되고 있다. 본 연구는 액체-액체상 이젝터의 최대 유량비와 공동현상 발생영역 비교를 위해 5가지 인자를 변경하여 2차원 축대칭 전산해석을 진행하였다. 액체 이젝터의 공동현상에서는 특히 노즐각도가 중요한 역할을 하였으며, 유량비 성능 특성은 혼합챔버각도 35°가 가장 유리한 것으로 판단된다. 이를 통해 공동 현상을 최소화 시키면서 성능 최적화를 달성할 수 있는 조합을 얻을 수 있음을 확인하였다.Abstract: An ejector is a type of non-powered pump that is used to supply a secondary flow via the ejection of a primary flow. It is utilized in many industrial fields, and is used for fueling the vehicle because of less failures and simple structure. Since most of ejectors in industry are gas-to-gas and liquid to gas ejector, many research activities have been reported in optimization of gas ejector. On the other hand, the liquid ejector is also applied in many industry but few research has been reported. The liquid ejector occurs cavitation, and it causes damage of parts. Cavitation has bees observed at the nozzle throat at the specified pressure. In this study, a two-dimensional axisymmetric simulation of a liquid-liquid ejector was carried out using five different parameters. The angle of the nozzle plays an important role in the cavitation of a liquid ejector, and the performance characteristics of the flow ratio showed that an angle of 35° was the most advantageous. The simulation results showed that the performance of the liquid ejector and the cavitation effect have to be considered simultaneously.

Secondary Flow Patterns of Liquid Ejector with Computational Analysis

In this study, we have carried out development and performance evaluation of optimized MEMS(Multi-Effect-Multi-Stage) fresh water generator with for solar thermal desalination system. The developed MEMS was composed of high temperature part and low temperature part. This arrangement has the advantage of increasing the availability of solar thermal energy. The MEMS consists of 2 steam generators, 5 evaporators, and 1 condenser. Tubes of heat exchanger used for steam generators, evaporators and condenser were manufactured by corrugated tubes. The performance of the MEMS was tested through in-door experiments, using an electric heater as heat source. The experimental conditions for each parameters were for sea water inlet temperature to condenser, /hour sea water inlet volume flow rate, for hot water inlet temperature to generator of high temperature part, 3.6 4.8, 6.0 for hot water inlet volume flow rate. As a result, The developed MEMS was required about 85 kW heating source to produce of fresh water. It was analyzed that the performance ratio of MEMS was about 2.6.

Experimental Study on Performance of MEMS(Multi-Effect-Multi-Stage) Distiller for Solar Thermal Desalination

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with /day capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were for sea water inlet temperature, /hour sea water inlet volume flow rate, for hot water inlet temperature, 2.4, 3.6, and /hour for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce /day of fresh water. Based on the results of this study, It makes possible to secure economics of desalination system with solar energy which is basically needed development of high efficiency fresh water generator.

Development of Multi Effect Distillation for Solar Thermal Seawater Desalination System

In this study, the ejector design was modeled using Fluent 6.3 of FVM(Finite Volume Method) CFD(Computational Fluid Dynamics) techniques to resolve the flow dynamics in the ejector. A vacuum system with the ejector has been widely used because of its simple construction and easy maintenance. Ejector is the main part of the desalination system, of which designs determine the efficiency of system. The effects of the ejector was investigated geometry and the operating conditions in the hydraulic characteristics. The ejector consists mainly of a nozzle, suction chamber, mixing tube(throat), diffuser and draft tube. Liquid is supplied to the ejector nozzle, the fast liquid jet produced by the nozzle entrains and the non condensable gas was sucked into the mixing tube. In the present study, the multiphase CFD modeling was carried out to determine the hydrodynamic characteristics of seawater-air ejector. Two-dimensional geometry was considered with the quadrilateral-mashing scheme. The gas suction rate increases with increasing Motive flow circulating rate.

https://www.koreascience.or.kr:443/article/JAKO201013351027601.pdf

Hee-Youl Kwak

Papers

Development of Multi Effect Distillation for Solar Thermal Seawater Desalination System

Analysis of the ejector for low-pressure evaporative desalination system using solar energy