Abstarct: Clean water is used for three main reasons: residential, industrial, and agricultural. Most countries with arid and semi-arid climates such as Iran face problems for freshwater supply. As a result, these countries are seeking to provide high-quality water supplies by desalination of seawater or well water. This project is baxsed on the modeling of the MED desalination process and empirically investigates the parameters affecting the rate of heat transfer in this Plant. The basis of MED units is that a low temperature and pressure steam first enters the first effect. When the feed water enters the first effect, it is sprayed in to the vacuum evaporator on horizontal tubes falling film Heat exchanger. The primary steam flows through the tubes. Thus, a part of the feed water evaporates and enters the second evaporator with a greater vacuum. The primary steam inside the tubes of evaporator heat exchanger is condensed back into the boiler due to its heat loss. The condensation of steam is then collected as fresh water and final treatment is carried out on it. So far, these plants have been designed and researched mostly for large scale (more than 1000 cubic meters of fresh water per day); However, the construction of centralized and high-capacity plants for fresh water production faces a problem due to the lack of financial resources for capital cost and not being suitable from a strategic point of view. Considering that this device can use energy with low exergy and low temperature to produce water, it is also necessary to use it on a small scale (one to one hundred cubic meters per day) to increase the energy efficiency of the plant and produce fresh water. But small-scale design faces the problem of lack of information and overall optimization of the device, especially the design of the falling film heat exchanger and the heat transfer coefficient. Therefore, in this research, the factors affecting the design such as flow rate, pressure, heat flux and salt concentration have been experimentally investigated. Also factors such as start-up and sudden shutdown of the device, the effect of changes in the flow rate and pressure of the ejector, have been investigated dynamically; in order to be able to design the optimal plant and obtain the necessary information for control systems. In this way, it is possible to provide the fresh water needed for small industries, limited agriculture, and the supply of fresh water for the consumption of sparsely populated residential complexes. The dynamic results showed that with the smallest decrease in the ejector motive pressure from the design pressure, GOR decreases by 33%, and with a 10% decrease in the motive flow rate, the water level in each evaporator increases 5-fold. While a 10% decrease in the motive pressure causes a 10-fold increase in the water level in evaporators; which will cause overflow the system. The experimental results showed that using the Taguchi method can be a suitable tool with sufficient accuracy to reduce the cost and time of taking tests to design tests and it will better identify the trend of the results. In these results, it was found that the heat transfer coefficient increases with the increase of absolute pressure and heat flux and decreases with the increase of salt concentration. Also, the transition boundary of laminar flow to turbulent flow was detected around the falling film flow rate of 0.04 kg/s.