**3.1 Installation for loading of working fluid**

Figure 6 shows an outline of the facility for loading working fluid. It consists of an array of 2 resistors of the band type with an electrical power of 250 W each. The supply of electricity to the resistance was provided by a voltage variable autotransformer of 1.4 kW and power was calculated from data obtained by a voltmeter and an ammeter, both digital.

Before starting the loading procedure of fluid inside the thermosyphon, the tube was cleaned with soapy water and rinse with distilled water followed by methyl alcohol and finally dried by applying heat. After that the process of loading fluid began.

First to fill the thermosyphons with the required filling rate, it must be known how quickly the fluid evaporates in the loading process. To carry out this process a known mass of water was introduced, then the evaporator section was heated and some time was allowed to evaporate this water mass.

In this research seven tests of loading were performed at different times. The testing time was measured when the steam started to leave the thermosyphon from the needle valve installed on the top, until closing the valve. After valve was closed and the device was cooled off, the working fluid was removed to check how much fluid was ejected from thermosyphon during the loading process.

The loading process consisted of heating for some time the thermosyphon filled with a little more than the desired amount of fluid. This in order to evaporate the difference, and so fill all the volume with water vapor, so that it forces the non-condensable gases to escape through the needle valve installed on the top of the thermosyphon, along with water vapor excess. Knowing the rate of evaporation of the fluid, the loading process time depends on the amount of fluid is desired to leave inside the thermosyphon.

Fig. 6. Outline of the facility for loading working fluid.

To check the amount of fluid evacuated during the loading time, the steam was captured and taken through a condenser to a container where the mass ejected can be measured by a scale. The electrical resistances arrangement of the evaporator was isolated with mineral wool and a stainless steel shell, in order to minimize heat losses.

With this method of loading the inner volume of the thermosyphon fills only with working fluid as vapor or liquid. This ensures that there are no non-condensable gases accumulated in it. The time that takes to perform this procedure depends on the excess fluid that has to be removed, in that way that at the end of the procedure only the desired amount of working fluid stays in the thermosyphon.
