Characterization of heat pipes for space applications/ETCA Facility
The experimental facility, called ETCA, allows to carry out tests on heat pipe devices.
The facility loop is characterized by an evaporator section (test section), a condenser section and a channel, with subcooler, which connects the condenser exit to the evaporator collector inlet.
The working fluid (water), after its evaporation and subsequence condensation, is drawn back to the collector by the capillary action exerted by a suitable wick which lines the heated evaporator surface and which is partially submerged in the collector.
The initial system liquid level set up (fluid inventory), allows to carry out tests with or without gravity head assistance.
Experimental facility - Test loop
Cylindrical stainless steel evaporator housing with optical window at the top and with heated wicked surface inside.
In the present configuration a circular plane horizontal heated wicked surface of 50 cm2 is being employed with either sintered stainless steel material or packaged screens (mesh width = 0.209 mm, wire diameter = 0.11 mm) in different thickness (1 or more screen layers). The heated surface lined by the wick is in copper material..
Experimental facility - Test section
In the 1st and 2 nd configuration a circular shaped truncated-cone heated wick of 150 and 100 cm2 of surface was used respectively. The wick was in sintered stainless steel material (porous media of 90 mm in porosity) of 3 mm in thickness. The heated surface lined by the wick was in stainless steel.
The above figure is referring to the 1st evaporator configuration and the graph shows the relative-steady state results obtained. The maximum evaporator heat flux q"ev measured was of 13 W/cm2 at a pressure value of 400 kPa.
The above figure is referring to the 2 nd evaporator configuration and the graph shows the relative steady-state results obtained. The maximum evaporator heat flux q"ev measured was of 20 W/cm2 at a pressure value of 400 kPa.
1st and 2 nd Series of tests were performed with circular shaped truncated-cone heated wick of 150 and 100 cm2 of surface respectively.
Present tests are being performed with a circular plane horizontal heated wicked surface of 50 cm2.
The above two graphs show the system parameter behaviour during one of several transient tests performed and relative to the 2nd evaporator configuration. Then, it is possible to evidence the system capability to approach steady-state conditions, at a pressure of 4 bar and with a heat flux transferred through the steam flow passage q of about 150 W/cm2 supporting an electric power step (heat load), Qel , of about 1.8 kW .