Aluminum heat pipes applied in solar collectors

• Special aluminum alloy extruded heat pipes applied to solar collectors were developed.
• Flat plate collectors and evacuated tube solar collectors were made of them.
• Hydraulic and thermal resistances of both kinds solar collectors are very low.
• Their heat transfer ability is super high.
• They could be easily integrated and adapted to building designs due to modularity.

The previous researchers have developed a variety of liquid thermal solar collectors designs for water heating. It was reported by the other authors, that metal heat pipes applications to liquid solar collectors, especially to evacuated glass tube ones, is an efficient solution for water heating plants. However, the majority of thermal solar collectors do not meet the requirements on small weight, easy assembly and installation, versatility, scalability, and adaptability of the design, which are particularly important when they are façade integrated. Very high hydraulic resistance, from 2000 Pa to 20,000 Pa, in liquid solar collectors and low thermal efficiency of some of them, less than 0.5, also are the problems to be solved by the developers. Current research is proposing to apply extruded aluminum alloy made heat pipes of original cross-sectional profile with wide fins and longitudinal grooves in order to avoid the above-mentioned drawbacks of liquid thermal collectors. Absorber plate of flat collectors could be composed of several fins. Fins at the opposite end of the heat pipe serve as a heat sink surface. Multiple tests proved that new lightweight and inexpensive heat pipes show high thermal performances. Maximum heat transfer power of one heat pipe is up to 210 W; and its thermal resistance is very low – from 0.02 to 0.07 °C/W. Hydraulic resistance of flat plate solar collector and evacuated one utilizing aluminum profiled heat pipes, could be reduced to less than 100 Pa, at the same time their thermal efficiency is rather high, up to 0.72. In the issue of authors study, the feasibility of the developed aluminum profiled heat pipes application to thermal solar collectors was proved; and they can be successfully integrated to building façades and roofs.