There are black tubes of solar water heaters with water and others without water. The vacuum collector tube (black vacuum tube) receives sunlight, then converts the converted sunlight into thermal energy to heat the medium in the collector, which is water. Once the water is heated, the heat in the collector is continuously transferred by natural circulation. . Go to the water storage tank and heat the water in the water storage tank. The principle of cold and hot water circulation of the vacuum collector is that hot water is less dense than cold water and will automatically float and circulate to transfer thermal energy. The entire heat collection effect and the automatic circulation principle of cold and hot water are the work of black solar vacuum tubes. The black vacuum tube consists of two layers, the exterior is transparent and the inner and outer walls of the tube are covereds of chemical raw materials. In simple terms, it is like the thermos bottle that we commonly use. There is a vacuum between the two layers and it looks black, that's why we call it a black vacuum tube.
Light includes infrared rays, visible light, ultraviolet rays and other rays. Visible light is the red, orange, yellow, green, blue, indigo, and violet we usually see, as well as infrared and ultraviolet rays. rays. The reason we see the color of an object is that it reflects visible light, and black does not reflect any light and is absorbed, including infrared rays, so it receives the most energy, so it appears warmer.