2023-06-25 21:43:35
Article regarding research and development work published in Applied Energy magazine. The novelty of the collector lies in the fact that it is designed on the basis of a composite heat accumulator, which is made by fusing a phase change material and copper foam.
“The new collector more than doubled the thermal conductivity compared to the collector without copper foam. It switched to the heat accumulation mode for half an hour faster, the accumulation period turned out to be shorter, the amount of accumulated heat was much larger, and the heating temperature was higher. In other words, the heat storage capacity of the device has improved. This allowed him to release more thermal energy at night, that is, the efficiency of heat transfer increased. At the same time, the heat release time was reduced by 20 percent, and the decrease in air temperature at the outlet of the collector was up to 10 percent, ”comments Vladimir Alekhin, head of the Department of Computer-Aided Design of Construction Facilities at the Institute of Construction and Architecture of the Ural Federal University, head of research from the Russian side, co-author of the article.
Collector test circuit / ©UrFU press service
Thanks to the improvements, the distribution of heat in the room has become more even, the range of temperature fluctuations in the room has decreased, and it has become more comfortable to be in it. And the stock of heat stored in the collector increased, so its cooling was slower. Thus, the new collector is more economical than its predecessors.
The new solar air collector has been successfully tested in China, at temperatures from -15 to +5 degrees. Tests have shown that if previous world studies focused on one or two factors in the efficiency of solar air collectors, then a group of Russian and Chinese scientists managed to improve a whole range of parameters.
The design of “classic” solar air collectors, which are installed on the outer walls of buildings, includes transparent glass covers, solar heat-absorbing panels, insulating layers and metal shells. Solar absorbers are the main components that convert light energy into heat energy and then use the air to transfer heat into the room.
“Due to the intermittency of solar energy, traditional solar air collectors cannot provide heating at night. Science solves this problem by developing models of solar air collectors using phase change materials. They provide an increased speed and density of energy accumulation, its storage inside the collector and, thus, help to reduce temperature fluctuations and increase thermal comfort in the room,” explains Vladimir Alekhin.
Collector device / ©UrFU press service
However, solar collectors made of phase change materials have their drawbacks: the low thermal conductivity of such materials reduces the efficiency of heat storage in the collector. This affects the thermal performance of the collectors and increases the requirements for integrated heating for building users. To improve thermal conductivity, researchers around the world are combining phase-change materials and foam metals, in particular porous and lightweight copper foam, which is known for its high thermal conductivity.
Rural areas are characterized by low population density and dispersed residential buildings, so they are often unsuitable for the installation of central heating systems. For this reason, rural residents still use stoves and fireplaces, charcoal. These traditional home heating methods are inefficient and cause serious environmental pollution. By 2030, the UN predicts that these buildings will emit regarding 30 percent of the world’s carbon dioxide emissions.
Therefore, further development of solar air collectors that use environmentally friendly energy is extremely important. The main advantages of such collectors are simplicity of design, operation, high efficiency, frost resistance and reliability.
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