Study On Thermal And Energy Saving Performance Of Aerogel Foamed Concrete Insulation Wall

The research on the thermal characteristics and energy-saving performance of aerogel foamed concrete insulation walls in different climate zone has become a critical issue that needs to be addressed for its application and promotion,bearing significant importance for building energy conservation and carbon reduction.However,existing studies on the thermal performance of aerogel foamed concrete insulation walls face several challenges:the synergetic insulation mechanism between aerogel and cement-based materials at the micro-level remains unclear;the heat transfer mechanism of aerogel-cement-based enclosure structure products is not well-defined;the climate zone applicability of aerogel-cement-based enclosure structure products needs to be addressed immediately.To bridge these gaps,here we focus on the climate zone applicability of the thermal characteristics and energy-saving performance of aerogel foamed concrete walls by conducting the following research:(1)Study on the preparation method of aerogel foamed concrete materials with lightweight and high insulation performance.We adopted an equivalent volume replacement method and substituted traditional Si O2 aerogel with ultralight Si O2 aerogel.We prepared two types of aerogel foamed concrete by filling foamed concrete with lightweight(170kg/m~3)and ultralight(75kg/m~3)insulating Si O2 aerogel powder,and analyzed the effects of different aerogel densities on the micro-structure characteristics,thermal conductivity,compressive strength,and density of foamed concrete.When the specifications for compressive strength were met and the foam volume ratio increased to 70%,the density of ultralight aerogel foamed concrete was 186.15 kg/m~3,and the thermal conductivity was reduced to 0.058W/(m·K),decreasing by 10.7%and 10.4%,respectively,with a 56%reduction in aerogel consumption.(2)Study on a simplified one-dimensional thermal resistance-capacitance network model of aerogel foamed concrete insulation walls.We examined the heat transfer mechanism of aerogel foamed concrete insulation walls and conducted dynamic thermal performance experiments on aerogel foamed concrete insulation boxes to validate the one-dimensional simplified thermal resistance-capacitance network model;finally,based on the thermal resistance-capacitance network model,we compared the dynamic thermal performance of aerogel foamed concrete insulation boxes,ordinary concrete insulation boxes,and traditional EPS insulation boxes under periodic convective boundary conditions input into the insulation boxes.The thermal inertia index of aerogel foamed concrete insulation boxes was the highest,with a delay time(0.5h)twice that of the other two types of insulation boxes;it exhibited good resistance to the temperature amplitude,with a decay multiple(5.85)about 3.5 times that of the concrete box(1.68)and close to the polystyrene box’s decay multiple(6.2).It is evident that aerogel foamed concrete has better insulation performance compared to traditional insulation materials.(3)Study on the climate adaptability of aerogel foamed concrete insulation walls.We compared the dynamic thermal characteristics of aerogel foamed concrete walls in China’s five major climate zones throughout the year based on wall parameters and indoor and outdoor boundary conditions,and explored the energy-saving performance of aerogel foamed concrete compared to ordinary foamed concrete in various climate zones.The results showed that when aerogel foamed concrete insulation walls were used in severe cold zones,cold zones,hot summer and cold winter zones,hot summer and warm winter zones,and mild zones,the heat transfer was reduced by 23.7%,22.6%,23.4%,20.7%,and 25.1%,respectively,with a mean value of 23.1%,compared to traditional insulation materials.(4)By using professional building energy consumption simulation software and a life-cycle model,we compared the application of aerogel foamed concrete and traditional foamed concrete in the exterior walls of actual residential buildings,focusing on analyzing the impact of building annual,monthly energy consumption,and wall thickness on energy consumption,as well as the economic applicability of aerogel foamed concrete throughout its life cycle.The comparison revealed that in the overall trend,as latitude increased,the annual cooling energy-saving potential gradually decreased,and the annual heating energy-saving potential gradually increased.The total energy-saving potential of four typical cities in different climate zones,from small to large,are as follows:Guangzhou in the hot summer and warm winter zone at 0.05 k Wh/m~2,Shanghai in the hot summer and cold winter zone at 0.24k Wh/m~2,Beijing in the cold zone at 0.27 k Wh/m~2,and Harbin in the severe cold zone at 1.4k Wh/m~2.Comparing monthly cooling and heating energy consumption,it was found that the greatest energy-saving potential generally occurred in July,the month with the highest cooling energy consumption,with the Guangzhou saving up to 0.017k Wh/m~2.In January and December,the months with the highest heating energy consumption,the greatest energy-saving potential was observed,with Harbin in January saving up to 0.37k Wh/m~2.Aerogel foamed concrete has the highest economic applicability in severe cold zones and can be prioritized for use.