Abstract
Abstract In order to clarify the dependence relationship between the heat storage & preservation wall and the thermal environment, and to provide data base and theory foundation for the north wall construction of the Chinese solar greenhouse (CSG), the experimental measures has been employed to investigate the distributions of temperature, humidity and heat transfer of three different wall materials (i.e. perforated brick, fine coal ash brick, common clay brick). The dynamic variations of the heat-storage and heat-release processes were identified, and the thermal response characteristics were discussed. The effect of north wall materials on the thermal environment of the solar greenhouse in northern China was revealed. The results indicated that the daily heat-storage and heat-release of fine coal ash brick wall can reach ϕimput = 34.5~130.6 W·m−2 and ϕoutput = −24.15~-45 W·m−2, respectively. The daily heat-storage time can reach t = 5~8 h, and the wall temperature at night can be 3~4 ∘ C higher than the air temperature. Moreover, the maximum indoor temperature of the fine coal ash brick wall can be maintained at t ≤ 16.7 ≤ 31.1 ∘ C, the minimum humidity can be maintained at 29.75~45%. Fortunately, the construction cost is moderate, while the physical properties are obviously better than those of perforated brick and common clay brick in the CSG. The overall thermal performance of fine coal ash brick is the best of the three north wall materials, and it can make the most advantage of the heat-storage and heat-preservation performances of the CSG. As a consequence, the fine coal ash brick wall of the solar greenhouse has good promotion value in northern China and other high latitude, high altitude and long winter regions.
Highlights
Most areas of northern China are in the cold and freezing natural climate, and the lowest temperature in winter are mostly in the range of below zero
In order to clarify the dependence relationship between the heat storage & preservation wall and the thermal environment, and to provide data base and theory foundation for the north wall construction of the Chinese solar greenhouse (CSG), the experimental measures has been employed to investigate the distributions of temperature, humidity and heat transfer of three different wall materials
The results indicated that the daily heat-storage and heat-release of fine coal ash brick wall can reach φimput = 34.5~130.6 W·m−2 and φoutput = −24.15~-45 W·m−2, respectively
Summary
Most areas of northern China are in the cold and freezing natural climate, and the lowest temperature in winter are mostly in the range of below zero. The north wall material has higher requirements for heat storage and heat preservation in northern China, because the natural environment is especially awful and the temperature is below zero for a long time in winter. The optimal method to research the effect of the north wall materials on the thermal environment inside the solar greenhouse is the combination of experiment measures and numerical simulations. There is no systematic research on the effect of wall materials (i.e. common clay brick, perforated brick and fine coal ash brick) which widely used in solar greenhouses in northern China. The daily average heat-storage and heat-release characteristics, the heat-storage time, the maximum maintainable temperature, the humidity and the construction cost of different north wall materials in the CSG have been discussed in this experimental research. The thermal performances of the different north wall materials can be systematically studied to provide the theory foundation for agricultural applications
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