| According to 2020 Chinese building energy consumption report,building energy consumption reached 1 billion tons of standard coal in 2018,accounting for 21.7%in the country’s total energy consumption,most of which comes from residential heating and cooling energy consumption.Facing to the increasing energy consumption,it is urgent to develop energy-saving technologies,which could meet the indoor comfortable and reduce the energy consumption in buildings.Trombe wall and phase change materials(PCMs)are clean,pollution-free and easy to maintain passive energy-saving technologies that can effectively improve indoor heating in winter and reduce indoor load in summer,so as to achieve the reduction of indoor air-conditioning energy consumption.A lightweight building and a Trombe wall building located in Changsha were selected in this paper as the research object.With different melting temperatures,layout and operation strategies,the thermal performance of PCM Trombe wall system was simulated and analyzed during summer,winter and the whole year.As was shown by the research results,first of all,the optimization of PCM layer to IDH in summer increased with the increase of the melting temperature,and the ability of temperature regulation was stronger when the PCM was installed next to inner surface than next to outer surface.The IDH reached minimum,whose optimum was of 16.26%when PCM28 was installed next to the inner surface.Secondly,in winter,the heating effect of PCM layer decreased with the increase of the melting temperature,the heating function was stronger when PCM layer was installed next to the inner surface.The maximum reductions in ID and IDH were 8.06%and 14.21%when PCM 18 was installed next to the inner surface.Then,during the whole year,PCM25 is the most effective PCM for the optimization of indoor thermal environment in hot summer and cold winter region,and the installation next to the inner surface showed better thermal behaviors.Compared with the traditional building,the optimization rate of ID and IDH were 7.01%and 14.14%,respectively.Natural ventilation in Trombe wall reduced 6.94%of indoor discomfort duration and 10.66%of discomfort degree-hour,while the optimization rate when combined with PCMs reduce 6.42%of IDH,respectively.Compared with doublePCM layers Trombe wall model,the discomfort duration of single-PCM layer model reduced by 1.00%without ventilation,while ID and IDH reduced by 2.53%and 1.32%,respectively.Finally,with the increase of the melting temperature of PCM layer,the range of ambient temperature for the efficient heat transfer also expanded,which showed better environmental adaptivity.The PCMs,whose melting temperature was 8℃ less than the outdoor peak average temperature in summer,was recommended to solve overheating problem.For nighttime heating,the PCMs,whose melting temperature was 7℃ higher than the outdoor average temperature during nighttime in winter,could be recommended. |
