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 同济大学学报(自然科学版)  2019, Vol. 47 Issue (2): 269-274.  DOI: 10.11908/j.issn.0253-371x.2019.02.016 0

### 引用本文

CHENG Fei, ZHANG Xu, SU Xing. Comparative Assessment of External and Internal Insulation for Energy Conservation of Intermittent Air-Conditioned Buildings[J]. Journal of Tongji University (Natural Science), 2019, 47(2): 269-274. DOI: 10.11908/j.issn.0253-371x.2019.02.016

### 文章历史

Comparative Assessment of External and Internal Insulation for Energy Conservation of Intermittent Air-Conditioned Buildings
CHENG Fei , ZHANG Xu , SU Xing
School of Mechanical Engineering, Tongji University, Shanghai 201804, China
Abstract: A comparative assessment of the external and internal insulation for an intermittent air-conditioned building was numerically performed. The energy consumed for cooling was used to evaluate the insulation configurations of exterior walls. There was concern about the effect of the periods that the building was occupied, the air conditioner (AC) operation modes and the power of the heat source in this study. The results show that the external insulation configuration have a better thermal performance compared to the internal insulation configuration, when the building was occupied at daytime. When the building was occupied at night, the internal insulation configuration have a better thermal performance if the AC runs continuously. If the cold storage of the building was applied for energy conservation, the power of the heat source should be considered to determine the insulation configuration. The determination of the insulation configuration of the exterior walls should take those three factors into consideration, including the occupancy time of the building, the AC operation modes, and the power of the heat source.
Key words: occupancy time of the building    air conditioner operation modes    power of the heat source    external insulation    internal insulation    energy consumption

Kolaitis等[4]基于TRNSYS软件计算得出，夜间无通风时，对于卧室空调能耗而言，采用外墙内保温的节能效果要优于外墙外保温.而当利用夜间通风时，采用外墙外保温更有利于降低卧室空调能耗.在不考虑潜热的情况下，夜间是否通风相当于附加给室内空气不同大小的冷热源，因此可以看出，不同的热源强度也会导致不同保温形式的选择.Barrios等[5]建立了墙体室内空气的一维模型，将人员的适应性舒适温度与空调开关行为相结合，通过数值计算得出，采用外墙外保温方式，建筑物的空调能耗低于采用外墙内保温方式建筑物的空调能耗.潘黎等[6]以外墙空气二元系统作为研究对象，通过实验得出，如果在建筑使用时间段内空调持续运行，采用外墙内保温的形式更有利于降低建筑物的空调能耗.从以上的研究结论中可以看出，建筑物在使用时间段内空调器的具体运行方式也会造成所选择的适宜的保温形式的不同.

1 数值计算模型 1.1 建筑物模型

1.2 建筑热过程数学方程

 图 1 建筑物热过程示意图 Fig.1 Heat transfer process of building
 ${\rho _{{\rm{e}},j}}{c_{{\rm{e}},j}}\frac{{\partial {T_{{\rm{e}},j}}}}{{\partial \tau }} = {\lambda _{{\rm{e}},j}}\frac{{{\partial ^2}{T_{{\rm{e}},j}}}}{{\partial {x^2}}}$ (1)

 ${T_{{\rm{e}},j}} = {T_{{\rm{e}},\left( {j + 1} \right)}}$ (2)
 ${\lambda _{{\rm{e}},j}}\frac{{\partial {T_{{\rm{e}},j}}}}{{\partial x}} = {\lambda _{{\rm{e}},\left( {j + 1} \right)}}\frac{{\partial {T_{{\rm{e}},\left( {j + 1} \right)}}}}{{\partial x}}$ (3)

 $- {\lambda _{{\rm{e}},1}}\frac{{\partial {T_{{\rm{e}},1}}}}{{\partial x}}\left| {_{x = 0}} \right. = {h_{{\rm{in}}}}\left( {{T_{{\rm{e,in}}}} - {T_{{\rm{in}}}}} \right)$ (4)
 $- {\lambda _{{\rm{e}},N}}\frac{{\partial {T_{{\rm{e}},N}}}}{{\partial n}}\left| {_{x = \sum {{\delta _{{\rm{e}},j}}} }} \right. = {h_{{\rm{out}}}}\left( {{T_{{\rm{sa}}}} - {T_{{\rm{e,out}}}}} \right)$ (5)

 ${\rho _{\rm{i}}}{c_{\rm{i}}}\frac{{\partial {T_{\rm{i}}}}}{{\partial \tau }} = \frac{\partial }{{\partial y}}\left( {{\lambda _{\rm{i}}}\frac{{\partial {T_{\rm{i}}}}}{{\partial y}}} \right)$ (6)

 $- {\lambda _{\rm{i}}}\frac{{\partial {T_{\rm{i}}}}}{{\partial y}}\left| {_{y = \delta /2}} \right. = {h_{{\rm{in}}}}\left( {{T_{{\rm{i,}}\delta {\rm{/2}}}} - {T_{{\rm{in}}}}} \right)$ (7)
 $- {\lambda _{\rm{i}}}\frac{{\partial {T_{\rm{i}}}}}{{\partial y}}\left| {_{y = - \delta /2}} \right. = {h_{{\rm{in}}}}\left( {{T_{{\rm{i,}} - \delta {\rm{/2}}}} - {T_{{\rm{in}}}}} \right)$ (8)

 $\frac{{\partial {T_{\rm{i}}}}}{{\partial y}}\left| {_{y = 0}} \right. = 0$ (9)

 $\begin{array}{l} {\rho _{{\rm{in}}}}{c_{{\rm{in}}}}{V_{{\rm{in}}}}\frac{{{\rm{d}}{T_{{\rm{in}}}}}}{{{\rm{d}}\tau }} = \sum {{h_{{\rm{in}}}}{A_{\rm{e}}}\left( {{T_{{\rm{e,in}}}} - {T_{{\rm{in}}}}} \right)} + \\ \;\;\;\;\;\;\;\sum {2{h_{{\rm{in}}}}{A_{\rm{i}}}\left( {{T_{{\rm{i,}}\delta {\rm{/2}}}} - {T_{{\rm{in}}}}} \right)} + {Q_{{\rm{AC}}}} + {Q_{\rm{E}}} \end{array}$ (10)

1.3 建筑物使用时间段及空调器运行方式的设置

1.4 室外综合温度及内热源的设定

 ${T_{{\rm{sa}}}} = {{\bar T}_{{\rm{sa}}}} + {A_{{\rm{sa}}}}\cos \left( {\omega \left( {t - {\varphi _0}} \right)} \right)$ (11)

 ${T_{{\rm{sa}}}} = 32.5 + 6.0\cos \left( {\omega \left( {t - 12} \right)} \right)$ (12)

 $\begin{array}{*{20}{c}} {{Q_{{\rm{AC}}}} = - 0.7 \times \left( {0.001\;5f_\tau ^3 - 0.494\;2f_\tau ^2 + } \right.}\\ {\left. {68.477\;0{f_\tau } - 583.490\;0} \right)} \end{array}$ (13)

 ${f_\tau } = {f_0} + \int_{{\tau _0}}^\tau {\left( {3\left( {{{T''}_{{\rm{tn}}}} - 24} \right)/60} \right){\rm{d}}\tau }$ (14)

2 结果及分析

 $\begin{array}{l} {R_{\rm{L}}} = \\ \;\;\;\left( {1 - \frac{{保温层厚度为\;L\;时建筑物的耗冷量}}{{保温层厚度为\;0\;{\rm{mm}}\;时建筑物的耗冷量}}} \right) \times \\ \;\;\;100\% \end{array}$ (15)

 ${\varepsilon _{\rm{d}}} = \frac{{{Q_{{{\rm{w}}_1},{\rm{d}}}}}}{{{Q_{{{\rm{w}}_2},{\rm{d}}}}}}$ (16)

 ${\varepsilon _{\rm{n}}} = \frac{{{Q_{{{\rm{w}}_1},{\rm{n}}}}}}{{{Q_{{{\rm{w}}_2},{\rm{n}}}}}}$ (17)

2.1 空调器使用方式对外墙内外保温节能效果的影响

 图 2 白天使用的建筑物的供冷能耗随保温层厚度的变化特性 Fig.2 Variation of energy conservation rate at different thicknesses of insulation layer of building at daytime

 图 3 夜间使用的建筑物的供冷能耗随保温层厚度的变化特性 Fig.3 Variation of the energy conservation rate for different thicknesses of the insulation layer of the building which occupied during the night time

2.2 热源大小对外墙内外保温节能效果的影响

 图 4 白天使用建筑物两种保温形式的能耗相对差异特性随热源的变化 Fig.4 Variation of performance difference between external and internal insulation at different powers of the heat source of building at daytime

 图 5 夜间用能建筑物两种保温形式的能耗相对差异特性随热源的变化 Fig.5 Variation of performance difference between external and internal insulation at different powers of heat source of building at night
3 结论

(1) 建筑物外墙内外保温的相对优劣特性与建筑物的使用时段、空调的运行方式以及建筑物热源的大小有着密切的关联.

(2) 对于使用时段在白天的建筑物，采用外墙外保温更有利于降低建筑物的空调能耗.

(3) 对于使用时段在夜间的建筑物，如果在使用时段内空调器持续运行，采用外墙内保温的形式更有利于降低建筑物的空调能耗；如果利用建筑物的蓄冷量，使空调器在使用时段内间歇运行则应当评估建筑物热源的大小以确定适宜的外墙保温形式.

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