全空气系统设计说明

全空气系统设计说明一.冷负荷计算：1.条件：1.教室的长、宽、高为：15m、8m、4m。外墙为内抹灰两砖外墙，浅色，属于II型，传热系数为K]=1.27W/(m2.^)。内墙为两面抹灰一砖内墙，传热系数K3=1.72W/(m2.^)。外窗为双层窗，内设遮阳，3mm厚的普通玻璃，窗框为铝合金，80%玻璃,总面积Aw=4X3X3=36m2传热系数K2=4.0W/(m2.^)0保定市夏季大气压力998.6kPa，空气调节日平均温度28.6°C，夏季空气调节室外计算湿球温度26.4C，室内空气干球温度26C，室内空气相对W65%。设计为舒适性空调。南外墙冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00tC（T）35.33534.634.233.933.533.232.932.832.933.133.433.934.434.935.335.736tR26Vt9.398.68.27.97.57.26.96.86.97.17.47.98.48.99.39.710K1.27A15X4-4X3X3=24Q 1C（T）283274.3262249.9240.8228.6219.5210.3207.3210.3216.4225.6240.8256271.3283.5295.7304.82.计算过程：由附录2-4查得II型南外墙冷负荷计算温度，将其逐时值及计算结果列入表2-17中，计算公式：Q1c(t)=KAVt南外窗瞬时传热冷负荷根据ai=8.7W/(m2・K)，ao=18.6W/(m2・K)，由附录2-8查得Kw=3.01W/(m2・K)。再由附录2-9查得玻璃窗传热系数的修正值Cw=1.2南外窗瞬时传热冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00t25.42626.927.92929.930.831.531.932.232.23231.630.829.929.128.427.8tD26Vt-0.600.91.933.94.85.55.96.26.265.64.83.93.12.41.8K3.01X1.2=3.612A4X3X3=36Q" gJ、 -780117247.1390.1507.1624.2715.2767.2806.2806.2780.2728.2624.2507.1403.1312.1234.1透过玻璃窗日射得热引起的冷负荷由附录2-15查得双层钢窗有效面积系数C=0.75，故窗的有效面积Aw=36Xa0.75=27m2。由附录2-13查得遮挡系数C=0.86，由附录2-14查得遮阳系数C=0.5，于是综合遮阳s i系数Ccs=0.86X0.5=0.43

再由附录2-12查得(保定纬度约为北纬38度，以40度的数值来参考)，南向日射的热因数最大值D.,max=114W/m2。保定属于北区，由附录2-17查得内遮阳的玻璃窗冷负荷系数逐时clq。j计算逐时进入玻璃窗日射得热引起的冷负荷，列如下表中。南窗透入日射得热引起的冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00C0.590.540.540.650.750.810.830.830.790.710.60.610.680.170.160.150.140.13LQD114―j,max Cc.sA0.4336X0.75=27Q"3c(t) 586536536645.2744.5804.1823.9823.9784.2704.8595.6605.5675168.8158.8148.9139129人员散热引起的冷负荷教室属于极轻运动，查表2-13,当室温为26°C,每人散发的显热和潜热量为60.5W人员散热引起的冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00CTQ0.870.890.90.920.930.940.940.950.960.960.970.970.970.50.40.330.280.24q一60.5sn120◎0.96Q6064620362736412648265516551662166916691676167616761348527882300195116731C(T)q 1 73.3Q844484448444844484448444844484448444844484448444844484448444844484448444合计Q C 145081464714717148561492614995149951506515135151351520515205152051192911232107441039510117和73.3W，群集系数取0.96，由附录2-23查得人体显热散热冷负荷系数逐时值，按公式:Q4c(T)=qs凹CLQ计算人体显然散热逐时冷负荷，并列入下表。照明散热形成的冷负荷教室101的荧光灯安装，^=1.0；n2=0.7；由Q5c=1000n1n2NCLQ,计算结果列入下表:照明散热冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00CLQ0.740.770.790.810.830.390.350.310.280.250.230.20.180.160.150.140.120.11n11n20.7N32X0.040=1.280Q5c(t)663690708726743.7349.4313.6277.8250.9224206.1179.2161.3143.4134.4125.4107.598.56其他散热设备：电脑一台功率200w，投影仪一台功率200w，音响功率200w。散热设备总散热量Q6c(t)=600w在工作时间段内，各分项逐时冷负荷汇总表总冷负荷时间6:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Q283274.3262249.9240.8228.6219.5210.3207.3210.3216.4225.6240.8256271.3283.5295.7304.8Q-780117247.1390.1507.1624.2715.2767.2806.2806.2780.2728.2624.2507.1403.1312.1234.13c(t) 586536536645.2744.5804.1823.9823.9784.2704.8595.6605.5675168.8158.8148.9139129合计QC 145081464714717148561492614995149951506515135151351520515205152051192911232107441039510117Q…663690708726743.7349.4313.6277.8250.9224206.1179.2161.3143.4134.4125.4107.598.56Q6c(t)QJ总600165626001674760016940600173246001764560017484600175766001769260017745600176806001762960017596600176106001372160012904600123056001184960011483由表可知工作时间段内最大冷负荷出现在14:00，Q冷负荷=17745W。湿负荷计算Mw=0.278n^gX10-6=0.278X120X0.96X68X10-6=0.0022kg/s热湿比：£=Q冷负荷/mw=17.745/0.0022=8066KJ/Kg新风量按每人20m3/(h*人)的新风量计算，则总新风量为qv新风=20X120=2400m3/h气流组织计算由焓湿图可确定送风状态点，送风温差为6°C,总送风量G=1.996kg/s=1.547m3/s,新风比为m=43%。布置散流器，，选用6台散流器，每台承担的送风区域面积为20皿，每台送风量为0.258m3/s。根据送风量选取中340的圆形散流器，颈部面积为0.091m2。实际出口面积约为颈部面积的90%，则散流器出口的风速为：V0=1.547/(6X0.091/0.9)=3.15m/s射流末端速度为0.5m/s的射程：X=KV0A1/2/Vx-X0=1.4X3.15X(0.091/0.9)0.5/0.5-0.07=2.45m室内平均风速：'Vm=0.381X2.45/(52/4+42)0.5=0.2m/s符合设计要求。送、回风管的确定(1)推荐风速2-3m/s，回风量为1.547-2400/3600=0.88m3/s

选择风速为3m/s,3个回风口，每个风量大约为0.29m3/s。回风口面积A=0.10皿管段流量长*宽管长(m)V(m/s)管段阻力(Pa)局部阻力(Pa)局部构件10.88800X4007.52.751.26阀门，两个回风装置，变径20.29400X25050.291.76回风装置(2)送风管管段流量长*宽管长(m)V(m/s)管段阻力(Pa)局部阻力(Pa)局部构件11.551000*4002.53.870.627.84变径，阀门21.03630*40053.971.666.62变径30.52400*400113.133.03113.0890°弯头，两个散流器，阀门1-1，0.52400*40063.131.65112阀门，弯头三通，两个散流器1-2-2’0.52400*40063.131.65112阀门，弯头三通，两个散流器阻力平衡计算：最不利环路总阻力为△p=0.62+7.84+1.66+6.