新风系统设计计算

新风系统设计计算经过处理的新风都必须通过风道才能送入空调房间，而且空调房间的送风量能否达到设计要求，则完全取决于风道系统的压力分布以及风机在该系统中的平衡工作区。所以风道设计将直接影响空调房间气流组织和空调效果。同时，空气在风道内流动所损失的能量，是靠风机消耗电能予以补偿的。所以风道设计也直接影响空调系统的经济性。因此，风道系统的设计是要在满足设计风量要求等的前提下，尽可能节省能量。风管水力计算的基本任务如下：假定流速求出风管断面面积，结合建筑特点确定断面尺寸。由断面尺寸算出风管内空气的实际流速，校核其是否在规范的推荐流速范围内。算出最不利环路的阻力损失，校核高静压风管机或新风全热交换器的机外静压是否满足要求。平衡各并联管路的阻力。7.1楼层新风风管型式的选择风管材料的选用。风管一般采用钢板材料，其优点是不燃烧、易加工、耐久，也较经济。风管形式的确定。风管的形式很多，一般采用圆形或矩形风管。圆形风管——强度大,耗材料少，但加工工艺复杂，占用空间大，不易布置得美观，常用于安装。矩形风管——易布置，弯头及三通等部件的尺寸较圆形风管的部件小，且容易加工，使用较为普遍。因此，本设计中选用矩形风管。7.2新风管的布置和制作要求1）风管应注意布置整齐，美观和便于维修、测试，应与其他管道统一考虑，设计时应考虑各管道的装拆方便。2）风管布置时，要尽量减少局部阻力。弯曲的中心曲率半径要不小于其风管直径或边长，一般可采用1.25倍直径或边长。大断面风管，为减少阻力，可以作导流叶片，导流叶片以流线型为佳，其局部阻力系数Z=0.1。支风管与主风管相连接时，应避免90°垂直连接，通常支管应在顺着气流方向上制作一定的导流曲线或三角形切割角。风管的更多资料，关注微信公众号：资料小超市变径宜做成渐扩管和渐缩管，渐扩管每边扩展角度不宜大于15°，渐缩管每边扩展角度不宜大于30°。风管法兰间应放置具有弹性的垫片，如橡皮、海绵橡胶、浸油硬纸板等，以防漏风。风管以及风管接口不应有看得见的孔洞。风管涂漆。本设计中选用镀锌薄钢板，可以不涂漆。但咬口损坏处要涂漆，施工时已发现锈蚀时要涂漆。7.3新风管的水力计算新风系统管道均选用镀锌薄钢板(粗糙度K=0.15mm)制矩形风道，且均按照低速风道标准进行设计。风管水力计算方法有假定流速法、压损平均法和静压复得法等几种，本次设计校核采用假定流速法，假定流速法的特点是先按技术经济要求选定风管的流速，再根据风管的风量确定风管的断面尺寸和阻力。下面以首层新风管道系统为例来说明风管水里计算的详细过程。该层新风管道布置如图7-1：图7-1一层一路新风管路布置图由图可知该新风系统的最不利环路为0-1-2-3-4-5-6-7-8-9以此管段0-1为例，其风量为2860m3/h，管长为9.35m。假定流速法中风管的推荐流速见表7-1。表7-1风管推荐风速室内允许噪声dB(A)主管风速m/s支管风速m/s新风入口风速m/s25〜353〜4<2335〜504〜72〜33.550〜656〜92〜54—4.565〜858〜125〜85办公室噪声要求V40dB(A),假定该段管路流速为5m/s，则风管断面面积为:=0.159m27-1)G2860=0.159m27-1)F= =3600xv3600x5根据矩形通风管道统一规格，选用风管断面尺寸为630X250mm,所以风管实际流速为：G3600F=为：G3600F=5.04m/s3600x6.3x2.57-2)7-3)7-3)7-4)在推荐流速范围内。1）沿程阻力损失单位管长沿程阻力损失R可用下式计算：m九V2R= •—*pmd2s式中：入——摩擦阻力系数;P 空气密度，kg/m3；风管当量直径，m。而风管的阻力系数入由雷诺数确定，雷诺数为：Re=叫V式中：V——运动粘度，空气在20°C时的运动粘度为15.06X10-6。因风管当量直径为d=芟X =358mm，e630+2505.3x0.358则Re= =1.25x105。15.06x10-6若选用钢板制风管，则查得其当量粗糙度为K=0.15mm；所以K=015=0.000417，de358九=0.11fK+Vd68丫25九=0.11fK+Vd68丫25Re丿=0.11xf0.1568 V25+ 1.25x105丿=0.0194九v2 0.01945.042则R= - -p= x x1.2=0.826Pa/mmd2 0.358 2s该段管长为l=9.35m则管段1沿程阻力为P=R•/=0.826x9.35=7.72Pamlm2）局部阻力损失7-5)(7-6)7-7)管段1的局部阻力部件有一个软接头Z二0.05x2二0.1消声器‘0.4防火阀0.19一个矩形弯头g二0.14災=0.1+0.4+0.19+0.14=0.83管段1的局部阻力为：P=£21Zg=1.2x5.042%0$3=13.55Pa (7-8)j22则管段1的阻力损失为：P+P=7.72+13.55=21.27Pa (7-9)mlj其余管段的水力计算同上,水力计算汇总见表7-2：表7-2一层一路风管水力计算表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)v(m/s)R(Pa/m)△Py(Pa)动压(Pa)△Pj(Pa)△Py+APj(Pa)0--128606302509.355.0440.8267.72310.8915.24113.5521.271--2258050025010.055.7331.02210.2710.1819.6873.543713.8152--323005002501.725.1110.8311.42930.1815.6452.81614.24543--421004002504.8355.8331.1625.61830.1820.3793.66829.28654--516104002001.925.591.2792.45570.1418.7162.62025.07595--614003202006.486.0761.63810.6140.1822.1133.980314.5956--711903202001.925.1651.2232.34820.1815.9772.87595.2247--87002001606.486.0762.43215.7590.1422.1133.095818.8558--92101201203.294.0511.916.28392.279.82822.3128.593小计120.97最不利环路0-1-2-3-4-5-6-7-8-9的总阻力为120.97，考虑10%的富余量，故所需的系统作用压力为：120.97x(1+10%)=133.07Pao而选用的HDK-04吊顶式新风机组的机组余压为18OPa>133.07Pa，故符合要求。与之并联的环路0-1-2-3-4-5-6-7-8-10阻力计算如下：表7-3一层一路最不利环路并联环路风管水力计算表序号风量管宽管高管长v(m/s)R(Pa/m)△Py(Pa)动压△Pj(Pa)△Py+APj(Pa)

(mA3/h)(mm)(mm)(m)(Pa)0--128606302509.355.0440.8267.72310.8915.24113.5521.271--2258050025010.055.7331.02210.2710.1819.6873.543713.8152--323005002501.725.1110.8311.42930.1815.6452.81614.24543--421004002504.8355.8331.1625.61830.1820.3793.66829.28654--516104002001.925.591.2792.45570.1418.7162.62025.07595--614003202006.486.0761.63810.6140.1822.1133.980314.5956--711903202001.925.1651.2232.34820.1815.9772.87595.2247—87002001606.486.0762.43215.7590.1422.1133.095818.8558--102101201201.554.0511.916.28392.189.82822.31234.386小计116.77不平衡率计算120.97-116.77不平衡率计算120.97-116.77120.97x100%=3.47%<10%满足要求。其余并联环路的计算同上，不平衡率不满足要求的，用阀门找平。二层新风管道布置，如图7-2：图7-2一层二路新风管路布置图表7-4一层二路各管段水力计算表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)v(m/s)R(Pa/m)△Py(Pa)动压(Pa)△Pj(Pa)△Py+APj(Pa)0--11220010006303.75.3790.3321.2280.8917.33015.42416.6521--21156010006304.95.0970.3011.4750.5615.5598.71310.1882--31132010005005.046.2890.5272.6560.1823.6874.2646.9203--41112010005000.756.1780.5100.3830.1822.8574.1144.4974--5946010005002.55.2560.3800.9500.1816.5422.9783.9285--6584080040012.365.0690.4655.7470.5615.3918.61914.3666--748006304004.035.2910.5572.2450.1816.7663.0185.2637--837606303204.035.1810.6362.5630.1816.0752.8945.457

8--927205002504.036.0441.1254.5340.1821.8813.9398.4729--10168040020012.35.8331.38116.9860.2820.3795.70622.69210--1116004002001.95.5561.2652.4040.1818.4853.3275.73111--1215204002001.435.2781.1531.6490.1816.6823.0034.65212--1311202502004.876.2221.9359.4230.1823.1874.17413.59713--1456020020011.243.8890.94810.6562.289.05720.65031.305小计153.72最不利环路0-1-2-3-4-5-6-7-8-9-10-11-12-13-14的总阻力为153.719Pa，考虑10%的富余量，故所需的系统作用压力为：153.72(1+10%)=169.092PaO而选用的DX16x4吊顶式新风机组的机组余压为400Pa>169.02Pa，故符合要求。二层一路新风管道布置图，如图7-3：图7-3二层一环路新风管路布置图表7-5二层一路各管段水力计算结果表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)v(m/s)R(Pa/m)△Py(Pa)动压(Pa)△Pj(Pa)△Py+APj(Pa)0--11220010006303.75.3790.3321.2280.8917.33015.42416.6521--21156010006304.95.0970.3011.4750.5615.5598.71310.1882--31132010005005.046.2890.5272.6560.1823.6874.2646.9203--41112010005000.756.1780.5100.3830.1822.8574.1144.4974--5946010005002.55.2560.3800.9500.1816.5422.9783.9285--6584080040012.365.0690.4655.7470.5615.3918.61914.3666--748006304004.035.2910.5572.2450.1816.7663.0185.2637--837606303204.035.1810.6362.5630.1816.0752.8945.4578--927205002504.036.0441.1254.5340.1821.8813.9398.4729--10168040020012.35.8331.38116.9860.2820.3795.70622.69210--1116004002001.95.5561.2652.4040.1818.4853.3275.73111--1215204002001.435.2781.1531.6490.1816.6823.0034.65212--1311202502004.876.2221.9359.4230.1823.1874.17413.59713--1456020020011.243.8890.94810.6562.289.05720.65031.305小计153.72最不利环路0-1-2-3-4-5-6-7-8-9-10-11-12-13-14的总阻力为153.719Pa,考虑10%的富余

量，故所需的系统作用压力为：153.72(1+10%)=169.092Pao而选用的DX16x4吊顶式新风机组的机组余压为400Pa>169.02Pa,故符合要求。图7-4二层二环路新风管路布置图表7-6二层二路各管段水力计算表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)v(m/s)R(Pa/m)△Py(Pa)动压(Pa)△Pj(Pa)△Py+APj(Pa)0--188608005006.256.1530.5573.481250.8922.67220.178123.659331--286208005002.6855.9860.531.423050.1821.4613.862985.286032--334606303205.9154.7670.5483.241420.5613.6127.6227210.864143--426805002508.45.9561.0959.1980.1821.2423.8235613.021564--517203202508.175.9721.35411.06220.1821.3613.8449814.907165--676025016015.455.2781.68626.04870.2816.6824.6709630.719666--74401601609.554.7741.79617.15182.2813.65131.124348.27608小计146.73396最不利环路0-1-2-3-4-5-6-7的总阻力为146.73Pa,考虑10%的富余量，故所需的系统作用压力为：146.71x(1+10%)=161.38PaO而选用的DX16x4吊顶式新风机组的机组余压为400Pa>161.38Pa，故符合要求。三、四层一路新风管道布置,如7-5图：

图7-5 三、四层一路新风管路布置图表7-7三、四层一路各管段水力计算结果表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)V(m/s)R(Pa/m)△Py(Pa)C动压(Pa)△Pj(Pa)△Py+APj(Pa)0--1523063040012.265.7650.6517.981260.8919.90517.715525.696711--250206304006.585.5340.6043.974320.1818.3383.300847.275162--348106304001.875.3020.5591.045330.1816.8363.030484.075813--446006304001.85.0710.5160.92880.1815.3982.771643.700444--542006303204.735.7870.7773.675210.1820.0573.610267.285475--638706303201.8955.3320.671.269650.2117.0293.576094.845746--735405003206.646.1460.9596.367760.2122.6214.7504111.118177--832105003201.7355.5730.8031.393210.2118.63.9065.2992058--928805003206.66550.664.39890.2114.9733.144337.543239--1026705002501.835.9331.0881.991040.1821.0843.795125.7861610--1122504002506.6656.251.3168.771140.2123.3954.9129513.6840911--1219204002501.435.3330.9881.412840.2117.0353.577354.9901912--1315003202509.1955.2081.0589.728310.2816.2464.5488814.2771913--147402501607.185.1391.60711.53830.2815.8164.4284815.9667414--155602001605.0444.8611.638.221722.2214.15231.417439.63916小计171.183465最不利环路0-1-2-3-4-5-6-7-8-9-10-11-12-13-14-15的总阻力为171.18Pa,考虑10%的富余量，故所需的系统作用压力为171.18x(1+10%)=188.30Pa而选用的HDK-07吊顶式新风机组的机组余压为500Pa>188.30Pa，故符合要求。三层二路新风管道布置,如图7-6：更多资料，关注微信公众号：资料小超市图7-6三层二路新风管路布置图表7-8三层二路各管段水力计算表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)V(m/s)R(Pa/m)△Py(Pa)C动压(Pa)△Pj(Pa)△Py+APj(Pa)0--160808004008.555.2780.53.8450.8916.68214.84718.691981--258408004005.7255.0690.4652.662130.1815.3912.770385.4325052--350106304003.095.5220.6021.860180.1818.2653.28775.147883--441806303209.225.7590.7717.108620.1819.8673.5760610.684684--5388063032010.2175.3460.6746.886260.1817.1173.081069.9673185--625875002506.9285.7491.0277.115060.1819.7943.5629210.6779766--7129325025010.15.7471.45414.68542.1819.77843.11657.80144小计118.403779最不利环路0-1-2-3-4-5-6-7的总阻力为156.8Pa,考虑10%的富余量，故所需的系统作用压力为：156.8x(1+10%)=172.48PaO而选用的HDK-07吊顶式新风机组的机组余压为500Pa>172.48Pa，故符合要求。五层一路新风管道布置，如7-7图：图7-7五层一路路新风管路布置图表7-9五层一路各管段水力计算表序号风量(mA3/h)管宽(mm)管高(mm)管长(m)V(m/s)R(Pa/m)△Py(Pa)C动压(Pa)△Pj(Pa)△Py+APj(Pa)0--1594080040012.95.1560.486.1920