空調系統中冷凍水系統水平管和立管的水力計算過程案例1冷凍水系統水平管的水力計算冷凍水系統管路設計的合理與否將會直接影響到空調系統是否能夠正常運行與經濟運行問題，因此在設計時要符合實際情況，在計算時要更加仔細，避免出現錯誤。水管管徑的確定和風管管徑的確定類似，所以都采用假定流速法來進行水力計算。以第一層冷凍水系統為例，水力計算步驟如下：a.對管段進行編號如下圖，由于該層水系統布置為異程式，所以最不利環路以末端新風機為供回節點，參考下圖，則最不利環路為0-2-4-6-8-10-12-14-16-新風機-回水管段q-o-m-k-i-g-e-c-a。 圖7-1第一層供回水布置圖b.根據各管段的冷負荷，計算各管段的流量，計算公式如下：（7-1）式中——管段流量，；m3/h；——各管段冷負荷，k；——水的比熱，為4.18kJ/kg?℃；——水的密度，為1000kg/m3；——冷凍水回水溫度，查閱《實用供熱空調設計手冊》，取12℃；——冷凍水供水溫度，查閱《實用供熱空調設計手冊》，取7℃。以管段15為例

G=c.用假定流速法確定管段管徑。查閱《民用建筑空調設計》，流速的取值范圍如下：表7-2水管流速推薦表（）管徑(mm)20253240506580100125150閉式0.5-0.60.6-0.70.7-0.90.8-10.9-1.21.1-1.41.2-1.61.3-1.81.5-2.01.6-2.2開式0.4-0.50.5-0.60.6-0.80.7-0.90.8-1.00.9-1.21.1-1.41.2-1.61.4-1.81.5-2.0根據假定的流速和計算出的流量確定管徑，計算公式如下：（7-2）式中——管段流量，；——假定的水流速度，。以管段15為例

d=1000在水系統的管道選型中常用的是鍍鋅鋼管和不鍍鋅的無縫鋼管，其規格以公稱直徑（DN）表示。在本設計中采用鍍鋅鋼管，根據國家標準的公稱直徑選取管徑，按照比所算管徑值大的原則，選取公稱直徑為25mm的鍍鋅鋼管。校核：將所選的公稱直徑為25mm鍍鋅鋼管代入公式7-2，則該管段的實際流速為

ν=4×d.計算出管段的比摩阻從而求出沿程阻力。沿程阻力計算公式（7-3）式中——單位長度管段的摩擦阻力（稱比摩阻），；——管段長度，。單位長度管段的摩擦阻力計算公式（7-4）式中——摩擦阻力系數；——水的密度，1000；——水流速度，。摩擦阻力系數可由下式確定（7-5）式中——管內表面的當量絕對粗糙度，；查閱《實用供熱空調設計手冊（下）》，可得閉式水系統=0.2mm。——雷諾數。其中雷諾數計算公式（7-6）式中——實際流速，；——運動黏度，水在7℃時的運動黏度系數為。管段15的雷諾數

Rλ=0.0055管段15的比摩阻R=管段15的管長為3.25m，則沿程阻力為He.用局部阻力系數法求出管段的局部阻力，計算公式如下：（7-7）式中——管段中總的局部阻力系數；——水的密度，1000；——水流速度，。管段16中有一個90°彎頭，其局部阻力系數為0.3，以及一個流向確定的三通，其局部阻力系數為1.5，所以該管段局部阻力系數為1.8該管段的局部阻力為

Hf.計算管段的總阻力。管段的總阻力即為沿程阻力和局部阻力相加，則管段16的總阻力為ΔP=197.21+592.0591=789.27Pa表7-2第一層供水管段的水力計算表進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力038.296.596500.93278.063.57992.670.5211.921210.5911.550.268200.2468.970.3524.141.542.0566.19236.746.328500.90256.7710.292642.190.4160.472802.6632.570.443200.39174.644.74821.791.5115.38943.17434.175.885500.83223.362.19489.160.269.39558.5554.800.827250.47182.173.19581.131.8191.21778.34629.375.058500.72161.215.55928.020.251.26979.2874.800.827250.47182.173.2582.951.8191.21780.16824.574.231400.94371.473.841426.430.281.581514.0195.050.870250.49200.384.58911.761.5181.911099.671019.523.362400.74239.012.28544.950.255.27600.22114.800.827250.47182.172.97541.051.8191.21738.261214.722.535320.88435.426.973034.850.276.733111.58135.050.870250.49200.383.57715.371.5181.91891.28149.671.665250.94688.341.911314.740.288.861403.60154.800.827250.47182.173.25592.061.8191.21789.27164.870.838200.74579.561.64404.680.382.474481.15表7-3第一層回水管段的水力計算表回水管段冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力a6.596500.93278.064.521256.830.5211.921474.75b0.268200.2468.970.855.171.542.0591.23c6.328500.90256.7711.242886.130.4160.473046.60d0.443200.39174.645.28922.101.5115.381031.48e5.885500.83223.362.11471.290.269.39540.68f0.827250.47182.172.12386.201.8191.21583.42g5.058500.72161.215.58933.030.251.26984.29h0.827250.47182.172.16393.491.8191.21590.70i4.231400.94371.473.881441.290.281.581528.87j0.870250.49200.385.121025.971.5181.911201.88k3.362400.74239.012.3549.730.255.27605.00L0.827250.47182.172.15391.671.8191.21588.88m2.535320.88435.426.953026.140.276.733102.87n0.870250.49200.385.161033.981.5181.911215.89o1.665250.94688.341.821252.790.288.861341.65P0.827250.47182.172.17395.311.8191.21592.53q0.838250.47186.901.621424.160.333.781451.94型號為HDK-01的新風機水阻為23.4，回水管段q-o-m-k-i-g-e-c-a的總阻力為15406.46，由此可得出第一層冷凍水系統最不利環路0-2-4-6-8-10-12-14-16-新風機-回水管段q-o-m-k-i-g-e-c-a的總阻力為53.73kPa。圖7-2第二層供回水布置圖表7-4第二層供水管段的水力計算表進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力052.939.12650.76135.344.16563.0270.5145.77708.7912.140.37200.33124.030.82101.7011.579.75181.45250.798.75650.73125.073.98491.7950.4101.37605.1732.190.38200.33129.433.84491.0161.8100.23591.24448.608.37650.70114.983.53405.8780.249.16455.0452.190.38200.33129.433.72481.4841.8100.23581.71646.411.99650.67105.303.05321.1780.244.83366.0072.140.37200.33124.033.08381.9991.895.70471.70844.271.63650.6496.252.64254.1120.240.79294.9092.190.38200.33129.433.72481.4841.8100.23581.711042.081.25650.6181.411.24108.3860.236.85145.24112.140.37200.33124.033.14389.4401.895.70485.141239.946.88500.97301.522.46741.7460.294.82836.57132.190.38200.33129.433.97513.8421.8100.23614.071431.756.50500.92270.511.06286.7430.284.71371.45續表7-4進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力152.310.40200.35142.513.07431.5181.8111.22548.741635.446.11500.86239.652.52603.9160.274.67678.59172.190.38200.33129.433.87500.8991.8100.23601.121833.255.73500.81212.061.27269.3200.265.73335.05192.310.40200.35142.512.94418.9911.8111.22530.212030.955.33500.75184.812.57474.9570.256.92531.88212.730.47200.42194.603.72723.9191.8155.52879.442228.224.86500.69154.971.06164.2670.241.33211.60232.310.40200.35142.513.11443.2191.8111.22554.442425.914.46500.63131.762.63346.5200.239.91386.43252.700.47200.41191.423.91748.4591.8152.79901.252623.214.00500.57106.910.94100.4960.232.01132.51272.310.40200.35142.513.06436.0931.8111.22541.312820.903.60500.5181.732.22194.7550.225.96220.72292.720.47200.41193.013.94760.4541.8154.15914.613018.183.13400.69208.871.46304.9510.241.99352.94312.310.40200.35142.513.14441.4941.8111.22558.713215.882.73400.60161.412.22358.3240.236.58394.91332.730.47200.42194.873.91761.9331.8155.75911.683413.152.26400.50113.011.41159.3490.225.08184.43352.310.40200.35142.513.07431.5181.8111.22548.743610.841.87400.4178.702.16169.9900.211.05181.04372.750.47200.42191.003.76740.7331.8151.58898.31388.091.39400.3145.741.986.9070.29.5196.41392.310.40200.35142.513.14441.4941.8111.22558.71405.791.00320.3474.822.16161.6090.211.87173.47413.550.61200.54318.333.14999.5541.8262.911262.47422.240.39200.34134.953.08415.6400.311.48433.12表7-5第二層回水管段的水力計算表回水管段冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力a9.117650.76135.343.744506.7240.5145.77652.49a010.369200.33124.030.73891.5311.579.75171.28b8.749650.73125.073.582448.0160.4101.37555.39b030.377200.33129.433.456441.3151.8100.23541.54c8.371650.70114.983.177365.2900.249.16414.45c050.377200.33129.433.348433.3361.8100.23533.56d1.994650.67105.302.745289.0600.244.83333.89d070.369200.33124.032.772343.7991.895.70439.50e1.625650.6496.252.376228.7010.240.79269.49e090.377200.33129.433.348433.3361.8100.23533.56f1.248650.6181.411.11691.5470.236.85134.40f110.369200.33124.032.826350.4961.895.70446.20g6.880500.97301.522.214661.5710.294.82762.39g130.377200.33129.433.573462.4581.8100.23562.68h6.502500.92270.510.954258.0690.284.71342.78h150.397200.35142.512.763393.7661.8111.22504.99i6.105500.86239.652.268543.5240.274.67618.19i170.377200.33129.433.483450.8091.8100.23551.03j5.728500.81212.061.143242.3880.265.73308.12j190.397200.35142.512.646371.0921.8111.22488.31k5.330500.75184.812.313421.4610.256.92484.39k210.470200.42194.603.348651.5271.8155.52801.04l4.861500.69154.970.954141.8400.241.33195.17l230.397200.35142.512.799398.8971.8111.22510.12m4.463500.63131.762.367311.8680.239.91351.78m250.466200.41191.423.519673.6141.8152.79826.41n3.997500.57106.910.84690.4460.232.01122.46n270.397200.35142.512.754392.4841.8111.22503.70o3.600500.5181.731.998175.2800.225.96201.24o290.468200.41193.013.546684.4091.8154.15838.56p3.132400.69208.871.314274.4560.241.99322.44p310.397200.35142.512.826402.7451.8111.22513.97q2.735400.60161.411.998322.4920.236.58359.07q330.470200.42194.873.519685.7401.8155.75841.49r2.265400.50113.011.269143.4140.225.08168.50r350.397200.35142.512.763393.7661.8111.22504.99續表7-5回水管段冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力s1.867400.4178.701.944152.9910.211.05170.04s370.473200.42191.003.384666.6591.8151.58824.24t1.394400.3145.741.7178.2160.29.5181.72t390.397200.35142.512.826402.7451.8111.22513.97u0.997320.3474.821.944145.4480.211.87151.31u410.611200.54318.332.826899.5981.8262.911162.51v0.386200.34134.952.772374.0760.311.48391.55型號為FP-68的風機盤管水阻為28，回水管段q-o-m-k-i-g-e-c-a的總阻力為15406.46，由此可得出第一層冷凍水系統最不利環路0-2-4-6-8-10-12-14-16-18-20-22-24-26-28-30-32-34-36-38-40-42-風機盤管-回水管段v?a的總阻力為43.52kPa。圖7-3第三層供回水布置圖表7-6第三層供水管段的水力計算表進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力048.968.43650.71116.614.37509.3530.5124.72634.0712.140.37200.33124.030.86106.7861.579.75186.54246.828.06650.68101.084.18441.5020.491.24538.7533.270.56200.50273.184.031101.4511.8223.451324.90443.551.50650.6393.303.71345.8160.239.47385.29進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力53.060.53200.47241.203.91942.1151.8195.671131.79640.496.97500.99309.573.20991.4060.291.451088.8672.140.37200.33124.033.23401.0991.895.70496.80838.356.61500.93278.842.77772.9520.281.42860.3793.060.53200.47241.203.91942.1151.8195.671131.791035.296.08500.86231.671.30309.4430.274.03383.47112.140.37200.33124.033.30408.9121.895.70504.611233.155.71500.81210.812.58544.5150.265.32609.84133.270.56200.50273.184.171138.7401.8223.451362.191429.885.15500.73172.841.11192.3710.253.07245.44152.140.37200.33124.033.22399.7961.895.70495.501621.744.78500.68150.012.65396.9190.245.74442.66172.40.41200.37153.354.06623.1211.8120.37743.491825.344.36500.62126.301.33168.4180.238.17206.59192.140.37200.33124.033.09382.8671.895.70478.572023.24.00500.57106.852.70288.3330.231.99320.33213.830.66200.58361.943.911431.1841.8306.541743.732219.373.34500.4776.031.1184.6220.222.30106.92233.830.66200.58361.943.271201.5171.8306.541508.062415.542.68400.59154.982.76421.9700.235.05463.02253.830.66200.58361.944.111510.5891.8306.541811.132611.712.02320.70281.360.99271.7020.248.58326.28271.881.36320.47133.063.21421.5331.5165.00592.53283.830.66200.58361.942.33851.6740.351.09908.76表7-7第二層回水管段的水力計算表回水管段冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力a8.43650.71116.614.28499.170.5124.72623.89A0.37200.33124.030.84104.651.579.75184.40b8.06650.68101.084.10438.550.491.24529.80c1.50650.6393.303.63338.900.239.47378.37d6.97500.99309.573.14971.580.291.451069.03e6.61500.93278.842.72751.490.281.42844.91f6.08500.86231.671.28303.250.274.03371.28g5.71500.81210.812.53533.620.265.32598.95h5.15500.73172.841.09188.520.253.07241.59i4.78500.68150.012.59388.980.245.74434.72j4.36500.62126.301.31165.050.238.17203.22k4.00500.57106.852.64282.570.231.99314.56m3.34500.4776.031.0982.930.222.30105.23n2.68400.59154.982.71419.410.235.05454.46o2.02320.70281.360.97272.150.248.58320.73p0.66200.58361.942.28840.520.351.09891.61型號為FP-136的風機盤管水阻為40，回水管段a?p的總阻力為7388.35，由此可得出第一層冷凍水系統最不利環路0-2-4-6-8-10-12-14-16-18-20-22-24-26-28-風機盤管-回水管段p?a的總阻力為54.91kPa。圖7-4第四層供回水布置圖表7-8第四層供水管段的水力計算表進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力015.522.67400.59154.603.62559.650.581.39641.0411.090.19200.1736.310.9233.401.520.6954.09214.432.49400.55134.713.01405.470.460.44465.9031.820.31200.2892.064.15382.051.869.22451.27412.612.17400.48104.494.38451.650.223.08480.7351.080.19200.1635.714.16148.561.824.37172.94611.531.99320.69273.190.97264.990.241.10312.0973.670.63200.56339.464.121398.581.8281.461680.0481.861.35320.47132.433.44455.560.221.89471.4591.090.19200.1736.313.09112.191.824.83131.02106.771.17320.40100.164.00400.650.216.24416.88112.250.39200.34136.064.13561.951.8105.79661.74124.520.78320.2741.441.5171.630.21.2478.87132.270.39200.35138.313.07424.621.8101.68532.30142.250.39200.34136.065.69774.210.311.63791.84表7-9第四層回水管段的水力計算表回水管段冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力a2.673400.59154.603.58553.470.5081.39640.85A0.188200.1736.310.8932.311.5020.6953.00b2.486400.55134.713.21432.410.4060.44492.84c2.172400.48104.494.12430.490.2023.08453.56d1.986400.4488.334.29378.930.2019.29398.22e1.354320.47132.433.51464.830.2021.89486.72f1.166320.40100.163.87381.620.2016.24403.86g0.779320.2741.441.4870.210.201.2471.44h0.388200.34136.065.45741.550.3011.63759.18型號為HDK-01的新風機水阻為23.4，回水管段a?h的總阻力為3712.10，由此可得出第一層冷凍水系統最不利環路0-2-4-6-8-10-12-14-新風機-回水管段h?a的總阻力為30.78kPa。圖7-4第五層供回水布置圖表7-10第五層供水管段的水力計算表進水管段管段負荷冷凍水量所選管徑實際流速比摩阻管長沿程阻力局部阻力系數局部阻力總阻力014.972.58400.57144.396.87991.990.232.521024.51110.11.74320.60212.462.71575.771.5271.06846.8425.050.87320.3058.162.42140.761.881.32222.083-45.050.87320.3058.166.30366.440.836