某5層建筑樓空調(diào)系統(tǒng)的風(fēng)系統(tǒng)設(shè)計(jì)計(jì)算過(guò)程案例目錄TOC\o"1-3"\h\u7498某5層建筑樓空調(diào)系統(tǒng)的風(fēng)系統(tǒng)設(shè)計(jì)計(jì)算過(guò)程案例 1272201.1風(fēng)系統(tǒng)設(shè)計(jì)要點(diǎn) 174471.2風(fēng)管水力計(jì)算方法 148221.3確定合理的空氣流速 1134291.4水力計(jì)算步驟 1501.5風(fēng)系統(tǒng)余壓校核 101.1風(fēng)系統(tǒng)設(shè)計(jì)要點(diǎn)a.風(fēng)道布置要盡可能短，避免復(fù)雜的局部管件。彎頭、三通等管件要安排得當(dāng)，與風(fēng)管的連接要合理，以減少阻力和噪聲。同時(shí)也要考慮便于風(fēng)系統(tǒng)的安裝、調(diào)節(jié)、控制與維修。b.當(dāng)輸送有可能在風(fēng)道內(nèi)凝結(jié)的氣體時(shí)，風(fēng)道應(yīng)有不小于0.005的坡度，以利于排除積液，并在風(fēng)道的最低點(diǎn)設(shè)置水封泄液管。c.風(fēng)系統(tǒng)布置好后，要在適當(dāng)部位放置風(fēng)管閥門，如一次性調(diào)節(jié)閥、經(jīng)常開(kāi)關(guān)的調(diào)節(jié)閥和防火閥等。1.2風(fēng)管水力計(jì)算方法風(fēng)管水力計(jì)算方法有：a.假定流速法其特點(diǎn)是先按技術(shù)經(jīng)濟(jì)要求選定風(fēng)管的流速，再根據(jù)風(fēng)管的風(fēng)量確定風(fēng)管的斷面尺寸和阻力。b.壓損平均法它是在已知總作用壓頭的情況下，將其平均分配給最不利環(huán)路的各管段，即最不利環(huán)路采用相同比摩阻進(jìn)行設(shè)計(jì)。c.靜壓復(fù)得法根據(jù)在某一斷面上的流體在全壓為一定值時(shí)，動(dòng)壓的減少量即成為靜壓的增加量。如果不計(jì)算摩擦阻力及局部阻力，動(dòng)壓的減少量應(yīng)完全等于靜壓的增加量。綜合考慮，本設(shè)計(jì)采用假定流速法。1.3確定合理的空氣流速查閱《實(shí)用供熱空調(diào)設(shè)計(jì)手冊(cè)》得下表：1.4水力計(jì)算步驟以第一層新風(fēng)管道為例，采用假定流速法進(jìn)行風(fēng)道水力計(jì)算的步驟如下：表6-1空調(diào)系統(tǒng)通風(fēng)管風(fēng)速選用表風(fēng)管類型新風(fēng)入口主風(fēng)道水平支風(fēng)道垂直支風(fēng)道送風(fēng)口推薦風(fēng)速（）2.53.5~4.53.02.51~2最大風(fēng)速4.04~63.5~4.03.25~4.02.0~3.0a.對(duì)第一層新風(fēng)管道布置及管道編號(hào)如下圖6-1所示，確定最不利環(huán)路為0-3-6-8-11圖6-1第一層新風(fēng)管路布置圖b.根據(jù)各管段的風(fēng)量及表1.1選定的風(fēng)速，確定各管段的斷面尺寸，然后根據(jù)標(biāo)準(zhǔn)規(guī)格選定風(fēng)管的斷面尺寸，再算出風(fēng)道內(nèi)實(shí)際風(fēng)速。以管段0為例，其風(fēng)量G為1321.99m3/h，管長(zhǎng)為7.73m，由表1.1假定該管段的風(fēng)速v為4.5m/s，則風(fēng)管的斷面面積為：F=根據(jù)矩形通風(fēng)管道統(tǒng)一規(guī)格，選用風(fēng)管斷面尺寸為320×320mm，則風(fēng)管實(shí)際風(fēng)速為：v=c.根據(jù)風(fēng)量或?qū)嶋H風(fēng)速和斷面當(dāng)量直徑計(jì)算得到單位長(zhǎng)度摩擦阻力。風(fēng)管當(dāng)量直徑（6-1）式中a——矩形風(fēng)管的短邊，mm；b——矩形風(fēng)管的短邊，mm。管段0的當(dāng)量直徑

雷諾數(shù)（6-2）式中——實(shí)際風(fēng)速，；——運(yùn)動(dòng)粘度，空氣在25℃時(shí)的運(yùn)動(dòng)粘度為。管段0的雷諾數(shù)

R風(fēng)管材質(zhì)選用鍍鋅薄鋼板，則查閱《民用建筑空調(diào)設(shè)計(jì)》得其當(dāng)量粗糙度為=0.15mm；所以

Kd，查《流體力學(xué)泵與風(fēng)機(jī)》尼古拉茲粗糙管沿程損失系數(shù)表，其在紊流過(guò)渡區(qū)內(nèi)。為簡(jiǎn)化計(jì)算，摩擦阻力系數(shù)可使用阿里特蘇里公式進(jìn)行計(jì)算：λ=0.11（單位長(zhǎng)度摩擦阻力可按下式計(jì)算：（6-3）式中——空氣密度，。管段0的單位長(zhǎng)度摩擦阻力

Rd.計(jì)算沿程阻力和局部阻力沿程阻力（6-4）式中——管段長(zhǎng)度，m。管段0的沿程阻力Δ局部阻力（6-5）式中——局部阻力系數(shù)；——空氣密度，；——實(shí)際風(fēng)速，。管段0的局部阻力部件有防火閥，四通，則。管段0的局部阻力

P則管段0的總阻力Δe.并聯(lián)支管的阻力平衡計(jì)算以管段9和管段10為例，其不平衡率為：Δ表6-2第一層風(fēng)管水力計(jì)算表管段編號(hào)風(fēng)量風(fēng)管尺寸（mm）管長(zhǎng)實(shí)際風(fēng)速雷諾數(shù)Re摩擦阻力系數(shù)沿程阻力局部阻力系數(shù)局部阻力總阻力寬高Pa/mPaPaPa01321.993203207.733.6720000.02130.5574.310.791.6010.911177.931601202.812.57220650.02800.8712.450.622.655.102205.131601203.682.97254380.02731.1294.150.563.187.343938.932502508.844.17652030.02210.9958.800.61.7415.534177.931601203.812.57220650.02800.8713.320.622.655.975205.131601203.672.97254380.02731.1294.140.563.187.326555.872002001.293.86482530.02371.1407.170.484.6111.787177.931601204.052.57220650.02800.8713.530.582.481.018377.941601605.014.10410090.02481.6838.430.525.6414.079177.931601203.692.57220650.02800.8713.220.622.655.87101201201203.892.31173610.02950.8493.300.561.945.241157.9312012010.071.1283810.03420.2302.310.810.652.97第一層最不利環(huán)路0-3-6-8-11的總阻力為55.18Pa。圖6-2第二層新風(fēng)管路布置圖表6-3第二層風(fēng)管水力計(jì)算表管段編號(hào)風(fēng)量風(fēng)管尺寸（mm）管長(zhǎng)實(shí)際風(fēng)速雷諾數(shù)Re摩擦阻力系數(shù)沿程阻力局部阻力系數(shù)局部阻力總阻力寬高Pa/mPaPaPa026405003200.994.51090240.01960.6470.640.7910.1810.8212401601602.82.6260420.02680.7342.060.682.975.0322401601603.242.6260420.02680.7342.380.682.975.3531201201202.742.3173610.02950.8492.330.812.805.1341201201200.492.3173610.02950.8490.420.812.803.2251201201202.322.3173610.02950.8491.970.812.804.7761201201200.472.3173610.02950.8490.400.812.803.20721605003205.353.8914630.02020.4692.510.474.261.7781201201204.482.3173610.02950.8493.810.812.801.6091201201204.512.3173610.02950.8493.830.812.801.631019205002501.474.3888890.02050.7231.060.475.521.58111201201203.872.3173610.02950.8493.290.812.801.09121201201203.812.3173610.02950.8493.240.812.801.041316805002504.723.7777780.02100.5662.670.474.231.90141201201203.452.3173610.02950.8492.930.812.805.73151201201203.882.3173610.02950.8493.300.812.801.101614405002001.554.0714290.02160.7791.210.474.851.06171201201203.472.3173610.02950.8492.950.812.805.75181201201203.462.3173610.02950.8492.940.812.805.741912004002004.724.2694440.02180.9154.320.475.269.58續(xù)表6-3管段編號(hào)風(fēng)量風(fēng)管尺寸（mm）管長(zhǎng)實(shí)際風(fēng)速雷諾數(shù)Re摩擦阻力系數(shù)沿程阻力局部阻力系數(shù)局部阻力總阻力寬高Pa/mPaPaPa211201201203.672.3173610.02950.8493.120.812.805.92201201201203.482.3173610.02950.8492.960.812.805.76211201201203.672.3173610.02950.8493.120.812.805.92229603202001.594.2641030.02221.0121.610.475.261.87231201201203.742.3173610.02950.8493.180.812.805.98241201201203.682.3173610.02950.8493.130.812.805.93257202502004.824.0555560.02301.0665.140.474.859.99261201201203.592.3173610.02950.8493.050.812.805.85271201201203.732.3173610.02950.8493.170.812.805.97284802002001.473.3416670.02430.8711.280.473.374.65291201201203.942.3173610.02950.8493.350.812.801.15301201201204.012.3173610.02950.8493.410.812.801.21312401601205.053.5297620.02651.5047.590.473.6511.25321201201203.772.3173610.02950.8493.200.762.635.83331201201203.892.3173610.02950.8493.300.762.635.93第二層最不利環(huán)路0-7-10-13-16-19-22-25-28-31-33的總阻力為85.4Pa。圖6-3第三層新風(fēng)管路布置圖表6-4第三層風(fēng)管水力計(jì)算表管段編號(hào)風(fēng)量風(fēng)管尺寸（mm）管長(zhǎng)實(shí)際風(fēng)速雷諾數(shù)Re摩擦阻力系數(shù)沿程阻力局部阻力系數(shù)局部阻力力總阻力寬高Pa/mPaPaPa01968.35002500.414.4911250.02050.7570.310.799.7510.061768.312502004.194.3592830.02271.2025.040.748.7013.732175.391601202.622.5217500.02800.8492.220.793.285.513592.922002005.934.1514690.02351.2837.610.647.0014.614175.391601202.442.5217500.02800.8492.070.813.365.445242.131601604.22.6262730.02680.7463.130.562.495.636175.391601201.752.5217500.02800.8495.730.893.709.43712004002002.084.2694440.02180.9151.901.1312.6514.5681201201203.182.3173610.02950.8492.700.812.805.5091201201203.792.3173610.02950.8493.220.812.801.02109603202003.094.2641030.02221.0123.130.581.499.62111201201203.262.3173610.02950.8492.770.812.805.57121201201204.042.3173610.02950.8493.430.812.801.23137202502004.524.0555560.02301.0664.820.585.9910.81141201201203.122.3173610.02950.8492.650.812.805.45151201201203.662.3173610.02950.8493.110.812.805.91164802002001.533.3416670.02430.8711.330.584.165.49171201201203.722.3173610.02950.8493.160.812.805.96181201201204.012.3173610.02950.8493.410.812.801.21192401601205.163.5297620.02651.5047.760.624.8212.58201201201203.542.3173610.02950.8493.010.762.635.63211201201204.262.3173610.02950.8493.620.762.631.25第三層最不利環(huán)路0-7-10-13-16-19-21的總阻力為69.36Pa。圖6-4第四層新風(fēng)管路布置圖表6-5第四層風(fēng)管水力計(jì)算表管段編號(hào)風(fēng)量風(fēng)管尺寸（mm）管長(zhǎng)實(shí)際風(fēng)速雷諾數(shù)Re摩擦阻力系數(shù)沿程阻力局部阻力系數(shù)局部阻力總阻力寬高Pa/mPaPaPa0537.22002001.613.7466320.02381.0707.071.029.1611.2311201201203.412.3173610.02950.8492.900.812.805.7021201201203.362.3173610.02950.8492.850.812.805.653297.22001602.542.6286650.02620.6331.610.472.023.62441.581201203.380.860160.03680.1270.430.720.300.735255.621601203.213.7316990.02621.6885.420.645.6511.066214.041201203.174.1309660.02672.4427.740.818.9111.657115.861201204.122.2167620.02970.7973.280.812.615.89898.181