1、HVAC基本知識(shí)培訓(xùn)課件HVAC 基本知識(shí)培訓(xùn)培訓(xùn)人：岳 文2005-6-2HVAC基本知識(shí)培訓(xùn)課件培訓(xùn)內(nèi)容培訓(xùn)內(nèi)容Day1: 空調(diào)的基本功能空氣的狀態(tài)參數(shù)及焓濕圖空調(diào)系統(tǒng)中幾種典型的空氣處理過程常用空調(diào)系統(tǒng)的分類定風(fēng)量空調(diào)系統(tǒng)和變風(fēng)量空調(diào)系統(tǒng)空氣的熱濕處理設(shè)備（空調(diào)系統(tǒng)的組成）風(fēng)管內(nèi)的壓力分布（動(dòng)壓和靜壓）應(yīng)用舉例HVAC基本知識(shí)培訓(xùn)課件Day2：1、空調(diào)水系統(tǒng)、空調(diào)水系統(tǒng)2、冷凍水系統(tǒng)控制原理、冷凍水系統(tǒng)控制原理3、Honeywell 風(fēng)閥和水閥介紹風(fēng)閥和水閥介紹4、水閥選型計(jì)算公式、水閥選型計(jì)算公式培訓(xùn)內(nèi)容培訓(xùn)內(nèi)容HVAC基本知識(shí)培訓(xùn)課件空調(diào)系統(tǒng)的基本功能空調(diào)系統(tǒng)的基本功能 Ventil

2、ation 空氣流通空氣流通 Heating 制熱制熱 Humidification 加濕加濕 Cooling 制冷制冷 Dehumidification 去濕去濕 Distribution 氣流分配氣流分配 Filtration 空氣過濾空氣過濾 Air Volume Control 空氣流量控制空氣流量控制 HVAC基本知識(shí)培訓(xùn)課件 空氣的狀態(tài)參數(shù)空氣的狀態(tài)參數(shù)-干球溫度：用溫度計(jì)直接讀取的溫度- 濕球溫度：在定壓絕熱條件下，空氣與水直接接觸達(dá)到熱濕平衡時(shí)的絕熱飽和溫度。- 露點(diǎn)溫度：當(dāng)空氣含濕量不變，降低溫度，在飽和狀態(tài)下，出現(xiàn)冷凝水 時(shí)的溫度。- 含濕量(d)：濕空氣中，所含水蒸汽的質(zhì)

3、量與干空氣質(zhì)量之比，即每公斤干 空氣所含有的水蒸汽量，其單位：kg/kg干空氣- 絕對濕度：每1立方濕空氣中所含有的水蒸汽重量- 相對濕度()：空氣中水蒸汽分壓力和同溫度下飽和水蒸汽分壓力之 比，它 反映了空氣接近飽和的程度。-焓(i)：物質(zhì)所具有的一種熱力學(xué)性質(zhì)，焓值大小取決于空氣溫度和含濕量兩個(gè)因素。對于近似定壓過程，可直接用濕空氣的焓的變化來度量空氣的熱量變化HVAC基本知識(shí)培訓(xùn)課件焓濕圖焓濕圖HVAC基本知識(shí)培訓(xùn)課件焓濕圖的組成焓濕圖的組成 紅線：等焓線 水平的綠線：等溫線（干球溫度） 垂直的深藍(lán)色線：等含濕量線 藍(lán)色的弧線：等相對濕度線 等濕球溫度線：在i-d 圖上，從等溫度線與10

4、0%相對濕度線的交點(diǎn)出發(fā)， 作= 4.19ts 的熱濕比線，則可得等濕球溫度線。在圖上 它近似等于等焓線。 飽和溫度線：空氣中濕空氣的含量達(dá)到飽和時(shí)的溫度曲線 熱濕比：=i / d , 等焓線的=0 。單位：kj/kg,熱濕比有正有負(fù)，它代 表濕空氣狀態(tài)變化的方向。HVAC基本知識(shí)培訓(xùn)課件顯熱和潛熱顯熱和潛熱顯熱（顯熱（ SENSIBLE HEATSENSIBLE HEAT）-溫度改變而含濕量不變所帶來的能量的變化。溫度改變而含濕量不變所帶來的能量的變化。潛熱（潛熱（LATENT HEATLATENT HEAT）-當(dāng)溫度不變時(shí)，水變?yōu)檎羝蛘羝優(yōu)樗鶐淼哪芰孔兓?。?dāng)溫度不變時(shí)，水變?yōu)檎羝?/p>

5、蒸汽變?yōu)樗鶐淼哪芰孔兓?。How Latent and Sensible Heat affect water?HVAC基本知識(shí)培訓(xùn)課件空氣的狀態(tài)變化過程空氣的狀態(tài)變化過程總熱量：總熱量：GTH= 潛熱（潛熱（TSH）顯熱（）顯熱（TLH) GTH = 1.19 x L/s x h L/s: 總的送風(fēng)量，總的送風(fēng)量， h：空氣狀態(tài)點(diǎn)：空氣狀態(tài)點(diǎn)A 和狀態(tài)點(diǎn)和狀態(tài)點(diǎn)B的焓差的焓差總的顯熱：總的顯熱： TSH= 1.20 x L/s x t L/s: 總的送風(fēng)量，總的送風(fēng)量， t：空氣狀態(tài)點(diǎn)：空氣狀態(tài)點(diǎn)A 和狀態(tài)點(diǎn)和狀態(tài)點(diǎn)B的溫差的溫差總的潛熱：總的潛熱： TLH= 3.0 x L/s x L/s

6、: 總的送風(fēng)量，總的送風(fēng)量， t：空氣狀態(tài)點(diǎn)：空氣狀態(tài)點(diǎn)A 和狀態(tài)點(diǎn)和狀態(tài)點(diǎn)B的含濕的含濕量差量差HVAC基本知識(shí)培訓(xùn)課件空氣的典型狀態(tài)變化過程空氣的典型狀態(tài)變化過程 濕空氣的加熱過程濕空氣的加熱過程- 利用熱水、蒸汽及電能等類熱源，通過表面間接對濕空氣加熱，利用熱水、蒸汽及電能等類熱源，通過表面間接對濕空氣加熱，其溫度增高而含濕量不變，即：空氣的顯熱增加。其溫度增高而含濕量不變，即：空氣的顯熱增加。 熱濕比熱濕比 濕空氣的等濕冷卻過程濕空氣的等濕冷卻過程- 利用冷水或其它冷媒通過金屬表面對濕空氣冷卻，當(dāng)冷表面溫度利用冷水或其它冷媒通過金屬表面對濕空氣冷卻，當(dāng)冷表面溫度等于或大于濕空氣的露點(diǎn)溫

7、度時(shí)，空氣中的水蒸汽不會(huì)凝結(jié)，因等于或大于濕空氣的露點(diǎn)溫度時(shí)，空氣中的水蒸汽不會(huì)凝結(jié)，因此其含濕量也不回變化，只是溫度將降低。此其含濕量也不回變化，只是溫度將降低。 熱濕比熱濕比HVAC基本知識(shí)培訓(xùn)課件 等焓加濕過程等焓加濕過程- 利用定量的水通過噴灑與一定狀態(tài)的空氣長時(shí)間直接接觸，則利用定量的水通過噴灑與一定狀態(tài)的空氣長時(shí)間直接接觸，則此種水或水滴及其表面的飽和空氣層的溫度即等于濕空氣的濕球此種水或水滴及其表面的飽和空氣層的溫度即等于濕空氣的濕球溫度，因此，此時(shí)空氣狀態(tài)的變化過程就近似于等焓過程。溫度，因此，此時(shí)空氣狀態(tài)的變化過程就近似于等焓過程。 熱濕比熱濕比4.19ts4.19ts 等焓

8、減濕過程等焓減濕過程- 利用固體吸濕劑干燥空氣時(shí)，濕空氣的部分水蒸汽在吸濕劑的微利用固體吸濕劑干燥空氣時(shí)，濕空氣的部分水蒸汽在吸濕劑的微孔表面上凝結(jié)，濕空氣含濕量降低，溫度升高孔表面上凝結(jié)，濕空氣含濕量降低，溫度升高 熱濕比熱濕比0 0空氣的狀態(tài)變化過程（續(xù)一）空氣的狀態(tài)變化過程（續(xù)一）HVAC基本知識(shí)培訓(xùn)課件空氣的狀態(tài)變化過程（續(xù)二）空氣的狀態(tài)變化過程（續(xù)二）熱濕比熱濕比狀態(tài)參數(shù)變化趨勢狀態(tài)參數(shù)變化趨勢過程特征過程特征idt 0 0 /-增焓增濕，噴蒸汽可近似實(shí)現(xiàn)增焓增濕，噴蒸汽可近似實(shí)現(xiàn)等溫過程等溫過程 0 0 0 / 減焓，減濕減焓，減濕 0 0 減焓，增濕，降溫減焓，增濕，降溫HVAC

9、基本知識(shí)培訓(xùn)課件練習(xí)練習(xí)1What is the RH of the air at all points on the What is the RH of the air at all points on the saturation temperature linesaturation temperature lineANS: RH = 100%What is the dew point at 21What is the dew point at 21 C dry bulb and 50% C dry bulb and 50% RHRHDew point = 10 CWhat is the

10、Dew Point of air that has an absolute What is the Dew Point of air that has an absolute humidity (moisture content) of 10 g/kghumidity (moisture content) of 10 g/kg Dew point = 14 oCWhat is the RH of the air at 30What is the RH of the air at 30 C dry bulb and a C dry bulb and a dew point temperature

11、 of 5dew point temperature of 5 C CRH = 20.3%HVAC基本知識(shí)培訓(xùn)課件練習(xí)練習(xí)1 （續(xù)一）（續(xù)一）What is the moisture content of the air at 22 What is the moisture content of the air at 22 C C dry bulb and 50% RHdry bulb and 50% RHMoisture content = 8.4 g/kgWhat is the RH at 26 What is the RH at 26 c dry bulb and 17 c dry bu

12、lb and 17 c wet c wet bulbbulbRh = 40%What is the wet bulb temperature of the air at What is the wet bulb temperature of the air at 20 20 C dry bulb and 50% RHC dry bulb and 50% RHWet bulb temperature = 14 CWhat is the RH at 22What is the RH at 22C dry bulb and 15C dry bulb and 15C wet bulb C wet bu

13、lb RH = 47%HVAC基本知識(shí)培訓(xùn)課件練習(xí)練習(xí)1 （續(xù)二）（續(xù)二）What is the wet bulb temperature of the air at What is the wet bulb temperature of the air at 24 24 C dry bulb and 40% RHC dry bulb and 40% RHWet bulb temperature = 15.5 C Air at 24 Air at 24 C dry bulb and 20 C dry bulb and 20 C wet bulb is cooled C wet bulb is

14、cooled to 8to 8C along the saturation curve and then C along the saturation curve and then reheated to 21 reheated to 21 c. What is the rh of the air at c. What is the rh of the air at this conditionthis conditionRH = 42%HVAC基本知識(shí)培訓(xùn)課件混合空氣的處理混合空氣的處理 在空調(diào)系統(tǒng)中，空氣的處理過程是從混風(fēng)開始，因此我們在空調(diào)系統(tǒng)中，空氣的處理過程是從混風(fēng)開始，因此我們需要

15、在需要在i-d 圖上確定混風(fēng)狀態(tài)點(diǎn)。圖上確定混風(fēng)狀態(tài)點(diǎn)。（一）、通過計(jì)算方式確定（一）、通過計(jì)算方式確定 T3 = (T1xQ1)+(T2xQ2) / (Q1+Q2) Q1: 新風(fēng)量新風(fēng)量 Q2: 回風(fēng)量回風(fēng)量（二）、通過（二）、通過 i-d 圖確定圖確定 1. 確定新風(fēng)狀態(tài)點(diǎn)確定新風(fēng)狀態(tài)點(diǎn)A和回風(fēng)狀態(tài)點(diǎn)和回風(fēng)狀態(tài)點(diǎn)B 2. 通過通過A/B 連線連線 3. 根據(jù)送風(fēng)量，確定其混合比例，如：新風(fēng)根據(jù)送風(fēng)量，確定其混合比例，如：新風(fēng)20%，回風(fēng)，回風(fēng) 80%，則將，則將AB線段分為線段分為5份，混風(fēng)位于距回風(fēng)份，混風(fēng)位于距回風(fēng)1/5距距 離處離處HVAC基本知識(shí)培訓(xùn)課件 按負(fù)擔(dān)室內(nèi)熱濕負(fù)荷所用的介

16、質(zhì)分：- 全空氣系統(tǒng)- 全水系統(tǒng)- 空氣水- 制冷劑 按空氣處理設(shè)備的集中程度：- 集中式空調(diào)- 半集中式空調(diào)系統(tǒng)- 分散式空調(diào)系統(tǒng) 按熱量傳遞方式：- 對流和輻射 按被處理空氣的來源：- 封閉式- 直流式- 混合式空調(diào)系統(tǒng)分類空調(diào)系統(tǒng)分類HVAC基本知識(shí)培訓(xùn)課件空調(diào)系統(tǒng)分類空調(diào)系統(tǒng)分類HVAC基本知識(shí)培訓(xùn)課件集中式空調(diào)系統(tǒng)分類集中式空調(diào)系統(tǒng)分類 封閉式：-全部為循環(huán)空氣，系統(tǒng)無新風(fēng)；-它主要是給設(shè)備使用的空調(diào)，無人居留。 直流式：-全部用新風(fēng)，不使用循環(huán)空氣；-它主要用于：室內(nèi)有有害氣體，不能循環(huán)使用的空調(diào)系統(tǒng)。 一次回風(fēng)系統(tǒng)：- 除部分使用新風(fēng)外，使用相當(dāng)數(shù)量的循環(huán)空氣- 在AHU 前混合

17、- 普通應(yīng)用最多的全空氣空調(diào)系統(tǒng) 二次回風(fēng)系統(tǒng)：-除部分使用新風(fēng)外，使用相當(dāng)數(shù)量的循環(huán)空氣- 在AHU 前混合，在AHU 后再混合一次- 為減小送風(fēng)溫差而又不用再熱器時(shí)的空調(diào)方式HVAC基本知識(shí)培訓(xùn)課件集中式空調(diào)系統(tǒng)分類集中式空調(diào)系統(tǒng)分類另外，根據(jù)其他原則，進(jìn)行分類：根據(jù)系統(tǒng)風(fēng)量：定風(fēng)量和變風(fēng)量根據(jù)風(fēng)道內(nèi)空氣流速：低速（V8m/s）和高速（V=2030m/s ）系統(tǒng)用途：工藝性和舒適性空調(diào)系統(tǒng)1. 系統(tǒng)精度：一般性空調(diào)系統(tǒng)和恒溫恒濕空調(diào)系統(tǒng)HVAC基本知識(shí)培訓(xùn)課件一次回風(fēng)和二次回風(fēng)空調(diào)的特性一次回風(fēng)和二次回風(fēng)空調(diào)的特性HVAC基本知識(shí)培訓(xùn)課件定風(fēng)量空調(diào)系統(tǒng)和變風(fēng)量空調(diào)系統(tǒng)定風(fēng)量空調(diào)系統(tǒng)和變風(fēng)量

18、空調(diào)系統(tǒng)定風(fēng)量空調(diào)系統(tǒng)：定風(fēng)量空調(diào)系統(tǒng)：- 定風(fēng)量空調(diào)系統(tǒng)是指送風(fēng)量恒定，通過改變送風(fēng)溫度來適應(yīng)室內(nèi)定風(fēng)量空調(diào)系統(tǒng)是指送風(fēng)量恒定，通過改變送風(fēng)溫度來適應(yīng)室內(nèi)負(fù)荷的變化。平常所用的大部分空調(diào)系統(tǒng)都是采用定風(fēng)量方式負(fù)荷的變化。平常所用的大部分空調(diào)系統(tǒng)都是采用定風(fēng)量方式。 變風(fēng)量空調(diào)系統(tǒng)：變風(fēng)量空調(diào)系統(tǒng)：-是指送風(fēng)溫度不變，而改變送風(fēng)量的方式來適應(yīng)負(fù)荷的變化，而是指送風(fēng)溫度不變，而改變送風(fēng)量的方式來適應(yīng)負(fù)荷的變化，而風(fēng)量的變化是通過專用的變風(fēng)量末端裝置來實(shí)現(xiàn)風(fēng)量的變化是通過專用的變風(fēng)量末端裝置來實(shí)現(xiàn)。根據(jù)它的控制根據(jù)它的控制方式，可以分為兩類：方式，可以分為兩類：w 定靜壓控制的變風(fēng)量空調(diào)系統(tǒng)w 變

19、靜壓控制的變風(fēng)量空調(diào)系統(tǒng)HVAC基本知識(shí)培訓(xùn)課件定靜壓控制的變風(fēng)量空調(diào)系統(tǒng)定靜壓控制：-恒定送風(fēng)管道靜壓的空調(diào)系統(tǒng)。當(dāng)末端的VAV 根據(jù)室內(nèi)溫度的要 求開度變小后導(dǎo)致管道內(nèi)的靜壓變高，這時(shí)，通過調(diào)節(jié)送風(fēng)機(jī)的頻率，減少送風(fēng)量，使風(fēng)機(jī)管道上的靜壓維持設(shè)定值。這種依賴靜壓傳感器來控制風(fēng)量的方法，稱為定靜壓變風(fēng)量空調(diào)系統(tǒng)。HVAC基本知識(shí)培訓(xùn)課件變靜壓控制的變風(fēng)量空調(diào)系統(tǒng)變靜壓控制：-控制系統(tǒng)讀取末端所有VAV 控制器風(fēng)門開度信號(hào)，并綜合這些VAV 閥門的開度信息并加以運(yùn)算和判斷來調(diào)節(jié)變頻送風(fēng)機(jī)的風(fēng)量，使其具有最大靜壓值的VAV 閥門處于接近全開的狀態(tài),即盡量使風(fēng)機(jī)在最低靜壓下運(yùn)轉(zhuǎn)，以節(jié)省能源同時(shí)減少

20、噪音。例如：當(dāng)系統(tǒng)中有一臺(tái)VAV 閥門開度為100%，說明其入口靜壓不足，風(fēng)機(jī)應(yīng)增速，以增大風(fēng)量，使其VAV 開度接近全開即可；當(dāng)閥門開度處于80%90%之間，說明入口靜壓適中，風(fēng)量滿足要求，風(fēng)機(jī)不調(diào)節(jié)；當(dāng)全部風(fēng)閥開度處于80%以下時(shí)，說明風(fēng)量過多，此時(shí)降低風(fēng)機(jī)轉(zhuǎn)速，減少送風(fēng)量。這種不依賴靜壓來控制風(fēng)量的方法，稱為變靜壓閥。 HVAC基本知識(shí)培訓(xùn)課件末端末端VAV 控制器類型控制器類型 壓力相關(guān)型壓力相關(guān)型VAV：75 %22 CDamperTemp21.5 CSetpointElectric ReheatStage 1Stage 2Stage 3ONSTOFFSTOFFSTHVAC基本知識(shí)培

21、訓(xùn)課件 壓力無關(guān)型壓力無關(guān)型末端末端VAV 控制器類型控制器類型75 %22 CDamperTemp21.5 CSetpointAir Flow80 l/sHeating Valve50 %HCHVAC基本知識(shí)培訓(xùn)課件空調(diào)的基本構(gòu)件空調(diào)的基本構(gòu)件 表面換熱器表面換熱器 風(fēng)閥門風(fēng)閥門 加濕設(shè)備加濕設(shè)備 去濕設(shè)備去濕設(shè)備 加熱設(shè)備加熱設(shè)備 風(fēng)機(jī)風(fēng)機(jī) 空氣過濾設(shè)備空氣過濾設(shè)備HVAC基本知識(shí)培訓(xùn)課件加濕設(shè)備類型加濕設(shè)備類型 等焓加濕設(shè)備：等焓加濕設(shè)備：- 噴水室噴水室- 壓縮空氣噴霧壓縮空氣噴霧- 高壓噴水加濕高壓噴水加濕- 濕簾濕簾- 超聲波加濕器超聲波加濕器- 離心式加濕器離心式加濕器 等溫加濕

22、設(shè)備等溫加濕設(shè)備- 干蒸汽加濕干蒸汽加濕- 電極式加濕器電極式加濕器- 電熱式加濕器電熱式加濕器- PTC 蒸汽加濕器（蒸汽加濕器（PTC： 熱電變阻器熱電變阻器 氧化陶瓷半導(dǎo)體氧化陶瓷半導(dǎo)體）- 紅外電加濕紅外電加濕HVAC基本知識(shí)培訓(xùn)課件去濕設(shè)備去濕設(shè)備 冷凍去濕冷凍去濕 液體吸濕劑液體吸濕劑 固體吸濕器固體吸濕器HVAC基本知識(shí)培訓(xùn)課件常用風(fēng)門常用風(fēng)門 Dampers used in HVAC systems are typically air flow throttling devices and can be either modulating or two position. So

23、 it have two major type of damper actuator. They usually have multiple blades mounted on parallel shafts which are rotated in unison by an external actuator to change the blades from open to closed or closed to open Depending on the requirements of the system the assembly can be arranged as “normall

24、y open” or “normally closed” by means of the arrangement of the actuator device used to drive the damperHVAC基本知識(shí)培訓(xùn)課件 Depending on how the adjacent shafts are linked Depending on how the adjacent shafts are linked together the damper assembly is either :-together the damper assembly is either :-A par

25、allel blade damper-An opposed blade damper Parallel blade dampers are constructed so that Parallel blade dampers are constructed so that each blade rotates in parallel with or in the each blade rotates in parallel with or in the same direction as the blade next to itsame direction as the blade next

26、to it Opposed blade dampers are constructed so that Opposed blade dampers are constructed so that adjacent blades rotate opposite to each other adjacent blades rotate opposite to each other -The damper rotation increases the resistance to the air flow since the air is funnelled through a smaller ope

27、ning-An opposed blade damper must be open further than a parallel damper to obtain the same resistance to air flow常用風(fēng)門常用風(fēng)門HVAC基本知識(shí)培訓(xùn)課件常用風(fēng)門常用風(fēng)門 The following diagram shows a basic parallel blade damper assembly together with the air flow pattern with the damper at 33% closedHVAC基本知識(shí)培訓(xùn)課件常用風(fēng)門常用風(fēng)門 The f

28、ollowing diagram shows a basic opposed blade damper The following diagram shows a basic opposed blade damper assembly together with the air flow pattern with the damper at assembly together with the air flow pattern with the damper at 33% closed33% closedHVAC基本知識(shí)培訓(xùn)課件常用風(fēng)門常用風(fēng)門 Round or butterfly dampe

29、rs are typically used to control air flows Round or butterfly dampers are typically used to control air flows in ducts that have high static pressure and high velocity in ducts that have high static pressure and high velocity characteristicscharacteristicsHVAC基本知識(shí)培訓(xùn)課件常用風(fēng)門常用風(fēng)門 Fire dampers are used t

30、o prevent superheated air, gases or flames Fire dampers are used to prevent superheated air, gases or flames from crossing a fire barrier. They can be duct mounted or installed from crossing a fire barrier. They can be duct mounted or installed directly in a fire barrierdirectly in a fire barrier Th

31、ey are always two position devicesThey are always two position devicesHVAC基本知識(shí)培訓(xùn)課件通風(fēng)機(jī)通風(fēng)機(jī) 離心式離心式- 前曲式前曲式- 后曲式后曲式- 徑向式徑向式 軸流式軸流式HVAC基本知識(shí)培訓(xùn)課件離心風(fēng)機(jī)離心風(fēng)機(jī) CENTRIFUGAL FANSCENTRIFUGAL FANS-Found in supply air applications and quietly move air at moderate pressures-Utilise VSD drives for capacity control-Olde

32、r installations may have fans with inlet guide vanes to vary air flow-Almost always belt driven and not normally rated to operate in smoke extract applications CENTRIFUGAL FANS CAN HAVE EITHER :-CENTRIFUGAL FANS CAN HAVE EITHER :-Forward inclined blades-Backward inclined bladesHVAC基本知識(shí)培訓(xùn)課件 Centrifug

33、al fans with forward inclined bladesCentrifugal fans with forward inclined blades-Used in the majority of HVAC installations as supply air fans-Used from small domestic applications to large commercial applications in multi story buildings Centrifugal fans with backward inclined bladesCentrifugal fa

34、ns with backward inclined blades-Generally larger and quieter in operation than forward inclined bladed fans-Should always be used in variable volume systems-More expensive to manufacture than forward inclined bladed fans and therefore contractors are reluctant to use them離心風(fēng)機(jī)離心風(fēng)機(jī)HVAC基本知識(shí)培訓(xùn)課件典型離心風(fēng)機(jī)典

35、型離心風(fēng)機(jī)A TYPICAL CENTRIFUGAL FAN WITH BACKWARD INCLINED BLADES IS DETAILED A TYPICAL CENTRIFUGAL FAN WITH BACKWARD INCLINED BLADES IS DETAILED BELOW :-BELOW :-HVAC基本知識(shí)培訓(xùn)課件 AXIAL FANSAXIAL FANS-Generally used for moving large volumes of air at low pressures-Usually directly driven and may use vsd drive

36、s for capacity contriol-Used in extract, return air, cooling tower and smoke control applications where high noise levels are not an issue THE MOST COMMON TYPE OF AXIAL FANS USED IN THE THE MOST COMMON TYPE OF AXIAL FANS USED IN THE HVAC INDUSTRY ARE :-HVAC INDUSTRY ARE :-Propeller fan-Tube axial fa

37、n-Vane axial fan軸流風(fēng)機(jī)軸流風(fēng)機(jī)HVAC基本知識(shí)培訓(xùn)課件 Propeller Fans are low pressure high air flow units which work up Propeller Fans are low pressure high air flow units which work up to a maximum static pressure of 19 pa. to a maximum static pressure of 19 pa. Tube axial fans are heavy duty units arranged for ins

38、tallation in Tube axial fans are heavy duty units arranged for installation in ducts. It work up to maximum static pressure of 750 pa. ducts. It work up to maximum static pressure of 750 pa. Vane axial fans are basically tube axial fans with straightening Vane axial fans are basically tube axial fan

39、s with straightening vanes and are quieter in operation than tube axial fansvanes and are quieter in operation than tube axial fans軸流風(fēng)機(jī)軸流風(fēng)機(jī)HVAC基本知識(shí)培訓(xùn)課件 CHARACTERISTICS OF AIR FLOW IN DUCTSCHARACTERISTICS OF AIR FLOW IN DUCTS-A pressure difference (PD) must exist within the duct work to enable air fl

40、ow to be transferred from the air handling unit fan to the field registers-The PD required must be sufficient to overcome the frictional losses within the duct work and to accelerate the air flow to the required outlet operational velocity DUCT SYSTEMS HAVE A CERTAIN AMOUNT OF RESISTANCE DUCT SYSTEM

41、S HAVE A CERTAIN AMOUNT OF RESISTANCE TO THE FLOW OF AIRTO THE FLOW OF AIR-This is known as frictional loss and results from shear forces in the fluid near the duct wall-Frictional loss causes a measurable loss of static pressure in the duct-Frictional loss is proportional to velocity squared-Double

42、 the flow rate and four times the pressure loss will occur風(fēng)管中氣流的特性參數(shù)風(fēng)管中氣流的特性參數(shù)HVAC基本知識(shí)培訓(xùn)課件 The following fan affinity laws describe what happens to the The following fan affinity laws describe what happens to the flow rate, pressure and motor power when one parameter of a fan flow rate, pressure and

43、 motor power when one parameter of a fan system changessystem changes風(fēng)管中氣流的特性參數(shù)風(fēng)管中氣流的特性參數(shù)HVAC基本知識(shí)培訓(xùn)課件 A typical curve of air flow rate against static pressure A typical curve of air flow rate against static pressure in a duct is detailed below :-in a duct is detailed below :-風(fēng)管中氣流的特性參數(shù)風(fēng)管中氣流的特性參數(shù)HVAC基本知識(shí)培訓(xùn)課件In HVAC systems the air supplied by the fan includes two In HVAC systems the air supplied by the fan includes two types of pressuretypes of pressure-Velocity pressure Velocity pressure -Static pressureStatic pressureVelocity Pressur