HPV 莖流量傳感器/Sap Flow Sensor       

HPV莖流量傳感器是一款校準(zhǔn)型、低成本的熱脈沖液流傳感器，輸出校準(zhǔn)液流量、熱速、莖水含量、莖溫等數(shù)據(jù)，功耗低，內(nèi)置加熱控制，同時(shí)改善了傳統(tǒng)的加熱方式，其原理采用熱脈沖速率法，測(cè)量范圍：-200~+1000cm/hr(熱流速度)或-100~+2000cm3/cm2/hr (莖流通量密度)，可廣泛用于于莖流量監(jiān)測(cè)、植物莖流蒸發(fā)計(jì)算、植物莖流蒸騰量、植物灌溉等
植物莖流是樹(shù)木內(nèi)部的“水”運(yùn)動(dòng)，而蒸騰是從葉片通過(guò)光合作用蒸發(fā)流出的水分。樹(shù)液流量和蒸騰量之間有很強(qiáng)的關(guān)聯(lián)性，通常理解是同一回事。但是，嚴(yán)格地說(shuō)，它們是不同的，這體現(xiàn)在它們是如何被測(cè)量的。
         SAP流量以L/hr（或每天、每周等）為單位進(jìn)行測(cè)量。蒸騰量以每小時(shí)、每天、每星期等毫米（mm）為單位測(cè)量。
 蒸散量=蒸騰量+蒸發(fā)量 
蒸騰量以毫米為測(cè)量單位，可與降雨量以毫米計(jì)作比較。隨著時(shí)間的推移，降雨量（水輸入）應(yīng)與蒸騰量（輸出）相匹配。如果蒸騰作用更高，通常是樹(shù)木作物的蒸騰作用，那么這種差異必須通過(guò)灌溉來(lái)彌補(bǔ)。
    蒸發(fā)量（evaporation），蒸發(fā)量是指在一定時(shí)段內(nèi)，由土壤或水中的水分經(jīng)蒸發(fā)而散布到空中的量。

1mm(降雨量)=1㎡地面1kg水
1mm(蒸騰量)=1㎡葉面積的1升樹(shù)液流量（水）
 
例如：在果園和葡萄園等有管理的樹(shù)木作物系統(tǒng)中，蒸發(fā)量與蒸騰量相比非常小。因此，為了簡(jiǎn)化測(cè)量，通常忽略蒸發(fā)量，將蒸騰量取為平均蒸散量（ETo）。

莖流量傳感器廣泛應(yīng)用
    計(jì)算總流量
    低液流和零液流速率
    反向液流速率
    夜間水分損失
    根莖液流速度
    貧瘠生態(tài)系統(tǒng)及干旱
    徑向液體流速
    葡萄藤的液流
 
 莖流量傳感器技術(shù)指標(biāo)
測(cè)量范圍：-200~+1000cm/hr(熱流速度)
分辨率：0.001cm/hr
準(zhǔn)確度：±0.1cm/hr
探針尺寸：φ1.3mm*L30mm
溫度位置：外10mm，內(nèi)20mm
針距：6mm
探針材質(zhì)：316不銹鋼
溫度范圍：-30~+70℃
響應(yīng)時(shí)間：200ms
加熱電阻：39Ω，400J/m
電源：12V DC
電流：空閑5mA, 測(cè)量<270mA
線纜：5m，*大60m



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