趙文濤，張 毅，于光鑫，F(xiàn)RANK Behrendt,2，何 芳

炭棒與生物質(zhì)棒穩(wěn)態(tài)陰燃特性對比

趙文濤1，張 毅1，于光鑫1，F(xiàn)RANK Behrendt1,2，何 芳1※

（1. 山東理工大學(xué)交通與車輛工程學(xué)院，淄博 255049；2. Institute of Energy Engineering，Technische Universit?t Berlin，Berlin 10623，Germany）

為研究炭與生物質(zhì)穩(wěn)態(tài)陰燃的特性差異，對不同直徑（2～8 mm）的炭棒與絕干、空干生物質(zhì)棒豎直向下的陰燃進行了試驗，并編寫程序計算了棒狀燃料陰燃過程的耗氧速率。結(jié)果表明：1）所制炭棒與生物質(zhì)棒均能自行調(diào)節(jié)反應(yīng)區(qū)形狀以維持穩(wěn)態(tài)陰燃。2）炭棒的陰燃傳播速度約為生物質(zhì)棒的4.2倍，最高溫度比生物質(zhì)棒高約50 ℃，反應(yīng)區(qū)長度約為相應(yīng)生物質(zhì)棒的3.8倍，燃料消耗速率約為生物質(zhì)棒的2.4倍。3）計算和試驗煙氣輪廓吻合較好，炭棒耗氧速率約為生物質(zhì)棒的3.4倍。研究結(jié)果可為穩(wěn)態(tài)陰燃機理的深入研究及應(yīng)用中燃料選擇提供參考。

炭；生物質(zhì)；穩(wěn)態(tài)陰燃；傳播速度；耗氧速率

0 引 言

中國農(nóng)林生物質(zhì)廢棄物總量約為1.2×109t/a[1]，資源量巨大，將其在低氧條件下高溫?zé)崃呀饪芍瞥缮镔|(zhì)炭[2-4]。炭及農(nóng)林生物質(zhì)常見的利用方式為燃燒，這種方式易造成設(shè)備腐蝕和環(huán)境污染等問題[5]。陰燃是一種緩慢、低溫、無焰的燃燒過程[6]，具有燃料適應(yīng)性強、固相低溫可避免鉀逸出造成設(shè)備粘污[7]、灰分可做肥料[8]等優(yōu)勢，發(fā)展?jié)摿薮?。炭及農(nóng)林生物質(zhì)的陰燃在中國傳統(tǒng)上常用于冬季農(nóng)村住宅[9]或蔬菜大棚[10]供暖等場景（如炕、燃池等）。其陰燃特性（如陰燃最高溫度[11]、傳播速度[12]、燃料消耗速率[13]等）的進一步研究，有助于對應(yīng)用中的陰燃過程有更為普遍的理解，包括確定燃料配比[11,14]、通風(fēng)條件[15-16]、煙氣處理策略[17]及提高能源效率[18]等，并可為陰燃裝置的設(shè)計及開發(fā)連續(xù)運行工藝提供重要參考。

炭及生物質(zhì)陰燃的研究已有幾十年的歷史，主要涉及煤炭[19-20]、森林[21]的火災(zāi)，香煙的燃燒[22]，近期有機固廢的處理利用[23-24]和建筑的供暖[25-26]等。從應(yīng)用的角度來說，一般需要陰燃過程的穩(wěn)態(tài)和可控，便于煙氣處理，并滿足不同熱負荷的供暖需求。穩(wěn)態(tài)陰燃研究多采用棒狀燃料[27]。早在1967年，KINBARA等[28]在不同溫度的燃燒室中對熏香陰燃傳播速度進行了研究，發(fā)現(xiàn)其陰燃傳播速度范圍在1～8 mm/min，并給出了陰燃傳播速度（）與點火溫度（i）及環(huán)境溫度（a）之間的關(guān)系（2∝1/(i-a)）。近年來，對棒狀燃料穩(wěn)態(tài)陰燃的研究主要集中在不同含水率、空氣流速、氧含量及氧分壓等因素下的陰燃傳播過程。高振強等[29]研究了含水率對佛香陰燃傳播速度的影響，發(fā)現(xiàn)不同含水率（0～35%）的佛香，其傳播速度在初始階段（< 20 min）有顯著差異。MUKUNDA等[30]研究了不同空氣流速（0～7 m/s）及氧含量（23%～44%）對佛香陰燃過程的影響，發(fā)現(xiàn)正向陰燃時，其傳播速度隨氣流速度及氧含量的增加而增加，而在逆向陰燃時其傳播速度存在峰值。LIN等[31]對不同空氣流速下的佛香陰燃進行了研究，發(fā)現(xiàn)隨空氣流速增大，佛香陰燃會依次進入氧氣控制、熱控制及化學(xué)控制階段。KADOWAKI等[32]對不同氧氣質(zhì)量分數(shù)（0.1～0.5）下艾柱的陰燃過程進行了研究，發(fā)現(xiàn)傳播速度及最高溫度隨氧氣質(zhì)量分數(shù)的增加而增加。YAMAZAKI等[33]研究了佛香陰燃的火焰轉(zhuǎn)捩，發(fā)現(xiàn)氧分壓低于0.3時不會出現(xiàn)明火。YAN等[34]研究了不同直徑、不同灰分含量炭棒的陰燃特性，發(fā)現(xiàn)氧氣在其陰燃過程中起主導(dǎo)作用。這些研究為穩(wěn)態(tài)陰燃技術(shù)開發(fā)提供了依據(jù)。

然而，同一種生物質(zhì)和其制備的炭在穩(wěn)態(tài)陰燃特性方面的異同，目前并不明確，也未見報道。本文擬采用試驗的方法解決這一問題，并對過程中起關(guān)鍵作用的氧傳輸進行理論分析。試驗中應(yīng)用中國傳統(tǒng)佛香制備方法制作生物質(zhì)棒，并對其熱解制備炭棒。以期為深入研究穩(wěn)態(tài)陰燃機理和改進陰燃應(yīng)用提供參考。

1 材料與方法

1.1 炭棒與生物質(zhì)棒的制備

購買產(chǎn)自四川省、顆粒直徑小于0.15 mm的純榆樹皮粉和純柏木粉為原料，制得空干、絕干生物質(zhì)棒和炭棒。具體制作方法如下：將榆樹皮粉、柏木粉和水按質(zhì)量比例約1∶1∶4混合均勻，擠壓成直徑3、5、8 mm的生物質(zhì)棒，在空氣中自然風(fēng)干（>48 h），得到空干生物質(zhì)棒；將空干生物質(zhì)棒置于101型電熱鼓風(fēng)干燥箱中，在105 ℃下保溫24 h制得絕干生物質(zhì)棒，絕干生物質(zhì)棒制作完成后放置于干燥皿中儲存；炭棒由空干生物質(zhì)棒熱解制成：將空干生物質(zhì)棒放在石英試管中，并用石棉將試管口封堵，放置在馬弗爐中，以10 ℃/min的加熱速率將其從室溫加熱至500 ℃，保溫2 h后，關(guān)閉電源即制得炭棒，待其在爐中冷卻后（>12 h），放入密封袋中儲存。

對所制炭棒與生物質(zhì)棒進行測量，并參照GB/T 28731—2012（固體生物質(zhì)燃料工業(yè)分析方法）進行分析，分析結(jié)果如表1所示。需要注意的是，在制作過程中，因水分蒸發(fā)或揮發(fā)分逸出導(dǎo)致的收縮，使炭棒與生物質(zhì)棒的實際直徑和制作直徑（3、5、8 mm）略有差別。

表1 樣品參數(shù)及工業(yè)分析

注：表中“-”表示成分含量可忽略；*為在炭棒工業(yè)分析測定揮發(fā)分含量時，為防止炭粉的氧化，在其表面覆蓋約4 mm厚的珍珠巖粉。

Note: The “-” in the table indicates that the component content can be ignored. *is in the proximate analysis of char rods to determine volatile content, to prevent the oxidation of char powder, about 4 mm thick perlite powder was covered on its surface.

1.2 試驗方法

在大氣環(huán)境中（25±3）℃，對棒狀燃料豎直向下的穩(wěn)態(tài)陰燃過程進行試驗。具體試驗方法如圖1所示。首先使用點火器將長度約15 cm的棒狀燃料頂部點燃。待陰燃穩(wěn)定后（約4 min），采用刻度尺和計時器記錄反應(yīng)前鋒移動距離（Δ）和時間（Δ），可得陰燃傳播速度（sm=Δ/Δ）。棒狀燃料穩(wěn)態(tài)陰燃過程中采用紅外熱成像儀（ThermoProTM TP8）記錄反應(yīng)區(qū)溫度分布，并利用自制紋影系統(tǒng)記錄棒狀燃料的煙氣層輪廓。隨后將棒狀燃料插入生物質(zhì)灰中，隔絕氧氣使其熄滅，并用徠卡顯微鏡（M135C）記錄反應(yīng)區(qū)形狀。需要注意的是，紅外圖像分析時取各棒狀燃料發(fā)射率為0.93。

注：Δx、Δt、usm分別為移動距離、移動時間及陰燃傳播速度。

2 結(jié)果與分析

試驗發(fā)現(xiàn)，各棒狀燃料在豎直狀態(tài)下均能穩(wěn)定陰燃。炭棒與生物質(zhì)棒的反應(yīng)區(qū)形狀及紅外溫度圖像如圖2所示，圖中“+”為最高溫度的位置標記?？梢钥闯觯鞣磻?yīng)區(qū)（炭錐）形狀明顯不同，這表明不同的炭棒與生物質(zhì)棒可通過自行調(diào)節(jié)其反應(yīng)區(qū)形狀以維持穩(wěn)態(tài)陰燃。另外，棒狀燃料陰燃高溫范圍也隨反應(yīng)區(qū)形狀有明顯不同，最高溫度范圍均在620～770℃之間。

3種物料陰燃特性參數(shù)隨直徑變化的試驗結(jié)果如圖3所示。由圖3可知，炭棒與生物質(zhì)棒在陰燃傳播速度、最高溫度、反應(yīng)區(qū)長度和燃料消耗速率方面均有差異。

注：圖中d、Tmax分別為炭棒與生物質(zhì)棒的直徑及最高溫度；各圖中左圖與右圖分別為炭棒與生物質(zhì)棒的反應(yīng)區(qū)形狀及紅外溫度圖像。

圖3 炭棒與生物質(zhì)棒陰燃特性對比

2.1 炭棒與生物質(zhì)棒陰燃傳播速度對比

由圖3a可知，炭棒與生物質(zhì)棒的陰燃傳播速度分別在6.7～11.2及1.3～3.1 mm/min之間。且直徑2.27 mm炭棒的陰燃傳播速度最高，約為1.1 cm/min；生物質(zhì)棒陰燃傳播速度與文獻[27,29,31]中佛香的陰燃傳播速度（3.2～6.5 mm/min）在同一數(shù)量級。若將各炭棒的陰燃傳播速度分別與絕干、空干生物質(zhì)棒作比并平均，可知炭棒的陰燃傳播速度顯著大于生物質(zhì)棒，整體上約為生物質(zhì)棒的4.2倍，分別約為絕干、空干生物質(zhì)棒的3.9和4.5倍。而絕干生物質(zhì)棒的陰燃傳播速度僅約為空干生物質(zhì)棒的1.1倍。

2.2 炭棒與生物質(zhì)棒陰燃最高溫度對比

由圖3b可知，炭棒與生物質(zhì)棒的陰燃最高溫度分別在660～760和620～720 ℃之間，二者的溫度區(qū)間分別與文獻[27]和文獻[32]中的溫度值相近。在相同時間內(nèi)，炭棒的傳播速度較大帶來了更多的熱量；且本試驗中生物質(zhì)棒陰燃與相關(guān)文獻[27,33]類似，未有明顯的揮發(fā)分燃燒，熱解過程仍表現(xiàn)為吸熱，導(dǎo)致炭棒的陰燃最高溫度整體上比生物質(zhì)棒高約50 ℃，分別比絕干、空干生物質(zhì)棒高約43和55 ℃。含水率不同對生物質(zhì)棒的陰燃最高溫度無顯著影響[12,35]，絕干生物質(zhì)棒的最高溫度僅比空干生物質(zhì)棒高約7～20 ℃。

2.3 炭棒與生物質(zhì)棒反應(yīng)區(qū)長度對比

2.4 炭棒與生物質(zhì)棒燃料消耗速率對比

3 陰燃煙氣及耗氧速率分析

氧氣傳輸控制著棒狀燃料的陰燃過程[31-32]，影響其穩(wěn)態(tài)陰燃特性。下述將對棒狀燃料陰燃過程中的耗氧速率進行計算。

3.1 氧傳輸模型

炭棒及生物質(zhì)棒陰燃過程的氧傳輸模型及單元劃分如圖4所示。在圖4a中，氧傳輸模型可分為固體區(qū)和氣體區(qū)。固體區(qū)從上到下又可分為灰分區(qū)、碳氧化區(qū)、炭錐區(qū)、熱解區(qū)（炭棒無此區(qū)）、干燥區(qū)和原物料區(qū)。氣體區(qū)從中軸線到外側(cè)分為煙氣區(qū)和空氣區(qū)。煙氣區(qū)由碳氧化產(chǎn)生的煙氣和干燥及熱解產(chǎn)生的煙氣（炭棒無熱解煙氣）構(gòu)成。陰燃過程中氧氣需穿過煙氣區(qū)和灰分區(qū)才能到達碳氧化區(qū)進行氧化反應(yīng)。具體的單元劃分如圖4b所示。

注：圖4b中，r為單元的半徑；z為單元距炭錐底面的高度；下標1、i、n分別表示第1、i、n個單元，zp為炭錐單層高度。

3.2 數(shù)學(xué)描述

計算棒狀燃料碳氧化區(qū)耗氧速率的主要思路：首先需確定煙氣層半徑，然后確定煙氣層及灰分區(qū)中的氧氣傳質(zhì)阻力，進而確定其表達式。

3.2.1 棒狀燃料煙氣層半徑計算

式中sc為標準狀況下，1 mol氣體所占體積，0.022 4 m3；為煙氣溫度313 K時，對sc的修正系數(shù)313K/273K≈1.15；c為固定碳的密度，kg/m3；a、s分別為灰分區(qū)及碳氧化區(qū)的半徑，m；sm為棒狀燃料的陰燃傳播速度，m/s；c為碳的摩爾質(zhì)量，kg/mol。

式中f,c為碳氧化產(chǎn)生的煙氣半徑（m）；f為煙氣流速，m/s，本文取0.01 m/s。

由于c=c,1，可得因碳氧化產(chǎn)生的煙氣半徑：

碳氧化產(chǎn)生的煙氣周圍還環(huán)繞著干燥及熱解產(chǎn)生的煙氣，其滿足下述表達式：

式中rod為棒狀燃料的半徑，m；w、v分別為水分及揮發(fā)分的密度，kg/m3；w、v分別為水及熱解煙氣的摩爾質(zhì)量，kg/mol，本文取v=31.22×10-3[36]；tf為煙氣層半徑，m。

由式（4）可得棒狀燃料陰燃產(chǎn)生的煙氣層半徑：

需要注意的是，絕干生物質(zhì)棒及炭棒的煙氣層半徑表達式中分別不含w/w及v/v項。

3.2.2 煙氣層及灰分區(qū)氧氣傳質(zhì)阻力計算

氧氣在煙氣層中的擴散量由菲克定律確定：

式中f為氧氣在煙氣層中的擴散系數(shù)，m2/s，本文取4.53×10-5m2/s[37]；f為氧氣在煙氣層進行擴散的單元面積，m2；為氧氣濃度，kg/m3；為半徑，m。

對上式移項，并在積分區(qū)間（從c→a，從tf→a）內(nèi)積分，可得：

式中c、a分別為外界環(huán)境及灰分區(qū)表面的氧氣濃度，kg/m3。由式（7）可確定煙氣層內(nèi)單位面積的氧氣傳質(zhì)阻力為f

同樣地，可利用菲克定律確定灰分區(qū)單位面積的氧氣傳質(zhì)阻力為a

式中a為氧氣在灰分區(qū)的擴散系數(shù)，m2/s，本文取其計算式為a= 0.677g1.18[a/ 273]1.75[38]；為灰分區(qū)孔隙，%；s為棒狀燃料碳氧化區(qū)的氧濃度，kg/m3。

3.2.3 耗氧速率表達式

式中0為棒狀燃料碳氧化區(qū)的面積，m2。

3.3 計算流程圖

耗氧速率的計算流程如圖5所示。需根據(jù)試驗獲得的炭錐，采用圖像數(shù)據(jù)處理軟件，沿軸方向進行單元劃分，取各單元的半徑值。多次試算發(fā)現(xiàn)，炭棒與生物質(zhì)棒劃分的單元數(shù)分別為55和35個，是滿足讀圖誤差和離散誤差兩者均較小的較優(yōu)組合。自=0向上，計算每個單元的反應(yīng)面積、煙氣層半徑、氧氣傳質(zhì)阻力，最終計算出耗氧速率。計算采用自編程的Matlab程序進行。

圖5 計算流程圖

3.4 煙氣層計算結(jié)果及驗證

由式（8）及式（10）可知，棒狀燃料的煙氣層半徑對耗氧速率存在影響。因此以制作直徑5 mm的炭棒與生物質(zhì)棒為例，驗證煙氣層半徑計算值的合理性。炭棒與生物質(zhì)棒的煙氣層輪廓如圖6所示。從試驗直拍圖片中可以看出，灰色背景下直接觀察并不能清晰捕捉到煙氣層輪廓。而從數(shù)值計算結(jié)果及紋影試驗圖片中可以看出，計算出的煙氣層輪廓（紅色及白色虛線所示）及紋影試驗煙氣層輪廓在陰燃前鋒處都有弧形且增長較快，炭錐處增長緩慢，炭錐以上幾乎沒有增長；整個煙氣層外輪廓的計算與試驗尺寸相差并不大，兩者的煙氣層輪廓吻合較好。

注：各圖中從左至右依次為數(shù)值計算結(jié)果、試驗直拍圖片和紋影試驗圖片。

3.5 炭棒與生物質(zhì)棒耗氧速率計算結(jié)果

炭棒與生物質(zhì)棒陰燃過程的耗氧速率如圖7所示?？梢钥闯觯堪襞c生物質(zhì)棒的耗氧速率分別在70～470和19～100 mg/min之間。若將各炭棒的耗氧速率分別與絕干、空干生物質(zhì)棒作比并平均，可知炭棒的耗氧速率顯著大于生物質(zhì)棒，約為2種生物質(zhì)棒的3.4倍，分別約為絕干、空干生物質(zhì)棒的3.1和3.6倍；絕干生物質(zhì)棒的耗氧速率約為空干生物質(zhì)棒的1.2倍。需要注意的是，炭錐輪廓取點常存在誤差，可能使耗氧速率結(jié)果存在0～15%的誤差。

炭棒與絕干、空干生物質(zhì)棒耗氧速率的比值、傳播速度的比值、反應(yīng)區(qū)長度的比值三者大致相近?？梢灶A(yù)見，相同來源的炭棒與生物質(zhì)棒穩(wěn)定陰燃時，當外界空氣條件一定的情況下，反應(yīng)區(qū)尺寸增大，其陰燃傳播速度增加。在應(yīng)用設(shè)計中，需根據(jù)所選物料及陰燃強度，合理設(shè)計反應(yīng)區(qū)尺寸。

圖7 炭棒與生物質(zhì)棒耗氧速率對比

4 結(jié) 論

1）所制炭棒與絕干、空干生物質(zhì)棒在豎直狀態(tài)下，均能自行調(diào)節(jié)反應(yīng)區(qū)形狀以維持穩(wěn)態(tài)陰燃；陰燃最高溫度范圍均在620～770 ℃之間。

2）炭棒的陰燃傳播速度約為生物質(zhì)棒的4.2倍，最高溫度比生物質(zhì)棒高約50 ℃，反應(yīng)區(qū)長度約為相應(yīng)生物質(zhì)棒的3.8倍，燃料消耗速率約為生物質(zhì)棒的2.4倍。

3）計算和試驗煙氣輪廓吻合較好，炭棒陰燃耗氧速率約為生物質(zhì)棒的3.4倍。相同來源的炭棒與生物質(zhì)棒穩(wěn)定陰燃時，當外界空氣條件一定的情況下，反應(yīng)區(qū)尺寸增大，其陰燃傳播速度增加。在應(yīng)用設(shè)計中，需根據(jù)所選物料及陰燃強度，合理設(shè)計反應(yīng)區(qū)尺寸。

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Comparison on the steady smoldering characteristics of char and biomass rods

ZHAO Wentao1, ZHANG Yi1, YU Guangxin1, FRANK Behrendt1,2, HE Fang1※

(1.,,255049,;2.,,10623,)

To investigate the different characteristics of char and biomass rods in steady smoldering, experiments were carried out on the vertical downward smoldering of char, absolute dried biomass and air-dried biomass rods with different diameters (2-8 mm) made from elm-bark powder and cypress powder. The detailed production methods of three rod fuels are as follows: The elm bark powder, cypress powder and water were mixed uniformly at a mass ratio of about 1:1:4, and extruded into biomass rods with diameters of 3, 5, 8 mm. The rods were dried in the air (>48 h) to obtain air-dried biomass rod. The air-dried biomass rod was placed in electric drying oven and kept at 105 ℃ for 24 h to obtain absolute dried biomass rod. After absolute dried biomass rod was cooled, it was placed in drying basin for storage. The char rod was made by pyrolysis of air-dried biomass rod: The air-dried biomass rod was placed in quartz tube, and the nozzle was sealed with asbestos. It was placed in muffle furnace and heated from room temperature to 500 ℃ at a heating rate of 10 ℃·min-1. After holding for 2 h, the power supply was turned off to obtain a char rod. After it was cooled (> 12 h), it is stored in a sealed bag. The char and biomass rods were characterized by proximate analysis following GB/T 28731-2012. In the smoldering experiment, the tops of the respective char and biomass rods (about 15 cm in length) were ignited. After the smoldering got stabilized (about 4 minutes), smoldering propagation velocity was obtained by using the scale and timer to record the moving distance and time of reaction front, respectively. During the steady smoldering process of the rod, the temperature distribution of the reaction zone was taken using infrared thermal imager (ThermoProTM TP8), and the contours of flue gas layer around the rod were recorded by a self-made schlieren device. The rod fuel was then inserted into biomass ash to isolate oxygen and get extinguished, and the shapes of reaction zone were recorded by Leica microscope (M135C). The emissivity of each rod was measured as 0.93 in infrared image analysis. Moreover, the oxygen consumption rate of char and biomass rods was calculated by a self-written code. The results showed that 1) the char and biomass rods can self-adjust the shape of reaction zone to maintain steady smoldering, and the maximum temperature range of each rod fuel is between 620 and 770 ℃. 2) The smoldering propagation velocity of char rods is about 3.9 and 4.5 times that of absolute dried and air-dried biomass rods, respectively. Not endothermic pyrolysis in the smoldering process of char rods is observed, and the larger smoldering propagation velocity produces more heat during the same time, thus the maximum temperature of char rods is about 43 and 55 ℃ higher than that of absolute dried and air-dried biomass rods, respectively. The length of reaction zone of char rods is increased due to the greater propagation velocity and higher maximum temperature provide a larger reaction area to maintain steady smoldering. The length of the reaction zone of char rod is about 3.5 and 4.1 times that of absolute dried and air-dried biomass rods, respectively. The fuel consumption rate of char rods is about 2.4 times that of biomass rods. 3) The calculated and experimental contours of flue gas layer are in good agreement, and the oxygen consumption rate of char rods is about 3.1 and 3.6 times that of absolute dried and air-dried biomass rods, respectively. In the process of steady smoldering of char and biomass rods from the same source, when the external air conditions are certain, the size of reaction zone increases, so that the smoldering propagation velocity increases. In the application design, the size of reaction zone should be reasonably designed according to the selected materials and smoldering intensity. The finding can provide a theoretical reference to study further the steady smoldering mechanism and fuel options in the application.

char; biomass; steady smoldering; propagation velocity; oxygen consumption rate

2022-12-01

2023-04-10

中德合作交流互訪項目（M-0183）；山東省自然科學(xué)基金項目（ZR2022ME038）；科技型中小企業(yè)創(chuàng)新能力提升工程項目（2021TSGC1114）

趙文濤，研究方向為生物質(zhì)能利用。Email：zwtaow@163.com

何芳，博士，教授，研究方向為生物質(zhì)燃燒基礎(chǔ)理論和燃燒設(shè)備開發(fā)研究。Email：hf@sdut.edu.cn

10.11975/j.issn.1002-6819.202212009

S21; TK6

A

1002-6819(2023)-08-0215-07

趙文濤，張毅，于光鑫，等. 炭棒與生物質(zhì)棒穩(wěn)態(tài)陰燃特性對比[J]. 農(nóng)業(yè)工程學(xué)報，2023，39(8)：215-221. doi：10.11975/j.issn.1002-6819.202212009 http://www.tcsae.org

ZHAO Wentao, ZHANG Yi, YU Guangxin, et al. Comparison on the steady smoldering characteristics of char and biomass rods[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(8): 215-221. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.202212009 http://www.tcsae.org