不同干燥方法对人工林樟子松木材干燥特性的影响

doi:10.11707/j.1001-7488.20201116

Abstract

Abstract:

Objective: This current study was carried out to investigate the effects of different drying method on drying characteristics with the aim to provide theoretical bases for the high temperature energy-saving and green drying of plantation-grown Pinus sylvestris var. mongolica. Method: Four drying methods including conventional drying, high temperature drying, solar-conventional joint drying and solar-high temperature joint drying were used to study the drying characteristics of P. sylvestris var. mongolica focusing on drying time, drying rate, drying quality, drying energy consumption, etc. Result: The results showed that the drying characteristics of wood varied greatly with different drying methods. 100 ℃ showed that the comprehensive drying characteristics of P. sylvestris var. mongolica were grade 1. Moisture content of solar energy pre-drying wood was reduced from 80% to 30%, drying time was about 78 h, daytime drying speed was about 1.07%·h^-1, night drying speed was about 0.36%·h^-1. In the early and middle stages of drying, the drying speed of high temperature drying was higher than that of conventional drying by 136.15% and 113.30%, respectively, and only about 20.87% higher in the latter stage drying. The time of solar-conventional and solar-high temperature joint drying were 92 h and 86 h, respectively, which was about 3-5 times of conventional and high temperature drying. The wood drying quality after conventional drying was grade 1, and after high temperature drying was grade 2. The wood drying quality after solar energy joint drying was grade 3. High temperature drying made the wood color changed severely, turning dark yellow/dark yellow. Compared with conventional drying, high temperature drying could save 48.53% energy. Compared with conventional drying and high temperature drying, solar-conventional joint drying could save 40.09% and 17.08% energy, solar-high temperature joint drying could save 68.76% and 57.76% energy. Conclusion: The high temperature drying of P. sylvestris var. mongolica presented a good drying effect. Solar predrying could save a lot of energy consumption, whereas the joint of solar energy and high temperature drying could show efficient and green drying.

Key words: plantation-grown Pinus sylvestris var. mongolica, high temperature drying, solar drying, joint drying, drying characteristics, energy consumption evaluation

CLC Number:

S781.71

Yulin Shen,Zhe Wang,Lijuan Ping,Meiling Li,Xiaoyan Liu,Ximing Wang. Effect of Different Drying Methods on the Drying Characteristics of Plantation-Grown Pinus sylvestris var. mongolica[J]. Scientia Silvae Sinicae, 2020, 56(11): 151-158.

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References 0

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木材含水率 Wood moisture content(%)	干球温度 Dry bulb temperature/℃	干湿球温度差 Wet-bulb temperature depression/℃	EMC(%)
＞40	70	7	10.5
40~30	75	11	8.0
30~25	80	14	6.5
25~20	85	17	5.5
20~15	90	22	4.5
＜15	95	30	3.3

木材含水率 Wood moisture content(%)	干球温度 Dry bulb temperature/℃	干湿球温度差 Wet-bulb temperature depression /℃	EMC(%)
预热阶段Preheating stage	100	0	22
＞35	115	25	3.5
35~20	118	33	3.1
＜20	120	38	2.3

天气条件 Weather conditions	室外温度 Ambient temperature/℃	空载最高温度 No-load maximum temperature/℃	空载平均温度 No-load mean temperature/℃	负载最高温度 Maximum load temperature/℃	负载平均温度 Load mean temperature/℃	日累计辐射量 Daily cumulative radiation/(MJ·m^-2)
晴天Clear	22.40~37.80	66.60	56.70	64.00	53.61	38.54
晴间多云Partly cloudy	19.00~34.70	64.10	50.42	60.60	50.10	32.14

干燥方法 Drying method	全程干燥时间 Drying time/h	不同含水率阶段的平均干燥速度 Mean drying rate at different moisture content stages/(%·h^-1)
干燥方法 Drying method	全程干燥时间 Drying time/h	> 30%	30%~20%	< 20%
常规干燥 Conventional drying(CD)	30	2.473	1.995	1.696
高温干燥 High temperature drying(HD)	18	5.840	4.250	2.050
太阳能-常规联合干燥 Solar-conventional joint drying(Solar-CD)	92(太阳能预干燥时间为80 h The solar pre-drying time is 80 h)	0.640 (预干Pre-drying)	1.640	1.466
太阳能-高温联合干燥 Solar-high temperature joint drying(Solar-HD)	86(太阳能预干燥时间为80 h The solar pre-drying time is 80 h)	0.640 (预干Pre-drying)	3.075	1.990

干燥方法 Drying method	初含水率 Initial moisture content(%)	终了含水率 Final moisture content(%)		厚度含水率偏差 Deviation of moisture content on thickness(%)			残余应力 Residual stress(%)	可见缺陷 Visible defects
干燥方法 Drying method	初含水率 Initial moisture content(%)	平均 Mean	干燥均匀度 Dryness uniformity	表层 Surface layer	芯层 Core layer	偏差 Deviation	残余应力 Residual stress(%)	可见缺陷 Visible defects
常规干燥CD	67.22	8.65	0.032	7.325	8.69	1.365	1.62	有极少量端裂出现 Very few end cracks
高温干燥HD	81.84	7.95	1.727	7.08	10.00	2.92	1.88	有端裂和轻微变形 End crack, slight deformation
太阳能-常规联合干燥 Solar-CD	31.36	8.27	2.36	6.65	7.80	1.15	3.13	无明显缺陷产生 No obvious defects
太阳能-高温联合干燥 Solar-HD	26.86	5.92	1.27	6.28	7.30	1.02	5.30	有少量端裂出现 A few end cracks

Effect of Different Drying Methods on the Drying Characteristics of Plantation-Grown Pinus sylvestris var. mongolica

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NBS单位色差 NBS chromatic aberration value	色差感觉程度 Sense of chromatic aberration
0~0.5	(微小色差)感觉极微 (Tiny chromatic aberration)feel extremely slight
0.5~1.5	(小色差)感觉轻微 (Small chromatic aberration)feel slight
1.5~3	(较小色差)感觉明显 (Smaller chromatic aberration) feel clear
3~6	(较大色差)感觉很明显 (Relatively large chromatic aberration) feel clearer
＞6	(大色差)感觉强烈 (Large chromatic aberration) feel strong

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