Bamboo is widely distributed in Southeast Asia, Africa, and Latin America. As a major non-wood forest product and wood substitute, bamboo is of increasing interest to ecologists owing to its rapid ...

Carbon sequestration by Chinese bamboo forests and their ecological benefits: assessment of potential, problems, and future challenges

Bamboo is widespread in the subtropics and tropics of Asia, Africa, and Latin America. The total area of bamboo forests of various species is 22.0 × 106 ha, accounting for about 1.0% of the total global area of forest. Although the total forest areas in many countries have decreased drastically, bamboo forests have increased at a rate of 3% annually. China has the richest resources of bamboo in the world, with over 500 species in 39 genera. Carbon storage of vegetation, soils, and litter in bamboo forest system in China was 0.2511 × 1015, 0.8516 × 1015, and 0.0361 × 1015 g C, respectively, giving a total of 1.1388 × 1015 g C. This paper reviews carbon storage of vegetation, soils, and litter in bamboo forest system and compares the carbon fixation abilities of bamboo forest ecosystems with those of other tree species in subtropical China.

Review of Carbon Fixation in Bamboo Forests in China

In the past decades, solar heat for industrial processes (SHIP) have been rapidly developed and applied, and also getting more and more attention all over the world. China is the largest energy consumer with industry accounting for almost 70% of its total energy consumption. Low- and medium-temperature heat takes up 45% of process heat, covering 50–70% of industrial energy consumption, which provides a favorable condition for solar application in industrial processes. China has built developed some demonstration projects to make industrial processes well integrated with solar heating systems. This paper briefly summarizes the status of China's energy consumption, integration of SHIP, as well as available matching solar technologies. Ten typical industrial sectors are selected to specifically describe their potential of SHIP. Moreover, 26 SHIP cases covering the selected 10 sectors are presented by field researches, with capacity of energy saving and emission reduction previously investigated according to their own proportion of SHIP. The potential of SHIP in the 10 sectors are further predicted by optimistically and conservatively making their proportion in SHIP 5.5% and 2% respectively during the period of 2016–2020. The results show that at least 39.40 million tons of coal equivalent and 98.22 million tons of CO2 emission is expected to be reduced in 2020 in China's all industrial sectors although solar can meet different proportions of heat demand in different industrial sectors.

Status and prospect of solar heat for industrial processes in China

Drying of agricultural food products is one of the most attractive and cost-effective applications of solar energy. The solar dryer is less reliable due to the intermittent nature of solar energy. This shortcoming can be overcome to some extent by storing solar energy. Information on sensible and latent heat storage materials and systems is spread widely in the literature. In this paper, we try to gather information about the previous and current research works in the field of thermal energy storage technology for solar air heater and dryer. The relative studies are classified on the basis of the type of storage material used in solar dryers, i.e. phase change material (PCM), rock, water, etc. Several designs of solar dryers with different heat storage materials were proposed by researchers. Recent studies focused on PCMs such as Paraffin and salt hydrate, due to their high heat storage capacity per unit volume.

A review of research and development work on solar dryers with heat storage

Bamboo and climate change mitigation.

Effects of different management models on carbon storage in Phyllostachys pubescens forests

In order to analyze the effect of temperature gradient on moisture movement during highly intensive drying, such as microwave-vacuum drying, the profile of the temperature and moisture content in sealed wood whose opposite faces were subjected to temperature gradient for a short time was measured. The ratio of the moisture content (MC) gradient to the temperature gradient (dM/dT) was calculated and the factors influencing moisture movement under nonisothermal conditions were discussed. The results indicate that moisture moved in wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperatures for a short period. The moisture content on the cold surface was higher than that on the warm surface. The moisture content gradient opposite to the temperature gradient was established, and the dM/dT was below 0.9%/°C. The temperature in the sample and the distance from the hot surface of the sample was strongly linearly correlated. With an increase in temperature, initial moisture content and experimental time, the dM/dT was significantly increased.

Nonisothermal moisture movement in wood

Solar dryer with latent heat storage system was designed in order to solve the problems of continuity of solar drying. The system was used to dry grape. The results of experiment show that the dryer met the requirement of continuous drying. At solar radiation of 600Wm-2-900Wm-2 and ambient temperature range of 35-42iae, the solar collector instantaneous thermal efficiency is 56%, the minimum heating efficiency of collector is 70%, the average heat storage efficiency is 66%. The average consuming time of drying 1kg grape from 87.9% (wb) to 14%(wb) was 6 days.

Experimental Research of Grape Drying Using Solar Dryer with Latent Heat Storage System

Larch lumbers with the dimension of 200mm×100mm×20mm are used as the experimental materials to find a correlation between drying rate and drying defects under the different absolute pressures of 0.02MPa, 0.04MPa, 0.06MPa and 0.08MPa and different temperatures of 60℃ and 80℃. Following conclusions are drawn: under the same absolute pressure, the drying rate of samples dried under 80℃ is 1.77～3.85 times as fast as that of samples under 60℃, and as the absolute pressure decreases,the drying rate increases; when the drying temperature increases, the increment speed of drying rate under the condition which the EMC is above FSP (fiber saturation point) is smaller than the condition which the EMC is under FSP, and the drying rate increases as the absolute pressure decreases; when the drying temperature is 60℃,the absolute pressure exerts relatively small influence on the drying rate and the increment speed of drying rate; the drying defect increases as the absolute pressure decreases or the drying temperature increases.

Influence of Vacuum Medium Condition on Drying Rate and Drying Defect

We developed a model of water evaporation rate from wood surface under vacuum condition using birch as material with cross-sectional area of 20 mm × 20 mm and length of 100,150,200,250 and 300 mm.The internal water moving rates of specimen were studied under the temperature of 60,75 and 90℃ and absolute pressure of 0.02,0.04,0.06,0.07 and 0.08 MPa.The results show that the surface water evaporation rates were much faster than the internal water moving rates,and the ratio of the former to the later varied from 10 to 150.In addition,the relations of the drying rate with temperature and absolute pressure under different conditions were deduced based on the experimental results.Compared with the model of surface water evaporation rate,we can obtain the ratio of the wood surface water evaporation rate to the internal water moving rates from the regression equation.Finally,the optimum formula between temperature and absolute pressure was deduced according to the maximal ratio of the surface water evaporation rate to the internal water moving rate,which could cause drying defects during vacuum drying.

Zhang Bi-guang

Papers

Effects of different management models on carbon storage in Phyllostachys pubescens forests

Nonisothermal moisture movement in wood

Experimental Research of Grape Drying Using Solar Dryer with Latent Heat Storage System

Influence of Vacuum Medium Condition on Drying Rate and Drying Defect

A model of water evaporation rate from wood surface and its application under vacuum condition.