HỘI NGHỊ KHCN TOÀN QUỐC VỀ CƠ KHÍ - ĐỘNG LỰC NĂM 2017 Ngày 14 tháng 10 năm 2017 tại Trường ĐH Bách Khoa – ĐHQG TP HCM A MEASURE OF DRYING THE BAMBOO POWDER IN THE PROCESS OF MANUFACTUR
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Ngày 14 tháng 10 năm 2017 tại Trường ĐH Bách Khoa – ĐHQG TP HCM
A MEASURE OF DRYING THE BAMBOO POWDER
IN THE PROCESS OF MANUFACTURE OF BAMBOO PLYWOOD IN VIETNAM
Le Khanh Dien 1 , Tran Van Hung 1 , Vo Tuyen 2 , Nguyen Tan Hung 2
Nguyen Thanh Nam 2 , Nguyen Huy Bich 3
1
University of Technology, VNU-HCM, Vietnam
2
National Key Lab of Digital Control and System Engineering, HCMUT, VNU-HCM, Vietnam
3
Ho Chi Minh City Nong Lam University, Vietnam
ABTRACT:
In the process of production of the bamboo tree
products; the bamboo powder is the principal
material in a multiple bamboo products:
chopstick, bamboo art plywood, absorbent of
sweat mat… However, this kind of powder has a
huge absorbing characteristic of water even mist
in the wet climate therefore the process of
eliminating of water in bamboo powder is always
requisite in order to keep in good condition The
aim of the paper is to represent a design of a typical drying machine of bamboo tree powder that could be suitable to the domestic technology, salvage an unlimited natural energy
in Vietnam in order to save the energy and eliminating the pollution for the country The research could propose a measure of saving energy for all kind of drying processes in the future for domestic industry
Keywords: drying bamboo powder, natural energy, renewable energy, eliminating the pollution
1 Introduction
Bamboo is very popular in a large area in South
East of Asia, especially in Vietnam This
evergreen tree is considered as natural fence
that is unable to cross
Bamboo is also a very raw material for wattle,
canvas, basket, seat, chopsticks, village house
frame and even boats…
This paper represents a measure of drying
bamboo powder with recommended productivity
of the designed machine is 100 kg/h
2 Process of grinding trifling bamboo to powder
The following figures represent briefly the process of the process of grinding trifling bamboo that were performed in CAD-CAM workshop of the 2National Key Lab of Digital Control and System Engineering (DCSELab), University of Technology, VNU-HCMC, Vietnam
a Bamboo tree b After harvesting
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c Trivial residue bamboo grinding machine
d Bamboo powder
Figure 1 Process of production of bamboo powder
3 Design a typical drying bamboo powder machine
1- Motor, 2- Reduction gearbox, 3- Chain engagement, 4- Bearing, 5- Rotating bamboo powder tank, 6- Exhalation chamber silo, 7- Central heating, 8- Fan, 9- Motor and gearbox
Figure 2 A system of drying general powder
The price of bamboo powder will increase
by the consumption of energy in drying process
and a system of drying will engender a lot of
pollution when gas, liquid fuel or rigid carburant
are in central heating except electrical energy
However, the price of electrical power is so high
in comparison with the very low value of bamboo
powder In this study we recommend to use
direct thermal solar receivers that can satisfy all
the given conditions
3.1 Analyze and selection a suitable
system of direct solar
There are many types of direct thermal solar receivers; each of them has its own Prod and Cond:
- Circular disk has no concentric point, the heat cannot concentrated and the manufacture of circular disk is not practical (Figure 3a)
- Parabolic circular disk has a focus but it is difficult to manufacture The focus is a point so it
is difficult to dry continuously a big amount of bamboo powder
- Parabolic troughs is selected because it has a focus line, practical and relatively easy to manufacture
a) Photo of a typical dish/Sterling system b) a 400-m2 dish system in Australia [1]
Figure 3 Parabolic circular disk has a focus
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Parabolic trough is selected because its
flexibility in manufacture, according to [8]
the percentage of application of parabolic
troughs solar system is in the majority in application (Figure 4)
Figure 4 Reason of application of parabolic trough solar system 3.2 Parameters of a parabolic troughs solar system
Figure 5 a) Mathematical parabola b) Schema of the designed drying system: 1 axis of the system, 2:
bamboo powder, 3: conveyor worm, 4: circular open trough absorber, 5: fixed frame 6: parabolic
reflector
4 Computing of heating in a drying powder
bamboo
4.1 The necessary heat The quality of bamboo
powder is not depended on the uniform and
homogenous of the bamboo grain but it is
depended on its dryness According to [1] the
maximum moisture of wood in general is in the
range of 25% to 35% and the fungi cannot grow
in wood when the moisture content is less than
20% Hence the designed system has the duty to
decrease the moisture or increase the dryness of
bamboo powder from 5% to 15% The selected
average value of 10% of moisture is accepted
So the dryness
D= (mo - m1) 100
mo 10%,
Wherein m0: the output mass of bamboo powder
after drying,
m1: the input mass of bamboo powder
before drying,
With the given productivity of 100 kg/h, the output mass of bamboo powder after drying is 90kg and the mass of mixed water inside powder that is removed out of bamboo powder is 10 kg/h According to [7]:
Specific heat capacity of water liquid (250C) c= 4.1813 J/g.K = 4.1813 KJ/kg.K
Specific heat capacity water vapor (1000C)
=2.080 J/g.K = 2.080 KJ/kg.K According to [9] the temperature at collector can
be greater than 3000C Eliminating all the loss of reflection, diffusion, transferring the temperature
of the powder inside the worm tube cans greater
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than 1100 The necessary heat for alteration of
10 kg of water inside bamboo powder to steam
and evaporate out of powder The selected
ambient temperature is 250C and the selected
highest temperature when powder is out of the
conveyor is 1100C
Heat for alteration of 10 kg water from 250 to
1000 :
Q1 = m.C.t =10x 4.1813x (100-25)= 3135.975
kJ
Heat for alteration of 25 kg water at 1000 to
steam at 1000:
Q2 = m.C=10x2.080=20.8 kJ
Heat for alteration of 10 kg water from 1000 to
1100:
Q1 = m.C.t =10x 2.080 x (110-100)=208 kJ
Total necessary heat: Q= Q1 + Q2 +
Q3=3364.775 kJ for 100 kg of initial bamboo
powder per hour The total heat had to be
received per second or the needed heat power
Q=3364.775/3600= 0.93 kW For security we
selected the total heat power that the parabolic
trough have to provide to the bamboo powder is
Q=1 kW
According to [9] and [10] the direct energy on
surface of the earth at a rate of about q=220
W/m2 With the loss of parasitic energy and the coefficient lost heat is about 20%, the real solar heat is q=220x80%=176 W/m2 and the total area
of the designed parabolic collector solar energy
is A= Q/q=1000/176= 5.68 m2
4.2 Design the parameters of parabolic trough reflector
A parabolic trough solar system in Figure 6 is selected to gain the area of 5.68 m2:
- The parameter reflector 6 is made by a stainless steel sheet SUS304 with a dimension
of 0.5x3000x2000 Thus the width of the sheet 0.5 mm and the area of the stainless steel reflector is 2000x3000=6 m2, bigger than the demanded area of 5.68 m2
The axial length is 2 m and the parabolic circumference arc is 3 m that allows the length of circular absorber trough which hold the conveyor worm is stable with 2 roller bearings at 2 ends The sheet is bended and assembled its back to a composite frame of 20 mm width that is considered as thermal isolator
-The focus distance OF is f = 0.5 mm, the equation of the parabola in Cartesian coordinate system is very simple:
Figure 6 Mathematical parabola diagram, focus distance f =OF=0.5 m 4.3 Design the parameters of worm conveyor - The conveyor worm A with the diameter of
250 which is adjusted to be coaxial with the
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Ngày 14 tháng 10 năm 2017 tại Trường ĐH Bách Khoa – ĐHQG TP HCM
focus line (point F in Figure 6) of the parabolic
reflector is assembled to the center line of the
open top circular absorbers trough B via a
couple of end flanges roller bearing C in the
Figure 7 Selected length of trough and worm
conveyor is 2000 mm (a bearing at a middle of the conveyor worm is no need), selected worm pitch is 250 mm hence there are about 8 spiral pitches along the worm
Figure 7 Structure of conveyor bamboo powder absorber:
a: Worm shaft b.Trough (solar receiver that is painted in black color outside) b End flange seft
alignment roller bearing The parabolic reflector and the absorber are fixed each other and can rotate around a hint (F)
4.4 Orienting the axis of solar system to the
Sun
The Sun, the focus F and the vertex O of the
parabolic solar system are always keep in a
slightly straight line by the rotation motion of
shaft F of the system The angular velocity of the
system is equal to the one of the Earth That
means:
=2 radians/24 h= 2/(24x3600) rad/s=
7.272e-5=0.00007272 rad/s
Or the rotating demanded angle of the system
per minute =0.1250 =0.75’
This angle too small so we decided that it can be
adjust time by time by hand in such a way that
the shadow of the absorber F is at the vertex O
of the reflector
With the suitable direction of parabola axis, line
rays from the Sun are considered from infinite
and are parallel to the axis and reflex to the
center of focus line or the absorber trough 4
(Figure 7) The worm A is co-axis of trough B is activated by a motor to transport the bamboo powder in the absorber open top tube 4 All these above components are fixed together and with the parabolic trough 6 All the system can be adjusted by hand to direct the parabola axis to the Sun The support 5 is nailed to the earth and bears the system via the bearing A
5 Conclusion
The design of drying bamboo powder machine
by direct solar energy is a suitable measure of drying powder that is practical and saving energy The design almost achieved and ready
to be manufactured We hope that the designed will save energy and sustainable in the protection
of environment The ability of manufacture is enabling and in the near future the automatic orientation to the Sun installation will be included
to ensure the better performance of the system
ACKNOWLEDGMENT
This research is supported by DCSELAB and
funded by Vietnam National University
HoChiMinh City (VNU-HCM) under grant number GEN 2016.48.02.06
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REFERENCES
[1] Jack Robinson RRC,”Determining acceptable
moisture content in plywood sheathing”,
Professonal roofing, April 1996
[1] “Direct Solar Energy”, Intergovernmental
panel on climate Chanes, Contribution to
Special Report Renewable Energy Sources
(SRREN)
[2] “Solar energy renewable & sustainable
Energy”, Science & Technology, Stellenbosh
University, Republic of South Africa
[3] Dan Arvizu (USA) and Palani Balaya
(Singapore/India) “Direct Solar Energy”,
Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA
[4] S C Bhattacharya, S Kumar “Direct solar
energy”, Renewable energy systems: direct
solar energy- Direct Solar Energy
[5] Catalog No 787E, “Screw Conveyor Catalog
& Engineering Manual”
[6] I S Sintali, G Egbo and H Dandakouta
“Energy Equations for Computation of Parabolic-Trough Collector Efficiency Using Solar Position Coordinates”, American Journal of Engineering Research (AJER) e-ISSN: 2320-0847 p-ISSN : 2320-0936 Volume-3, Issue-10, pp-25-33 www.ajer.org
[7] Thermal capacity, Creative Commons Attribution-Share Alike 3.0 Unported
http://creativecommons.org/licenses/by-sa/3.0/
[8] Matthias Gunther, Michael Joemann, Simon
Sambor “Parabolic trough technology”,
Avanced CSP Technology, Enermena [9] G.N Tiwari, Arvind Tiwari, Shyam “Handbook
of energy solar theory, hand book and application”, Spinger Edition [10] “Solar energy”, National Energy Strategy,
Executive Summary, 1991/1992
MỘT BIỆN PHÁP SẤY KHÔ BỘT TRE TRONG QUI TRÌNH
CHẾ TẠO VÁN ÉP BẰNG TRE TẠI VIỆT NAM
Tóm tắt
Trong quy trình sản xuất các sản phẩm từ
nguyên liệu tre thì bột tre là nguyên liệu chủ yếu
cho nhiều loại sản phẩm tre đa dạng như: đũa
tre, ván ép mỹ thuật làm bằng tre, chiếu tre hút
mồ hôi,… Tuy nhiên, loại bột này lại có tính hút
nước rất cao, ngay cả khi nó cũng hút sương mù
trong thời tiết ẩm ướt Vì vậy quy trình loại trừ
nước trong bột tre luôn luôn là vấn đề tiên quyết
để duy trì tình trạng khả dụng của loại vật liệu
này Mục tiêu của bài nghiên cứu này là trình bày
công việc thiết kế một chủng loại bột tre phù hợp với công nghệ trong nước, sử dụng nguồn năng lượng thiên nhiên vô tận tại Việt Nam nhằm tiết kiệm năng lượng và tránh ô nhiễm cho môi trường Chúng tôi hy vọng rằng biện pháp tiết kiệm năng lượng và tránh được ô nhiễm trong bài nghiên cứu này có thể giúp tiết kiệm năng lượng cho các loại máy sấy khác trong nước
Từ khóa: sấy bột tre, năng lượng tự nhiên, năng lượng tái tạo, loại bỏ ô nhiễm