physical characteristics and energy content of biomass

INTERNATIONAL JOURNAL of RENEWABLE ENERGY RESEARCH P. Hwangdee et al., Vol.11, No.1, March, 2021

Physical Characteristics and Energy Content of Biomass Charcoal Powder

Phisamas Hwangdee*,**,***, Chaiyan Jansiri *,**,‡, Somposh Sudajan*,**, Kittipong Laloon*,**

* Department of Agricultural Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen, Thailand 40002

** Agricultural Machinery and Postharvest Technology Research Center, Department of Agricultural Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen, Thailand 40002

*** Department of Agricultural Machinery, Faculty of Agriculture and Technology, Nakhon Phanom University, Nakhon Phanom, Thailand 48000

([email protected], [email protected], [email protected], [email protected])

‡ Corresponding Author; C Junsiri, Tel: +66 81 661 4515, Fax: +66 4320 2598, [email protected]

Received: 28.12.2020 Accepted:27.01.2021

Abstract- The objective of this study is to investigate potential biomass materials for charcoal briquette production by comparing physical properties and energy content. The charcoal powder was obtained from 3 sources. The first group was charcoal from industrial factories which is charcoal from biomass power plant (CBPP). The second group was charcoal from a by-product of agricultural products, consisting of rice husk coal (RHC), coconut-shell coal (CSC), corn cob coal (CCC), cassava stump coal (CStC) and eucalyptus bark coal (EuBC). The third group was charcoal from recycling vegetal coal, consisting of recycling eucalyptus coal (REuC) and recycling assorted wood coal (RAWC). The results showed the physical properties of charcoal powder with an average bulk density of 189.19–563.73 kg/m3 and average angle of repose of 35.05°– 43.21°. The material flowability was ranged between fair to passable flow and free-flowing with average particle size of 0.31–1.29 mm. The static coefficient of friction on the material surface was 0.46–0.66 on mild steel, 0.39–0.57 on stainless steel, 0.45–0.59 on zinc sheet, 0.43–0.61 on galvanized steel, and 0.52–0.66 on rubber. The energy content of charcoal powder revealed the HHV to range from 3,393.78 – 7,303.86 cal/g, the commercial briquettes charcoal range value from 5,205.34 – 5,382.62 cal/g. The results of the physical properties of the charcoal power provide useful data for engineering design. Whilst, the comparison between the commercial briquette charcoal and the biomass charcoal powder shows the potential of biomass as a raw material to produce charcoal briquettes to replace woody biomass, thereby increasing the value of that material.

Keywords Biomass Charcoal, Physical characteristics, Energy content of biomass charcoal, Charcoal briquettes.

1. Introduction

According to the energy crisis that caused by the draneticly increasing of global energy demand due to expanding of population and industrial section, global warming situation, and environmental pollution, green and renewable energy sources become more favourable approach as for a replacement of fossil fuel [1,2]. Currently, biomass energy source, which accounts for 14% of the world energy consumption, is prioritized at the fourth place after petroleum, gas, and coal [3]. The biomass is a sustainable energy source that can be found anywhere in the world [4] and restored to their original form and multiply in quantity. There are several methods converting biomass into energy[5,6] such as direct

combustion, gasification or pyrolysis, anaerobic digestion, hydrolysis, hydrogenation or fermentation and briquettes which the later is preferable for household use for direct combustion.

In Thailand, the high energy consumption in the year 2019 was 85,7088 ktoe, an increased 2.1% from the previous year. The total value of final energy consumption was 1,245 Billion Bath. Refined oil is the highest consumption energy source at 49.1% of the total consumption [7]. Although LPG (liquid petroleum gas) is generally used in household as for cooking fuel [8], it also requires substantial subsidies of importation because the LPG production in Thailand is insufficient for the


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domestic demand. Besides, natural gas is not a renewable resource[9,10].Charcoal and firewood are major fuel sources for household cooking in developing countries [11-13]. However, they have a great impact on forest resources and environment, including health issues caused by smoke pollution [14] which the later reason discourage the usage of firewood. Regardless of the impact, the demand for wood charcoal and charcoal briquettes in the household is still high both nationally and internationally because of the charcoal-grilled food culture and popularity of barbecue business that rise a high demanding of charcoal fuel. Moreover, charcoal usage reduces the smoke pollution issues due to its less smoke during cooking [15]. The firewood provides calorific value or heating value of 4,539-4,778 kcal/kg with 70% volatile content, 28% fixed carbon content, and 2% ash content [16]. After undergone the heating process in the absence-air condition to remove the volatile compounds but left fixed carbon content, the firewood turns into charcoal with a higher calorific value of about 7,167 kcal/kg but lower volatile content of 15–20%. At present, biomass briquettes are majorly used for household fuel in the developed countries [17] because of wood charcoal depletion [18]. As for raw material resource for firewood and charcoal, forest area declined to 25.6% which implies an increasing rate of deforestation. For this reason, the utilization of biomass is an urgent need. Thailand generally produced a wide variety of agricultural products and is one of the world's top exporters of agricultural and food products [19]. Thus, variety of biomass sources are available for biomass fuel production, especially by-products or wastes from harvesting and processing of agricultural products such as coconut shell, palm shell, corn cob, rice husk, rice straw, cassava stems and rhizomes, bagasse and sugarcane leaves, rubberwood chips, etc. Moreover, the energy generated by these biomass materials each year is equivalent to 54 million tons of lignite coal. The biomass fuel is a sustainable supply for energy consumption and is advantage approach to replace fossil fuel in the future [20]. In any case, a crucial part is what process and how to enhance the heating value/weight unit of these biomass materials [21]. Higher heating value (HHV) is a factor affecting an increase in biomass energy utilization in the energy industry. The biomass utilization is not only meeting the energy demand but also help people to protect forest resources and maintaining the ecological balance including environment friendly because the biomass contains a low N and S composition. The biomass material has the potential to reduce the greenhouse effect by releasing an estimate of zero CO2 emission [22] and lower acidic gas emission compared to fossil fuel [23].

Charcoal briquette type is an optimal format for the management because the briquette type helps the producer to reduce transportation cost, storage space, and charcoal dust issue [24], but to enhance the heating value and combustion period. Considering biomass material as for fuel purpose, physical properties, and energy content of the substrates must be verified and determined to prioritized their quality and value [25,26]. However, the raw material or biomass are generally obtained from various sources of production, biomass species, harvesting periods and methods, product processing, and storage process that affecting the changing of internal properties.[27] Therefore, the study of these factors is needed and should thoroughly be examined.

Figure 1. The charcoal from and biomass power plant (industrial factories)

Figure 2a. The charcoal from a by-product of agricultural products

Figure 2b. The charcoal from a by-product of agricultural products

Figure 3. The charcoal from recycling vegetal coal


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The research aims to study physical properties and energy content of biomass charcoal powder to provide basic information of characteristics and types of biomass powder for the charcoal briquette production. In this study, types of charcoal were selected from manufacturing scrap for material reuse and adding value. The testing charcoal types consisted of 3 groups, group 1 was charcoal from a biomass power plant (CBPP) (Figure 1), group 2 was charcoal from a by-product of agricultural products (Figure 2a) which were coconut-shell coal (CSC), corn cob coal (CCC) (i.e., corn stalks or maize cobs), cassava stump coal (CStC) (i.e., Cassava rhizome charcoal), eucalyptus bark coal (EuBC), and rice husk coal (RHC) (Figure. 2b), whilst group 3 was manufacturing scarp/waste (Figure. 3) which were recycling eucalyptus coal (REuC) and recycling assorted wood coal (RAWC). The charcoal material from group 1 and 3 must be grided to reduce particle size before compressed by briquettes machine.

2. Materials and methods

2.1 Preparation of biomass charcoal powder sample

As for charcoal powder preparation, biomass materials were collected from plantations and production sites in the northeast region of Thailand. Corn Cob was collected from Khon Kaen Province, whilst, Cassava Stump was collected from Sakon Nakhon Province. Coconut-shell, Rice Husk, and Charcoal from a Biomass Power Plant (CBPP) were collected from Nakhon Phanom Province. Eucalyptus Bark was obtained from wood chip factory in Nakhon Phanom Province. The Recycling Eucalyptus Coal (REuC) and Recycling Assorted Wood Coal (RAWC) were collected from Kalasin Province. The biomass raw materials(corn cob, cassava stump, coconut-shell, eucalyptus bark) were stored to reduce the moisture content to less than 20% before carbonized in a 200-litre tank. (Figure 2a) Rice husk in production of coal by igniting heaps around traditional chimneys. (Figure 2b) The obtained all charcoals were not suitable for the process. They had to be ground converting them into fine particles. The materials were grinder by a hammer mill with sieve size 6 mm, at 1,000 rpm of drum speed, using an electric motor of 3 horsepower, before storing in a sealed plastic container.

2.2 The study of physical properties of charcoal powder

The physical properties of the material are important keys for a designing of management systems such as transportation, handling, and storage etc.[28,29]. This study investigated several physical properties which were moisture content, average particle size, bulk density, angle of repose, and static coefficient of friction.

2.2.1 The study of moisture content

It is a parameter for engineering applications, design for drying method, handling, storage, and feeding facilities and conversion process. [25]. In this study, the moisture content was measured by Halogen Moisture Analyzer (Model MB45, OHAUS, Corporation., Parsippany, NJ 07054 USA) at

temperature condition of 105 °C using the powder weight of 1 gram per sample, then recorded the constant moisture content value every 1 minute [28].

2.2.2 The study of particle size

The particle size and size range of the charcoal powder influence options for conveying system as well as combustion behaviour of biomass briquette. Homogeneity of the particle size has an impact on the size and shape of the briquette that could be a marketable product [30,31]. Whilst, the particle size affects the quality and performance of flowability, density, and strength of the charcoal briquettes [32,33]. The smaller the particle size, the higher the density and strength. Accordingly, the bulk density of each charcoal type impact directly on performance, strength value, and density of the charcoal briquettes product [34,35]. Sieve analysis is a method to evaluate solid particle size or fineness by sieve known-weight solid matter through a set of test sieves based on the testing standards of ASAE S319.1 [36-40]. The vibratory sieve shaker (Retsch; AS 200 control, Germany) which consisted of different sieve sizes were used and arranged following the Canadian series sieve numbers as 4, 8, 16, 30, 50, 100, and 200 with the mesh size of 4.75, 2.36, 1.18, 0.60, 0.30, 0.15, and 0.075 mm, respectively (Table 1). Sieve trays were weighed and recorded all data, then put 100 ±5 g of each charcoal powder type on the topmost tray before shaking by the vibratory sieve shaker for 10 minutes, before weighing the trays and calculate the remaining percentage of the charcoal powder on the trays. The particle size and size range were evaluated by geometric mean diameter (dgw) using equation (1) and by geometric standard deviation (Sgw) using equation (2) from data collection of 5 testing replications. The charcoal powder sample must contain less than 10 % (w.b.) of moisture content, [26] if not, the samples must be dried up at 50 °C prior the testing to prevent sieve obstruction.

d"# = log() *+ ,#- ./"01-2

3-45∑ #-3-45

7 (1)

s"#= log() 9: ,./" ;<=(./" ;>?2

@

?=∑A=

B

)CD

(2)

where,

d"# = geometric mean diameter (mm.)

s"# = geometric standard deviation

wF = weight fraction on i’th sieve

dF = diameter of sive openings of the i’th sive

dFG) = diameter of the opening in next larger than i’th

sive (just above in a set)

d<F = geometric mean diameter of particles on i’th sieve

= (dF × dFG))5@


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Table 1. Sieve number, mesh number and mesh size.

Sieve number Mesh number Mesh size (mm)

1 4 4.75

2 8 2.36

3 16 1.18

4 30 0.60

5 50 0.30

6 100 0.15

7 200 0.075

pan - -

Figure 4. Seedburo filling hopper and stand for bulk density Measurement.

2.2.3 Density of the charcoal powder

Density is one of the crucial attributes for evaluating combustion properties, management characteristics, and flammability of the biomass briquettes [35]. The density of the biomass briquettes depends on the initial density of the biomass, binder, and compression and pressing processes during the production. The density also related to several properties such as compressive strength and impact resistance index (IRI), a higher density, higher compressive strength and IRI. As for a combustion property of biomass fuel, the high density and compaction of the briquette extend the combustion period. The density also plays an essential feature in the designing of the logistic and handling system. The moisture content, size and shape, and particle size are factors affecting the density [23,30,41]. As for the measurement of the density, the charcoal powder was weighed as per 1,000 cm3-volume using test kit of the Seedburo filling hopper and stand (Seedburo Equipment Co., Chicago, IL.60607) by setting the distance between the hopper bottom and the measuring cup at 17.2 cm (Figure 4). Then, The charcoal powder was placed inside the hopper before open the funnel orifice valve and let the charcoal powder flow rapidly into the measuring cup until it exceeds the rim of the cup, then remove the excess powder in a zigzag stroke by a smooth wood, length over the cup’s diameter [42,43]. The testing procedure was repleted for 20 replications, then calculated the bulk density of the charcoal powder using the equation (3).

𝜌 = MN

; kg m-3 (3)

where 𝜌 is the bulk density, 𝑚is the mass of charcoal powder and 𝑣is the volume of measuring cup.

2.2.4 Angle of repose

The angle of repose is an angle of material piling on flat ground, which is the steepest angle of material pile holding up and does not fall due to gravity. The angle of repose is an indicator for flowability of a material [26]. The angle depends on the internal friction among particles and the flowability of that material, which are influenced by the moisture, density, particle size and shape of that material, as well as environmental factors such as gas aggregation and adsorption, relative humidity. The angle of repose is useful information for the transportation management and designing of hopper and feeder devices [41] and indicating the cohesive force of the particles and flowability of each material. The material flowability was characterized by Carr for 5 levels from <30° as a very free-flowing, 30-38° as a free-flowing, 38-45° as a fair to passable flow, 45-55° as cohesive, to > 55° as very cohesive (non-flowing).

Figure 5. Seedburo filling hopper and stand for angle of respose(fixed-base) measurement.

The angle of repose was measured using the test kit of the Seedburo filling hopper and stand (Seedburo Equipment Co., Chicago, IL.60607) with known-diameter circle base. The testing began with pouring the charcoal powder into the hopper, then, let the charcoal free-flowing before measure the pile height from base to tip (Figure 5). The angle of repose


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was calculated from the testing data of 20 replications using the equation (4).

𝛽 = tan(),𝑦 𝑥D 2 (4)

where 𝛽 is the angle of repose, 𝑦 is the height of slope and 𝑥 is the radius of a base (d/2)

2.2.5 Static coefficient of friction

Before testing for the static coefficient of friction, the moisture content must be re-tested because the moisture conditions before the testing must be less than 10%(w.b.) as same as the study of the particle size. The static coefficient of friction was evaluated by the method of tilting plane as shown in Figure 6. The charcoal powder was stored in a cylindrical container (50 mm-diameter and 50 mm-height) at the top end of the testing plane. In this study, the coefficient of friction was tested on 5 surface materials, stainless steel, mild steel, zinc sheet, rubber, and galvanized steel. The cylindrical container was placed 2 mm above the material surface plane before slowly adjusting a rotating rope to lift the plane until the charcoal powder begins to slide, then stop and record the friction angle[44][45][46]. The static coefficient of friction was calculated from the testing data of 20 replications using the equation (5).

𝜇 = tan∅ (5)

where 𝜇 is the static coefficient of friction and ∅ is the angle of a plane when charcoal powder began to slide.

Figure 6. Tilting plane and different surface materials for Static coefficient of friction measurement 2.3 Energy content of charcoal

Heating value or calorific value is an indicator of the energy content of biomass material. It is the quantity of energy stored in a unit of biomass, usually measured by using the heat of combustion which energy will be released as heat when it is completely burned with oxygen under standard conditions [30,46,47]. Heating value demonstrated as higher heating value(HHV) according to the condition of the sample as-determined basis ASTM D 3180-89. It can be calculated from the analysis of the sample and has the same moisture remaining at the time of testing.

From 8 types of charcoal powder with higher heating value potential. (Figure 1,2, and 3) The charcoal from a biomass power plant (CBPP) was reduced moisture content by sun-dried, so that all 8 types of charcoal powder had a moisture content of <10%(w.b.). HHV was determined according to ASTM D5865 standard by using the PARR Bomb Calorie Meter, Model 1341 of the Agricultural

Machinery Department, Faculty of Agriculture and Technology, Nakhon Phanom University. Samples from commercial charcoal briquettes in Thailand were tested and compared. 3. Data Analysis

Data of physical properties was calculated the mean value, standard deviation and analysis of variance as well as compared the differences among the samples by using Least Significant Difference (LSD) at a significant level of 0.05. Data of heating properties were analyzed for variance between the type of charcoal powder and compared the mean by using Ducan's Multiple Range Test (DMRT) method. Charcoal with the same level of heating value was grouped. The heating value of the commercial charcoal in Thailand as compared to obtain information about the mixing ratio for producing charcoal briquettes.

4. Results and Discussion

4.1 The results of physical properties of charcoal powder

4.1.1 Moisture Content

From the study of the moisture content of 8 types of charcoal powder found that Corn cob coal (CCC), Cassava stump coal (CStC), Coconut-shell coal (CSC), Eucalyptus Bark coal (EuBC), Rice husk coal (RHC), Charcoal from a biomass power plant (CBPP), Recycling Eucalyptus coal (REuC) and Recycling assorted wood coal (RAWC) had average moisture content (w.b.) between 5.78%–15.33% (Table 2.). Charcoal from a biomass power plant (CBPP) contained high moisture content due to the charcoal obtained from the process of temperature reduction by soaking in water, it was stored in a storage shed without drying.

4.1.2 Particle size analysis

The study of mean particle size and standard deviation of the charcoal particle size found that charcoal from a biomass power plant (CBPP) had the coarsest particle size, followed by coconut-shell coal (CSC), the mean particle size of 1.29 and 1.26 mm. Other charcoal powders had a mean particle size of less than 1 mm. The finest mean particle size was rice husk coal (RHC) of 0.14 mm (Table.2 and Figure 7). When charcoal from a biomass power plant (CBPP) and coconut-shell coal (CSC) was ground to reduce the size, it becomes pellets due to the strength of charcoal. While corn cob coal (CCC) became charcoal flakes that similar to the powder after the ground process, due to the coagulation structure of the corncob. Rice husk coal (RHC) was more powdery than other charcoals. The charcoal particle size has a direct effect on the density of charcoal briquettes [43]. Small particle size can increase the density of charcoal briquettes, increase the surface area of bonding material that increase strength and reduce shattering from impact or falling [44]. Abdul-Razzak et al. [45] found that medium particle size of charcoal powder (2.36 mm) enhanced water temperature, fine particle (0.59 mm) raised combustion time and large particle (2.41 mm) increased specific gravity or relative density. Therefore, hammer mill grinder with 6mm sieve size can produce suitable fineness of charcoal powder for making


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charcoal briquette. Using a sieve size of 6 mm instead of 3 mm can increase the working performance of miller.

4.1.3 Bulk density

The study on physical properties of 8 charcoal powder types with average moisture of 5.78–15.33%(w.b.) found that average bulk density ranged from 189.9-563.73 kg/m3. Coconut-shell coal (CSC) had highest bulk density, followed by eucalyptus bark coal (EuBC), recycling assorted wood coal (RAWC), rice husk coal (RHC), charcoal from a

biomass power plant (CBPP), recycling eucalyptus coal (REuC), cassava stump coal (CStC) and corn cob coal (CCC); bulk density of 563.73 (8.73), 385.66 (7.13), 371.59 (8.46), 362.05 (2.88), 351.33 (15.33), 275.34 (6.84), 207.16 (4.99) and 189.19 (9.95) kg/m3 respectively (Table.2).

The analysis of variance (ANOVA) showed that type of charcoal had a significantly different effect on the bulk density (P <0.01). Mean values of 8 types of charcoal were significantly different when compared using LSD method at 5% significance level (Table.2).

Table. 2. Moisture content (as-determined basis), Mean of geometric mean diameter; dgw (geometric standard deviation; Sgw ),

Density and Angle of repose of charcoal powder.

No. Type of Charcoal

Moisture Content (average) ; %(w.b.)

geometric mean diameter(mm.) ; dgw(Sgw)

Density

(kg.m-3)

Angle of repose

(°) Carr Classification of flowability

1 CCC 9.47-10.48 (9.95) 0.79 (1.92) 189.19a 39.83 c Fair to passable flow

2 CStC 5.44 - 6.76 (6.19) 0.46 (1.98) 207.16b 38.15 b Fair to passable flow

3 CSC 7.85 – 9.34(8.73) 1.26 (1.70) 563.73h 38.95bc Fair to passable flow

4 EuBC 6.51 – 7.64(7.13) 0.31 (3.38) 385.66g 43.21 d Fair to passable flow

5 RHC 5.45 – 6.23(5.78) 0.14 (1.58) 362.05e 35.05 a Free flowing

6 CBPP 14.59 – 16.48(15.33) 1.29 (1.28) 351.33 d 43.50 d Fair to passable flow

7 REuC 6.33 -7.18 (6.84) 0.35 (3.04) 275.34 c 42.64 d Fair to passable flow

8 RAWC 7.62 – 9.27 (8.46) 0.31 (3.20) 371.59 f 39.97 c Fair to passable flow

P - value < 0.01 < 0.01

LSD(0.05) 5.84 1.16 a – h Mean values with different letters for each column are a significant difference (LSD)

Figure 7. Particle size distributions of charcoal powder

0

10

20

30

40

50

60

70

80

90

100

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Cum

ulat

ive

wei

ght ;

%

Particle size ; µm

RHC ; 0.14 mm. dgw

EuBC ; 0.31 mm. dgw

RAWC ; 0.31 mm. dgw

REuC ; 0.35 mm. dgw

CStC ; 0.46 mm. dgw

CCC ; 0.79 mm. dgw

CSC ; 1.26 mm. dgw

CBPP ; 1.29 mm. dgw


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4.1.4 Angle of repose

The result of the angle of repose of charcoal powder (Table.2) found that the angle of repose of charcoal powder ranged from 35.05 degrees to 43.50 degrees. Charcoal from a biomass power plant (CBPP) had the highest angle of repose, followed by eucalyptus bark coal (EuBc), recycling eucalyptus coal (REuC), recycling assorted wood coal (RAWC), corn cob coal (CCC), coconut-shell coal (CSC), cassava stump coal (CStC) and rice husk coal (RHC); angle of repose 43.50, 43.21, 42.64, 39.97, 39.83, 38.95, 38.15 and 35.05 degree, respectively. When considering the material flowing property, Carr used the angle of repose to classified the flowing property [41] They found that rice husk coal (RHC) had free-flowing property, whereas the other charcoal were fair to passable flow.

The analysis of variance (ANOVA) showed that type of charcoal had a significantly different effect on the angle of repose (P <0.01). Mean values were significantly different when compared using LSD method at 5 % significance level (Table.2). Rice husk coal (RHC) had the lowest angle of repose and was significantly different from other charcoal. Coconut-shell coal (CSC) and cassava stump coal (CStC) were not significantly different. Recycling assorted wood coal (RAWC), corn cob coal (CCC) and coconut-shell coal (CSC) were not significantly different on the angle of repose. As well as eucalyptus bark coal (EuBc), recycling eucalyptus coal (REuC) and charcoal from a biomass power plant (CBPP) were not significantly different on the angle of repose.

4.1.5 Static coefficient of friction

The static coefficient of friction of charcoal was shown in Table.3 and Figure 8. Corn cob coal (CCC) at 9.83% (w.b.) moisture had a mean static coefficient of friction on rubber sheet higher than on mild steel, zinc sheet, galvanized steel and stainless steel (0.61, 0.51, 0.50, 0.44 and 0.41, respectively). Cassava stump coal (CStC) at 6.21% (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than mild steel, zinc sheet, galvanized steel and

stainless steel (0.57, 0.52, 0.50, 0.47 and 0.44, respectively). Coconut-shell coal (CSC) at 9.25 % (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than on mild steel, zinc sheet, galvanized steel and stainless steel (0.52, 0.46, 0.45, 0.43 and 0.39 respectively). Eucalyptus bark coal (EuBC) at 5.89% (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than on mild steel, zinc sheet, galvanized steel and stainless steel (0.56, 0.55, 0.54, 0.49 and 0.43 respectively). Rice husk coal (RHC) at 5.97% (w.b.) moisture had a mean static coefficient of friction on the rubber sheet equal to mild steel but found higher than galvanized steel, zinc sheet and stainless steel (0.66, 0.61, 0.59 and 0.57, respectively). Charcoal from a biomass power plant (CBPP) at 7.76 % (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than on mild steel, zinc sheet, galvanized steel and stainless steel (0.61, 0.58, 0.53, 0.52 and 0.42, respectively). Recycling eucalyptus coal (REuC) at 7.21 % (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than on mild steel, zinc sheet, galvanized steel and stainless steel (0.66, 0.54, 0.53, 0.48 and 0.42, respectively). Recycling assorted wood coal (RAWC) at 9.36 % (w.b.) moisture had higher mean static coefficient of friction on the rubber sheet than on mild steel, zinc sheet, galvanized steel and stainless steel (0.61, 0.56, 0.51, 0.49 and 0.47, respectively). The results of this study conformed to the study of Kittipong Laloon [33] and Baryeh EA. [46]. This study also found that the stainless sheet had a low static coefficient of friction (Figure 9) due to its glossy and slippery surface. The result conformed to the report of Singh KK and Goswami TK. [47]

The analysis of variance (ANOVA) showed that the type of charcoal had a significantly effect on the static coefficient of friction (P <0.01). Mean values were compared using the LSD method at 5 % significance level (Table. 3). The static coefficient of friction of charcoal made from woods such as recycling eucalyptus coal (REuC), eucalyptus bark coal (EuBC), recycling assorted wood coal (RAWC) and charcoal from a biomass power plant (CBPP) was not significantly different on the various surface.

Table. 3 The static coefficient of friction of charcoal powder at the moisture content (as-determined basis; adm)

No. Type of Charcoal

Moisture Content (average) ; % (w.b.)

Static coefficient of friction

Mild steel Stainless steel Zinc sheet Galvanized steel Rubber

1 CCC 9.07 – 10.46 (9.83) 0.51bC 0.41 abA 0.50 bC 0.44 aB 0.61 cD

2 CStC 5.84 – 6.61 (6.21) 0.52 bC 0.44 cA 0.50 bC 0.47 bB 0.57 bD

3 CSC 8.72 – 9.96 (9.25) 0.46 aC 0.39 aA 0.45 bBC 0.43 aB 0.52 aD

4 EuBC 5.49 – 6.78 (5.89) 0.55 cC 0.43 bA 0.54 dC 0.49 bB 0.56 bC

5 RHC 5.18 – 6.97 (5.97) 0.66 eC 0.57 eA 0.59 eAB 0.61 dB 0.66 dC

6 CBPP 7.08 – 8.05 (7.76) 0.58 dC 0.42 bcA 0.53 cdB 0.52 cB 0.61 cD

7 REuC 6.73 – 8.17 (7.21) 0.54 cbC 0.42 bA 0.53 cdC 0.48 bB 0.66 dD

8 RAWC 8.97 – 9.73 (9.36) 0.56 cdC 0.47 dA 0.51 bcB 0.49 bAB 0.61 cD

P - value < 0.01 a – e Mean values with different letters for each column are significantly difference (LSD) at P < o.o5, 0.02 A – D Mean values with different letters for each row are significantly difference (LSD) at P < o.o5, 0.02


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Figure 8. The static coefficient of friction of charcoal powder

4.2 Higher Heating Value of Charcoal

The study of higher heating value (HHV) of charcoal was conducted by comparing the heating value at residual moisture (As-determine basis) (Table. 4). Commercial charcoal briquettes sample no. 1-3 had to mean higher heating value of 5,301.66, 5,382.62 and 5,205.34 cal/g, respectively, and qualified for the Thai Community Product Standards of Charcoal Briquettes (TCPS No.238/2004) [48]. Recycling eucalyptus coal (REuC) had highest HHV, followed by Coconut-shell coal (CSC), Corn cob coal (CCC), Recycling assorted wood coal (RAWC), Charcoal from a biomass power plant (CBPP), Rice husk coal (RHC), Eucalyptus bark coal (EuBC) and Cassava stump coal (CStC) produced the lowest HHV (7,303.86, 7,154.16, 6,526.38, 6,085.04, 5,991.17, 4,863.29, 3,779.97 and 3,393.77 cal/g, respectively). The HHV of charcoal was then compared by statistical method. It was found that the HHV of Cassava stump coal (CStC), Eucalyptus bark coal (EuBC), Charcoal from a biomass power plant (CBPP), Recycling assorted wood coal (RAWC), Corn cob coal (CCC), Coconut-shell coal (CSC) and Recycling eucalyptus coal (REuC) was not significantly different when compared using the DMRT method at a significant level of P < 0.01.

The higher heating value of charcoal of Eucalyptus bark coal (EuBC) and Cassava stump coal (CStC) were lower than the standard of Bionic Charcoal (TCPS No.946/2005) [49] and standards of Charcoal briquette (TCPS 238-2004). However, the Cassava stump coal (CStC) had HHV potential as reported by Nitipong Soponpongpipat. et al. [50]. when cassava stump coal was processed through the Torrefaction at temperature 280 °c for 60 minutes, its heating value was 5,045.57 cal/g (21.12 0.34 MJ/kg). Rice husk coal (RHC) had higher HHV than the standard of Bionic Charcoal Briquette (TCPS No.946/2005) but found to be lower than the standard of Charcoal briquette (TCPS 238-2004). Whilst, Charcoal from a biomass power plant (CBPP), Recycling assorted wood coal (RAWC), Corn cob coal (CCC), Coconut-shell coal (CSC)

and Recycling eucalyptus coal (REuC) had higher HHV than the standard of Bionic Charcoal Briquette (TCPS No.946/2005) and standards of Charcoal briquette (TCPS 238-2004). They also had HHV that equivalent to and higher than HHV of wood charcoal. The reported HHV of wood charcoal was 4,468–7,955 cal/g [51-53]. The study of Michael Lubwama et al. [44] reported that biochar briquette had HHV of 3,965–5,255 cal/g. Moreover, the result of HHV of Corn cob coal in this study was higher than Corn cob coal that was processed through the Torrefaction, as reported in the study of Nitipong Soponpongpipat. et al. [50], J.J. Lu and W.H.Chen.[51]. Nakasorn K. et al. [54] The HHV of Corn cob coal in this study was also higher than corn cob coal briquette that reported by Sunardi et al. [52]. Although the HHV of Rice husk coal (RHC) in this study was lower than the standards of Charcoal briquette (TCPS 238-2004) that indicate the HHV of more than 5,000 cal/g. However, the HHV of Rice husk coal was found to be higher than the heating value of Rice Husk Biochar and Rice Husk Biochar Pellets that reported by Hu Q. et al. [53], Rice Husk Charcoal that reported by Suryaningsih S. et al. [55], and Rice husks briquettes that reported by Michael Lubwama and Vianney Andrew Yiga. [11]. The Recycling eucalyptus coal (REuC) and Charcoal from a biomass power plant (CBPP) that contained eucalyptus woods as one of the material, had HHV higher than eucalyptus woods that was processed through the Torrefaction in the study of S. de O. Araújo. et al. [56] and the HHV of Coconut-shell coal (CSC) was found similar than coconut shell charcoal in the study of D. P. Biswas [57]

Except for the Cassava stump coal (CStC) and Eucalyptus bark coal (EuBC), most of the charcoal samples qualified the standard of Bionic Charcoal Briquette (TCPS No.946/2005) and the standard of Charcoal briquette (TCPS 238-2004) that defined the HHV of more than 4,000 cal/g and 5,000 cal/g, respectively. They were also had HHV higher than commercial briquettes charcoal as shown in Table 7, and

0,20

0,30

0,40

0,50

0,60

0,70

0,80

C C C C S T C C S C E U B C R H C C B P P R E U C R A W C

stat

ic c

oeff

icie

nt o

f fric

tion

Type of charcoal

Mild steel Stainless steel Zinc sheet Galvanized steel Rubber


166

higher than the heating value of commercial briquettes charcoal, 5,447 cal/g, that reported by Michael Jerry Antal JR. et al. [58]. Moreover, the HHV of charcoal samples were higher than sawdust charcoal briquette, 4,820 cal/g, in the study of Akowuah JO. et al. [59], of which similar to the HHV of Rice husk coal (RHC) in this study. Eucalyptus bark coal (EuBC) had HHV of 3,996 cal/g, which was lower than the report of Juizo CGF. et al. [60] at 4,669.67 cal/g. According to the report of Lubwama M. et al. [44], it can be used as household cooking fuels as compared to the heating value of firewood. The Eucalyptus bark coal had the potential to be used as the secondary ingredient in charcoal briquettes production, due to its large amount, especially in the Eucalyptus wood ships factory areas. Moreover, eucalyptus

bark is not a major material for industry, nor is Bionic Charcoal Briquette (TCPS No.946/2005) production. The Cassava stump coal (CStC) had mean HHV of 3,393.78 cal/g. According to the study of Nakasorn K. et al. [54], it was found that the combustible component (volatile substance + fixed carbon) and the higher heat value (HHV) was 89.17–95.05% and 4,310–6,025 cal/g, which conformed to the study of Sen R. et al. [23] and Tippayawong N. et al. [61]. Therefore, Cassava stump has the potential to be used as raw material for charcoal briquette production. It could be used as secondary material in charcoal briquettes production or Bionic Charcoal Briquette (TCPS No.946/2005) as well as Eucalyptus bark coal (EuBC). However, the materials must be collected before material decay or destroyed by pests.

Table 4. Higher Heating Value of Charcoal (As-Determined Basis, adm)

Type of Charcoal Moisture content (%) Higher Heating Value; HHV, (cal/g)

TISI; Charcoal Briquette (TCPS No.238/2004) ≤ 8 ≥ 5,000

TISI; Bionic Charcoal Briquette (TCPS No.946/2005) ≤ 8 ≥ 4,000

Commercial Briquettes Charcoal 1, (CBC 1) 4.91 5,301.66 ±48.34



CCC 9.83 6,526.38d ±265.38

CStC 6.21 3,393.78a ±480.12

CSC 9.25 7,154.16e ±448.73

EuBC 5.89 3,779.98a ±106.00

RHC 5.97 4,863.29b ±153.80

CBPP 7.76 5,991.18c ±197.59

REuC 7.21 7,303.86e ±159.58

RAWC 9.36 6,085.04cd ±208.18 a – e Mean values with different letters for each row are significantly different (DMRT) at P < 0.01

5. Conclusion

Charcoal powder in this study had a mean moisture content of 5.78–15.33 % (w.b.), mean bulk density of 189.19–563.73 kg/m3, angle of repose 35.05–43.21 degrees. The flowing ability of material was fair to passable flow and free-flowing. The mean particle size was 0.31–1.29 mm, at the mean moisture content of less than 10% (w.b.). At the mean moisture content of 5.89–9.83% (w.b.), static coefficient of friction on mild steel was 0.46–0.66, on stainless steel was 0.39–0.57, on zinc sheet was 0.45–0.59, on galvanized steel was 0.43–0.61 and on a rubber surface was 0.52–0.66, at the average moisture content of 5.97–13.21% (w.b.). The higher heating value of 8 charcoal samples had an average higher

heating value of 3,393.78–7,303.86 cal/g. While 3 commercial briquette charcoal samples had higher heating value was 5,205.34 – 5,382.62 cal/g, followed the standard of Charcoal briquette (TCPS 238-2004) that defined the HHV of more than 5,000 cal/g.

The results of physical properties of charcoal powder benefits for the engineering design. Higher heating value compared between commercial briquettes and charcoal from biomass materials demonstrated the potential of biomass that can be used as raw material for charcoal briquettes production and substitute biomass from trees. Thereby the value of such material can be increased (Zero Waste).


167

Acknowledgements

This article is a part of “a study of charcoal powder mixture ratio for charcoal briquettes production”. The researchers would like to thank the Agricultural Machinery and Postharvest Technology Research Center, Khon Kaen University, the Postharvest Technology Innovation Center, Office of the Higher Education Commission, Bangkok, and the Faculty of Agriculture and Technology, Nakhon Phanom University, for research fund and facility support, including useful information and collaboration.

References

[1] K. E. Okedu and M. Al-Hashmi, “Assessment of the Cost of Various Renewable Energy Systems to Provide Power for a Small Community: Case of Bukha, Oman,” Int. J. SMART GRID, vol. 2, 2018.

[2] F. Ayadi, I. Colak, I. Garip, and H. I. Bulbul, “Impacts of Renewable Energy Resources in Smart Grid,” in 8th International Conference on Smart Grid, icSmartGrid 2020, 2020, pp. 183–188, doi: 10.1109/icSmartGrid49881.2020.9144695.

[3] G. Roberto, P. Consuelo, A. G. Lavin, and J. L. Bueno, “Characterization of Spanish biomass wastes for energy use.” Bioresource Technology 103, pp. 249–258, 2012.

[4] X. Song, S. Zhang, Y. Wu, and Z. Cao, “Investigation on the properties of the bio-briquette fuel prepared from hydrothermal pretreated cotton stalk and wood sawdust,” Renewable Energy, vol. 151. pp. 184–191, 2020, doi: 10.1016/j.renene.2019.11.003.

[5] I. Carlucci, G. Mutani, and M. Martino, “Assessment of potential energy producible from agricultural biomass in the municipalities of the Novara plain,” in 2015 International Conference on Renewable Energy Research and Applications (ICRERA), Palermo, 2015, 2015, pp. 1394–1398, doi: 10.1109/ICRERA.2015.7418636.

[6] C. Belghit and A. Djeddi, “Valorization of Agricultural Waste for the Production of Biogas in the framework of Renewable Energy Development in Algeria,” in 2019 1st International Conference on Sustainable Renewable Energy Systems and Applications (ICSRESA), 2019, pp. 1–5, doi: 10.1109/ICSRESA49121.2019.9182363.

[7] Department of Alternative Energy Development and Efficiency., “ENERGY BALANCE OF THAILAND 2019.”

[8] N. Tangmankongworakoon, “The production of fuel briquettes from bio-agricultural wastes and household wastes,” Journal of Science and Technology, vol. 12. pp. 66–77, 2014.

[9] A. Gendek, M. Aniszewska, J. Malaťák, and J.

Velebil, “Evaluation of selected physical and mechanical properties of briquettes produced from cones of three coniferous tree species,” Biomass and Bioenergy, vol. 117. pp. 173–179, 2018, doi: 10.1016/j.biombioe.2018.07.025.

[10] W. Wongchai, A. Promwungkwa, and W. Insuan, “Above-ground Biomass Allometric Equation and Dynamics Accumulation of Eucalyptus Camalensis and Acasia,” Int. J. Renew. ENERGY Res., vol. 10, no. 4, pp. 1664–1673, 2020.

[11] M. Lubwama and V. A. Yiga, “Characteristics of briquettes developed from rice and coffee husks for domestic cooking applications in Uganda,” Renewable Energy, vol. 118. pp. 43–55, 2018, doi: 10.1016/j.renene.2017.11.003.

[12] S. Gladstone, V. Tersigni, J. Kennedy, and J. A. Haldeman, “Targeting briquetting as an alternative fuel source in Tanzania.” Procedia Engineering 78, pp. 287–291, 2014.

[13] K. Chaiwong, C. Karnjanapiboon, N. Wichan, N. Jaiinta, and C. Thawonngamyingsakul, “The IoT Based Temperature Monitoring and Air Inlet Optimization Controlling for Gasification Stove.,” in 2019 Joint International Conference on Digital Arts, Media and Technology with ECTI Northern Section Conference on Electrical, Electronics, Computer and Telecommunications Engineering (ECTI DAMT-NCON), Nan, Thailand, 2019, 2019, pp. 387–391, doi: 10.1109/ECTI-NCON.2019.8692283.

[14] R. Perez-Padilla, A. Schilmann, and H. Riojas-Rodriguez, “Respiratory health effects of indoor air pollution,” International Journal of Tuberculosis and Lung Disease, vol. 14, no. 9. pp. 1079–1086, 2010.

[15] G. Y. Obeng, E. Mensah, G. Ashiagbor, O. Boahen, and D. J. Sweeney, “Watching the smoke rise up: Thermal efficiency, pollutant emissions and global warming impact of three biomass cookstoves in Ghana,” Energies, vol. 10, no. 5. 2017, doi: 10.3390/en10050641.

[16] R. C. de Miranda, R. Bailis, and A. de O. Vilela, “Cogenerating electricity from charcoaling A promising new advanced technology.pdf.” Energy for Sustainable Development, pp. 171–176, 2013.

[17] O. A. Sotannde, A. O. Oluyege, and G. B. Abah, “Physical and combustion properties of charcoal briquettes from neem wood residues,” International Agrophysics, vol. 24, no. 2. pp. 189–194, 2010.

[18] P. Lapanupat, “A Feasibility Study for Investment in Corn Core Charcoal Briquettes Production in Amphoe Long, Changwat Phrae,” Chaing Mai University, 2010.


168

[19] J. Wannapeera, N. Worasuwannarak, and S. Pipatmanomai, “Product yields and characteristics of rice husk, rice straw and corncob during fast pyrolysis in a drop-tube/fixed-bed reactor,” Songklanakarin Journal of Science and Technology, vol. 30, no. 3. pp. 393–404, 2008.

[20] T. Vasiliki et al., “Biomass Availability in Europe as an Alternative Fuel for Full Conversion of Lignite Power Plants: A Critical Review,” Energies, vol. 13, no. 3390, pp. 1–29, 2020, doi: doi:10.3390/en13133390.

[21] U. B. Deshannavar, P. G. Hegde, Z. Dhalayat, V. Patil, and S. Gavas, “Production and characterization of agro-based briquettes and estimation of calorific value by regression analysis: An energy application,” Materials Science for Energy Technologies, vol. 1, no. 2. pp. 175–181, 2018, doi: 10.1016/j.mset.2018.07.003.

[22] R. Wang, Y. Tian, L. Zhao, Z. Yao, H. Meng, and S. Hou, “Industrial analysis and determination of calorific value for biomass based on thermogravimetry,” Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering, vol. 30, no. 5. pp. 169–177, 2014, doi: 10.3969/j.issn.1002-6819.2014.05.022.

[23] R. Sen, S. Wiwatpanyaporn, and A. P. Annachhatre, “Influence of binders on Physical properties of fuel briquettes produced from cassava rhizome waste,” Int. J. Environ. Waste Manag., 2016, doi: 10.1504/IJEWM.2016.076750.

[24] S. Mopoung and V. Udeye, “Characterization and evaluation of charcoal briquettes using banana peel and banana bunch waste for housahold heating,” Am. J. Eng. Appl. Sci., vol. 10, no. 2, pp. 353–365, 2017.

[25] J. Cai et al., “Review of physicochemical properties and analytical characterization of lignocellulosic biomass,” Renew. Sustain. Energy Rev., 2017, doi: 10.1016/j.rser.2017.03.072.

[26] P. S. Lam and S. Sokhansanj, “Engineering properties of biomass. In : Shastri Y., Hensen A., Rodriguez L. and Ting K.(eds),” Engineering and science of biomass feedstock production and provistion. 2014, doi: 10.1201/9781420028805.

[27] B. Khalida, Z. Mohamed, S. Belaid, H. O. Samir, K. Sobhi, and S. Midane, “Prediction of Higher Heating Value HHV of Date Palm Biomass Fuel using Artificial Intelligence Method,” in 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA), 2019, pp. 59–62, doi: 10.1109/ICRERA47325.2019.8997113.

[28] K. E. Ileleji and B. Zhou, “The angle of repose of bulk corn stover particles,” Powder Technology, vol. 187, no. 2. pp. 110–118, 2008, doi: 10.1016/j.powtec.2008.01.029.

[29] I. Obernberger and G. Thek, “Physical characterisation and chemical composition of densified biomass fuels with regard to their combustion behaviour,” Biomass and Bioenergy, vol. 27, no. 6. pp. 653–669, 2004, doi: 10.1016/j.biombioe.2003.07.006.

[30] Z. Yaning, Ghaly A.E., and L. Bingxi, “Physical Properties of Corn Residues.” American Journal of Biochemistry and Biotechnology 8(2), pp. 44–53, 2012.

[31] J. Zhang and Y. Guo, “Physical properties of solid fuel briquettes made from Caragana korshinskii Kom,” Powder Technol., 2014, doi: 10.1016/j.powtec.2014.02.025.

[32] P. Sathitruangsak, T. Madhiyanon, and S. Soponronnarit, “Design of an extrusion screw and solid fuel produced from coconut shell.” Songklanakarin J. Sci. Technol 28(2), pp. 387–401, 2006.

[33] K. Laloon, “A study and development of machinery for charcoal block production from bio-charcoals,” Khon Kaen University, 2014.

[34] Z. Ghorbani, A. Hemmat, and A. A. Masoumi, “Physical and mechanical properties of alfalfa grind as affected by particle size and moisture content,” Journal of Agricultural Science and Technology, vol. 14, no. 1. pp. 65–76, 2012.

[35] D. Rajkumar and P. Venkatachalam, “Physical properties of agro residual briquettes produced from Cotton , Soybean and Pigeon pea stalks,” International Journal on Power Engineering and ENergy, vol. 4, no. 4. pp. 414–417, 2013.

[36] A. Yank, M. Ngadi, and R. Kok, “Physical properties of rice husk and bran briquettes under low pressure densification for rural applications,” Biomass and Bioenergy, vol. 84. pp. 22–30, 2016, doi: 10.1016/j.biombioe.2015.09.015.

[37] N. Y. Harun and M. T. Afzal, “Effect of Particle Size on Mechanical Properties of Pellets Made from Biomass Blends,” Procedia Engineering, vol. 148. pp. 93–99, 2016, doi: 10.1016/j.proeng.2016.06.445.

[38] S. V. Bhagwanrao and M. Singaravelu, “Bulk density of biomass and particle density of their briquettes.,” International Journal of Agricultural Engineering, vol. 7, no. 1. pp. 221–224, 2014.

[39] M. D. Shaw, C. Karunakaran, and L. G. Tabil, “Physicochemical characteristics of densified untreated and steam exploded poplar wood and wheat straw grinds,” Biosystems Engineering, vol. 103, no. 2. pp. 198–207, 2009, doi: 10.1016/j.biosystemseng.2009.02.012.


169

[40] C. L. Clementson, K. Rosentrater, and K. E. Ileleji, “Evaluation of measurement procedures used to determine the bulk density of Distillers Dried Grains with Solubles (DDGS),” Transactions of the ASABE , American Society of Agricultural and Biological Engineers, vol. 53(2). pp. 485–490, 2010, doi: 10.13031/2013.29557.

[41] H. M. Beakawi Al-Hashemi and O. S. Baghabra Al-Amoudi, “A review on the angle of repose of granular materials,” Powder Technology, vol. 330. pp. 397–417, 2018, doi: 10.1016/j.powtec.2018.02.003.

[42] A. A. Adebowale, G. O. Fetuga, C. B. Apata, and L. O. Sanni, “Effect of Variety and Initial Moisture Content on Physical Properties of Improved Millet Grains,” Nigerian Food Journal, vol. 30, no. 1. pp. 5–10, 2012, doi: 10.1016/s0189-7241(15)30007-2.

[43] C. Antwi-Boasiako and B. B. Acheampong, “Strength properties and calorific values of sawdust-briquettes as wood-residue energy generation.pdf.” Biomass and Bioenergy, pp. 144–152, 2016.

[44] M. Lubwama, V. A. Yiga, F. Muhairwe, and J. Kihedu, “Physical and combustion properties of agricultural residue bio-char bio-composite briquettes as sustainable domestic energy sources,” Renewable Energy, vol. 148. pp. 1002–1016, 2020, doi: 10.1016/j.renene.2019.10.085.

[45] R. S. Abdul-Razzak, K. A.-M. Talal, and A. T. S. Al-Takay, “Influence Of Adhesive Type And Particles Size On Compressed Charcoal Briquettes Manufacturing,” Australian Journal of Basic and Applied Sciences. pp. 56–62, 2013.

[46] E. A. Baryeh, “Physical properties of millet,” Journal of Food Engineering, vol. 51, no. 1. pp. 39–46, 2002, doi: 10.1016/S0260-8774(01)00035-8.

[47] K. K. Singh and T. K. Goswami, “Physical Properties of Cumin Seed,” J . agric . Engng Res . 64, vol. 64, pp. 93–98, 1996, doi: 10.1016/S0260-8774(00)00049-2.

[48] Thai Community Product Standard., “Charcoal Briquetts(TCPS 238-2004),” Thailand Industrial Standards Institute, Ministry of Industry, 2004. [Online]. Available: http://tcps.tisi.go.th/pub/tcps238_47.pdf. [Accessed: 22-Aug-2018].

[49] Thai Community Product Standard., “Bionic Charcoal Briquetts(TCPS 946-2005),” Thailand Industrial Standards Institute, Ministry of Industry, 2005. [Online]. Available: http://tcps.tisi.go.th/pub/tcps946_48.pdf. [Accessed: 22-Aug-2018].

[50] N. Soponpongpipat, D. Sittikul, and U. Sae-ueng, “Higher heating value prediction of torrefaction char produced from non-woody biomass,” Front. Energy, vol. 9, no. 4, pp. 461–471, 2015, doi: DOI 10.1007/s11708-015-0377-3.

[51] J. J. Lu and W. H. Chen, “Product yields and characteristics of corncob waste under various torrefaction atmospheres,” Energies, vol. 7, no. 1. pp. 13–27, 2014, doi: 10.3390/en7010013.

[52] Sunardi, Djuanda, and M. A. S. Mandra, “Characteristics of charcoal briquettes from agricultural waste with compaction pressure and particle size variation as alternative fuel,” International Energy Journal, vol. 19, no. 3. pp. 139–147, 2019.

[53] Q. Hu, J. Shao, H. Yang, D. Yao, X. Wang, and H. Chen, “Effects of binders on the properties of bio-char pellets,” Applied Energy, vol. 157. pp. 508–516, 2015, doi: 10.1016/j.apenergy.2015.05.019.

[54] K. Nakason, J. Pathomrotsakun, W. Kraithong, P. Khemthong, and B. Panyapinyopol, “Torrefaction of Agricultural Wastes Influence of lignocellulosic type and treatment temperature on fuel properties of biochar,” Int. Energy J., pp. 253–266, 2019.

[55] S. Suryaningsih, O. Nurhilal, Y. Yuliah, and E. Salsabila, “Fabrication and characterization of rice husk charcoal bio briquettes,” AIP Conference Proceedings, vol. 1927. 2018, doi: 10.1063/1.5021237.

[56] S. de O. Araújo, D. M. Neiva, A. de C. Carneiro, B. Esteves, and H. Pereira, “Potential of mild torrefaction for upgrading the wood energy value of different Eucalyptus species,” Forests, vol. 9, no. 9. 2018, doi: 10.3390/f9090535.

[57] D. P. Biswas, “Physicochemical Property and Heating Value Analyses of Charcoal Briquettes from Agricultural Wastes: An Alternative Renewable Energy Source,” in International Conference on Computer, Communication, Chemical, Material and Electronic Engineering, IC4ME2 2018, 2018, doi: 10.1109/IC4ME2.2018.8465639.

[58] J. Michael Jerry Antal, E. Croiset, X. Dai, C. DeAlmeida, W. S.-L. Mok, and N. Norberg, “High-Yield Biomass Charcoal.” Energy & Fuels , 10, pp. 652–658, 1996.

[59] Joseph O Akowuah, Francis Kemausuor, and Stephen J Mitchual, “Physico-chemical characteristics and market,” Int. J. Energy Environ. Eng., vol. 3, no. 20, 2012, doi: 10.1186/2251-6832-3-20.

[60] C. G. F. Juizo, M. R. Lima, and D. A. Da Silva, “Quality of the bark and wood of nine Eucalyptus species for the charcoal production,” Revista Brasileirade Ciencias Agrarias, vol. 12, no. 3. pp. 386–390, 2017, doi: 10.5039/agraria.v12i3a5461.

[61] N. Tippayawong, P. Rerkkriangkrai, P. Aggarangsi, and A. Pattiya, “Biochar Production from Cassava Rhizome in a Semi-continuous Carbonization System,” Energy Procedia, vol. 141. pp. 109–113, 2017, doi: 10.1016/j.egypro.2017.11.021.

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