DESIGN AND PERFORMANCE TEST OF SOLAR WAX MELTER MACHINE

1Hailemariam Girmay Kahsay

Mechanical Engineering, Engineering Technology, Adigrat University, Adigrat ,Ethiopia

1. AbstractDesign solar wax melter was performed used data temperature and observed from the honey

and the materials. The solar wax extractor consists of a transparence glass and box containing a

sloped sheet of metal. The dimension solar honey wax melter was 1000mm length and 500mm

width, the useful heat gain from this dimension flat plat solar collector about 67.6W. A raw

material (hifti) was placed on the metal sheet and as it melts, wax runs down the metal slope to

a container. The sheet of metal can be bent at the edges to funnel wax towards the container.

Crusts in the raw material or hifti tend to remain on the metal, and others can be scraped off the

final solidified block of wax in the conical shape of container.

The temperature to which the melting wax could be raised depended on the solar energy

intensity and the period of sunshine. With high solar energy intensity, a solar melting has wide

applications in improving traditional wax melting technology, especially in preventing wax

from being polluted and burnt. Since the temperature of melting wax like the one I constructed

can exceed 64oC, but did not reached this temperature hole day sunshine hour’s .the model

tested at different temperature of read from collector from ambient temperature up to above the

limitation raw material melting temperature. During the experiment test from one Kg of raw

material of “hefti” it produced about 450gram of pure wax output and the prototype efficiency

was 55%.

From this research the wax melter was very alternative for farmers and other stake holders to

produce a good quality wax material.

Keywords: useful energy; wax; solar irradiation, hefti

2. Introduction

The solar wax extractor consists of a glass or clear plastic-lidded box containing a sloped sheet

of metal. Pieces of honeycomb are placed on the metal sheet and as they melt, wax runs down

the metal slope to a container. The sheet of metal can be bent at the edges to funnel wax

towards the container. A screen of wire mesh prevents pieces of comb and debris from slipping

down into the container.

Impurities in the wax tend to remain on the metal, and others can be scraped off the final

solidified block of wax. The dimensions of the extractor can vary according to the container

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size used to make it. Beeswax is a valuable product that can provide a worthwhile income in

addition to honey. One kilogram of beeswax is worth more than one kilogram of honey. Unlike

honey, beeswax is not a food product and is simpler to deal with - it does not require careful

packaging which this simplifies storage and transport. Beeswax as an income generating

resource is neglected in some areas of the tropics. Some countries of Africa where fixed comb

beekeeping is still the norm, for example, Ethiopia and Angola, have significant export of

beeswax, while in others the trade is neglected and beeswax is thrown away[1]. Worldwide,

many honey hunters and beekeepers do not know that beeswax can be sold or used for locally

made, high-value products. Knowledge about the value of beeswax and how to process it is

often lacking. It is impossible to give statistics, but maybe only half of the world’s production

of beeswax comes on to the market, with the rest being thrown away and lost. Beeswax is the

creamy colored substance used by bees to build the comb that forms the structure of their nest.

Very pure beeswax is white, but the presence of pollen and other substances cause it to become

yellow. Beeswax, with its unique characteristics, is now being used in the development of new

products in various fields such as cosmetics, foods, pharmaceuticals, engineering and industry

[3]. Specifically, most of the wax produced now days are used in the manufacture of cosmetics,

such as hand and face creams, lipsticks and depilatory wax and many other uses. Moreover, the

pharmaceutical industry uses the wax in various ointments, for coating pills and suppositories

and other miscellaneous industrial products [4].

Beeswax is secreted in small wax platelets form by worker honeybees from four pairs of wax

glands on the underside of the abdomens which are functional when the bees are about 9–17

days old after being engorged with honey and resting suspended for 24 hours together [5].

Worldwide in general and in Ethiopia in particular, a lot of research activities had been

conducted and data regarding beeswax production, physical and chemical characterization,

processing and value addition and marketing are documented.

In whole the world bees wax produced by bees that could be harvested by beekeepers is wasted.

From the harvested at most one half of world production of the bee wax come to the market, the

rest production is lost [2]. When come in to Ethiopia about less than 10% is used for export [7].

The remaining production is waste due to lack of modern production and awareness the people

then loss the quality of the bees wax. In most Ethiopian people produced the wax material

using fire wood. In Ethiopia, as in most developing countries, firewood is the predominant

energy source, as are other traditional fuels as cow dung, and agricultural residues. There are

usually free, multiple- purpose fuel, providing much service such as heating and lighting. In

term of energy for melt the wax melt almost 85% of the population on average lilies of wood,

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with an even larger reliance regions and less on so in urban regions. In rural settings, the

production of the population that uses firewood is fairly consistent across countries a result of

its low cost and lack of available alternatives. Fire wood is burned in open stoves resulting in

low energy density and low total energy efficiency on combustion and health problem. For

these main problem and other problems solved by solar wax melter machine.

A solar wax extractor was developed to extract beeswax from honey combs using the solar

radiation energy. The main advantage of the solar wax extractor is safe and easy produced by

using conventional heating methods [6]. The main part of solar wax solar wax melter

manufacture from local material and easy technical need. This machine design was seeing in

many literature reviews but have many problem for example those designer does not consider

the heat loss, quality mold container and the inclination angle, traditional fire method is high so

that high heat kills constitute of the honey wax like protein and others problem solved in this

research work. However, in particular in Ethiopia, the production bees wax is in tradition

method and not available the modern technology to produce the quality product of beeswax. For

this main problem would tried solve by the design of solar wax melter machine. This work is

just an attempt to address the research gap existing in the field of solar wax melting for used a

solar energy.

2. Methods and Material

2.1 Site Selection and Wax Assessment

Assessment indicates that Ethiopia has got potential for production of bees wax because of huge

number of honey number of honey bee colonies being kept in traditional hives. For example in

the previous month (30/03/2020) we went in to Hagerselam town in the Tigray region then ask

to expert person in the place said that the wax is produced from tradition and modern hives

produced that about 0.6kg and 0.25kg per hives respectively. But this amount wax in most of

place produced in the traditional method. Then for set up the experment it flow these steps first

prepared hefiti (raw material), thermometer, digital mass measurment, flat plat solar wax melter

box, then it put the one kilogram raw material which contains impurity inside the solar wax

melter box and thermometer inside the solar wax melter box (one for measuring temperature of

wax, second is for measuring the temperature of environmental temperature inside the solar wax

melter box) then closed the solar wax melter box in short of time in order to avoid heat losses.

In the during the experment tested for two weeks in the both selected site and also tested the

tradiational perapared the wax.

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2.2 Materials

Raw material (hefiti).

Wax container

Insulator (aluminum foil )

Transparent glass( macia)

Wood

Hammer

Workshop equipment etc.

Assumptions

10 minutes interval time

Take solar radiation during that day

Stiffen constant number= 56.7 × 10-12KW/m2K4.

Ambient temperature: 20C-28C

Wind velocity < 4 m/s (at the melting wax)

Global irradiance (horizontal) >800 W/m2

Diffuse fraction < 20.

Density of air= 0.1 kg/m3

Mass of wax= 100 gram

3. Design of flat plat collectorIn this part, the collector that generates heat would be described. The solar energy that is collected

by the solar field will be converted thermal energy. The size of the melting was determined as a

function of the melting area needed per kilogram of raw wax honey. The melting temperature

was established as a function of the maximum limit of temperature of the raw material might

support. Specific heat of been wax was 3.4 (KJ/kg K) [8]. To carry out design calculations, the

design conditions applicable to rural area are required. The conditions, assumptions summarized

in table:1.1below for the design of the wax melter.

Table.1: design conditions and assumptions

Items Conditions or assumptions

Location Tigray, Mekelle, Hagere selam & wukro

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Sample melting bee wax

Melting period September to May

Melting per batch 1000gram

Melting time(sunshine and storage hours ) 10 hours

Incident solar radiation, I 640W/m2 K (average incidence solar radiation

of tigray regione )

Wind speed 2.5m/s

Figure 1: flat plat solar collector

Design of flat plat solar collector for wax melter in mathimetical analayses. The Physical

dimensions of the flat plate solar collector is

The collector length =1m

The collector width =0.5m

Thickness of the collector = 5cm

Title angle =15°

Amount of raw material 1kg of honey

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The dimension of the raw material holder box

60cm×50cm

The wax holder box: 30cm×30cm

Insulation ( made of wood)

At the bottom =10cm

At the side=10cm

Declination (δ ¿

This is the angle between the sun’s direction and the equatorial plane and is given by foerson.et.

δ= 23.45sin [0.9863(284+n)] (1 )

Where (n) is the day in year which varies from n=1, to n=365. For this design taken n=330

So; δ = 23.45sin [0.9863(284+330)] = 23°

The optimum collector slope is determined from:

∅=δ+β ( 2)

Where δ is the angle of declination for tigray region and β is the altitude of the Tigray but for

this calculation the altitude taken a :β =15°

∅= 23+15 =38°

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Table 2: Physical properties of beeswax and artificial waxes [5]

Type of wax Melting point ℃ Density

Beeswax 61-65 0.950-0.965

Artificial waxes

Ceresin 65-80 0.91-0.92

Paraffin 45-70 0.88-0.91

Stearin 52-55 0.89

Natural waxes

Bayberry-myrtle 48-50 -0.875-0.980

Montana crude wax 76-86 0.99-1.00

Sugar cane wax 75-79 0.98-0.99

Castor bean wax 86 86 0.98-0.99

Energy balance on the collector was calculated: In the solar collector the incident solar energy is

partially absorbed in the glass and absorber surfaces, some amount of this energy is transferred

to the raw material inside the collector and the remaining is lost to the environment.

I× AC=QV +Qcond .+Qconv .+Qrad .+Qref . (3)

Figure :2 free diagram of flat plat solar collector

Available solar energy: (Qav ): the total solar radiation available on the specific titled surfaces

of the drying cabinet and the solar air heater is calculated using the following formula:

Qav=I × AC = 640W/m2 *0.5m2 = 320W

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Absorber solar radiation (Qra d .): the absorbed solar radiation by both of the drying cabinet and

the solar air heater is calculated as follow:

Qab .= Qav . ×(τα ) = (I× AC)×(τα ) (4)

= 320*0.98*0.98 = 307.33W

Useful heat energy gain (QU): the use full heat energy gain is calculated as follows:

QU=AC F. [Iτα−U L (T mc−T a )] (5)

However, using this equation to calculate the useful heat gained and determines the

performance of the collector is problem due to the quantity mean fluid temperature, T mc of the

collector. To overcome this problem, Bliss expresses the performance of a solar collector using

an energy balance as follows:

QU= ACF’[Iτα−U L(T mc−T a)¿ (6)

QU = AFR[Iτα−U L(T Ci−T a)¿ (7)

Where: the plate efficiency factor F’ is a factor that measure the quality of heat the fluid and the

absorber plate.

F’ = [1+U L

h+[( 1

h+ 1

hr)]

−1

]−1

(8)

h=h1=h2

And FR where it is measure of the solar collector performance as a heat exchanger given by

FR=ṁCpAc U [1-exp(-

UL F ' AC

ṁCp)]

(9)

To calculate the heat loss I take the following values taken from literature.

T ambient, average = 25℃+273 k= 298k

T plate, average = 64℃+273 K = 337K

Global radiation, average = 640W/m2

For initial calculation, cover glass temperature : T g = 35℃

The Mean temperature between plate and the cover is :

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T m= (T plate+T glass)

2 = (64+35)/2 = 49.5 =322.5 K

Table 3: property air at one atmosphere [9]

T,℃ ρ , Kgm3 CP ,

JKg K,

Wm K

μ ,Pa s×10−5

α , m2

s×10−5 Pr

0 1.292 1006 0.0242 1.72 1.86 0.72

20 1.204 1006 0.0257 1.81 2.12 0.71

40 1.127 1007 0.0272 1.90 2.24 0.70

60 1.059 1008 0.287 1.99 2.69 0.70

80 0.999 1010 0.302 2.09 3.00 0.70

100 0.946 1012 0.318 2.18 3.32 0.69

120 0.898 1014 0.333 2.27 3.66 0.69

By interpolation, calculate the values of properties of air inside the plate at 49.5℃from the

above table

L= 140mm(gab between the absorber plate and glass cover)

β = 15°

K = 0.174

ε p= 0.27

ε g =0.88

Density ,ρ = 1.0947

Viscosity ,μ = 1.942×10−5

Wind speed = 2.5 m/s

α =2.453×10−5

The Reynolds number is

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Re = ρνDh

μ

Where: Dh is the hydraulic diameter

Dh=4×cross sectional area

wetted perimeter

= 4 ×(1×0.5)

2(1+0.5) = 0.667

Then Re = 1.0947× 2.5 ×0.667

1.942× 10−5 = 93996.51>4000

This means the flow is turbulent and fully developed and it can give a good heat transfer. The

Nusselt number can be calculate as

Nu = 0.0158 ℜ0.8 = 150.36

The convective heat transfer coefficient from plate to cover is :

Nu = hc , p− g× Dh

k

hc, p−g =Nu× k / Dh =7W

m2× K

Radiation heat loss coefficient from plate to glass covers,

hr , p−c=σ (T p−T c) (Tp2+Tg2)

1εp

+ 1εc

−1 =

5.68× 10−8(337+308)(3372+3082)1

0.27+ 1

0.88

= 1.9885 W/m2 K

Radiation heat loss coefficient from glass to air

hr ,c−a = εcσ (Tc2+Ta2)(Tc+Ta)

= 0.88×5.67 × 10−8(3082+2982)(308+298)

= 5.55 W/m2 K

Convective heat loss coefficient from glass to air due to wind

hw=max ¿] = max [5, 17.5] = 17.5W/m2K

To determine U L is the overall heat loss coefficient of the collector, which is a collective effect

of three coefficients that are:

I. Heat transfer from top covering (U t)

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II. Heat transfer from bottom plate (U b)

III. Heat transfer from edges (U e)

U L=U t+U b+U e

I. Energy loss through the top cover of the collector

U t= { N

CT pm

[T pm−T a

N+ f]

e+ 1hw

}−1

+{σ (T pm+T a)(Tpm2+Ta2)

(ε p+0.00591 N hw)−1+N + f −0.133 ε p

εg−N ¿

¿} =6.5W/m2K

Where:

C= 520(1-0.000051β2) for 0 °<β<70 ° β =15 = 514

f= (1+0.089hw-0.1166hw ε p) (1+0.07866N) = 2.16

e= 0.430(1-100T pm

) = 0.3

N= 1

hw= 17.5 W/m2K

The other method to calculate the top loss energy is

U t= ( 1hc , p−c+hr , p−c

+ 1hw+hr , c−a

)−1

= 6.5W/m2K

II. Bottom Heat loss coefficient

To calculation energy, loss from the bottom of the collector is transferred through the insulation

and by a combined convection and infrared radiation to the surrounding environment. However,

the temperature of the bottom of the collector is very low, and then the radiation loss was

commonly ignored. Must be known the insulation material and its thickness,

U b=K b

Lb [W/m2k] = 0.139

0.04 = 3.475 W/m2K

Where:

Kb= this is thermal conductivity of insulation

Lb= is thickness of insulation

III. Edges Heat loss coefficient

The heat transfer coefficient for the heat loss from the edges of the collector is determined by:

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U e=K e

te

However, edge heat loss is negligible compare to the other heat losses, because thickens of the

edges is very low.

The total heat loss coefficient will be summation of the three of the above:

U L=U t+Ub+U e[W/m2K]

= 6.5+3.475+0 = 9.975 W/m2K

Then to find the theoretical useful heat gain

Q = Ac FR[S−U l] (T i−Ta)

First, have to find the heat removal factor and collector efficiency factor

F’ = [1+U l

h+[ 1h 1

+ 1hr

]−1 ]

−1

Where h=h1=h2 = 7W

m2× K

F’ = 0.39

The dimensionless capacitance

ṁ Cp /A c UL F’ =0.41

F’’ = 0.411(1- e−1 /0.41) = 0.38

Finally the collector heat removal factor will be:

FR = F’F’’ = 0.15

QU=AC FR [Gt ( τα )−U l (T f −T a )] = 67.6W

Therefore useful heat gain from the collector is 67.6 W

Table:4 Absorptive and Emissivity of common selective surface [9]

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Determine Area of Solar Flat Plate Collector

Area of the collector is calculated as follows:

AC=Qmelting

I × t meltimg× ηC = 0.53m2

The solar collector has area of 1000mm length and 500mm width of half meter square. Single

glazing glass cover having a thickness of assume six mm is used the top of the collector..

4. Result and Discussion

The experimental testing of the solar wax melter was conducted at the testing area of Mekelle,

Hagerse Selam and Wukro city at sunshine time. During each test, the melting wax were

placed inside on the absorber of the solar wax melted and loaded with the same mass of wax

one kilogram (for one test) at the same temperature for two weeks wax heating test. The

temperatures of the wax in each absorber plat as well as in side collector temperature were

recorded at 10 minute intervals using digital thermometer. The solar wax melter was filled with

wax was placed in the melted, and was closed with transited mirror cover until test end. The

melter was manually oriented according to azimuth at an interval of 10 mm in order to collect

the maximum solar radiation. During experiment was test a one kilogram of “hifti” and

produce a wax material about 450gram from the input material. But at the traditional method

the output wax from one kilio gram hot about 600gram and test this wax to make a candle, the

candel and wax high quality from the solar wax melter model then traditional method.

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Surface Absorptivity Emissivity

Black chrome 0.95 0.1

Lead sulfide 0.89 0.2

Black nickel 0.9 0.17

Copper oxide 0.9 0.08

Flat black paint 0.98 0.98

Figure:3 Test the hifti to produced wax

Table:5 Heating Test

TIME TEMP.OF hifitiTEMP OF Cover

Plat3:10 22 303:20 24 323:30 27 353:40 30 383:50 32 434:00 35 514:10 39 534:20 45 604:30 49 634:40 53 654:50 55 675:00 56 695:10 57 725:20 58 685:30 59 735:40 60 705:50 62 706:00 63 70

Average 46.5 65.5

Sum 837 1179 From Table :5 show during heating test

Heat = mass*cw*(tw2-tw1) = 1*3400*(333-295) = 129200joul= 129.20KJ

Heat= I*a= 6400*0.53= 3392J

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Figure:4 shows plotting of temperature and solar radiation

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Table:6 After Melting Wax

timeMelting wax temperature (

℃)Environment temperature of inner plat

(℃)6:10 68 656:20 67 626:30 66 676:40 68 706:50 69 667:00 68 627:10 68 677:20 68 617:30 65 627:40 65 617:50 64 568:00 65 658:10 62 578:20 60 548:30 59 558:40 60 528:50 58 519:00 57 509:10 55 47

Figure:5 Shows the plotting of temperature of inner plat and mealting wax Assume Mass of

wax= 1000 gram

The wax also peraperaed in the rural area in the tranditional method:

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Figure:5 traditional method of the output wax

The during the experment compareded the output of wax from the flat plat collector hifiti

melting and cooking the raw material in the pot using biomass in table:7.

Table :7 compaired the solar wax melter flat plat and tradition method melting hifiti.

Solar wax melter flat plat Tradition method (using biomass)

Good quality Poor quality

Small output High output

No cost of source of energy High cost of source of energy

It regulated a temperature of wax It didnot regulated the temperature of wax

output

Friendly with envarioment Poluted the atmospher

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5. Conclusion The temperature to which the melting wax could be raised depended on the solar energy

intensity and the period of sunshine. Solar energy and its fluctuations were the major factor that

affected the performance of the melting process, and this depended on the natural phenomenon

that is beyond operator control. Better melting was obtained when the temperature of the

melting was higher than 64oC. With high solar energy intensity, a solar melting has wide

applications in improving traditional wax melting technology, especially in preventing wax

from being polluted and burnt. Since the temperature of melting wax like the one I constructed

can exceed 64oC, they can be used for pasteurization of wax and for other purposes. During the

experiment test from one Kg of raw material of “hefti” it produced about 450gram of pure wax

output. From this research the wax melter was very alternative for farmers and other stake

holders to produce a good quality wax material.

Reference

[1]. www.fao.org/docrep/w007E00

[2]. Crane, E. 1990. Bees and beekeeping: science, practice and world resources. Heinemann

Newness, London. pp. 614

[3] .Kameda, T. 2004. Molecular structure of crude beeswax studied by solid-state C NMR. J.

Insect Sci. 4:29

[4]. Brown, R.H. 1988. Honey bees: a Guide to management: The Crowood press Ltd London.

pp. 128.

[5]. Brwon, R.H. 1981. Bees wax. Butler and Tanner, LTD, Frome. pp. 74.

[6]. Petrus Johannes BRITZ: 2011, overview of renewable energy in the South African

agricultural sector: 1821-4487 (2011) 15; 3; p.208-211

[7]. FAO, 2005. Statistical year book, FAOSAT.

[8]. http://www.engineering tool box.com

[9] J.P Holman, heat transfer, tenth edition .

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