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Proceedings of ISES Solar World Congress 2007: Solar Energy and Human Settlement

952

absorbed by the refrigerant. The refrigerant directly

expanding inside the copper coil transfers the absorbed

thermal energy to the condenser, as well as makes the PV

cells operating at low and steady temperature to improve

the PV efficiency of the system.

Fig. 1: Cross-section view of a PV evaporator module.

2. MATHEMATICAL MODEL

The distributed model has been widely used to describe the

behavior of the dry expansion evaporator in the passed

decades (MacArthur et al., 1989; Wang et al., 1991; Tso et

al., 1999).

In this paper a distributed and steady model based on

homogeneous flow is established to evaluate the

performance of the PV evaporator. The temperature drop of

the refrigerant due to the pressure drop in the two-phase

flow region is taken into account in the model. To simplify

the calculation, the following assumptions are necessary:

(1) The temperature difference of the glass cover along the

flow direction is neglected, i.e. the temperature distribution

of the glass cover is considered to be a one-dimension

problem.

(2) The temperature of every PV cell is considered to be

uniform and the PV cell is located in the center of the

control volume of the basic panel.

(3) The contract thermal resistance of the solar collector

which is composed of the copper coil, aluminum panel and

aluminum alloy panel is neglected, i.e. the temperature of

the three elements is considered to be uniform in one

cross-section.

(4) The refrigerant flow inside the evaporator is considered

as one-dimensional homogeneous flow. The liquid and

vapor refrigerant have the same average cross-sectional

velocity, i.e. the slip between liquid and vapor is neglected.

(5) The liquid and vapor are in saturated thermal

equilibrium and the pressure of the liquid and vapor are

equal in one cross-section.

(6) The kinetic energy and potential energy are ignored in

the energy equation.

With the listed assumptions, a distributed model of the PV

evaporator with six equations can be obtained as follow:

2.1 Heat Balance Equation of the Glass Cover

(

)

(

)

()

()()( )()

=∂∂++

−++−+−

+−+−

yTlG

TTTT

λβ

ααξααξ

αα

(1)

2.2 Heat Balance Equation of the PV Cells

()

()()

()

GG TT

TT R

τβ τη α α−+ + −

+− =

(2)

3.3 Heat Balance Equation of the Solar Collector

()( )

()

()()

GA ATT

AT T R AT T AT T R

lA T y lA T z

τβ ξ α α ξ

ξα

λλ

−+ + − −+

−+−+−

+∂∂+∂∂=

(3)

3.4 Conservative Equations of the Refrigerant

()

0z =∂∂ uρ

(4)

where

ρ is the average density defined as:

()()

xx ρρρρρ −+= 1

()

zpPzuu ∂∂−∂∂−=∂∂ zρ

(5)

()

(

)

AuqπDh ρ



=∂∂ z

(6)

where

h is the average enthalpy of the refrigerant, which

is decided by the vapor quality and the specific enthalpy of

liquid and vapor refrigerant:

()

hxxhh −+= 1

3 SOLAR COLLECTOR TECHNOLOGIES AND SYSTEMS

953

In order to solve the above equations, the auxiliary

empirical correlations of the heat transfer coefficients for

the inside and outside surface of the glass cover are

necessary. An empirical correlation proposed by Müller-

Steinhagen and Heck [7] is employed in this paper to

calculate the frictional pressure of the refrigerant. The local

heat transfer coefficient of the refrigerant in two-phase flow

is calculated from a correlation which is based on the

Lockhart-Martinelli parameter [4].

Fig. 2: Cell division of the PV evaporator.

To obtain a solution for the problem, the solar collector

should be divided into small cells. Two types of divisions

have been shown in Fig. 2, one of which is according to the

flow direction and another is according to the Z and Y

direction. With the two types of divisions, the temperature

of the solar collector have two different form of expressions:

T and

kjc

T . To facilitate the programming procedure,

transformation between the two different expressions is

necessary. The matrix

()

∏

= ikj,

according to the coil

circuitry of the evaporator can be used to realize the

transformation

With the division shown in Fig. 2, the model can be solved

based on the implicit finite difference method.

3. RESULTS AND ANALY SIS

In order to investigate the behavior of the PV evaporator, a

numerical simulation program is written in C++ language.

The boundary conditions for the program are shown as

follow:

Solar irradiation in normal direction: 600 (W/m

)

Ambient Temperature: 278.15 (K)

Inlet pressure: 700 (kPa)

Mass velocity: 100 (kg/m

The pressure distribution along the copper coil in the

evaporator is given in Fig. 3. The frictional pressure drop

increases with the vapor quality in two-phase flow region

and declines in dry-out region (x>x

) [8]. Hence, the slope

of the pressure along the pipe escalates in two-phase region

and drops where the pipe length is about 16.2 m as shown

in the figure.

Fig. 3: The pressure distribution along the copper coil.

The distribution of the vapor quality and void fraction of

the refrigerant can also be given by our program. A s can be

observed in the figure, the vapor quality varies almost

linearly in two-phase flow region and keeps constant in the

superheat region. The void fraction increases rapidly from

0.5 to 0.9 where the pipe length L<3 m. It is because that

the void fraction is more sensitive with small value of the

vapor quality according to the following correlation:

()

[]

dxxd ρρρρρα +−>=<

(18)

The temperatures distribution of the PV cells, solar collector

and refrigerant along pipe length are illustrated in Fig. 5. As

can be seen, the temperature of the refrigerant keeps nearly

const with a tiny drop in two-phase flow region and increases

rapidly in superheat region due to the small heat capability of

the vapor refrigerant. The area of the superheat region is

about 10% of the total area. The degree of the superheat is

about 12 K. The temperatures of the solar collector and PV

cells show a similar trend as the refrigerant.

Proceedings of ISES Solar World Congress 2007: Solar Energy and Human Settlement

954

Fig. 4: The distribution of the vapor quality and void

fraction.

Fig. 5: The temperatures distribution.

The distribution of the average specific enthalpy of the

refrigerant is depicted in Fig. 6. The specific enthalpy of

the vapor and liquid refrigerant is nearly const in two-phase

flow region. Hence the average specific enthalpy can be

considered as a linear function of the vapor quality in this

region according its definition. As shown in the figure, the

average specific enthalpy rises more slowly in superheat

region than that in two-phase flow region which is because

of the smaller heat transfer coefficient of the vapor

refrigerant.

Two-dimensional temperature distribution of the solar

collector is depicted in Fig. 7. The temperature difference

along Z direction is much smaller than that along Y

direction. Because of the frames of every evaporator module,

Fig. 6: The distribution of the average specific enthalpy.

the effective thermal absorbed area for the marginal nodes

along Z direction is a little smaller than that of the other

nodes. Hence, the temperature shows a wavy trend in

two-phase flow region. The temperature along flow

direction in superheat region may drop due to the heat

conduction of the nodes with the others in the two-phase

flow region along Y direction.

Fig. 7: Two-dimensional temperature distribution of the

solar collector.

As shown in Fig. 8, two-dimensional distribution of

the PV efficiency experiences an opposite trend with

the temperature of the solar collector and PV cells. A

wavy changing in two-phase flow region and a sharp

drop in superheat region can also be observed from the

figure.

3 SOLAR COLLECTOR TECHNOLOGIES AND SYSTEMS

955

Fig. 8: Two-dimensional distribution of the PV efficiency.

4. CONCLUSIONS

A specially designed PV evaporator, which combines two

solar technologies into a system for dual production of

electricity and thermal energy, is presented in this paper. A

steady model based on the distributed parameter is

established to describe the behavior of the evaporator. With

the model, nearly linear distribution of the vapor quality

and average enthalpy of the refrigerant can be obtained.

The temperature difference of the refrigerant, solar

collector and PV cells in two-phase flow region is much

smaller than that in superheat region. The area of the

superheat region is about 10% of the total area when the

superheat degree can reach 12 K. The void fraction is more

sensitive with tiny changing of the vapor quality in the

region where the vapor quality is small.

5. ACKNOWLEDGMENTS

The work in this paper was sponsored by the National

Natural Science Foundation of People’s Republic of China

(No. 50478023) and Anhui Province Nature Science

Foundation of China (No. 070414161).

6. REFERENCES

(1) Kern Jr. E. C., Russell M. C., “Optimization of

photovoltaic/thermal collector heat pump systems”,

International Solar Energy Society meeting

, Atlanta,

GA, USA, 1979, pp.1870-1874.

(2) Sadasuke Ito, Nakatsu Miura, Jin Qi Wang, “Heat

pump using solar collector with photovoltaic modules

on the surface”, Journal of Solar Energy Engineering,

1997, Vol.119, pp.147-151.

(3) J.W. MacArthur, E.W. Grald, “Unsteady compressible

two-phase flow model for predicting cyclic heat pump

performance and a comparison with experimental data”,

International Journal of Refrigeration, 1989, Vol.12,

pp.29-41.

(4) H. Wang, S. Touber, “Distributed and non-steady-state

modeling of an air cooler”, International Journal of

Refrigeration, 1991, Vol.14, No.2, pp.98-111.

(5) X. Jia, C.P. Tso, P. Jolly, Y.W. Wong, “Distributed

steady and dynamic modeling of dry-expansion

evaporators”, International Journal of Refrigeratio,

1999, Vol.22, pp.126-136.

(6) Duffie JA, Beckman WA. “Solar engineering of

thermal processes”, 2nd Edition. New York: Wiley;

1991.

(7) Müller-Steinhagen H., Heck K., “A simple friction

pressure drop correlation for two-phase flow in pipes”,

Chemical engineering and processing , 1986, Vol. 20,

No.6, pp.297-308.

(8) M.B. Ould Didi, N. Kattan, J.R. Thome, “Prediction of

two-phase pressure gradients of refrigerants in

horizontal tubes”, International Journal of

Refrigeration, 2002, Vol. 25, No.7, pp.935-947.

APPLICATION OF SOLAR HEATING SYSTEM IN BIOGAS PRODUCTION

Rong Dai

1,2

, Chang Chun

, Zhibin Xu

, Xiaobing Liu

1,2

, Ζhifeng Wang

Himin Solar Energy Group Co., Ltd, Dezhou, Shangdong 253090, P.R. China

Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080, P.R.China

ABSTRACT

In the biogas production from agriculture manure by

anaerobic digestion, it is necessary to keep the bioreactor

optimum and steady temperature. The optimum condition

usually can not be achieved automatically in winter in

North China. The solar water heating system using

evacuated tubes with auxiliary electrical heater was

adopted to charge the thermal energy to the bioreactor,

which made the bioreactor work regularly. It was

experimentally investigated that the required solar

collector area, the production amount of the biogas and

the auxiliary electrical power at the temperature of 15 , ć

20 and 25 of the ććbioreactor. The biogas production

system has been running steadily for two years. As a

result, when the daily average solar flux was 13.2 MJ/m

and the temperature of a

bioreactor of 6m

was optimized

to be at (20±1) in the coldest month in Beijing, 3.85mć

of solar collector area was required, and 0.2-0.25m

of biogas can be obtained.

1. INTRODUCTION

Biogas can be produced from agriculture manure by

anaerobic digestion. This technology has many benefits in

view of environment, agriculture and sustainability[1,2].

Biogas plants for family have been extensively used in

most of the farms in China. Temperature is an important

factor that affects the performance of anaerobic

digestion[3]. This optimum condition for the anaerobic

digestion usually can not be achieved automatically due to

harsh cold climatic conditions. So electricity, oil or part of

the biogas produced in the process is used to keep the

reactor at the desired temperature. But using such

high-level fuel is very uneconomical[4]. In the meantime,

there is enough solar radiation in winter in North China, it

is possible to use a solar collector combined with a heat

exchanger to heating manure in the bioreactor. So the

bioreactor can achieved an optimum and steady condition

to produce biogas. As a rule, it is needed to input more

solar thermal energy into the bioreactor to keep the

bioreactor at higher temperature. The bioreactor

temperature is kept at 35 or 54ćć[5], at which more

biogas can be produced. But higher temperature of the

bioreactor will lead to an increase in the original

investment. So it is necessary to find the optimum

temperature of the bioreactor in view of cost.

2. DESCRIPTION OF SYSTEM

Figure 1 shows the schematic diagram of the proposed

system. Solar collectors combined with a heat exchanger

was used to heating the manure in the bioreactor, and

increased the bioreactor temperature to an optimum value

in a steady condition. In order to keep the system run in

steady condition, the control unit was adopted. If there was

not enough solar thermal energy input into the bioreactor

(e.g. cloudy), or the water temperature in solar tank is

below 45 ,ć the solar heating system stops working, then

the auxiliary electrical heating system starts to supply the

3 SOLAR COLLECTOR TECHNOLOGIES AND SYSTEMS

957

heat to the bioreactor. The bioreactor was positioned under

the ground. The biogas produced from the bioreactor was

transported to the kitchen by the designed pipe for cooking.

The heat balance of the system was shown in Fig. 2.

Fig. 1: Schematic of the system configuration.

1 solar collector; 2 pump; 3 control valve; 4 heat exchanger; 5 bioreactor;

6 movable cover of bioreactor; 7 H

O removal; 8 manometer; 9 H S removal

vessel; 10 gas counter; 11 biogas cooker; 12 kitchen

Fig. 2 Overall heat balance diagram.

The nomenclatures are as the follows.

losses from the solar collector, Q

heat losses from the

influent (W),T

the biogas temperature ( ), ć Q

aux

auxiliary

heat add to the reactor (W), Q

heat losses from biogas

volume to ambient (W), Q

heat losses from the effluent

(W), T

the temperature of the manure (ć), T

ambient

temperature (ć), Q

inner energy of manure (W), Q

heat

losses by convection from the liquid to biogas (W), Q

heat losses from the liquid via biogas bubbles (W),

overall radiation amount per day, Q

heat losses from

biogas volume to ground (W), Q

col

useful heat gain rate

from the collector (W);

2.1 The Bioreactor

In the proposed system, the volume of the bioreactor under

the ground was 6 m

in order that the biogas produced can

be enough for cooking of a family of three people. The

movable cover of the reactor is installed above the ground.

The raw material adopted agriculture manure. The

concentration of the water in the manure is 10%, and the

effective volume of the manure fed to the bioreactor is 5.2

. The other space (i.e 0.8m

) can hold the biogas

produced. The manure was fed to the system every three

days. The amount of manure added to the reactor was equal

to that of manure withdrawn from it.

It is assumed that the manure in the bioreactor is always

well mixed at a uniform temperature. The energy balance

equation for the bioreactor can be written as:

VC Q Q Q Q Q Q Q Q

ρ =+−−−−−+

˄1˅

where:

the density of the manure (kg/m

), V effective

reactor volume (m

), C

specific heat of manure(Jg kg

-1

t time (s), T

the temperature of the manure˄ć˅, Q

col

useful

heat gain rate from the collector (W), Q

aux

auxiliary heat

added to the reactor (W), Q

heat losses from the influent

(W), Q

heat losses from the effluent (W), Q

heat losses

from the manure to the ground (W), Q

heat losses from

the liquid via biogas bubbles (W), Q

heat losses by

convection from the liquid to biogas (W), Q

inner energy

of manure (W).

Assuming that the biogas temperature in the enclosure is

uniform, its heat balance equation can be written as:

VC Q Q Q Q

ρ =+−−

˄2˅

where

ρ the density of biogas (kg/m

), V

the volume of

biogas(m

), C

the specific heat of the biogas (Jgkg

-1

the biogas temperature (ć), t time (s), Q

heat losses

from the liquid via biogas bubbles (W), Q

heat losses by

convection from the liquid to biogas (W), Q

heat losses

from biogas volume to ground (W), Q

heat losses from

biogas volume to ambient (W).

Proceedings of ISES Solar World Congress 2007: Solar Energy and Human Settlement

958

2.2 Solar Collector

There are two solar collectors used in the system. They

were

fabricated at the tilt angel of 45

and faced to the south

direction. One solar collector was made up of 18 vacuum

tubes with 58mm in diameter and 1.9m in length. The

distance between two vacuum tubes is 21mm. The overall

area of one collector is 2.5m

. At the meantime, there is an

auxiliary electrical heater system with the power of 1500W

in the water tank. The volume of the water tank is 163L.

It can be assumed that the temperature distribution of the

collector and the water tank is linear, and their average

temperature are

T and T , respectively. The thermal

capacity of the collector can be neglected since it is very

small

[6]

. The obtained energy from the solar collectors can

be presented by the following equation,

()'[()]mC T T A F S U T T−= − −



(3)



is the flow rate of the water˄kggs

-1

˅, C specific heat

of water, (Jgkg

-1

), T

f,o

water outlet temperature from

the solar collector, ( )ć ˈT

f,i

water inlet temperature to the

solar collector, ( ),ć A

the solar collector area (m

), 'F the

collector efficiency factor,

S absorbed radiation(W/m

)ˈ

overall heat loss coefficient from the solar collector to

environment, (Wm

-2

-1

)ˈT

average temperature of the

water in the solar collector, T

ambient temperature( )ć .

2.3 Heat Exchanger

The heat exchanger is coiled by copper pipe with the

diameter of 16mm. This design is simple and the cost is

very low. The heat provided by the heat exchanger can

compensate for the heat loss from the bioreactor. The

logarithmic mean temperature difference for the heat

exchangeris calculated from the heat exchanger[7].

2.4 The Control System

The purpose of the control system is to keep the bioreactor

temperature constant. When the temperature of the

bioreactor was below the given temperature, the water

pump started to run and the heat can be input into the

bioreactor by the hot water from the solar collectors. The

pump stopped working when the temperature achieved the

given value. If the temperature of the water in the tank can

not reach the needed value, the auxiliary electrical heat

system started to work until the temperature of the tank

reached up to the needed value. The designed temperature

of the sensor can be adjusted ranging from 0 to 80 ,ćć

which can satisfy different digestion temperature for the

bioreactor.

3. EXPERIMENT METHOD

Because the original investment needs to be reduced and

the biogas produced can be enough for daily use for

farmers, an optimum temperature of bioreactor must be

found in the experiments. For this purpose, the experiments

at the temperatures of 15ć, 20ć and 25 ć were carried

out on the abovementioned proposed system.

3.1 The Digestion Temperature

The experiments were carried out at the digestion

temperatures of 15ć, 20ć and 25ć, respectively.

3.2 The Material of Digestion and Inoculant

The material of the digestion was the cattle manure that

came from the cattle farm near the laboratory. By the test,

the TS is16.98%, the VS is78.02% .The inoculant is gained

from swine manure. TS is 10.43% ,VS is 72.22 %.

4. RESULTS AND DISCUSSION

4.1 Measurement of Material Before and after Digestion

Test unit˖250ml, inoculantǃ60g cattle manureˈadd liquid

manure to1000ml˗

Comparision unit˖250ml, inoculant, add liquid manure

to1000ml˗

Digestion temperature:

(20+1)ć, pH is kept at 7.

Table 1 shows the value of TSǃVS before and after the

digestion. It can be seen from Fig. 1 that the concentrations

of TS and VS in anaerobic manure were very low. Based on

3 SOLAR COLLECTOR TECHNOLOGIES AND SYSTEMS

959

the color of the blaze of the biogas[8], we can know that

the content of the methane varied from 55% to 65%.

TABLE1: THE VALUE OF TS ǃ VS BEFORE AND

AFTER THE DIGESTION

BEFORE

DIGESTION

AFTER

DIGESTION

TS/% VS/% TS/% VS/%

Test 8.25 80.91 4.85 78.12

Comparison 4.85 79.37 3.57 78.49

4.2 Relationship Between Biogas Production and Digestion

Temperature

It also can be seen from Fig. 3 that in the range of 15ć-

25ć, more production biogas can be produced at higher

fermentation temperature. In the rural area of China, the

daily use of biogas for one person is about 0.4 m

3[9]

, so the

biogas production of 20ć can meet the need of a family of

three people. The production of the biogas at 25 ćis

0.0966m

/d higher than that at 20ć. The heat value of

is 35.882 MJ/m

. Assuming that CH

accounts for 65%

of the biogas, the difference of energy between the biogas

production in 20ć and 25ć is 2.25MJ.









day

biogas production

m /d

Fig. 3:

biogas production at 15 ,ć biogas production at

20 ć

biogas production at 25ć.

4.3 Relationship Between Radiation, Ambient Temper-

ature and Consumed Electricity

As shown in Fig. 4, the relationship between the consumed

electricity and solar irradiation was not linear, because the

consumed electricity is affected by several factors,

including water circulation by the pump, the electrical

consumption of the auxiliary heat system and the ambient

temperature. If the bioreactor temperature and the collector

area are kept constant, higher solar radiation can lead to

less electrical consumption.











day

value

Fig. 4:

ambient temperature( ),ć consumed electricity

˄kWh˅ˈ

radiation (MJ/m

4.4 Relationship Between Digestion Temperature and

Area of Solar Collector

The average daily solar radiation is 13.2 MJ/m

in the

coldest month in Beijing. The relationship between the

digestion temperature and the area of the solar collector is

shown in table 2. If the efficiency of the solar collector is

0.44, increasing 1.05m

area of the solar collector will lead

to the energy increasing to 6.09 MJ at the same ambient

temperature.

TABLE2: RELATIONSHIP BETWEEN THE TEMPE-

RATURE OF THE DIGESTION AND THE AREA OF

THE SOLAR COLLECTOR

FORMEMTATIO

N TEMPERTURE

˄ć˅

SOLAR

COLLECTOR

AREA˄m

BIOGAS

PRODUCTION

˄m

·d˅

20 3ˊ85 0.2-0.25

25 4ˊ91 0.2-0.27

5. CONCLUSIONS

In order to reduce the original investment of the solar

system and to meet the daily use of the farmers in the

meantime, a biogas production system was proposed.

Experiments were carried out at the bioreactor reactor of

15ć, 20ć and 25ć. The relationship between the biogas

production, the area of the collector and the electrical

consumption was built. The main conclusions are as

follows.

(1) In the same condition, the efficiency of biogas

Proceedings of ISES Solar World Congress 2007: Solar Energy and Human Settlement

960

production in 20 is higher than the efficiency in 25 . So ćć

the system deserves to popularize in the rural areas.

(2) Using solar thermal energy or other renewable sources

to heating the bioreactor is a good alternative, because

these sources are environmentally friendly. However, there

are still significant gaps between the costs of these sources

and that of traditional ones[10]. We give emphasis this

view to next research.

6. REFERENCES

(1) Van Velsen A F M; Lettinga G, “Effect of Feed

Composition on Digester Performance”. In: Anaerobic

Digestion (Stafford D A; Wheatley B I; Hughes D E,

eds). Applied Science Publishers Ltd., London,

UK.,1980

(2) De Baere L, “Anaerobic Digestion of Solid Waste”:

stateof-the-art. Water Science and Technology, 41 (3),

283-290, 2000

(3) MengjinZhou,“Biogas Practical Technology”[M], Beijing,

Chemical Industry Press, 2004

(4) Axaopoulos P; Panagakis P; Tsavdaris A; Georgakakis

D (2001). “Simulation and Experimental Performance

of A Solar-heated Anaerobic Digester”, Solar Energy,

70 (2), 155-164

(5) Zhenghong Yuan, Chuangzhi Wu, Longlong Ma,

“Principle and The Use of Biomass Technology”[M],

Beijing, Chemical Industry Press,2005.

(6) Wenhua Xi, “Solar Practical Engineering Technology”

[M], Lanzhou University press, 2001

(7) Dahl S D; Davidson J H, “Comparison of Natural

Convection Heat Exchangers for Solar Water Heating”,

Proceedings of Solar, 95. The 1995 American Solar

Energy Society Annual Conference, 15-20 July,

Minneapolis, MN, USA ,1995

(8) Yunhua Jiang, et al., “The Judgment of Methane

Gas Content by Flame Color”[J], China Gas, 1983,(3),

(9) Zeyang Wang, “Rural Methane Practical Technology”

[M], Shandong: Petroleum university press, 2004

(10) Sims R E H, “Renewable Energy: A Response to

Climate Change”, Solar Energy, 2004, 76, 9-17

THE SOLAR ENERGY MULTIPURPOSE ADJUSTABLE CONTROL GLASSHOUSE

Song Ziling, Zhong Xianliang, Zhang Lixin

LIAONING technology university,

Fuxi city Liaoning province,123000

SONGZILING-163@163.com

ABSTRACT

The glasshouse, which can be used to plant, stockbreeding

and the low temperature dryness industry, even though

built in temperate zone and cold zone also can adjust

various temperature and humidity to meet the request of

production. Its concrete measures as follows: Adjust

glasshouses layout and extend its scope for settling to

decrease area of dissipation and increase the area of usage.

Make use of efficient adopt light lead pieces and make

them vertical plane alignment and face to south, under the

no sun follow device situation make the sun light from

sunrise to sunset 100% can be collected, and from various

angle spread to leaf, receptacle, stem etc. to improve the

output and quality of agricultural product greatly. Make a

part of sunlight shoot straight at soil, making use of the

characteristics which the heat capacity of soil is larger to

save heat, make sure the room temperature invariable in

night and rainy day. The temperature and humidity may

regulate arbitrarily, keep plants away from various plant

diseases and pests. When the Solar Energy is used for

drying technique, regulate the temperature near to 100ć,

makes sunlight shoot straight at drying thing surface.

Make solar energy drying technique enter the high-effect

times.

1. INTRODUCTION

The Solar Energy Multipurpose Adjustable Control

Glasshouse technology supply solar energy high efficient

used, and be the same with various purpose. This is solar

energy utilizing technology, and is all-purpose

establishment for the vegetable, esculent mushroom, animal

breed, and peasant byproduct dryness.

Since 1980s, the saving energy solar light glasshouse, that

is Chinese protect soil establishment, gain ground in north

area. Ten year recently, it was more used in other area of

China. The saving glasshouse area is enlarging, and

obtaining remarkable economical, social, ecological benefit.

But such glasshouse utilized lower-efficient solar energy.

Mostly, these cause are that the temperature of glasshouse

is lower in winter, only 20ć in day, 8ć in nighttime, so as

to the more crop cannot get high yield. In freezing area, the

glasshouse cannot help but use assistant heat. In a word,

current solar light glasshouse has not extrusive effect to

save energy, and has not width applying field, and has more

energy saved in newly glasshouse.

The designing of the solar energy multipurpose adjustable

Труды Всемирного конгресса Международного общества солнечной энергии - 2007. Том 2

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