numerical investigation of heat transfer enhancement in

Numerical Investigation of Heat Transfer Enhancement in

Parabolic Trough Solar Collector with Twisted TapeInsert

Duraid M. Muter, Mustafa B. Al-Hadithi

College of Engineering, University of Anbar, Ramadi, Anbar, Iraq.

Email Address: Correspondence should be addressed to Duraid M. Muter [email protected]

Received: 16 Nov 2020, Revised: 11 Dec 2020, Accepted: 3 Jan 2021, Online: 12 Jan 2021

Abstract

In this research, an experimental and theoretical study was conducted to show the performance of a parabolic

trough solar collector in the case of inserting a twisted tape and in the case of not inserting a twisted tape. The

parabolic trough solar collector (PTSC) is designed and manufactured with a length of (2m) and with a width of

(3.48m) and an area of (5.48m2). The parabolic trough is coated with chrome steel sheets. A copper tube is used

to absorb heat. Its outer diameter is (0.022m) and its thickness (0.0195m) through which water used as a heat

transfer medium passes where the mass flow rate was (m ̇= 0.05Kg / sec). A twisted tape was used the twist

ratio is (y = 4). Simulation studies were carried out using the (ANSYS FLUENT 17) software on the receiver

tube. Measurements and calculations were made under the climatic conditions in the industrial zone of Fallujah

city on 5, 6 September. The performance of the parabolic trough solar collector was evaluated by calculating the

useful heat, thermal efficiency, and exit temperature numerical and experimental for both cases (insert, non-

insert of twisted tape), and a comparison of experimental results between the two cases was made. For both

cases, the results showed that the efficiency of the parabolic trough solar collector by inserting a twisted tape is

higher than the efficiency of the parabolic trough solar collector without a twisted tape insert.

Keywords: Parabolic Trough Solar Collector, Twist Tape, Receiver Tube, Solar Energy

1. Introduction

Energy is the main factor in the economic

advancement of all countries, through

which household appliances, factories, and

transportation are operated. Energy

sources are classified into two types of

non-renewable sources resulting from the

use of fossil fuels that are characterized by

being non-renewable and polluting the

environment. And renewable sources from

natural sources that are renewable without

being implemented or affecting the

environment. As a result of the human

being’s continuous need for energy and

non-renewable energy problems, scientists

have directed to study and develop how to

make use of renewable energy sources.

Parabolic trough collector , which will be

our aim from this study, is one of the

Global Scientific Journal of Mechanical

Engineering

www.gsjpublications.com/gsjme

www.gsjpublications.com

Global Scientific Journal of Mechanical Engineering

1 (1) 2021/ 1-15

mailto:[email protected]

http://www.gsjpublications.com/gsjme

http://www.gsjpublications.com/

Muter, D. M. & Al-Hadithi, M, B. Global Scientific Journal of Mechanical Engineering 2021/ 1 (1) 2

important applications to take advantage of

solar energy and convert it into thermal

energy.

The researcher Khaled Al-Zahrani

conducted [1] conducted a practical study

to find the efficiency of a Parabolic trough

solar collector where the reflector area was

0.75m2, the dia

2eter of the absorbent tube

is 0.03m and its thickness 0.006m, the tube

was painted in black and coated with a

glass cover . The flow rate was 0.03 kg/s.

The researcher concluded that the

efficiency rate was 38% and that the

highest efficiency of the collector was 52%

at noon.

Saha et al [2] conducted an experiment to

simulate the enhanced heat transfer

process of a tube with center-cleared

twisted tapes and coaxial fins. The

researcher concluded that it is a Nusselt

number that gets smaller when the larger

the hollow width of the tapes, but the flow

strength also reduced at the same time.

Eiamsa-ard and Promvonge [3] found that

an optimal spacing ratio of 0.5 yielded the

best Nu, which was 50% higher than that

gained using a plain tube.

Guo et al. [4] studied the general

performance of the tube with twisted tapes

with a width of 10 and 18 mm. The results

showed that a tube with a wide twisted

tapes enhanced heat transfer for the

laminar flow, while the improved narrow

twisted tapes enhanced heat transfer better

for turbulent flow.

The researcher Falah Abdul-Hassan

Mutlaq [5] studied a practical design of the

equivalent solar complex, where the solar

reflector was manufactured with an area of

(5.04). The inner surface of this reflector is

covered with mirrors. Industrial machine

oil has been used as the heat transfer

medium. Three types of experiments were

performed to evaluate the thermal

performance of the first type using an

absorbent metal tube without thermal

coating, the second type using a heat

absorbent metal tube covered with the

latter type using a pipette covered with a

glass tube and a vacuum. Experiments

were conducted under the climatic

conditions of Baghdad during the months

(October, November, and December). The

researcher found that the average thermal

efficiency of the collector is about 61%.

When using a vacuum receiver. Whereas,

the average thermal efficiencies decreased

to 51% and 40%, for the coated and

uncoated metal receivers, respectively.

Ouagued [6] carried out a numerical model

of a parabolic trough collector under

Algerian climate. In this model, the

receiver is divided into several segments,

and heat transfer balance equations which

rely on the, optical properties, heat transfer

fluid (HTF), collector type and ambient

conditions are applied for each segment.

This work led to the prediction of

temperatures, heat gain, and heat loss of

the parabolic trough. Results indicated that

with the increase in temperature of

absorber tube and heat transfer fluid

(HTF), the heat loss of the parabolic

trough collector increases and also heat

gain decreases.

K. Syed Jafar and B. Sivaraman [7] these

two researchers conducted an experimental

study to verify the thermal performance of

the parabolic trough collector (PTC)

equipped with two different configurations

of the twisted tape. The results showed that

the smaller twist ratio enhances the system

performance better than the larger ratio. It

also showed that the thermal performance

of the parabolic trough receiver in the case

of inserting a nails twisted tape is much

better than the normal twisted tape.

D N Elton and U C Arunachalaa [8] these

two researchers conducted an experimental

study to show the thermal performance for

plain receiver and receiver with twisted

tape of the parabolic trough. They


experimentally calculated the Nusselt

number for plain receiver and receiver

with twist ratio (y=3.48, 5.42 and 7.36)

and they also calculated Nusselt number of

generalized correlations for plain absorber

and absorber with twist ratio (y=3.48, 5.42

and 7.36). The results showed that the

error rate is between and Nusselt number

experimental and Nusselt number of

generalized correlations for plain receiver

and receiver with twisted tape is 20 .%

Sh. Ghadirijafarbeigloo, A. H. Zamzamian

and M. Yaghoubi. [9] These researchers

performed a numerical analysis to improve

the coefficient of thermal load in the

receiver tube of the parabolic trough

equipped with a perforated louvered

twisted tape. In numerical simulations

were used three different twist ratios (2.67,

4, and 5.33) Results show that the pressure

drop and heat transfer coefficient increase

significantly in comparison with a typical

plain twisted tape in the tube.

Ruby, Steve [10] (American Energy

Assets, California L.P.), this project

researched the viability of producing high

temperature industrial process heat from

the sun‟s energy. In this installation, high

temperature water in excess of 232°C is

produced by a concentrating solar field,

which in turn is used to produce

approximately 300 pounds per square inch

(20 bar) of process steam. The solar

thermal system is intended to improve

plant efficiency with minimal impact on

day‐to‐day production operations. Process

steam in the plant is used for heating

baking equipment, cooking equipment by

heating edible oil for frying and the steam

is also converted into hot water for

cleaning and sterilization operations.

2. Experımental Setup

The experimental setup of PTC consists of

the following parts:

2.1 Reflector

The chrome steel sheets were chosen to

form the reflector used in this experiment

because these plates have good light

reflection. The reflector is designed as

symmetrical part of a parabola around its

vertex according to the parabolic equation

is y =(x2 / 4f). The input parameters in

Parabolic Trough design were the focal

length (f) is 1m from the vertex (V) and

the aperture width (W) is 3.45 m. The plot

of above equation gives the surface

illustrated in the figure 1.

Figure 1. Designed parabola.


We manufactured two parts steel structure:

The first part is three steel arcs that were manufactured with a machine cnc and take the form

parabolic to give the parabolic shape to the chrome sheets that were placed on it and fixed

through the lower holes of these arches a spindle which is used to hold these arches and

plates and the parabolic trough rotation and install a tool to measure the angles (protractor) as

shown in the figure 2. The second part is a Stationary Main Base whose function is to hold

the parabolic trough and spindle as shown in the figure 3. The chrome steel plates is placed

on the parabola frame to take the form parabolic and fixed by adhesive paste as shown in the

Figure 4.

Figure 2. Manufacture parabola by CNC.

Figure 3. Fabricate reflector base parts. Figure 4. Parabolic frame and

reflector.

2.2 Tracking system

The tracking system used in this

experiment is a manual system, where the

center of the protractor is installed on the

center of the spindle shaft to ensure the

rotation of the parabolic trough and the

protractor at the same angle as shown in

Fig 5. For the purpose of tracking the sun,

the parabolic trough is rotated 5 degrees

every quarter of an hour, and these degrees

are read by the scale of the protractor. The

parabolic trough is fixed after each rotation

by adjustment mechanism as shown in

Figure 6.


Figurer 5. Manual tracking system. Figure 6. Mechanism for controlling

parabolic trough rotation.

2.3 Receiver Pipe

There are several design considerations

followed before choosing the type of tube

material received, and these considerations

are:

The material of the receiving tube should

not create chemical reactions when the

working fluid has passed through it. In

designing solar collectors, the minimum

design temperature is 250°C , so the

receiving tube must endure a temperature

higher than 250°C. The material of the

received tube must resist weather

corrosion because solar collectors are

always placed outdoors. The maximum

pressure of the system must be known in

order to provide the appropriate material

and thickness for the tube. Therefore, in

this study we used copper as a resistance to

chemical reactions, weather and high

temperatures. The dimensions of the

received tube are an important factor in

addition to the materials present in the

current work. The receiving tube is

covered with a glass tube as shown in

Figure 7. The space between the two tubes

is evacuated from the air to prevent the

heat losses which resulted from the

convection and conduction. We chose the

dimensions of the receiver pipe and the

dimensions of the glass cover as shown in

Table1. Thus the absorbed solar energy is

converted to heat and transmitted to fluid.

Figure 7. Photograph of receiver and glass cover pipe.


Table 1. Specifications of the receiver and glass cover pipe.

2.4 Twist Tape

The technical specifications for the twisted tape used in this study are given in the table 2.

Figure 8 shows a twisted tape.

Figure 8. Twisted tap.

Table 2. Specifications of twisted tape.

Item Value/Type

Length of receiver and cover pipe 2m

Absorber inner diameter (Dri) 0.0195

Absorber outer diameter (Dro) 0.022m

Glass cover pipe diameter 0.09m

transmittance of the glass cover 0.91

absorptance of the receiver 0.93

Pressure of vacuum space 0.005 Pa

Material of the absorber pipe Copper

Item Value

Length of twisted tape 2m

receiver pipe inner diameter 0.0238m

Pitch (H) 0.085m

Twist ratio (y) 4


2.5 Storage tank

The storage tank has diameter 1m, height

1.5m as shown in Figure 9. It has the

ability of holding amount of water of 200

liter, with maximum pressure of 300 psi.

The storage tank has a safety relief valve

that is open to the atmosphere. The glass

wool was used as insulator in order to save

the required working temperature for the

system with thickness of 8 cm. The tank's

bottom pipe (which is the cold end) is

attached to the pump and the pipe coming

from the trough (which is the hot end) is

attached to the upper end of the tank.

Figure 9. Storage tank.

2.6 Flow Meter

A flow meter is a device used to measure

the volumetric flow rate of a heat transfer

fluid .We need a flow meter that can

withstand high temperatures In the case of

solar applications as shown in Figure 10.

So we used a flow meter that works well

with temperatures up to 250 °C, and the

maximum pressure is 15 bar. It has

dimensions of 0.5 in outer diameter and 6

in long. The materials of the device body

is stainless steel 303, it has dimensions of

40mm length, width 45mm and height

225mm. and its core and piston made of

brass C 360.

Figure 10. Flow meter.


3. Experımental Procedure

The experimental planning used in this

experiment are shown schematically as in

the figure 11 and as a picture as in the

Figure 12. The test was carried outdoor

during 5, 6-September in the industrial

area of the city of Fallujah, from 9:00 am

to 03:00 pm. The tank is installed on one

side of the solar collector, after which the

pump is attached to the bottom tube of the

tank in order to pump the (cold) fluid from

the tank to the received tube through

flexible tubes .The flow meter was placed

after the pump. The tank is filled with

working fluid. Setting and positioning the

parabolic trough manually according to

sunlight, and running the system for 15

min prior to recording the first reading.

The time interval between each reading is

set to 15 min. The intensity of the solar

radiation was measured using a device

(pyranometer) at time intervals every 15

minutes. The working fluid temperatures

were measured at the inlet and outlet of the

received tube using the data acquisition

system continuously during the

experiment.

Figure 11. Layout of the experimental setup.

Figure 12. Photograph of the experimental setup.


4. Thermal Effıcıency

The thermal efficiency of a PTSC () can be defined as the ratio of heat useful gained by the

collector, to the total incident solar radiation. The thermal efficiency can be calculated using

the following equation.

𝜂 =𝑄

𝑢

𝐴𝑟 𝐼𝑏

Where ( Ib )Beam solar radiation measured at any instantaneous time.

𝐴𝑟 = 𝜋 𝐷𝑟,𝑜 𝐿

Useful heat gain (Qu)

The useful heat gain is the instantaneous heat energy obtained by the HTF during its flow

passage between the inlet and outlet of the PTC.

𝑄𝑈 = 𝑚 ̇ 𝑐𝑝 (𝑇𝑜𝑢𝑡 − 𝑇𝑖𝑛 )

Where: Tin and Tout represent the inlet and exit fluid temperature, respectively measured at

any instantaneous time. �̇� is the mass flow rate of the HTF in the flow circuit.

5. Numerıcal Analysıs

A simulation study was performed on the heat receiving tube using the ansys fluent 15

program. The heat receiving tube was drawn using ansys program and then the twisted tape

that was drawn using the solid work program was inserted. The meshing is an important

operation in modeling as the quality of the meshing determines the accuracy of the solution.

The meshing of the two parts model were made using the ansys program as shown in

Fig.13 and then entered the settings Required for the simulation and then a simulation study

was performed on the heat receiving tube without twisted tape as shown in Figure14.

(a) Lateral view (b) Front view

Figure 13. Sample mesh of absorber tube and fluid with twist tape.


(a) Lateral view (b) Front view

Figure 14. Sample mesh of absorber tube and fluid.

6. Governıng Equatıons

The numerical simulation conditions are assumed to be in steady state, Incompressible Flow

And laminar flow. Therefore, the governing equations are given as follows [12]:

Continuity equation

𝜕(𝜌𝑢𝑖)

𝜕�̅�𝑖 = 0

Momentum equation

Energy equation

𝜕

𝜕𝑥𝑗(𝜌�̅�𝑗 𝑐𝑃�̅�) =

𝜕

𝜕𝑥𝑗

(𝜆𝜕�̅�

𝜕𝑥𝑗+

𝑢𝑡

𝜎ℎ,𝑡 𝜕( 𝑐𝑃�̅�)

𝜕𝑥𝑗) + �̅�𝑗

𝜕�̅�

𝜕�̅�𝑗+ [𝜇𝑒𝑓𝑓 (

𝜕𝑢𝑖

𝜕𝑥𝑗+

𝜕𝑢𝑗

𝜕𝑥𝑖) −

2

3 𝜇𝑒𝑓𝑓

𝜕𝑢𝑖

𝜕𝑥𝑖 𝛿𝑖𝑗 −

𝜌�̅�𝑖 �̅�𝑗]𝜕𝑢𝑖

𝜕𝑥𝑗

𝜕

𝜕𝑥𝑗(𝜌�̅�𝑖 �̅�𝑗) = −

𝜕�̅�

𝜕�̅�𝑖 +

𝜕

𝜕𝑥𝑗

[𝜇𝑒𝑓𝑓 (𝜕𝑢𝑖

𝜕𝑥𝑗+

𝜕𝑢𝑗

𝜕𝑥𝑖) −

2

3 𝜇𝑒𝑓𝑓

𝜕𝑢𝑖

𝜕𝑥𝑖 𝛿𝑖𝑗 − 𝜌�̅�𝑖 �̅�𝑗]


7. Result and Discussion

To solve the model, the measured data

were taken experimentally for both cases

(insert, non-insert twisted tape) along with

the parameters and variables that were

taken and applied to the model as inputs

including the inlet temperature, flow rate,

ambient temperature, wind speed, receiver

area, reflector area, date and time. Then,

the model determined the outlet

temperature, heat gain, thermal efficiency,

with time interval of 15 minutes when

running the experiment. The modeled

results are plotted for each case and

compared with the experimental results .

Figure 17 shows the comparison between

experimental outlet temperature and the

theoretical outlet temperature during the

test day, for case inserted twisted tape

inside the receiving tube. It can be seen

that the agreement between the

experimental and theoretical results are

acceptable. However, there are some

discrepancies with a maximum error of 2

.%


the experimental and theoretical heat gain

throughout the test day, for case inserted

twisted tape inside the receiving tube. A

convergence between theoretical and

practical results was observed with some

contradictions (error of 5-11%).

Figure 19 shows illustrate the comparison

between the experimental and theoretical

thermal efficiency, for case inserted

twisted tape inside the receiving tube.

Some Contradictions were appeared with

maximum error of 10%.


experimental outlet temperature and the

theoretical outlet temperature during the

test day, for case not inserted twisted tape

inside the receiving tube. It can be seen

that the correspondence between the

experimental and theoretical results are

acceptable. But, there are some

discrepancies (error of 5-11%).


the experimental and theoretical heat gain

throughout the test day, for case not

inserted twisted tape inside the receiving

tube. A convergence between theoretical

and practical results was observed with

some contradictions, with a maximum of

12%.

Figure 22 shows illustrate the comparison

between the experimental and theoretical

thermal efficiency, for case not inserted

twisted tape inside the receiving tube.

Some opposition were appeared (error of

4-9%).

Generally, in all cases, the comparison

between theoretical and experimental

results is acceptable, although there are

some inconsistencies, and this is due to

several reasons. Generally, in all cases, the

comparison between theoretical and

experimental results is acceptable,

although there are some inconsistencies,

and this is due to several reasons,

including the accuracy of the

thermocouples and the thermocouple

reader, Manufacturing errors in the

parabolic trough and the center of the focal

point and errors in tracking the sun.


Figure 17. Comparison between experimental and numerical outlet temperatures for insert

twisted tape in evacuated receiver pipe.

Figure 18. Comparison between experimental and numerical heat gain for insert twisted tape

in evacuated receiver pipe.

0

500

1000

1500

2000

2500

3000

9:0

0

9:1

5

9:3

0

9:4

5

10

:00

10

:15

10

:30

10

:45

11

:00

11

:15

11

:30

11

:45

12

:00

12

:15

12

:30

12

:45

1:0

0

1:1

5

1:3

0

1:4

5

2:0

0

2:1

5

2:3

0

2:4

5

3:0

0

Use

ful h

eat

gain

(w)

Local time ( h )

Test Data

Model Data

0

20

40

60

80

100

120

140

9:00

AM

9:15

AM

9:30

AM

9:45

AM

10

:00

AM

10

:15

AM

10

:30

AM

10

:45

AM

11

:00

AM

11

:15

AM

11

:30

AM

11

:45

AM

12

:00

PM

12

:15

PM

12

:30

PM

12

:45

PM

1:00

AM

1:15

AM

1:30

AM

1:45

AM

2:00

AM

2:15

AM

2:30

AM

2:45

AM

3:00

AM

Ou

tlet

tem

pre

ture

(ºC

)

Local time ( h )

Test Data

Model Data


Figure 19. Comparison between experimental and numerical thermal efficiency for insert

twisted.

Figure 20. Comparison between experimental and numerical outlet temperatures for non-

insert twisted tape in evacuated receiver pipe.

0

5

10

15

20

25

30

٩:٠٠ AM

٩:٣٠ AM

١٠:٠٠ AM

١٠:٣٠ AM

١١:٠٠ AM

١١:٣٠ AM

١٢:٠٠ PM

١٢:٣٠ PM

١:٠٠ AM

١:٣٠ AM

٢:٠٠ AM

٢:٣٠ AM

٣:٠٠ AM

Effi

cien

cy (

η )

Local time ( h )

Test Data

Model Data

0

500

1000

1500

2000

2500

9:00AM

9:30AM

10:00AM

10:30AM

11:00AM

11:30AM

12:00PM

12:30PM

1:00AM

1:30AM

2:00AM

2:30AM

3:00AM

Use

ful h

eat

gain

(w)

Local time ( h )

Test DataModel Data


Figure 21. Comparison between experimental and numerical heat gain for non-insert twisted

tape in evacuated receiver pipe.

Figure 22. Comparison between experimental and numerical thermal efficiency for non-

insert twisted tape in evacuated receiver pipe.

8. Conclusıons

The following conclusions have been

obtained:

Practical results have shown that the

maximum thermal efficiency of the

PTSC are 44% and 67% using

inserting and non-inserting twisted

tape in the receiving tube, respectively.

Many factors lead to this low

efficiency such as poor tracking,

geometry errors, tubes misalignment,

and low absorptivity of the absorber.

The (PTSC) that has been performed is

suitable for space heating and hot

water loads, because of high

1

3

5

7

9

11

13

15

17

19

9:00AM

9:30AM

10:00AM

10:30AM

11:00AM

11:30AM

12:00PM

12:30PM

1:00AM

1:30AM

2:00AM

2:30AM

3:00AM

Effi

cien

cy (

η )

Local time ( h )

Test DataModel Data

0

20

40

60

80

100

120

9:00AM

9:30AM

10:00AM

10:30AM

11:00AM

11:30AM

12:00PM

12:30PM

1:00AM

1:30AM

2:00AM

2:30AM

3:00AM

Ou

tlet

tem

pre

ture

(ºC

)

Local time ( h )

Test Data

Model Data


temperature of storage that reaches

60°C.

It was concluded from this study

conducted on the parabolic trough

solar collector that the useful heat gain,

thermal efficiency of the solar collector

and the difference between the inlet

and outlet temperatures increases with

the increase in the amount of solar

radiation and increases when inserting

a twisted tape inside the receiving tube.

The study showed that inserting a

twisted tape in the receiving tube leads

to a noticeable increase in the

efficiency of the solar collector than

the efficiency of the solar collector

without the twisted tape.

9. References

[1] Khaled Al-Zahrani., (2013).The application

of parabolic trough technology under yanbu

climatein Saudi Arabia. World applied

sciences journal 23 (10), pp., 1386-1391.

[2] S. Eiamsa-ard, K. Wongcharee, S.

Sripattanapipat., (2009). 3-D numerical

simulation of swirling flow and convective

heat transfer in a circular tube induced by

means of loose-fit twisted tapes. Int.

Commun heat mass transfer 36 947–955.

[3] S. Eiamsa-ard, P. Promvonge., 2005.

Enhancement of heat transfer in a tube with

regularly-spaced helical tape swirl

generators Sol. Energy (78) 483–494.

[4] J. Guo, K. Yang, W. Liu., 2009. Numerical

simulation of heat transfer enhancement by

adding cross twisted-tape in the circular

tube. J. Eng. Thermophys. 30 (7) 1216–

1218.

[5] Falah Abd Alhasan Mutlak, “Design and

Fabrication of Parabolic Trough Solar

Collector for Thermal Energy Applications.

Thesis in college of science / university of

Baghdad. (2011).

[6] Ouagued, Malika, Abdullah Khellaf and

Larbi Loukarfi,.Estimation of the

temperature, heat gain and heat loss by

solar parabolic trough collector under.

[7] K. Syed Jafar and B. Sivaraman,. 2017.

Performance characteristics of parabolic

solar collector water heater system fitted

with nail twisted tapes absorber. Journal of

engineering science and technology Vol.

12, No. (3) 608 – 621.

[8] D N Elton and U C Arunachalaa,. 2018.

Twisted tape based heat transfer

enhancement in parabolic trough

concentrator – an experimental study. IOP

Conference series materials science and

engineering (376) 012034.

[9] Sh. Ghadirijafarbeigloo, A. H. Zamzamian

and M. Yaghoubi,. 2014. 3-D numerical

simulation of heat transfer and turbulent

flow in a receiver tube of solar parabolic

trough concentrator with louvered twisted-

tape inserts. Energy procedia (49) 373 –

380.

[10] Steve Ruby,.2012.Industrial process steam

generation using parabolic trough solar

collection. California energy commission.

Publication number. CEC-500-040.

[11] ANSYS® Academic Research, Release

14.0, ANSYS FLUENT, Theory Guide,

ANSYS, Inc.

[12] Braa Khalid Ameen, Mustafa B. Al-Hadithi

and Obaid T. Fadhil. " Heat Transfer

Enhancement of Flat Plate Solar Collectors

for Water Heating in Iraq Climatic

Conditions" Al-Nahrain University,

College of Engineering Journal (NUCEJ)

Vol.18 No.2, 2015 pp.259 – 272.

[13] Abdulnasser Al-abady, Suad Hassan

Danook, Kamal Jalal. Simulation of a Solar

Chimney Power Plant for Power

Generation. Journal of Global Scientific

Research. 2020. Vol. 6 pp: 637-647.

numerical investigation of heat transfer enhancement in

Documents