23
74 กกกก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND TURBINE ก กก . . 30000 0-4422-4410 0-4422-4411 E-mail: [email protected] Chalothorn Thumthae and Tawit Chitsomboon School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail: [email protected] กกกกกก Fluent กกก ก ก กกก กกกก ก (ก k-epsilon) กก (Local Grid Refinement) กก กกก National Renewable Lab. (USA) กกกก กก stall ก กก Fluent กกกก กกก Abstract This paper presents the numerical simulation of horizontal axis wind turbine with untwisted blade in steady state condition, using Fluent code. The objective is for validating Fluent in solving this class of flow. Simulation is carried out by solving conservation equations for mass and momenta in three dimensions using the unstructured-grid finite volume methodology. The rotating reference frame technique was used wherein the blades are fixed in relation to the rotating frame. Inviscid and turbulent flows with a k-epsilon turbulence model were set as study cases. Local grid refinement technique was employed and grid-independent study was also performed. Computational results compared well with field experimental data of The National Renewable Laboratory (USA), for both inviscid and turbulent conditions, especially when stalls did not occur. This study seems to suggest the adequacy of Fluent code in predicting the flow behaviors in a horizontal axis wind turbine. Consequently, it could be used as an engineering tool for an initial-stage design of wind turbine blades. : กก 2 27-29 กก 2549

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Page 1: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

74

ก��������ก������ ก��� ���ก � ���� CFD

SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND TURBINE

����� ����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected] Chalothorn Thumthae and Tawit Chitsomboon

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail:

[email protected]

/*=����� N��������ก��%�����ก��O ��"��P�� �����QR��ก�� ���ก�����"�OR"ก��N�STNก�� �� S��!

�U�ก� VFluentW �X����S��N���R�!������U�ก� ก��%�����ก��O �����S! �Q��Y�!����ก����#��กZ� �� � ����� S��!���"U�����%��ก�ST������ �S!T�����"ก����������[���X�����"�T �ก�� ���!\Rก�N�"�������"!Nก�Nก���������"� #�OU OS����ก���]กZ����ก� "̂ ��ก��� ก��O �NNOR��S��� ��S � NN��S��� ��S (�S!�����^�R�ก�NNN%��������U`a�Ub�� k-epsilon) OS�T�����"ก��U��Nก��SNN� ��"!S�YX� �"� (Local Grid Refinement) � OS��]กZ�����Ug����� ���Q���X���R����S���ก��SS��! �����U�"!N��"!NQ���X��ก�Nก���S���ก�� ������ National Renewable Lab. (USA) XN�R�Q�%�กก�������^��S�����ก�Nก���S����Ug��!R��S" ��k�ก� "̂�"�OR��S��� ��S� ��S��� ��S �S!�YX� T�ก� "̂�"�OR�ก�Sก�� stall �S!��#Uก��%�����ก��O �S��!�U�ก� Fluent "���R�!���X"!�X��"�% T�������!Xl��ก��ก��O ����ก�� ���NNก����OS� m]��% OS�T��T�ก���R�!��กNNก�� ������ ��NT�����%����R�OU

Abstract

This paper presents the numerical simulation of horizontal axis wind turbine with untwisted blade in steady state condition, using VFluentW code. The objective is for validating Fluent in solving this class of flow. Simulation is carried out by solving conservation equations for mass and momenta in three dimensions using the unstructured-grid finite volume methodology. The rotating reference frame technique was used wherein the blades are fixed in relation to the rotating frame. Inviscid and turbulent flows with a k-epsilon turbulence model were set as study cases. Local grid refinement technique was employed and grid-independent study was also performed. Computational results compared well with field experimental data of The National Renewable Laboratory (USA), for both inviscid and turbulent conditions, especially when stalls did not occur. This study seems to suggest the adequacy of Fluent code in predicting the flow behaviors in a horizontal axis wind turbine. Consequently, it could be used as an engineering tool for an initial-stage design of wind turbine blades.

-@A+�A2B : ก��U� �#����ก��������R�!X������ R�U� ���O�!���k��"� 2 ����"� 27-29 ก�กr�� 2549 ����!���!�������!"�#����" %�� ��S�������"�

Page 2: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

75

� �=+�DAEF�DA+F�G�H.+*I+J�AD=�EF��ก��F K��A������

CONCEPT FOR EFFICIENCY ENHANCEMENT OF A SOLAR STILL

N��^�� �����"!� � *�+, �+-�.�/0�12* ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected],[email protected]

Buncha Khunkhieo and Tawit Chitsomboon* School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology

Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail: [email protected],[email protected]

/*=�����

�������ก�����k��X�����SS"��������w�R���N�O�!T�P���"��� �X�� �k��N�S��T� ��!X�k��"�"�����[�\� T��N���P�� ����กZ��ก��OROS� U`%%#N���"k"�������ก�����k��S��!X�����SS ��!NN �RU� �����P�Xก��ก����!��ORS"��ก �S!P�X��% ก����OS��!R���ก�X"!�U� �^ 5 �����R����������R���� �����%�!�"k��������ST�ก���X��U� �����P�X���ก��ก�����k��X�����SS �S!% ����Ug��������ก�����k��NN 2 ��k� ( ����กก�R�) �S!% U�R�!T ��k��O �%�กS���N� ��������NN�Ug�xy��N���!R���R������� � "ก��O �!���ก��NOU�T���k�z�S��OU m]��������R�% �X��ก��S\Sm�N�������%�ก��SS� �X��ก����N�R����O��k��OS�

=��.��=�O: �������ก�����k��X�����SSNNxy��N��; ก��ก�����k��S��!��SS; �������ก�����k��

Abstract

Solar still is important for rural people in ThailandWs northeastern region, because ground water in many areas have high salinity, so it is not potable and cannot be used in agriculture either. Presently, the solar stills have many types; however, they are not of high efficiencies. In general current solar stills can distill water at about 5 lite/m2/day. This research proposes a new technique to improve the efficiency of a solar still in which the feeding water is allowed to flow continuously in thin film manner, passing two stages (or more) of the still. This should increase solar absorption and condensation of the still.

Keywords : Solar still using film flow; Solar distillation; Solar Stills -@A+�A2B : ก��U� �#����ก��������R�!X������ R�U� ���O�!���k��"� 2 ����"� 27-29 ก�กr�� 2549 ����!���!�������!"�#����" %�� ��S�������"�

Page 3: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

76

D=�EF���/���T���DG�E�ก�//T����� �+.�H: ���D�U���HG�H���A�����

FREE-FALL-PADDY RICE DRYER: A FAST AND ENERGY EFFICIENT DRYER

*�+, �+-�.�/0�12 * , XY�Z� �TU�ก�� � �ก�"!�Oก� �X[���k����"!�

������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����" �.���� %.�������"� 30000, ��� 0-4422-4410 ������ 0-4422-4413, E-Mail: [email protected]

Tawit Chiitsomboon * , Sorada khaengkarn and Krienggrai Pechnumkheaw

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4413, E-mail:

[email protected]

/*=����� ก���N �������U���ก�Ug�ก� N��ก�������wT��#��� ก������m]��T��X������� �����ก %]�OS���S���

���"ก���N ��NNT R �"���S��[�� U� !�SX������ก�R��S� ��k��"k�S!OR�ก�SQ���"!�R��#^P�X��[S��������"�OS�%�กก����S�" ���"ก���"k" ��กก����� �Ub���ก�������������S����R������R��N ���"���k��!\RT���S���� ��ก���S���N� m]��������ก�N�����U���ก��k��"��ก����S!���� %�กz��X�กS���N�S��!�����zR�� Q�ก���S����N�k����������������N ���"k�S�T �� [��R��S�����k�OS��!R����S��[��S!T������T�ก���N ���X"!�U� �^ 30 �����" �R����z�S�����k������U���ก%����� 1.5 กก. %�ก 23.75% d.b. z]� 15.5% d.b. OS��"��#^ P\���ก��

�N �� 100 °C T��X������U�P\�%���X� T�ก���N ����R�ก�N 1.4 MJ/kg�k��� � ! m]����N�R���S��[�� U� !�SX�������ก������"!Nก�N���"ก���N ��NN�"���!T�U`%%#N��

Abstract Drying of paddy is an important process in rice industry which consumes a lot of time and energy. A new drying method is thus invented that is fast and energy efficient without adversely affecting the quality of milled rice. The working principle of this method is by blowing hot air underneath a vertical drying column within which the moist paddy is free falling from its top under gravity. Initial tests have shown very rapid drying rate. By using a resident time of about 30 seconds, 1.5 kg of paddy could be dried from 23.75% db. to 15.5% db. at air temperature of 100 C. The specific primary energy consumption was only 1.4 MJ/kg which is very efficient comparing to the current drying technology -@A+�A2B : ก��U� �#����ก��������R�!X������ R�U� ���O�!���k��"� 2 ����"� 27-29 ก�กr�� 2549 ����!���!�������!"�#����" %�� ��S�������"�

Page 4: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

77

ก��������ก������ ก��� ���ก -�K��// 3 B/ก���

SIMULATION OF FLOW OVER A 3-BLADE VERTICAL AXIS WIND TURBINE

%��#���^ ��k�����ก#����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก����ก�������� ����!���!�������!"�#����" �.����

%.�������"� 30000 ��� (044) 224410 ������ (044) 224411, E-Mail: [email protected], [email protected]

Jaruwan Tangtonsakulwong and Tawit Chitsomboon

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology 111 University Ave., Muang District, Nakorn Ratchasima, Thailand 30000

Tel: 044-224410, Fax: 044-224411, Email: [email protected], [email protected]

/*=����� �����%�!�"k"%#SU� �����X���U� �����ก!P�X��� CFD T�ก���]กZ�ก��O �QR��ก�� ���ก���k� �S!

%������������������ก��O ������ก��QR��ก�� ���S��!�U�ก������� �ก��O � FLUENT ก�� ����"�%������Ug�ก�� ���ก���k����S��[กNN��!ก ก��%���������������ก� ����S!T��ก�����"U�����%��ก�ST� 3 ���NNO�����������U� ก�Nก�N������ก��������ก��S (Sliding mesh technique)T�ก�� �Q��Y�!����ก����#��กZ� �� � ����� Q�ก��%������"�OS�"�����S�����ก�N�lZr" �S!�R���N�S"ก���U�"�!�U��OU���S����m]����X����ก�N�����[���X����� #U � �"������\R �����Sก�� �� Q��Y�!%�กก�������^����z���OU ��R���U� ������ก��������ก�� ��OS� ก���]กZ�ก��O �QR��ก�� ���S!T��������ก��������ก��Sz���R�U� �NQ������[%T��N�k������ ��#UOS��R��U�ก�"��ก!P�X�X"!�X��"�% T��T�ก�������!ก��O �QR��ก�� ���ก���k� m]������zT��T�ก���R�!��กNN� X����U� �����P�X���ก�� ��OS��R�OU

Abstract This research aims to assess potentiality of CFD code in studying the flow field over a vertical axis

wind turbine by numerically simulating the flow using the CFD software �FLUENT�. The simulated turbine is small scale one of lift type. Simulation was carried out by using 3D unstructured-mesh finite volume method together with the sliding mesh technique to solve mass and momentum conservation equations. The results compare qualitatively well with theory. The simulated torque was varied with azimuth angle in relations with the changing relative velocities and incidence angles. The power coefficient was calculated from those CFD results. The investigation is regarded as successful at the beginning and seems to suggest the potentiality of Fluent code. Consequently, it could be used as a tool for research and development of vertical axis wind turbine. -@A+�A2B : ก��U� �#����ก��������R�!X������ R�U� ���O�!���k��"� 2 ����"� 27-29 ก�กr�� 2549 ����!���!�������!"�#����" %�� ��S�������"�

Page 5: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

78

ก��������D,+�-��D�TT��ก������ ก��� ���ก � *@F�@ก��/+�B/ NUMERICAL SIMULATION OF FLOW OVER TWISTED-BLADE, HORIZONTAL AXIS WIND

TURBINE

����� ����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected]

/*=����� N��������ก��%�����ก��O ��"��P�� �����QR��ก�� ���ก�����"�"ก��N�STNก�� ��S��!���"����

������ �X����S��N���R�!������U�ก� VFluentW m]��ก� ����S!ก�� �Q��Y�!����ก����#��กZ� �� � ����� S��!���"U�����%��ก�ST������ �S!T�����"ก����������[���X�����"�T �ก�� ���!\Rก�N�"�������"!Nก�Nก���������"� #�OU OS����ก���]กZ�T����ก� "̂ ��ก��� ก��O �NNOR��S��� ��S � NN��S��� ��S (�S!�����^�R�ก�NNN%��������U`a�Ub�� k-epsilon) OS�T�����"ก��U��Nก��SNN� ��"!S�YX� �"� (Local Grid Refinement) �����U�"!N��"!NQ���X��ก�Nก���S���ก�� ������ National Renewable Lab. (USA) XN�R�Q�%�กก�������^��S�����ก�Nก���S����Ug��!R��S" ��k�ก� "̂�"�OR��S��� ��S� ��S��� ��S �S!ก� "̂�"���S��� ��S% T �Q��"�R�!��ก�R�ก��OR��S��� ��S��[ก���! ������%�กOR�ก�Sก��U�� (stall) �S!��#U ก��%�����ก��O �S��!�U�ก� Fluent "���R�!���X"!�X��"�% T�������!Xl��ก��ก��O ����ก�� ���NNก����OS� m]��% ���OUT��T�ก���R�!��กNNก�� ������ ��NT�����%����R�OU

Abstract

This paper presents the numerical simulation of horizontal axis wind turbine with twisted blade in steady state condition, using VFluentW code. The objective is for validating Fluent in solving this class of flow. The simulation is made by solving the conservation equations for mass and momenta in three dimensions using the unstructured-grid finite volume methodology. The rotating reference frame technique was used wherein the blades are fixed in relation to the rotating frame. Inviscid and viscous turbulent flows with a k-epsilon turbulence model were set as study cases. Local grid refinement technique was employed and grid-independent study was also performed. Computational results compared well with field experimental data of the National Renewable Laboratory (USA), for both inviscid and turbulent conditions. The solutions from viscous cases were slightly more accurate than the inviscid cases because of its more realistic representation of stall. This study seems to suggest the adequacy of Fluent code in predicting the flow behaviors in a horizontal axis wind turbine. Consequently, it could be used as an engineering tool for an initial-stage design of wind turbine blades.

-@A+�A2B : ����������RN������%�! ก��U� �#����ก��������R�!����ก���������ก� R�U� ���O�!

���k��"� 20 18-20 �#��� 2549 %�� ��S�������"�

Page 6: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

79

ก����ก�//B/ก��� ��B��@*@F._�.����/G�HD*Y*�X��B,� *`[email protected]�+G

OPTIMAL BLADE SHAPE DESIGN OF WIND TURBINE FOR THAILAND USING STRIP THEORY

����� ����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected] Chalothorn Thumthae and Tawit Chitsomboon

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail:

[email protected]

/*=����� N�����"k������ ���ก��X����������TNก�� ���S��! �lZr" Strip m]�������%�กก�������� �ก���#��กZ��� ����� � ���������# ��� Strip ���T �OS������X����OU�\Rก����กNN#N�S���TNก�� ���"�� � � ���ก����"!��U�ก����lZr" Strip � �S��N�U�"!N��"!NQ���X��%�กก�������^�����lZr"ก�NQ�%�กก�� ����"�OS�"ก�������O�����XN�R���S�����ก��S" � ����T���lZr"�"kOU ��R��"�� � ���� ��N#N�S�"�U��!TN� ���S��������TN XN�R�����zT �U� �����P�X�\��#ST�����lZr"OS�z]� 41.46 % �^ �"�ก�� �������S�"U� �����P�X�!\R�"�U� �^ 30.18% %]����OU��กNNก�� ��������[�������� ��NT��T�U� ���O�! m]��TNก�� ���"���กNN�"k% ���OUT��������X���T�����%����R�OU

Abstract This paper analyzes the aerodynamics of wind turbine blade with Strip Theory. The theory is based on the analyses of conservation of mass, momentum and angular momentum in an annular strip. The relation for an appropriate blade twist can be carried out. A computer program based on the Strip Theory is created. Its results when compared to experimental data are very good. For an optimal design, tip pitch angle and chord length are studied. The theoretical optimum value of power coefficient is 41.46% while the original wind turbine is 30.18%. The new design technique shall be employed to build a HAWT in the future. -@A+�A2B : ����������RN������%�! ก��U� �#��������ก��������R�!X������ R�U� ���O�!���k��"� 3

23-25 XlZP�� 2550 ����TN !ก�ก�! %�� ��Sก�#���X�

Page 7: กก ก ก CFD SIMULATION OF FLOW OVER A HORIZONTAL AXIS WIND ...eng.sut.ac.th/research/2015/upload/abstract/49-51/05.pdf · This paper presents the numerical simulation of horizontal

80

T ��X�D� *@FD��H.�B ก��������ก������ ก��� ���ก �

Appropriate Domain Size for Numerical Simulation of Horizontal-Axis Wind Turbines

����� ����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected] Chalothorn Thumthae and Tawit Chitsomboon

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail:

[email protected]

/*=����� N��������Q�������S�S���R�ก��%�����ก��O ��"��P�� �����QR��ก�� ���ก���� S��!ก��

T�� CFD ก��%�����ก��O �����S! �Q��Y�!����ก����#��กZ� �� � ����� � NN%��������U`a�Ub��NN k-epsilon S��!���"U�����%��ก�ST�������S!T��ก��SNNO����������� � �S!ก��T�����"ก����������[���X�����"�T �ก�� ���!\Rก�N�"�������"!Nก�Nก���������"� #�OU XN�R�ก���!�!�S����กOU%�z]��R� �]��% ���T �OS������N�"�S"�]k������U�"!Nก�NQ�ก���S���%�ก National Renewable Laboratory (USA) � !��XN�R� �R� tip speed ratio �"��\��]k��R�Q�T �����T���S��S��� ����"�!���]k�

Abstract

This paper presents the effect of domain sizes on CFD solution of horizontal axis wind turbine. Finite volume methodology was used to solve conservation equations for mass and momenta in three dimensions coupled with a k-epsilon turbulence model and unstructured grid. The rotating reference frame technique was used wherein the blades are fixed in relation to the rotating frame. The results show that as the domains were continuously extended the solutions approached more and more those of the experimental data conducted by The National Renewable Laboratory (USA). It was found also that the upstream portion of the domain should be extended more as the tip speed ratio of the rotor increases. -@A+�A2B : ����������RN������%�! ก��U� �#����ก��������R�!����ก���������ก� R�U� ���O�!

���k��"� 21 17-19 �#��� 2550 %�� ��S��N#�"

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81

hSuWiTi XG��ก��DAEF�ก����ก�//��HG�HD�+ ก��� ��

hSuWiTi a Program for the Design and Evaluation of Wind Turbines

����� ����� � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ��� 0-4422-4410 ������ 0-4422-4411 E-mail: [email protected]

/*=����� �U�ก� VSuWiTW z\กX�����]k��Ug��U�ก���� ��N��กNN� U� ���U� �����P�X���ก�� ��

�ก���� �S!T���lZr" Blade Element Momentum �R�ก�NNN%�����ก���\w��"!�"�U��!TN� ���TNก�� �� ก��U��Nก��R� induction factor � NN%����� post-stall Q�ก�������^S��!�U�ก�������"!Nก�NQ�ก���S������ National Renewable Energy Laboratory (NREL, USA) XN�R���S�����ก���Ug��!R��S"�S!�YX� �!R��!����"������[�U��!TN���� OS�T�� SuWiT ��กNNก�� ���NN���TN�"������NNN�������� (linear-taper) OS�U� �����P�X�\��#Sz]� 46.6% �^ �"�ก�� �� NREL "U� �����P�X�\��#S�"� 37.5 %

Abstract The computer code SuWiT was developed for the purpose of the design and evaluation of HAWT by

using the Blade Element Theory as its basis, together with tip and hub loss models, induction factor and post-stall modifications. Comparisons with test data of The National Renewable Energy Laboratory (USA) showed very good agreements especially at low tip speed ratio. SuWit was then used to optimize the design of a linear-taper blade and was found to give as high as 46.6% efficiency compared to NRELWs peak of 37.5% -@A+�A2B : ����������RN������%�! ก��U� �#��������ก��������R�!X������ R�U� ���O�!���k��"� 4 14-16 XlZP�� 2551 �������ก����S�� �������OmS� �����X��� %�� ��S���U�

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82

��ก�H*/T�����_ � -��G�H.+*I+J�AT��D=�EF���/���T���DG�E�ก�//T����� �+.�H

EFFECT OF SWIRL DRYING AIR ON EFFICIENCY OF FREE-FALL-PADDY RICE DRYER

*�+, �+-�.�/0�12* XY�k� �TU�ก�� � �ก�"!�Oก� �X[���k����"!� ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ���. 0-4422-4410 ������ 0-4422-4413 E-Mail: [email protected] * Q\��R� ��ก

Tawit Chiitsomboon * , Sorada khaengkarn and Krienggrai Pechnumkheaw School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4413, E-mail:

[email protected] * corresponding author

/*=�����

ก���N �������U���ก�Ug�ก� N��ก�������wT��#��� ก������m]��T��X������� �����ก %]�OS���S������"ก���N ��NNT R �"���S��[�� U� !�SX������ก�R��S� ��k��"k�S!OR�ก�SQ���"!�R��#^P�X��[S��������"�OS�%�กก����S�" �"ก���"k" ��กก������Ub���ก�������������S����������R��N ���"���k��!\RT���S���� ��ก���S���N� m]��������ก�N�����U���ก��k��"��ก����S!���� %�กz��X�กS���N�S��!�����zR�� m]������z�S�����k�OS��!R����S��[� � U� !�SX�������ก������"!Nก�N���"ก���N ��NN�"���!T�U%̀%#N�� � ����T�RU�ก #�����"����������ก���N �� ���T ������ #�NN�����R������OUT��R��N ���Ug�ก���X��X�k��"���Q��� �R����ก���N ��� ��[S�����U���ก ����z�S�����k������U���ก%����� 600 ก�� %�ก 23.91% d.b. z]� 15.63% d.b. �"��#^ P\���ก���N �� 120o T������ 18.325 �����" � T��X������U�P\�%���X� T�ก���N ����R�ก�N 2.7 MJ/kg �k��� � ! m]���S�T �� [��R�ก�� #��������กR�������R��N ��"Q����T �����T�ก���N �����!��� U� !�SX�������X���]k�������"!Nก�NNNOR #���� � OR"Q���"!�R��#^P�X�������

Abstract Drying of paddy is an important process in rice industry which consumes a lot of time and energy. A

new drying method is thus invented that is fast and energy efficient without adversely affecting the quality of milled rice. The working principle of this method is by blowing hot air underneath a vertical drying column within which the moist paddy is free falling from its top under gravity. At the inlet dying air tube is installed blade for creating swirl drying air. This technique can increase the contact area between drying air and paddy kernel. The results shown faster drying time and lower specific primary energy consumption were 18.325 sec and 2.7 MJ/kg, comparing to the test without swirl drying air blade. -@A+�A2B : ����������RN������%�!ก�� U� �#����ก��������R�!����ก���������ก� R�U� ���O�!

���k��"� 20 18-20 �#��� 2549 %�� ��S�������"�

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83

ก����ก�//ก��� ��B�.��=����ก�/.l+-+�����DA�HAEK *@F

DESIGN OF WIND TURBINES TO IN A LOCAL WIND STATISTIC

��ก��S� ��"�S�1* � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ���.0-4422-4410 ������ 0-4422-4411 2Email: [email protected] *Email : [email protected]

/*=����� �����%�!�"k#R� �#�Q�� (Pitch angle) �"�S"�"��#S���TNก�� �� �S!T�����"ก�������lZ�"�R�ก�N�z����

�YX� X�k��"� �X���T �OS������!U��\��#S ���"��"k%]�OROS���กNN�"������[���X"!�%#S�S"!� �R����]�z]������[���"��U�"�!�OU���S��k�U� m]���lZr"�����w�"�T������lZr" Blade element momentum �R�ก�NNN%������S��!ก���\w��"!ก��O � �X���U��Nก�ก��O ������#S���T ���S�����ก�N����Ug�%���!����]k� OS�X�����U�ก���X�������T�P�Z� MATLAB N�X�k��������lZr"S��ก�R�� ����R������z������U�ก� OS�%�กก���U�"!N��"!NQ�ก�������!ก�NQ�ก���S������ก�� ��� T������กZ^ ���ก�� ���NNTN���� ก�� ���NNTNN�S OS�T���U�ก���� �#�Q���"�S"�"��#ST��z������� �]�� �S!ก��U��N#�Q��OU%�ก� ����OS������!U��\��#S %�ก��k�OS������^ �#�Q���"�S"�"��#S T�ก� "̂�"��z�����U�"�!�OU%�ก�S��S!!��"�����[���Y�"�!��R��S��R"����N�����z�����R��OU%�ก�S� XN�R�#�Q���"�S"�"��#S�U�"�!�OU%�ก�S� ��k��"k�R��Ug���� �#%�กก���"��R������[���"�T ���� ���R�ก����������\��#S�U�"�!�OU������N�����z���� XN�R�ก��U��N#�Q���X"!���[ก���! ��%�R�Q�T �OS������!U��R��ก��X�����T��z�����"�"����N��ก�R��ก�� m]���R�Q�ก� �N�R�� NN���Z����������ก�� ���OS��กX�����

Abstract

This research aims to find the best pitch angle for a wind turbine by using a theoretical approach in conjunction with annual wind statistics. Therefore, this is not a ysingle-velocityz design but rather a yyear-roundz design. The important theory employed was the Blade element momentum theory together with the various corrective models to improve theoretical predictions. A computer program in MATLAB was developed based on the mentioned theory. The credibility of the program was attained by comparing its predictions with those of the experiments comprising a straight-blade turbine and a twisted, taper blade turbine. The program was used to search for the best pitch angle in a wind statistic. Later, the program was used for two more statistics which have the same average as the first one but with different skews. It was found that the best pitch angles are not the same due probably to the shifts in the velocities that give maximum energy densities. A small change in best pitch angle could give quite different values in annual energy yield, affecting the economy of wind turbine in the commercial system.

-@A+�A2B : ����������RN������%�! ก��U� �#����ก��������R�!����ก���������ก� R�U� ���O�! ���k��"� 22 15-17 �#��� 2551 ����!���!��������� �\�!�������

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84

�_�D�+ *@F�@*@F._�T��B/ก��ก� ��.����/.l+-+�����DA�HAEK *@F

OPTIMAL PITCH ANGLE FOR WIND TURBINE IN A LOCAL WIND STATISTIC

��ก��S� ��"�S�1* � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ���.0-4422-4410 ������ 0-4422-4411 E-mail: [email protected]

/*=����� �����%�!�"k �#�Q���"�S"�"��#S���TNก�� ���ก�����X���T �OS������!U��"��ก�"��#S �S!X�%��^�

��X����ก�N�z����%���X� X�k��"� X�����k������[�� �����[�U��!TN (Tip speed) ���z� ���TNก��ก�� (Performance curve) �Ug���� ���U�� �R��"kz\ก������� ��X���T�������^ �����"�OS���!U� �S!#�Q��% z\กU��N �X������ �%#S� � ��"�OS������!U�S"�"��#ST��z�����R��� ก��OU OS��U�"!N��"!N���%�ก�z������NN�"�T ������[���U�"�!���R�ก�� �R"����N��R��ก�� Q�U��ก��R�OS�#�Q���"�S"�"��#S�R��ก��m]������z�R�Q�ก� �N�R�����#�T�ก�����#�OS��กX�����

Abstract This study is about finding an optimum blade pitch angle in relation to local wind statistic as well as

wind speed, tip speed, blade performance curve and so on. All of the design parameters are synthesized into a computer program for the determination of an annual power production. The pitch angles were varied to search for optimum annual power outputs in various wind statistics. Comparisons were made for power productions in three wind statistics having the same average velocity, with negative and positive curve shifts. The optimal pitches of the three cases were different which should somewhat affect return of investment.

-@A+�A2B : ����������RN������%�! ก��U� �#��������ก��������R�!X������ R�U� ���O�!���k��"� 4 14-16 XlZP�� 2551 �������ก����S�� �������OmS� �����X��� %�� ��S���U�

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85

Gm����D,+�ก�*@Fก�H*/-��G�H.+*I+��ก��A��D�E�ก��D,@��DAEF�ก���T��T�

MECHANICAL FACTORS AFFECTING THE EFFECTIVENESS OF SCULLING COMPETITION

X���X ������" � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ���.0-4422-4410 ������ 0-4422-4411 Email: [email protected]

/*=����� �]กZ�ก��X�!����ก����"!��X���ก���R����T�� ! ��� 2,000 ��� �X��������� �Q�ก� �N���U`%%�!

�R��� �R�����ก���R���� ��� ���S���TNX�! ���!��S��X�! � #ก��X�! �"�" ��กT�ก���]กZ����ก��%�����ก����������"��������S��!NN%��������� �̂������� NN%������"k�Ug��ก��NN��#X������[ �R�!U� ก�NS��!����N����������� ���������� � ���Y���!���������%�กก�����������������กก"�� ����N�������������k�ก�� �ST �ก� %�!��#ก��X�! ��k��RTNX�!���k��%�TNX�!X���k�� �S!%�������T ��Ug��\UNN�"�T����ก������k��� ��� � ���"�OS�%�กก����Sก����ก�������กก"������Uyก�� ���"���ก�S!��กก"��% �R�OU�"�TNX�! ���T ��ก�Sก����������"����TNX�! m]���R�Q�T ��ก�S��Y#ก� ��!กN�TNX�! m]���R�Q��R�%�� � T�ก��X�! ���T ��ก�Sก����������"����TNX�! m]���R�Q�T ��ก�S��Y#S� ��!กN�TNX�! m]���R�Q��R�%�� � T�ก��X�! ��� ��N�����������k�ก�� �ST �"�R�X"!�����"!S�������k���"�ก� ����R����� m]���Ug���S�R��ก�N�����[�����!กก�������� �R�����Y���!%�ก��กก"���"�����������ก��NOU�T�� �R��ก��X�!����ก[z���Ug�U`%%�!�"���%�R�Q�ก� �N�ก�R�U� �����Q�ก��X�!����OS� �X�� �k�� ��ก��������กก"��"�R��กก�R��k�� ��ก���� �����N����ก���"k ��S!ก�����"����������S��!ก��T���Uก� MatLab U� �S[������w���U� ก��T�ก���]กZ��"k�"��ก�R��OU%�กก���]กZ�T��S"������ก��%�!������� T��"��"kOS�ก�� �S������O�T � ����� T�ก��X�!���S� ! ��� 2,000 ��� �Ug��R����"� �S!�"������%�!T��S"���k�OS�ก�� �ST � �ก��������� T��R� %�� � ก��X�!�Ug��R����"� �"กU� ก�����T�ก���]กZ��"kOS�����]�z]�U`%%�!����"�ก������� �"�OS�X�%��^� ��กก�������"�- ���!���N�\ROUก�N ��กก�����ก�������S��! ก�� ������NT �ก�N�ก��� �̂�������OS��������T��P�X���� !#S����OU%�OS�� ! ��� 2,000 ��� XN�R����STNX�!�"�T wR�]k�S��X�!�"�!���]k� � #ก��X�!�"�ก�����]k� ���T �X�!����OS���[��]k� �Rก��T��U`%%�!� �R��"k��%OR����zก� ���OS�T��"���%���������%�ก���%��ก�SS���ก�!P�X� S����"�ก�������

-@A+�A2B : ����������RN������%�! ก��U� �#����ก��������R�!����ก���������ก� R�U� ���O�!

���k��"� 21 17-19 �#��� 2550 %.��N#�"

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86

ก��DA+F�G�H.+*I+��G�������DAEF��H/����ก�YB ��=��

ENHANCEMENTS OF SOLAR CHIMNEY FOR BUILDING VENTILATION

X������� ���TN � *�+, �+-�.�/0�12 ������������ก���������ก� �����ก��������ก�������� ����!���!�������!"�#����"

�.���� %.�������"� 30000 ���.0-4422-4410 ������ 0-4422-4411 E-mail : [email protected]

/*=����� U�R��SSz\กT��T�ก��� N�!��ก��T��������������S! U���^ก��� N�!��ก���]k��!\Rก�NU���^

��SS� U%̀%�!��������� ��R� � ! T���S���� �R���R���������� �R�������ก���� NN ���S����R���������� �R�������ก���ก��������R����ก�� � ���!�����U�R��SS �����%�!�"k�]กZ�Q�ก� �N���ก��ก� %�!���X�k��"� �����S����R�����O �T�U�R��SS ����k�U%̀%�!����� ��R� ���!�����U�R��SS ���ก��������R����ก�� � �����������SS �S!ก��T��ก���"���������� m]��XN�R�����z�X�������ก��� N�!��ก��OS��กX�����

Abstract Solar chimney was used in natural ventilation for building. The ventilation rate depends on solar

intensity and geometrical parameters of solar chimney, such as vertical distance between inlet and outlet, air gap width and solar chimney length. In this study, the effect of cross sectional area distribution of the air gap was investigated by a numerical method, together with other parameters such as solar chimney length, air gap width and solar intensity. It was found that these parameters can increase ventilation rate quite significantly. Keyword: ก��� !�!��ก��������� U�R��SS ก���X�������ก��O � -@A+�A2B : ����������RN������%�! ก��U� �#����ก��������R�!X������ R�U� ���O�!���k��"� 4

14-16 XlZP�� 2551 �������ก����S�� �������OmS� �����X��� %�� ��S���U�

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87

FLOW FIELDS IN A MIXED-SUSPENSION MIXED-PRODUCT-REMOVAL CRYSTALLIZER: A

NUMERICAL ANALYSIS

Jaruwan Tangtonsakulwonga, Adrian Floodb and Tawit Chitsomboonaa a School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology, b School of Chemical Engineering, Institute of Engineering, Suranaree University of Technology,

111 University Ave., Muang District, Nakhon Ratchasima, 30000 Thailand.

Abstract Isokinetic withdrawal of solution from research crystallizers is a key factor in obtaining a

representative crystal-size distribution and is critical for correct analysis of the crystallization process to accurately determine crystallization kinetic parameters such as crystal growth rates, nucleation rates, breakage rates, and agglomeration rates. Isokinetic withdrawal, in turn, depends upon the characteristics of the flow field in the crystallizer. This research numerically simulated the fluid flow field in a small-scale (experimental) cylindrical round-bottomed, continuous-flow, cooling crystallizer, which was set up for analysis of kinetic parameters in sugar production. The commercial software �CFX 5.5.1� was employed to perform the 3 dimensional simulation with the finite volume method using an unstructured mesh. The impeller used for increasing the gross velocity of the solution inside the crystallizer was modeled using a momentum source. Seven momentum source strength values were used to perform the simulation. The results showed that the momentum source strongly increased the axial flow velocity but only slightly influences the overall flow pattern, except the flow near the outlet tube. The isokinetic withdrawal condition was achieved at a momentum source strength of about 25,000 kg/m2/s2. The isokinetic condition for the nuclei crystals was best for the research MSMPR, as it would make the particle size distribution in the product stream most accurate for the analysis of the nucleation and growth rates in the crystallizer. For larger particles, the settling velocity was required for determination of isokinetic withdrawal. The power transmitted by impeller shaft was estimated as 0.6 W, which allowed the impeller rotational speed to be estimated. Furthermore, the velocity at the center of the tankWs bottom was lower than that of the surrounding region. This could cause a collection of settled crystals, which was problematic for the operation and analysis of the crystallizer. Abbreviation: MSMPR, mixed-suspension mixed-product-removal; CFD, computational fluid dynamics. Keywords: crystallizer modeling, computational fluid dynamics (CFD), fluid flow field.

Published in: Science Asia, V.32, No.4, 2006

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88

OPTIMAL ANGLE OF ATTACK FOR UNTWISTED BLADE WIND TURBINE

Chalothorn Thumthae and Tawit Chitsomboon School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology

Muang District, Nakorn Ratchasima 30000 Thailand Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail: [email protected]

Abstract

The numerical simulation of horizontal axis wind turbines (HAWTs) with untwisted blade was performed to determine the optimal angle of attack that produces the highest power output. The numerical solution was carried out by solving conservation equations in a rotating reference frame wherein the blades and grids were fixed in relation to the rotating frame. Computational results of the 12° pitch compare favorably with the field experimental data of The National Renewable Laboratory (USA), for both inviscid and turbulent conditions. Numerical experiments were then conducted by varying the pitch angles and the wind speeds. The power outputs reach maximum at pitch angles: 4.12°, 5.28°, 6.66° and 8.76° for the wind speeds 7.2, 8.0, 9.0 and 10.5 m/s, respectively. The optimal angles of attack were then obtained from the data. Published in: Renewable Energy (2008), doi:10.1016/j.renene.2008.09.017

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OPTIMAL PITCH FOR UNTWISTED BLADE HORIZONTAL AXIS WIND TURBINE

Chalothorn Thumthae and Tawit Chitsomboon

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology, Muang District, Nakorn Ratchasima 30000 Thailand

Tel: 0-4422-4410 Fax: 0-4422-4411 E-mail: [email protected]

Abstract This paper presents the numerical simulation of horizontal axis wind turbines with untwisted blade in

steady state condition. The objective is for investigating the condition for the optimal pitch that produces the highest power output. The numerical solution is carried out by solving conservation equations for mass and momenta in three dimensions using the unstructured-grid finite volume methodology (Fluent code). The rotating reference frame technique was used wherein the blades are fixed in relation to the rotating frame. Local grid refinement technique was employed and grid-independent study was also performed. Computational results of the 12 degree pitch are compared with field experimental data of The National Renewable Laboratory (USA), for both inviscid and turbulent conditions. The computational results give good agreement with experimental results both for inviscid and viscous conditions if stall do not occur (at 80% span). However, if stall occurs (at 30% span), the results of both inviscid and viscous simulations are quite different from the experiment. For power output comparison; the k-epsilon case produces only +3.6% errors. The power outputs reach maximum at the 8.82 degree and 4.2 degree pitch at wind speed 10.5 m/s and 7.2 m/s respectively. Published in: The 2nd Joint International Conference on �Sustainable Energy and Environment

(SEE 2006)� 21-23 November 2006, Bangkok, Thailand

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CFD SIMULATION OF TRANSIENT HEAT AND MASS TRANSFER INSIDE A SINGLE RICE

KERNEL DURING DRYING PROCESS

Chairerk Chuaprasat and Tawit Chitsomboon School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon

Ratchasima 30000, Thailand.

Abstract A commercially available Computational Fluid-Dynamics code developed by AEA Technology, CFX-5, has been chosen to carry out a computer simulation of the drying process in a rice kernel. A rice kernel is taken to be an ellipsoid. Unsteady heat conduction and moisture diffusion take place within the kernel, and only convective heat and mass transfer take place between the kernel surface and its drying environment. By giving an initial temperature and moisture content distributions inside the rice kernel, temperature and relative humidity of the heated air and proper boundary conditions, the governing equations can be numerically integrated to obtain the temperature fields and the moisture content distributions. The results obtained from the thin-layer drying test reported by Yang et al. (2002) will be used to validate the CFD prediction in this study.

A mathematical model develop in this study can be used for describing the coupled heat and mass transfer inside a single rice kernel during drying. A CFD code solved the temperature and moisture content equations. The theoretical prediction of moisture distribution of rice kernels was verified by experiment data. The results of the calculation can be used for rice grain quality evaluation, drying simulation studies and stress analysis of grain kernel. Published in: RGJ � Ph.D. Congress VII, Chonburi, Thailand, April 20�22 , 2006. Organized by:

The Thailand Research Fund

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CFD SIMULATION OF ROUGH RICE IN DRYING PROCESS

Tawit Chitsomboon1 and Chairoek Chueaprasat2 School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon

Ratchasima 30000, Thailand, Tel: 0-4422-3481, E-mail: [email protected], [email protected]

Abstract A mathematical model describing the simultaneous heat and mass transfers for a rice kernel during

drying process is simulated by using a CFD code based upon the finite volume method to predict the moisture content and temperature fields. It is assumed that the rice kernel is a continuous ellipsoid. Unsteady heat conduction and moisture diffusion take place within the kernel, and convective heat and mass transfer take place between the kernel surface and its drying medium. The corresponding boundary and initial conditions are giving by an initial temperature and moisture content inside the rice kernel, temperature and relative humidity of the heated air. The results obtained from the thin-layer drying test will be used to validate the CFD prediction in this study, the temperature and moisture content, especially will be compared. The results of the calculation can be used for drying simulation studies and improve rice grain quality. Published in: The 11th Annual National Symposium on Computational Science and Engineering (ANSCSE

11), March 28-30, 2007 Phuket, THAILAND.

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PARTIAL SIMILARITY IN SOLAR TOWER MODELING

Atit Koonsrisuk* and Tawit Chitsomboon** School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology,

Muang District, Nakhon Ratchasima 30000, Thailand E-mail: [email protected]* and [email protected]**

Abstract:

Dimensional analysis is employed to determine the similarity condition for the physical models of a solar tower (a solar power plant for generating electricity). In a previous study, full geometrical similarity had led to using different solar heat fluxes for each model in order to achieve dynamic similarity: a condition difficult to realize in an actual practice. This study aims to create dynamic similarity while using the same solar flux for all models. The study reveals that, to achieve the desirable condition, the models cannot be fully geometrical similar, hence partial similarity. The functional relationship that provides the condition for this partial similarity is proposed and its validity is proved by using numerical solutions of flows in solar towers. Published in: Proceedings of the 20th Conference on Mechanical Engineering Network of Thailand,

Nakhon Ratchasima, Thailand. [October 18-20, 2006]

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EFFECT OF TOWER AREA CHANGE ON THE POTENTIAL OF SOLAR TOWER

Atit Koonsrisuk* and Tawit Chitsomboon**

School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology, Muang District, Nakhon Ratchasima 30000, Thailand E-mail: [email protected]* and [email protected]**

Abstract:

Solar tower is a solar power plant for electricity generation by means of air flow induced through a tall tower. Guided by a theoretical prediction, this paper uses CFD technology to investigate the changes in flow kinetic energy caused by the variation of tower flow area with height. It was found that the tower area change affects the efficiency and mass flow rate through the plant. The divergent tower top leads to augmentations in kinetic energy at the tower base significantly.

Published in: Proceedings of the 2nd Joint International Conference on Sustainable Energy and

Environment, Bangkok, Thailand. [November 21-23, 2006]

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THE EFFECT OF PLANT GEOMETRY ON THE POTENTIAL OF A SOLAR TOWER

Atit Koonsrisuk* and Tawit Chitsomboon** School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology,

Muang District, Nakhon Ratchasima 30000, Thailand E-mail: [email protected]* and [email protected]**

Abstract

Solar tower is a solar power plant for electricity generation by means of air flow induced through a tall tower. This paper presents a detailed description of the flow power, efficiency, temperature change, velocity, and mass flow rate as dependent on the effects of roof radius and height, tower height and radius, and solar heat flux. The CFD investigation was performed to determine the system performance characteristics on the geometric and solar heat flux modifications, which shows good conformity with the theoretical model. It was observed that the flow power, efficiency, temperature change, velocity, and mass flow rate increase with roof radius increases. The increase of roof height, on the other hand, results in the decrease of flow power, efficiency, temperature change, velocity, and mass flow rate. It was also found that the increase of tower height will cause the increase of flow power, efficiency, velocity, and mass flow rate; but the decrease of outlet plant temperature as well. Specifically, decreasing tower radius results in decreasing mass flow rate; but increasing flow power, efficiency, temperature change and velocity. However, it would seem that there is an upper bound, depending on the whole plant size, on the tower radius that can enhance the plant performance. An observation revealed that the increase in solar heat flux leads to augmentations in the flow power, efficiency, temperature change, velocity, and mass flow rate.

Published in: Proceedings of the 11st Annual National Symposium on Computational Science and

Engineering, Phuket, Thailand [March 28-30, 2007]

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A SINGLE DIMENSIONLESS VARIABLE FOR SOLAR TOWER PLANT MODELING

Atit Koonsrisuk* and Tawit Chitsomboon** School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology,

Muang District, Nakhon Ratchasima 30000, Thailand E-mail: [email protected]* and [email protected]**

Abstract

Solar tower plant is a power plant that generates mechanical energy by using a rising, buoyant hot air, which is heated by solar energy, to turn a turbine which is located at the base of a tall tower. In this paper, dimensional analysis methodology is used together with engineering intuition to combine eight primitive variables into one (and only) dimensionless variable that governs similarity of model plants. Numerical simulations for several plants models were performed with geometrically similar, partial similar and dissimilar characteristics. The values of the proposed dimensionless variable for all these cases were found to be nominally equal, suggesting the validity of the variable. The value for the physical plant actually built and tested previously was also evaluated to be about the same as the computed value. Engineering interpretation of this variable is finally explained.

Published in: Proceedings of the 22th Conference on Mechanical Engineering Network of Thailand,

Pathum Thani, Thailand. [October 15-17, 2008]

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DYNAMIC SIMILARITY IN SOLAR CHIMNEY MODELING

Atit Koonsrisuk* and Tawit Chitsomboon** School of Mechanical Engineering, Institute of Engineering, Suranaree University of Technology,

Muang District, Nakhon Ratchasima 30000, Thailand E-mail: [email protected]* and [email protected]**

Abstract

Dimensionless variables are proposed to guide the experimental study of flow in a small-scale solar chimney: a solar power plant for generating electricity. Water and air are the two working fluids chosen for the modeling study. Computational fluid dynamics (CFD) methodology is employed to obtain results that are used to prove the similarity of the proposed dimensionless variables. The study shows that air is more suitable than water to be the working fluid in a small-scale solar chimney model. Analyses of the results from CFD show that the models are dynamically similar to the prototype as suggested by the proposed dimensionless variables Published in: Solar Energy 81 (2007) pp. 1439�1446 [ Solar Energy, 2007; doi:10.1016/j.solener.

2007.03.003. ]