Design and performance evaluation of an integrated hybrid photovoltaic greenhouse drying system.

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DESIGN AND PERFORMANCE EVALUATION OF AN INTEGRATED HYBRID PHOTOVOLTAIC

GREENHOUSE DRYING SYSTEM

by

PRADYUMAN BARNWAL

Centre for Energy Studies

Submitted

in fulfillment of the requirements of the degree of Doctor of Philosophy

to the

Indian Institute of Technology Delhi

JULY 2008

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Dedicated to my parents

Smt. Girija Barnwal & Shri Brija Bhushan Prasad Barnwal

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Certificate

This is to certify that the thesis entitled "Design and Performance Evaluation of an Integrated Hybrid Photovoltaic Greenhouse Drying System", being submitted by Pradyuman Barnwal to the Indian Institute of Technology Delhi, is worthy of consideration for the award of the degree of

`Doctor of Philosophy' and is a record of the original bonafide research work carried out by him under my guidance and supervision. The results contained in the thesis have not been submitted in part or full, to any other University or Institute for the award of any degree or diploma.

\-0 Dr. 0.Tiwari Professor

Centre for Energy Studies

Indian Institute of Technology Delhi Hauz Khas, New Delhi — 110 016

Date: 24 July 2008

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Acknowledgements

First of all, I acknowledge the energy from the Supreme Power which I receive like every one to do any type of work. I thankfully acknowledge the energy, in every form, which the Supreme Power showered on me throughout my research work.

I wish to express my deep sense of gratitude to Dr. G.N.Tiwari, Professor, Centre for Energy Studies for his practical approach in almost every aspects of life including research and development work. I am very much thankful to him for his wonderful co-operation, constant encouragement, proper guidance, fruitful academic discussions and freedom given to me for carrying out my research work.

It gives me indeed a great pleasure to express my heartfelt gratitude to Prof M.S.Sodha for his constant and consistent encouragement towards successful completion of the Ph.D. research work.

I am very much grateful to Director, CIPHET Ludhiana; Head (TOT Division, CIPHET Ludhiana) for deputing me to pursue the Ph.D. education and for their moral support and encouragement during the research work.

I also express my gratitude to Prof. S.C.Kaushik, Head; Prof. Avinash Chandra. Prof. S.C.

Mullick, Prof. M.K.G. Babu, Ex-Heads; Prof T.S.Bhatti, Dr. H.D. Pandey and Dr. Subodh Kumar etc. of Centre for Energy Studies, for providing moral support and encouragement for the present Ph.D. research work.

I express my deep sense of gratitude to Prof. S.K.Dube, Former Director, IIT Kharagpur, for his constant encouragement and moral support. I am also grateful to Prof V.K.Srivastava, Ex-Dean, IRD, for his moral support and encouragement.

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(P.Barnwal)

I am thankful to my colleagues Mr. Vivek Raman, Mr. V.K.Dwivedi, Mr. Shiv Kumar, Mr.

Arvind L. Chel, Mrs. Sujata Nayak, Mr. Swapnil Dubey, Mr. Jamil Ahmad, Mr. S.C. Solanki, Mr. Manoj Gaur, Mr. Basant Aggarwal and Mr. Rahul etc. for their positive criticism and moral support.

The patience of my spouse, Mrs. Saroj Baranwal in bearing with this research work in good humor is greatly appreciated. My special thanks go out to my daughter "Saanvi" for giving up her valuable time due to her, used in this research effort.

I wish to express my heartfelt gratitude to Dr. R. K. Goyal, Dr. Dilip Jain, Dr. S. N. Jha, Er.

R. K. Vishwakarma, Dr. V. K. Bhargav and Dr. D. M. Kadam etc. of CIPHET Ludhiana for motivation and moral support for the Ph.D. education and research.

I would like to extend my deep sense of gratitude to Mrs. Kamlawati Tiwari and family members for their blessings and encouragement throughout my Ph.D. study.

I am also thankful to Mr. Lakhmi Chand (Senior Mechanic, Solar Distillation Lab) and Mr.Dhanne Singh (Senior Lab Assistant, M.Tech. Lab) for their support during experimental . work.

I would like to thank all those who have helped me directly or indirectly in any form to achieve this work that it is not possible to thank them individually.

Last but not least, I express my deep heartfelt gratitude to my respected parents, Smt. Girija Barnwal and Sh. Brija Bhushan Prasad Barnwal and parents-in-laws for their blessings, which helped me to reach this target.

Date: 24 July 2008

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Abstract

Solar energy is a basic need of living plants and human being on earth. It can be collected and used in the form of either thermal energy or DC electricity.

The drying of crop helps to achieve proper moisture content for longer safe storage period and thus facilitates more food availability through reduction in post harvest losses. So, solar crop drying will ensure the conservation of conventional energy sources as well as more food available to sustain the growing world population.

For crop drying, a hybrid photovoltaic (PV) integrated greenhouse (roof type even span) dryer has been designed and constructed at Solar Energy Park, Indian Institute of Technology Delhi (IITD), New Delhi, India. Two PV modules (glass to glass) were integrated with greenhouse for thermal heating of greenhouse environment and to provide DC electrical power to operate a DC fan for forced mode condition. This ensures independent operation of the fan from grid electricity and thus makes it useful for the drying applications in rural areas or remote locations of developing and under-developing countries where grid electricity is not readily available.

The testing of the proposed hybrid dryer has been carried out by using the thermal loss efficiency factor. The convective heat transfer coefficient for grape drying under forced mode has been evaluated. Thermal models have been developed to predict the performance of the dryer under forced mode of operation and experimentally validated. The thermodynamic performance of the developed dryer has been carried out in terms of energy and exergy efficiencies under forced mode. The life cycle energy metrics namely energy pay back time (EPBT), energy

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production factor (EPF) and life cycle conversion efficiency (LCCE); net CO2 mitigations, carbon credit earned and life cycle cost for the developed hybrid photovoltaic PV integrated greenhouse dryer have also been analyzed.

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4

13 13 14 14 14 15 15 16 16 16 19 19 22 22 22 23 24 25

26 29 29 32

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2.2.3 Working Principle 33 2.2.3.1 Solar Radiation on PV Modules (Glass to Glass) 33 2.2.3.2 Solar Radiation on UV Stabilized Polyethylene Sheet 34

2.3 Modeling 34

2.3.1 Instantaneous Thermal Loss Efficiency Factor (77 _{, ,ioss} 34

2.3.1.1 Under Natural Mode 35

2.3.1.2 Under Forced Mode 36

2.4 Instrumentation 36

2.4.1 Experimental Observations 37

2.5 Testing Procedure 38

2.6 Results and Discussion 39

2.7 Summary 44

CHAPTER - III : Heat and Mass Transfer for Drying of Grapes

3.1 Introduction 45

3.2. Sample Preparation 48

3.3 Experimental Observations of Grape Drying 49

3.4 Modeling 51

3.4.1 Forced Convective Heat Transfer Coefficient 51

3.4.2 Physical Properties of Humid Air 56

3.5 Computation Procedure, Results and Discussion 57

3.6 Summary 70

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CHAPTER — IV : Thermal Modeling of Hybrid Photovoltaic (PV) Integrated Greenhouse Dryer for Forced Mode

4.1 Introduction 4.2 Thermal Modeling

72 75 4.2.1 Thermal Modeling under Forced Mode (Without Load) 78 4.2.1.1 Thermal Efficiency (Without Load) 79

4.2.1.2 Exergy Efficiency (Without Load) 80

4.2.1.3 Overall Efficiencies (Without Load): 81 4.2.2 Thermal Modeling under Forced Mode (With Load) 82

4.2.2.1 Moisture Evaporation 84

4.2.2.2 Thermal Efficiency (With Load) 84

4.2.2.3 Exergy Efficiency (With Load) 85

4.2.2.4 Overall Efficiencies (With Load) 87

4.3 Input Parameters and Computational Procedure 87

4.4. Results and Discussion 90

4.4.1 Without Load Condition 90

4.4.2 With Load Condition 94

4.5 Summary 101

CHAPTER — V : Investigation of Some Life Cycle Parameters of Hybrid Photovoltaic (PV) Integrated Greenhouse Dryer

5.1. Introduction 103

. 5.2 Life Cycle Energy Metrics 105

5.2.1 Energy Pay Back Time, EPBT 105

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5.2.2 Energy Production Factor, EPF 105 5.2.3 Life Cycle Conversion Efficiency, LCCE 106 5.3 CO2 Emissions, CO2 Mitigations and Carbon Credit 107

5.3.1 CO2 Emissions 107

5.3.2 CO2 Mitigations 108

5.3.3 Carbon Credit Earned 108

5.4 Energy Input or Energy Requirement for Hybrid PV Integrated Greenhouse 109 Dryer

5.4.1 Embodied Energy of PV Module (Glass to Glass) 109 5.4.2 Embodied Energy of Hybrid PV Integrated Greenhouse Dryer 113 5.5. Total Annual Output from Hybrid PV Integrated Greenhouse Dryer 116 5.5.1 Total Annual Output (Eaout, en) on Energy Basis 116 5.5.1.1 Annual Electrical Energy Output (E„„„,, eid 116 5.5.1.2 Annual Thermal Energy Output (E. _{how. en)} 119 5.5.2 Total Annual Output (Eaout, ex) on Exergy Basis 120

5.6 Results and Discussion 120

5.7 Summary 124

CHAPTER — VI : Cost Analysis of Hybrid Photovoltaic (PV) Integrated Greenhouse Dryer

6.1 Introduction 125

6.2 Theoretical Considerations (Cost Analysis) 128

6.2.1 Net Present Value (PNPv) 128

6.2.2 Payback Period (no) 129

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6.2.3 Annualized Uniform Cost, Unacost (R) 129 6.3 Computation Procedure, Results and Discussion 131

6.4 Summary 139

CHAPTER — VII : Conclusions and Recommendations

7.1 Conclusions 140

7.2 Recommendations 141

References 142

Brief Bio-Data of the Author and List of Publications 157

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Design and performance evaluation of an integrated hybrid photovoltaic greenhouse drying system.