EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF SNOW

5,25

MB

MELTING ON HEATED HORIZONTAL SURFACES

218

stron

6340

ID

Oklahoma State University

2002

rok

TABLE OF CONTENTS

CHAPTER 1 1

INTRODUCTION. 1

1.1 Background . 1

1.2 Thesis Organization. 3

CHAPTER 2 5

LITERATURE REVIEW. 5

2.1 Outline. 5

2.2 Snowmaking 5

2.3 Snow/Ice Physical Properties 7

2.4 Heat Transfer / Heat Balance 10

2.4.1 Surface Convection 10

2.4.2 Natural Internal Convection . 15

2.4.3 Radiation 19

2.5 Water Flow 29

2.6 Snow Metamorphism 34

2.7 Snow Melting from the Bottom 39

2.8 Road Effects 46

CHAPTER 3 48

NUMERICAL MODEL 48

3.1 Overview . 48

3.2 Model 48

3.3 Boundary condition model 49

3.4 Model Detail Considerations. 50

3.5 Geometry. 51

3.6 Mass Transfer 53

3.7 Heat Transfer. 54

3.8 Mathematical Model . 56

3.9 Model Changes 64

CHAPTER 4 70

EXPERIMENTAL APPARATUS. 70

4.1 Introduction . 70

4.2 Snow Making/ Environmental Chamber. 70

4.2.1 Top Section 74

4.2.2 Middle Section . 77

4.2.3 Bottom Section. 81

4.3 Snow Making Equipment 84

4.4 Mechanical Refrigeration Setup 89

4.5 Chamber Thermocouple Placement 95

4.6 Snow-melting apparatus 96

4.7 Weight Measurement 102

4.8 Height Measurement . 103

4.9 Instrument Calibration. 103

CHAPTER 5 104

RESULTS AND DISCUSSION 104

5.1 Experimental Procedure 104

5.1.1 Snow-Making Procedure 106

5.2 Preliminary Experiments. 106

5.2.1 Uneven melting/Hot spots on the plate 107

5.2.2 Water drainage experiment 109

5.2.3 Capillary Height . 110

5.2.4 Plate Temperature – Qualitative Analysis 113

5.2.5 Plate Temperature - Quantitative Analysis 117

5.2.6 Crystal Size 118

5.3 Snow Melting Results . 120

5.4 Thermodynamic Melt Time 128

5.5 Melt water Runoff . 131

5.6 Qualitative discussion of snow melt 133

5.7 Practical Guidance. 135

5.8 Additional Modeling . 137

CHAPTER 6 138

CONCLUSIONS AND RECOMMENDATIONS 138

6.1 Conclusions . 138

6.2 Recommendations . 139

BIBLIOGRAPHY . 141

APPENDIX A 146

INSTRUMENT CALIBRATION 146

APPENDIX B. 149

ERROR ANALYSIS/ UNCERTAINTY ANALYSIS 149

B.1: Overview . 149

B.2: Model. 149

B.2.1: Mass of Snow . 149

B.2.2: Melt Time . 161

B.2.8: Camera Light 162

B.2.9: Convection Heat Flux. 156

B.2.10: Radiation Heat Flux 163

B.2.11: Apparatus Radial Heat Gain. 165

B.2.12: Heat Gain from Backside of Plate 166

B.2.13: Initial Conditions 166

B.2.14: Heat Storage . 167

B.2.15: Overall Numerical Uncertainty 170

B.3: Experimental Uncertainty 171

B.4: Uncertainty Summary 180

APPENDIX C 181

WATER SATURATION LAYER MODEL. 181

Procedure. 182

Results . 183

APPENDIX D 188

OTHER EXPERIMENTAL DATA 189