Heat transfer in a beef manure anaerobic digester

266 Pages·2017·4.3 MB·English

by  Thomas Hobson Greiner

Iowa State University Capstones, Theses and
Retrospective Theses and Dissertations
Dissertations
1980
Heat transfer in a beef manure anaerobic digester
Thomas Hobson Greiner
Iowa State University
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Greiner, Thomas Hobson, "Heat transfer in a beef manure anaerobic digester " (1980).Retrospective Theses and Dissertations. 7374.
https://lib.dr.iastate.edu/rtd/7374
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300 N. ZEEB ROAD, ANN ARBOR. Ml 48106
18 BEDFORD ROW, LONDON WCIR 4EJ. ENGLAND
8019632
GRHNER, THOMAS HOBSON
HEAT TRANSFER IN A BEEF MANURE ANAEROBIC DIGESTER
Iowa State University PH.D. 1980
University
Microfilms
InternStiOn&l 300 N. zeeb Road, Ann Arbor. MI 48106 18 Bedford Row, London WCIR4EJ, England
Heat transfer in a beef manure anaerobic digester
by
Thomas Hobson Greiner
A Dissertation Submitted to the
Graduate Faculty in Partial Fulfillment of the
Requirements for the Degree of
DOCTOR OF PHILOSOPHY
Major: Agricultural Engineering
Approved:
Signature was redacted for privacy.
In Charge of Major Work
Signature was redacted for privacy.
Signature was redacted for privacy.
For the Graduate College
Iowa State University
Ames, Iowa
1980
ii
TABLE OF CONTENTS
Page
INTRODUCTION 1
THE NEED FOR A HEAT EXCHANGER 2
Heat Losses 2
An Illustrative Example of Effluent Losses 2
Methods to Reduce Losses 5
Effectiveness and Efficiency 6
Types of Heat Exchangers 8
OBJECTIVES 26
SYMBOLS AND EQUATIONS 28
Symbols 28
Equations 33
HEAT EXCHANGE THEORY 40
Design Equations 40
Application of the Equations 50
Heat Transfer in Direct Type Exchangers 52
Development of Design Equations for a Single Tank Mixed 56
Tank Exchanger
Development of Design Equations for a Multipass MixedT ank 66
Exchanger
Use of the Design Equations, an Example 70
Development of Equations to Determine U 91
Air Agitation Equations 93
iii
Page
EQUIPMENT AND OPERATION 103
Prototype Heat Exchanger 103
Operation of the Prototype 112
Laboratory Equipment to Determine h 113
Operation of the Laboratory Equipment 155
Laboratory Equipment to Determine Rheological Character- 159
istics
RESULTS 166
Prototype 166
Sample Information 176
Rheological Characteristics 180
Expected Temperature Profiles 181
Observed Non-Agitated Temperature Profiles 193
Evaluation of Equipment to Determine Thermal Conductivity 200
Evaluation of Equipment to Determine Free Convective Heat 200
Transfer Coefficients
Observed Agitated Temperature Profiles 205
Evaluation of Equipment to Determine Convective Heat 210
Transfer Coefficients
Air Agitation 212
Experimentally Determined h Values 220
Accuracy of Results 229
SUMMARY AND CONCLUSIONS 236
RECOMMENDATIONS FOR FURTHER STUDY 239
iv
Page
LITERATURE CITED 241
ACKNOITLEDGEMENTS 244
APPENDIX: SUMMARIZED DATA AND RESULTS 245
V
LIST OF TABLES
Page
Exchanger effectiveness, e, as a function of capacity- 64
rate ratio, Cmin/Cmax» and number of heat transfer
units, Nj.^, for a single tank, mixed tank exchanger
Overall exchanger effectiveness, e, as a function of 71
number of heat transfer units, and number of
passes (tanks), n, with capacity-rate ratio, Cmin/
Cmav» equal to 0.0 for a multipass mixed tank ex­
changer
Overall exchanger effectiveness, e, as a function of 72
number of heat transfer units, and number of
passes (tanks), with capacity-rate ratio, Cjnin/
Cjnax' equal to 0.2 for a multipass mixed tank ex­
changer
Overall exchanger effectiveness, e, as a function of 73
number of heat transfer units, Nj-u» and number of
passes (tanks), with capacity-rate ratio, Cmin/
Cmav, equal to 0.4 for a multipass mixed tank ex­
changer
Overall exchanger effectiveness, e, as a function of 74
number of heat transfer units, Ntuj and number of
passes (tanks), n, with capacity-rate ratio, Cmin/
Cmaxj equal to 0.6 for a multipass mixed tank ex­
changer
Overall exchanger effectiveness, e, as a function of 75
number of heat transfer units, N^-^, and number of
passes (tanks), with capacity-rate ratio, Cmin/
Cmav, equal to 0.8 for a multipass mixed tank ex­
changer
Overall exchanger effectiveness, e, as a function of 76
number of heat transfer units, Ntu, and number of
passes (tanks), n, with capacity-rate ratio, Cm-in/
Cjnax» equal to 1.0 for a multipass mixed tank ex­
changer
Prototype orifice flow rates 77
Thermocouple locations 139
vi
Page
Table 9b. Temperature sensitivity of the prototype with a 172
doubling of U
Table 10. Summary of selected experimental data from the proto- 177
type exchanger showing observed and calculated
effectiveness
Table 11. Data for determining rheological characteristics 182
Table 12a. Calculated rheological characteristics 183
Table 12b. Theoretical temperature profile in a circular 186
annulas with conductive heat transfer
Table 13. Theoretical pressure drops and power needed for air 214
agitation
Table 14. Air flow rates as used in the laboratory equipment 217
compared to the theoretical mixing rates
Table 15. Linear regression equation coefficients for sets of 221
digester effluent data sorted by total solids con­
centrations
Table 16. Linear regression equation coefficients for sets 222
of raw manure data sorted by total solids concen­
trations
Table 17. Summary of the SAS output and the F test to test for 225
differences between type 1 and type 2
Table 18. Summary of the SAS output for the general linear 227
model for digester effluent, type 1
Table 19. Summary of the SAS output for the general linear 228
model for raw manure, type 2
vii
LIST OF FIGURES
Page
Types of heat exchangers 9
Types of heat exchangers 10
Types of heat exchangers 11
Types of heat exchangers 12
Multipass, mixed tank exchanger 14
Top view of a multipass mixed tank exchanger 15
Front view, section A-A, of a multipass mixed tank 16
exchanger
Front view, section B-B, of a multipass mixed tank 17
exchanger
Top view of a single tank, mixed tank exchanger 58
Heat transfer effectiveness, £, as a function of 65
number of heat transfer units, N^-^, and capacity-
rate ratio, Cmin/Cmax» for a single tank, mixed
tank exchanger
Top view of a multipass, mixed tank exchanger 67
Heat transfer effectivess, e, as a function of 78
number of heat transfer units, Ntu> and capacity-
rate ratio, Cmin/Crnav equal to 0.0 for a multi­
pass mixed tank exchanger
Heat transfer effectiveness, £, as a function of 79
number of heat transfer units, N^u» and capacity-
rate ratio, Cmin/Cmav equal to 0.2 for a multi­
pass mixed tank exchanger
Heat transfer effectiveness, e, as a function of 80
number of heat transfer units, Ntu» and capacity-
rate ratio, Cmin/Cmav equal to 0.4 for a multi­
pass mixed tank exchanger
Heat transfer effectiveness, £, as a function of 81
number of heat transfer units, Ntu> and capacity-
rate ratio, C^-în/Cmav equal to 0.6 for a multi­
pass mixed tank exchanger