Notation ....................................................... xi
Preface ...................................................... xvii
Introduction: an invention ahead of its time .................. xxi
Part I A long-overdue reappraisal
1 The famous engine that never was ............................. 3
1.1 Status quo .............................................. 3
1.2 The legend .............................................. 5
1.3 History reconstructed ................................... 6
1.4 Exploratory firing tests ................................ 7
1.5 Reassessment ............................................ 9
1.6 Postscript ............................................. 10
2 What Carnot efficiency? ..................................... 13
2.1 Ideal cycle - or perfect alibi ......................... 13
2.2 What Carnot efficiency? ................................ 14
2.3 Old heat exchanger, new air pre-heater ................. 15
2.4 Resources for first-principles gas path design ......... 16
2.5 A further take on friction factor Cf - and not the
last ................................................... 22
2.6 Beyond the sound barrier ............................... 24
2.7 Geometric descriptors for the wire matrix .............. 25
2.8 Inconsistencies uncovered .............................. 26
2.9 Resume ................................................. 27
3 Counter-flow spiral heat exchanger - Spirex ................. 29
3.1 Heat provision as an integral part of the engine ....... 29
3.2 Thermal analysis ....................................... 30
3.3 Heat transfer and flow friction correlations ........... 34
3.4 Special case of high NTU* .............................. 35
3.5 Numerical integration .................................. 35
3.6 Specimen solutions ..................................... 36
3.7 Discussion ............................................. 37
4 A high-recovery-ratio combustion chamber .................... 39
4.1 The design problem ..................................... 39
4.2 Principle .............................................. 40
4.3 Operation .............................................. 43
4.4 Materials .............................................. 43
4.5 Preliminary operating experience ....................... 44
4.6 Second design iteration ................................ 45
Part II Living with incompressible flow data
5 The regenerator problem brought down to size ................ 55
5.1 Background ............................................. 55
5.2 Assumptions ............................................ 55
5.3 Defining equations ..................................... 57
5.4 Boundary conditions .................................... 58
5.5 Flush ratio ............................................ 59
5.6 Integration algorithm .................................. 60
5.7 Specimen temperature profiles .......................... 61
5.8 Design criterion for NTCR .............................. 61
5.9 Alternative formulation in corroboration ............... 64
5.10 Conclusions ............................................ 66
6 The regenerative annulus and shuttle heat transfer .......... 67
6.1 Introduction ........................................... 67
6.2 Background ............................................. 68
6.3 Reformulation .......................................... 69
6.4 Assumptions ............................................ 69
6.5 Analysis ............................................... 70
6.6 Cyclic shuttle loss .................................... 74
7 The rotating-displacer air engine ........................... 77
7.1 Résumé ................................................. 77
7.2 An alternative ......................................... 80
7.3 Taylor parameter ....................................... 84
7.4 A rotating-displacer air engine ........................ 85
7.5 Academic design exercise ............................... 89
8 The strange case of the self-regulating air engine .......... 94
8.1 Background ............................................. 94
8.2 Some realities ......................................... 95
8.3 Constructional details ................................. 96
8.4 Exploratory power and torque measurement ............... 99
8.5 'Self-regulation' ..................................... 101
8.6 Tentative explanation ................................. 102
8.7 Conclusions ........................................... 105
9 Some light on the inner workings of the'thermal lag'
engine ..................................................... 107
9.1 The concept ........................................... 107
9.2 'Thermal lag' engine .................................. 108
9.3 Ideal gas process sequence ............................ 109
9.4 A detailed model of the thermal processes ............. 110
9.5 Limited heat transfer ................................. 120
9.6 Flow losses ........................................... 123
9.7 A practical 'thermal lag' engine ...................... 128
9.8 Preliminary operating experience ...................... 129
9.9 Afterthought .......................................... 131
Part III Working with the reality of compressible flow
10 New correlations for old ................................... 135
10.1 Right data - wrong application ........................ 135
10.2 The misleading Cf - Re correlation .................... 135
10.3 Flow data acknowledging Ma ............................ 136
10.4 Dynamic Similarity to the rescue ...................... 140
10.5 Farewell to friction factor ........................... 142
10.6 The new format ........................................ 143
10.7 What the new format reveals about 'incompressible'
flow data ............................................. 144
10.8 Epitaph ............................................... 144
11 Regenerator thermal analysis - unfinished business ......... 147
11.1 Regenerator design in context ......................... 147
11.2 Assumptions ........................................... 148
11.3 Modified diffusion law ................................ 149
11.4 Numerical solution .................................... 151
11.5 Parameters of operation ............................... 151
11.6 Pressure and velocity fields .......................... 152
11.7 Inevitable asymmetry of flow cycle .................... 153
11.8 Anisotropic matrix .................................... 157
11.9 Discussion ............................................ 159
12 Flow passage geometry ...................................... 161
12.1 Scope ................................................. 161
12.2 Symmetrical gauze - flow perpendicular to plane
of weave .............................................. 162
12.3 Flow parallel to plane of weave ....................... 171
12.4 Commercial availability ............................... 174
12.5 Specimen isotropic material - metal foam .............. 175
12.6 Resume ................................................ 177
13 Beyond the performance envelope ............................ 179
13.1 Introduction .......................................... 179
13.2 Method of Characteristics ............................. 180
13.3 'Unit process' of the integration sequence ............ 183
13.4 High-speed operation - the wave engine ................ 184
13.5 Discussion ............................................ 189
Appendix ................................................... 190
14 For the sceptic ............................................ 192
14.1 What does it all add up to? ........................... 192
14.2 Flow in the isolated gauze aperture ................... 192
14.3 Defining equations .................................... 194
14.4 Radial component of kinetic energy .................... 197
14.5 The not-so-square-weave wire gauze .................... 198
14.6 Kinetic energy of rotation ............................ 200
14.7 'Real' (van der Waals) gas ............................ 201
14.8 Downstream pressure recovery .......................... 201
14.9 Simulated correlation Δplp = Δplp(Sg, Ma, γ, dwmw) ... 202
14.10 Implications for first-principles design ............. 205
14.11 Resume ............................................... 206
Part IV Some design considerations
15 Scaling - and the neglected art of back-of-the-envelope
calculation ................................................ 211
15.1 The overriding objective .............................. 211
15.2 Gas path scaling - update ............................. 211
15.3 Back-of-the-envelope Ma and Re in the regenerator ..... 214
15.4 Limiting Ma ........................................... 217
15.5 Compressibility vulnerability chart ................... 217
15.6 Heat transfer ......................................... 220
15.7 Implications for back-of-envelope design .............. 221
15.8 A 'screening' test .................................... 224
15.9 The wider role of scaling ............................. 225
16 'How to make a business out of Stirling engines today' ..... 226
16.1 Tribal wisdom ......................................... 226
16.2 From alchemy to appropriate technology ................ 226
16.3 What else has changed? ................................ 229
16.4 The VDF-750(aS) ....................................... 231
16.5 Drive mechanism/kinematics ............................ 235
16.6 General mechanical construction ....................... 236
16.7 Pressure-balanced seal ................................ 249
16.8 Beyond 2006 ........................................... 250
Appendix I Draft patent specification ......................... 252
What I claim is ............................................ 255
Abstract ................................................... 256
Appendix II Crank mechanism kinematics ........................ 257
Appendix III Equilibrium or 'temperature-determined'
picture of thermal lag engine .............................. 260
Appendix IV Tribal wisdom ..................................... 261
References and bibliography ................................... 262
Index ......................................................... 268
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