Design of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine hybrid system for distributed power generation = 분산발전을 위한 용융탄산염 연료전지와 예혼합압축착화 엔진 하이브리드 시스템 설계

다국어 초록 (Multilingual Abstract)

Recently, various energy issues, e.g. depletion of natural resources and growing environmental concerns, have been encountered year by year. For the reason, the demand for renewable power source increases, and fuel cell technology draws interest as a good applicant in the field due to high efficiency and low pollutant. In the previous work, a new MCFC hybrid system integrated with HCCI engine was developed. In the hybrid system, the HCCI engine replaces the catalytic combustor in the original fuel cell system and yields additional power by using the left-over fuel in the anode off-gas. In this thesis, the engine design is performed for the 250 kW-class MCFC system. For the thermodynamic analysis, thermodynamic modeling is performed and the parametric study is conducted with design options variation. With the determined engine specification, the hybrid system is analyzed at the design point and part-load operation. The hybrid system efficiency can achieve 57.1 %, which is 9.8 % higher than the standalone system efficiency at the design point operation. And the systematic control strategies are developed at the part-load conditions, and thus the hybrid system can operate at the various fueling levels. An economic assessment is also conducted for comparison between the standalone system and the hybrid system. The analysis is performed by calculating the levelized cost of electricity (LCOE) with total revenue requirement (TRR) method. The LCOE of the hybrid system is ~5.4 % lower than that of the standalone system, thus the economic feasibility of the hybrid system was verified. Based on the simulation results, the engine experiment is conducted to demonstrate the possibility of the HCCI engine operation in the system. As a result, the engine net indicated efficiency is measured to be ~17 %. Considering the small displacement volume of the tested engine with its relatively un-favorable heat transfer characteristic, the engine performances in the hybrid system are shown to be quite promising. It is anticipated that the results of this thesis would be considered the study leading up to the commercialization of the new MCFC-HCCI engine hybrid system for distributed power generation in near-future.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• 1.1 Research background 1
• 1.2 Literature survey 4
• 1.3 Development of hybrid system concept 11
• 1.4 Summary 14
• Chapter 2. Hybrid system thermodynamic analysis methods 16
• 2.1 Introduction 16
• 2.2 MCFC stack modeling description 17
• 2.3 HCCI engine modeling description 21
• 2.4 Blower and pump modeling description 23
• 2.5 System integration 23
• 2.6 Summary 26
• Chapter 3. Hybrid system engine design 27
• 3.1 Introduction 27
• 3.2 System operation with design options variation 28
• 3.2.1 System decision variables 28
• 3.2.2 Engine compression ratio variation 29
• 3.2.3 Engine intake charge equivalence ratio variation 35
• 3.2.4 Engine RPM variation 40
• 3.2.5 MCFC fuel utilization factor variation 42
• 3.3 Engine size decision 48
• 3.4 Summary 54
• Chapter 4. Hybrid system operation 56
• 4.1 Introduction 56
• 4.2 System performances with design point operation 57
• 4.2.1 System characteristics 57
• 4.2.2 Comparison between standalone and hybrid system performances 63
• 4.3 System performances with part-load operation 70
• 4.3.1 Operating strategy for part-load operation 70
• 4.3.2 System performances 73
• 4.4 Summary 75
• Chapter 5. Economic analysis 76
• 5.1 Introduction 76
• 5.2 Economic analysis methodology 77
• 5.2.1 Cost of equipment 78
• 5.2.2 Total capital investment 83
• 5.2.3 Total revenue requirement 88
• 5.2.4 Levelized cost of electricity 89
• 5.3 Results of LCOE calculation 92
• 5.3.1 LCOE of MCFC standalone system 92
• 5.3.2 LCOE of MCFC-HCCI engine hybrid system 96
• 5.3.3 Comparison of the standalone system and hybrid system 99
• 5.4 Summary 103
• Chapter 6. Hybrid system feasibility verification 104
• 6.1 Introduction 104
• 6.2 Experimental setup 107
• 6.2.1 Engine intake system 107
• 6.2.2 HCCI engine 113
• 6.2.3 Engine exhaust system and gas analyzer 118
• 6.2.4 Data acquisition 120
• 6.3 Experimental results 122
• 6.3.1 Design point operation 122
• 6.3.2 Part-load operation 126
• 6.3.3 Comparison between simulation and experimental results 1311
• 6.4 Summary 1377
• 7. Conclusion 138
• Appendix A. MCFC stack modeling description 143
• Appendix B. HCCI engine modeling description 152
• References 154
• 국 문 초 록 166