Geothermal Heat Pump and Heat Engine Systems

Andrew Chiasson is a faculty member in the Department of Mechanical & Aerospace Engineering, University of Dayton, where he teaches courses and conducts research in the areas of thermofluid sciences, and renewable and clean energy. He has academic and professional practice experience in a wide range of geothermal and hydrogeologic applications related to geothermal heat pumps (geoexchange), direct-use geothermal, small-scale electrical power generation, hydrogeological site evaluations, and groundwater flow and mass/heat transport modeling. Dr. Chiasson has been extensively involved in research and development of design and simulation tools for optimal earth heat exchanger coupling, hybrid geoexchange systems, and underground solar energy storage. As a Professional Engineer in the United States and in Canada, he has designed numerous closed and open-loop geoexchange systems and HVAC systems for a wide variety of building types. He is a member of ASHRAE Technical Committees and is an IGSHPA Accredited Ground Source Heat Pump Trainer.

• Series Preface xivPreface xvAbout the Companion Website xviii1 Geothermal Energy Project Considerations 11.1 Overview 11.2 Renewable/Clean Energy System Analysis 11.3 Elements of Renewable/Clean Energy Systems 41.4 Geothermal Energy Utilization and Resource Temperature 51.5 Geothermal Energy Project History and Development 51.6 Chapter Summary 18Discussion Questions and Exercise Problems 19Part I Geothermal Energy – Utilization and Resource Characterization 212 Geothermal Process Loads 232.1 Overview 232.2 Weather Data 242.3 Space Heating and Cooling Loads 262.4 Hot Water Process Loads 382.5 Swimming Pool and Small Pond Heating Loads 402.6 Snow-Melting Loads 462.7 Chapter Summary 53Discussion Questions and Exercise Problems 543 Characterizing the Resource 553.1 Overview 553.2 Origin and Structure of the Earth 563.3 Geology and Drilling Basics for Energy Engineers 593.4 Earth Temperature Regime and Global Heat Flows: Why is the Center of the Earth Hot? 623.5 Shallow Earth Temperatures 643.6 The Geothermal Reservoir Concept 663.7 Geothermal Site Suitability Analysis 683.8 Chapter Summary 79Discussion Questions and Exercise Problems 80Part II Harnessing the Resource 814 Groundwater Heat Exchange Systems 834.1 Overview 834.2 Why Groundwater? 844.3 Theoretical Considerations 854.4 Practical Considerations 1084.5 Groundwater Heat Pump Systems 1234.6 Chapter Summary 134Discussion Questions and Exercise Problems 1355 Borehole Heat Exchangers 1385.1 Overview of Borehole Heat Exchangers (BHEs) 1385.2 What is a Borehole Heat Exchanger? 1395.3 Brief Historical Overview of BHEs 1405.4 Installation of BHEs 1415.5 Thermal and Mathematical Considerations for BHEs 1425.6 Thermal Response Testing 1695.7 Pressure Considerations for Deep Vertical Boreholes 1755.8 Special Cases 1765.9 Chapter Summary 178Discussion Questions and Exercise Problems 1796 Multi-Borehole Heat Exchanger Arrays 1816.1 Overview 1816.2 Vertical GHX Design Length Equation and Design Parameters 1846.3 Vertical GHX Simulation 1986.4 Hybrid Geothermal Heat Pump Systems 1996.5 Modeling Vertical GHXs with Software Tools 2006.6 Chapter Summary 216Discussion Questions and Exercise Problems 2177 Horizontal Ground Heat Exchangers 2197.1 Overview 2197.2 Horizontal GHX Design Length Equation and Design Parameters 2217.3 Modeling Horizontal GHXs with Software Tools 2327.4 Simulation of Horizontal GHXs 2377.5 Earth Tubes 2387.6 Chapter Summary 244Discussion Questions and Exercise Problems 2448 Surface Water Heat Exchange Systems 2468.1 Overview 2468.2 Thermal Processes in Surface Water Bodies 2478.3 Open-Loop Systems 2508.4 Closed-Loop Systems 2518.5 Chapter Summary 266Discussion Questions and Exercise Problems 2669 Opportunistic Heat Sources and Sinks 2679.1 Overview 2679.2 Use of Existing Water Wells 2679.3 Heat Exchange With Building Foundations 2689.4 Utilization of Infrastructure from Other Energy Sectors 2689.5 Cascaded Loads and Combined Heat and Power (CHP) 2719.6 Integrated Loads and Load Sharing with Heat Pumps 2739.7 Chapter Summary 278Discussion Questions and Exercise Problems 27910 Piping and Pumping Systems 28010.1 Overview 28010.2 The Fluid Mechanics of Internal Flows 28110.3 Pipe System Design 28610.4 Configuring a Closed-Loop Ground Heat Exchanger 28910.5 Circulating Pumps 29810.6 Chapter Summary 305Exercise Problems 305Part III Geothermal Energy Conversion 30711 Heat Pumps and Heat Engines: A Thermodynamic Overview 30911.1 Overview 30911.2 Fundamental Theory of Operation of Heat Pumps and Heat Engines 30911.3 The Carnot Cycle 31111.4 Real-World Considerations: Entropy and Exergy 31211.5 Practical Heat Engine and Heat Pump Cycles 31711.6 The Working Fluids: Refrigerants 32011.7 Chapter Summary 322Discussion Questions and Exercise Problems 32312 Mechanical Vapor Compression Heat Pumps 32412.1 Overview 32412.2 The Ideal Vapor Compression Cycle 32512.3 The Non-Ideal Vapor Compression Cycle 32812.4 General Source-Sink Configurations 34212.5 Mechanics of Operation 34712.6 Transcritical Cycles 36612.7 Vapor Compression Heat Pump Performance Standards and Manufacturer’s Catalog Data 37012.8 Chapter Summary 373Discussion Questions and Exercise Problems 37413 Thermally Driven Heat Pumps 37613.1 Overview 37613.2 Cycle Basics 37713.3 Absorption Cycles 37813.4 Adsorption Cycles 39613.5 Thermally Driven Heat Pump Performance Standards and Manufacturer’s Catalog Data 39713.6 Chapter Summary 397Discussion Questions and Exercise Problems 39814 Organic Rankine Cycle (Binary) Geothermal Power Plants 39914.1 Overview 39914.2 The Ideal Rankine Cycle 40014.3 The Non-Ideal Rankine Cycle 40214.4 Organic Rankine Cycle Performance Modeling 41014.5 Chapter Summary 416Discussion Questions and Exercise Problems 416Part IV Energy Distribution 41915 Inside the Building 42115.1 Overview 42115.2 Heat Pump Piping Configurations 42115.3 Hydronic Heating and Cooling Systems 42515.4 Forced-Air Heating and Cooling Systems 42515.5 Ventilation Air and Heat Pumps 42615.6 Chapter Summary 431Discussion Questions and Exercise Problems 43116 Energy Economics and Environmental Impact 43316.1 Overview 43316.2 Simple Payback Period and Rate of Return 43416.3 Time Value of Money 43516.4 Cost Considerations for Geothermal Energy Systems 43716.5 Uncertainty in Economic Analyses 43916.6 Environmental Impact 44116.7 Chapter Summary 444Appendix A: Software Used in this Book 445A.1 The GHX Tool Box 445A.2 Engineering Equation Solver (EES) 445A.3 Installing and Using the Excel Solver for Optimization Problems 446What is the Excel Solver? 446Installing the Excel Solver 446Using the Excel Solver 446Appendix B: Hydraulic and Thermal Property Data 448Appendix C: Solar Utilizability Method 450Nomenclature 454References 459Index 464

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