CCHP/V Systems Integration PhD. Defense Fred Betz PhD. Candidate May 11th, 2009 Carnegie Mellon University Center for Building Performance and Diagnostics.
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CCHP/V Systems Integration PhD. Defense Fred Betz PhD. Candidate May 11th, 2009 Carnegie Mellon University Center for Building Performance and Diagnostics Dissertation Committee • Volker Hartkopf – Chair, Architecture • David Archer – Mechanical Engineering • John Wiss – Mechanical Engineering 2 Outline • Problem and Objectives • Sub-system Overview – Biodiesel Fueled CHP System – Steam Driven Double Effect Absorption Chiller – Enthalpy Recovery Ventilation System with Desiccant Dehumidification • TRNSYS Simulations – Intelligent Workplace (IW) – Building As Power Plant (BAPP) • Systems Integration • Future Work 3 Problem • According to the Department of Energy the main barriers to the adoption of the CHP systems are: – the high first cost, – the high operating cost (maintenance, personnel), and – the complexity of operation 4 Objectives • Integrate the biodiesel fueled CHP system with the steam driven absorption chiller and enthalpy recovery ventilation system with desiccant dehumidification. – To reduce first and operating costs – To simplify installation and operation • Cited by DoE as key barrier to adoption 5 Sub-System Overview • Biodiesel Fueled CHP System • Steam Driven Double Effect Absorption Chiller • Enthalpy Recovery Ventilation System with Desiccant Dehumidification 6 Biodiesel Fueled CHP System 7 CHP System Flow Diagram Power to IW/Grid ATS / SLC Exhaust Muffler Generator Absorption Chiller Steam Diesel Engine Radiator Exhaust Exhaust Gas Diversion Valve To Condensate Tank Steam Generator Hot Water Converter Coolant Loop Condensate Tank Coolant Heat Exchanger Chilled Water Supply and Return (IW/Grid) To CMU Campus Steam Grid Hot Water Supply and Return (IW/Grid) To CMU Campus Condensate Grid Regen Exhaust Condensate from Exhaust Air Absorption Chiller/Grid Regen Coil Hot Water Supply and Return (IW/Grid) Ventilation System Regen Air Return Air Outside Air Dehumidified Air to IW 8 Biodiesel Fueled CHP Systems Integration Coolant Heat Exchanger Biodiesel Diesel Fill Station 2 Fill Station 1 VFD Fuel Tank 2 Fuel Tank 1 Motor Valve 5 Valve 6 Motor Radiator Fan Motor Motor Pump Starter Valve 4 Motor Motor Valve 3 Engine-Generator Fuel Pump 1 Day Tank 1 Engine Generator Fuel Pump 2 Day Tank 2 Air Turbocharger Controler Electric Grid Automatic Transfer Switch Intelligent Workplace Mullion Steam Generator Bypass Tee Muffler Blowdown Separator Steam Generator Back Pressure Valve Control Column Steam Converter Motor Valve 2 Fan Coil Supplier/Manf/Integrator Baldor John Deere Stamford Intelligen ASCO Vaporphase Kickham Broad ITT Pryco Magnetek BorgWarner Belimo Bell & Gossett Highland Tank Marathon Penn Separator Corp. Thermoflo General Electric Siemens Nelson Pomeco OPW Marathon Electric Campus Steam Grid Motor Valve 1 Absorption Chiller Radiant Panel Cool Wave Feed Water Valve Condensate Pumps (2) Motor (2) Condensate Receiver w/ Controller 9 Biodiesel Fueled CHP I/O • Measured Inputs – – – – Fuel (Biodiesel or Petrol-Diesel For Engine) Air (For Engine) Condensate (For Steam Generator) Hot Water Return (For Coolant Heat Exchanger) • Measured Outputs – Electricity (For IW and Campus Grid) – Exhaust (For Steam Generator) – Steam (For Space Heating, Absorption Chiller, or Campus Grid) – Hot water Supply (For Space Heating or Desiccant Regeneration) 10 CHP Results Winter CHP Soy Based Biodiesel Results Power Output (kWe) Fuel Input (kWc) Plant Power (kWe) Coolant Heat Recovered (kWt) Exhaust Heat Recovered (kWt) CHP Efficiency (%) 25 76 4 18 18 76% • Evaluated Diesel and soy based biodiesel fuel over four power levels (6, 12, 18 and 25 kWe) • Nearly identical performance, except higher biodiesel fuel consumption. • Electrical and CHP efficiency drops as power level decreases. 11 Emissions Results Averaged Diesel Emissions Load (kWe) % O2 % CO % CO2 25 9.6 0.1 8.2 UHC NO (PPM) (PPM) 12 502 NO2 (PPM) 4 Averaged Biodiesel Emissions Load (kWe) % O2 % CO % CO2 25 9.7 0.0 8.4 UHC NO (PPM) (PPM) 3 498 PPM (NO2) 9 • Completed 6-gas exhaust gas analysis for both Diesel and biodiesel fuel. • Reasonable AFR based on %O2 and %CO2. • Reduction in %CO and UHC shows improved combustion for biodiesel fuel consistent with published data. • NOX doesn’t increase, which is inconsistent with published data. 12 May be due to engine timing. Steam Driven Double Effect Absorption Chiller 13 Absorption Chiller I/O • Measured Inputs – – – – High Pressure Steam (From Steam Generator) Chilled Water Return (From IW) Electricity (For Pumps, Fan, Controls) Treated Water (For Cooling Tower) • Measured Outputs – Chilled Water Supply (For IW and/or Grid) – Condensate (For Steam Generator) – Water Vapor (From Cooling Tower) 14 Absorption Chiller Operation • Uses approximately 16 kWt of steam at – 87 psig (6 bar) – 360oF (160oC) – 28 kg/hr (65lb/hr) • Average COP of 1.1 • Reduces water temperature from 57oF to 45oF (14oC to 7oC) 15 Ventilation system with Enthalpy Recovery and Solid Desiccant Dehumidification 16 Ref: Images from Chaoqin Zhai, www.cmu.edu/iwess Ventilation Operation Psychrometric Chart of Ventilation System 17 Ventilation System I/O • Measured Inputs – Outside Air for Ventilation and Desiccant Regeneration – Natural gas (For Desiccant Regeneration) – Electricity (For fans, wheels and controls) – Return Air (From Conditioned Space) • Measured Outputs – Dehumidified Ventilation Air (For IW) – Exhaust Air (To atmosphere) – Exhaust (From Desiccant Regeneration) 18 Ventilation Results • The desiccant wheel accounts for 62% of the operating cost due to natural gas consumption for regeneration. • 95oC heat at 12 GPM from the engine coolant can be used to regenerate the desiccant. Ventilation System Operating Cost Breakdown 19 Ref: Slide presented by Dr. Zhai at 2008 ASME Energy Sustainability Conference TRNSYS Simulations • An integrated model based on empirical data collected from the absorption chiller, ventilation system, and the CHP system has been created. • Inputs: – The IW’s heating, cooling, and regeneration load files. • Outputs: – A look up table with operational data from the CHP system including power level, fuel consumption, and temperatures and flows of the various heat streams for cooling, heating, and desiccant regeneration. 20 TRNSYS Simulations • The controller currently can operate in three different modes: -Mode 0: Operate at 100% (25 kWe) -Mode 1: Thermal Load Follow (Cooling, Heating) -Mode 2: Regeneration Load Follow Note: – The controller prioritizes coolant energy for heating over steam, which can be exported. – The engine will not operate below 25% of rated capacity. 21 IWESS Mode Zero Results Mode Zero Results: Design Operation at 25 kWe Annual Net Energy Export 1,015,470 MJ Annual Net Thermal Energy Export 706,442 MJ Annual Net Electrical Energy Export 309,028 MJ Hours of Operation 8,760 Hours Heating Hours Not Met 351 Hours Cooling Hours Not Met 191 Hours Regeneration Hours Not Met 265 Hours Total Energy Used 1,791,999 Total Fuel Consumption Total Fuel Energy Consumption 19,921 2,712,360 Average Annual Efficiency MJ Gallons MJ 66% • Only achieves a 66% efficiency – due to rejection of coolant heat and, – rejecting high temperature exhaust after heat recovery. 22 IWESS Model Discussion • Average annual CHP efficiency is 65% to 68% depending on the operational mode due to. – the relatively large amount of coolant heat is rejected, – the engine operating at an inefficient load, and/or – due to the relatively high rejected exhaust temperature. • Low and intermittent loads from high performance buildings presents a significant controls challenge. • Potential Solutions: – Have a larger hot water grid that can absorb the excess coolant energy. – Install a single effect absorption chiller to make chilled water and export it to the grid. – Use thermal storage to maintain a higher load, and then shut off the engine. – Have several smaller engines that can be banked together using a modular approach. 23 BAPP Simulations • The BAPP simulations use a modified 200 kWe Diesel engine generator based on a manufacturer’s specification sheet and data collected from the 25 kWe engine generator. • The same CHP controller was utilized for this simulation with three operational modes. • Modified IW load files were used as no BAPP simulation file is available. 24 BAPP Mode One Results Mode One Results: Thermal Load Follow Annual Net Energy Import 2,363,485 MJ Annual Net Thermal Energy Import 2,058,830 MJ Annual Net Electrical Energy Import 304,655 MJ Hours of Operation 5,165 Hours Heating Hours Not Met 5,817 Hours Cooling Hours Not Met 2,981 Hours Regeneration Hours Not Met 3,450 Hours Total Energy Used Total Fuel Consumption Total Fuel Energy Consumption Average Annual Efficiency 5,663,109 54,107 7,366,797 MJ Gallons MJ 77% • The BAPP mode 1 simulation operates about 5,000 hours. • The efficiency higher than the IWESS results because the CHP system is under sized, and is a net energy import. • Turndown ratio is an issue as the load is often below 25% 25 of the engine’s capacity. BAPP Model Discussion • The fact that a BAPP load file with cooling, heating, and regeneration loads does not exist makes design recommendations difficult. • A modular approach to the CHP system with several smaller prime movers will assist in solving the turn down ratio if a thermal load follow operational mode is desired. • Connections to hot water grids in MMCH, Donner Hall, etc would assist in finding loads for hot water. Alternately, a single effect absorption chiller could be used to generate additional chilled water for export to the campus grid. 26 Systems Integration • Combine three separate sub-systems – Steam driven double effect absorption chiller – Enthalpy recovery ventilation system with desiccant dehumidification – Diesel engine generator with heat recovery 27 Energy Cascade Fuel Energy Engine Generator Electricity Chilled Water Return Absorption Chiller Chilled Water Supply Exhaust Coolant Exhaust Heat Recovery (DHW) Exhaust Heat Recovery (SH) Regeneration Heat Exchanger Coolant Heat Exchanger Domestic Hot Water Preheat City Water / Preheated DHW Domestic Hot Water Hot Water Return Hot Water Supply Outside Air Regeneration Air Hot Water Return Hot Water Supply City Water Preheated DHW 28 Sub-Systems to be Integrated Control Data Control Data Intelligen Controls Automatic Transfer Switch / Soft Load Controller Electricity Engine Generator Air Pneumatic Controls Exhaust Heat Recovery / Steam Generator ALC Controls Radiator Coolant Heat Recovery Fuel Hot Air Hot Water Loop Compressed Air Steam Control Data Hot Exhaust Condensate ALC Controls Exhaust Air Enthalpy Recovery Module Desiccant Module Heat Pump Module Regen Burner Return Natural Air Gas Electricity Outside Air Regeneration Air Exhaust Control Data Broad Controls Absorption Chiller Cooling Tower Electricity Dehumidified Supply Air Treated Water High Pressure Low Quality Steam Steam 29 Summary of I/O Existing IWESS Configuration Inputs / Outputs CHP System Inputs Fuel (Biodiesel) Outputs Absorption Chiller System Inputs Ventilation System Outputs Inputs Outputs Exhaust Fuel (Natural Gas) Dehumidified Air Regeneration Exhaust Air Exhaust Air Electricity Electricity Air Exhaust High Pressure Steam Condensate Outside and Return Air Condensate High Pressure Steam Chilled Water Return Chilled Water Supply Regeneration Air Hot Water Return Hot Water Supply Makeup Water (Cooling Tower) Steam (Cooling Tower) Electricity Compressed Air 30 IWESS Systems Integration Control Data Automatic Transfer Switch / Soft Load Controller Electricity Control Data Intelligen Controls ALC Controls Engine Generator Air Radiator Coolant Heat Recovery Fuel Hot Air Dehumidified Supply Air Hot Exhaust Pump Exhaust Air Enthalpy Recovery Module Desiccant Module Broad Controls High Pressure Steam Hot Water Loop ALC Controls Control Data Pneumatic Controls Exhaust Heat Recovery / Steam Generator Regeneration Air Exhaust Regeneration Air Supply Cooling Tower Chilled Water Loop Heat Pump Module Regen Burner Regen Coil Outside Return Air Air Absorption Chiller Control Data Electricity Natural Gas Electricity Terminal Heating Units Pump City Water Domestic Hot Water Exhaust Treated Water Low Quality Steam Terminal Cooling Units Pump DHW 31 Natural Gas Electricity Cutting First Costs • Removed Components – 1 major component (heat pump) – 2 minor components (regeneration burner and cooling tower) – 7 control systems with their respective interfaces – 2 heat rejections • Added Components – 3 minor components (heating coil, cooling coil, and DHW preheat heat exchanger) – 1 supervisory controller that handles all control features with one interface 32 Packaged System Supervisory Controller Electricity Regeneration Air Exhaust Regeneration Air Supply Engine Exhaust Engine Exhaust Regen Coil Automatic Transfer Exhaust Engine Switch / Heat Generator Soft Load Recovery Controller Electricity Coolant Heat Recovery Absorption Chiller Radiator Domestic Hot Water Preheat Air Fuel Enthalpy Recovery Module Heating Coil Cooling Coil Desiccant Module City Outside Return Water Air Air Hot Air Pump Chilled Water Loop Dehumidified Supply Air Pump Domestic Hot Water DHW Pump Hot Water Loop Terminal Heating Units Terminal Cooling Units 33 Operating Cost Savings • Regenerating the solid desiccant of the ventilation system will reduce the operational costs of the ventilation system by approximately 60%. • Operating a pump with heating and cooling coils in place of the compressor on the heat pump. • Using the reject heat from the cooling tower will save treated cooling tower water, and will provide a heat source for preheating domestic hot water. 34 Contributions • Complete installation, operation, and evaluation of a biodiesel fueled CHP system. • A generic preliminary CHP design guide. • A TRNSYS simulation platform for CHP systems to test operational strategies. • An example of systems integration for a CHP system with an absorption chiller and a ventilation system. 35 Conclusions • A biodiesel fueled CHP system performs as well as a Diesel fueled CHP system. • If CHP systems and high performance buildings are to be combined, it is necessary to make thermal grids available to maintain a high efficiency. • The BAPP CHP system should be a modular system that can achieve a high turndown ratio to maintain a high CHP efficiency. 36 Future Work • Automation and Integration – Complete the automated startup and control system via Automated Logic software. – Physically connect the engine coolant system to the ventilation regeneration system to validate the simulation. – Extend exhaust heat recovery to include DHW. – Link the operation of the engine directly with the chiller and ventilation operation. 37 Future Work • Work with researchers and manufacturers on an integrated system to reduce first costs by a factor of 10 to 20. Biodiesel Fueled Engine Generator with Heat Recovery Cost Breakdown Facilities, $18,692.72, 3% Instrumentation & Controls, $90,818.85, 13% Engineering, $48,014.38, 7% Installation, $397,613.00, 60% Capital Equipment, $117,756.00, 17% Other, $2,886.52, 0% 38 Installation Other Capital Equipment Engineering Instrumentation & Controls Facilities Future Work • Recreate the BAPP simulation file and determine new loads for the TRNSYS file to explore design strategies for the mechanical systems. – Test additional control strategies. – Test modular prime mover size options. – Add DHW and or a single effect chiller to the model to complete the energy cascade. – Determine the effect of multiple BAPPs in a campus grid. 39 Questions? 40 Acknowledgements Special thanks to my committee and their tireless efforts supporting and reviewing my work Special thanks to Dr. Chris Damm at the Milwaukee School of Engineering for getting me involved in this project Special thanks to Flore Marion for her TRNSYS work, which made this dissertation possible! 41 Preliminary CHP Design Guidelines 1. Determine electrical and thermal loads, load profiles, and required flow rates and temperatures of cooling and heating streams. 2. Determine which fuel types are locally available, how they are distributed, and their cost. 3. Determine what energy grids are available, what their operating conditions and costs are, and if it is possible to interface with them. 42 Preliminary CHP Design Guidelines 4. Select a prime mover that best fits the load profiles, load proportions, and fuel selection. 5. Select auxiliary and heat recovery equipment to match the prime mover and the fluids used to transfer energy. 6. Choose an operating strategy (thermal or electrical load follow, base load, design, etc.) 7. Evaluate the options on a capital, operating, and environmental cost basis. 43 Additional Ventilation System Results Moisture Removal Breakdown Enthalpy Removal Breakdown 44 Computational TRNSYS Model 45 Method • Phase I – – – – Component survey of chiller and ventilation systems. Analyze existing TRNSYS simulation models. Complete evaluation of biodiesel fueled CHP system. Complete CHP TRNSYS model. • Phase II – Integrate TRNSYS models into a single model. – Show potential first cost reductions by creating a packaged CCHP/V system. • Phase III – Apply operating strategies using integrated TRNSYS model. – Show potential operating cost reductions using a packaged CCHP/V system. 46 CHP Results Summer CHP Diesel Results Power Output (kWe) Fuel Input (kWc) Plant Power (kWe) Coolant Heat Recovered (kWt) Exhaust Heat Recovered (kWt) CHP Efficiency 6 25 3 6 3 47% 12 43 3 9 7 59% 18 57 3 12 12 68% 25 76 3 18 18 76% Winter CHP Diesel Results Power Output (kWe) Fuel Input (kWc) Plant Power (kWe) Coolant Heat Recovered (kWt) Exhaust Heat Recovered (kWt) CHP Efficiency 6 25 4 6 4 49% 12 43 4 11 7 61% 18 57 4 14 12 70% 25 76 4 18 17 74% Winter CHP Biodiesel Results Power Output (kWe) Fuel Input (kWc) Plant Power (kWe) Coolant Heat Recovered (kWt) Exhaust Heat Recovered (kWt) CHP Efficiency 6 26 4 8 4 54% 12 42 4 10 9 65% 18 59 4 14 13 68% 25 76 4 18 18 76% 47 Emissions Results Low Sulfur Diesel Emissions Results Load (kWe) % O2 % CO % CO2 UHC (PPM) NO (PPM) NO2 (PPM) 6 16.1 0.0 3.7 4 251 4 12 13.9 0.1 5.2 9 424 6 18 11.6 0.1 6.8 11 466 5 25 9.6 0.1 8.2 12 502 4 Soy Based Biodiesel Emissions Results Load (kWe) % O2 % CO % CO2 UHC (PPM) NO (PPM) NO2 (PPM) 6 16.3 0.0 3.8 0 224 5 12 13.9 0.0 5.4 1 357 8 18 11.5 0.0 7.1 2 450 10 25 9.7 0.0 8.4 3 498 9 48 Absorption Chiller vs. Vapor Compression Chiller Heat Rejection to Cooling Tower High Temperature Heat Source Condenser Generator or Desorber Electricity P Evaporator Absorber Heat From Load (Building) Heat Rejection to Cooling Tower • Absorption Chiller – COP = 0.6 – 1.1 – Uses heat to generate cooling Condenser Expansion Valve Compressor Expansion Valve Heat Rejection to Cooling Tower Electricity Evaporator Heat From Load (Building) • Vapor Compression Chillers – COP = 2.0 – 6.0 – Uses electricity to generate cooling 49 Absorption Chiller Components High Temperature Heat Source Condenser Steam supply Strong LiBr Refrigerant solution Refrigerant LTRG condensate HTRG Cooling water LTHX HRHX HTHX Evaporator Chilled water loop Absorber High Condenser Expansion Valve Heat Rejection to Cooling Tower Electricity P Low Condenser Expansion Valve Dilute solution High Generator Low Generator Electricity P Evaporator Absorber Heat From Load (Building) Heat Rejection to Cooling Tower Schematic diagram 50 Ref: Slide presented by Dr. Yin at 2008 ASME Energy Sustainability Conference Absorption Chiller Construction • – – – – – Condenser Steam supply Strong LiBr Refrigerant solution Refrigerant LTRG condensate HTRG Cooling water LTHX HRHX Evaporator HTHX Chilled water loop Absorber Dilute solution Schematic diagram 5 major heat transfer components • 4 minor heat exchanger components – – – – • the evaporator the absorber the high temperature regenerator low temperature regenerator the condenser high temperature heat exchanger low temperature heat exchanger steam heat recovery exchanger by-pass heat exchanger Other associated components include: – cooling tower – pumps – spray nozzles and valves 51 Ref: Slide presented by Dr. Yin at 2008 ASME Energy Sustainability Conference Absorption Chiller Results Vary five operating parameters individually chilled water return temperature (cooling load) chilled water flow rate cooling water supply temperature cooling water flow rate steam pressure COP Qcooling Qheat _ input steam (hsteam hcondensate ) Qheat _ input m CHW Cp (Treturn Tsup ply ) Qcooling m h – enthalpy m . – flow rate Cp – heat capacity of water T – temperature 52 Ref: Slide presented by Dr. Yin at 2008 ASME Energy Sustainability Conference • 807 hours or 9% of the year not met. Most of this is due to near simultaneous heating and cooling in the data files. The IW’s light weight construction allows for significant outdoor temperature changes to switch 53 from heating to cooling relatively quickly. Integrated TRNSYS Model Based On Look Up Tables 54 IWESS Mode One Results Mode One Results: Thermal Load Follow Annual Net Energy Import 104,613 MJ Annual Net Thermal Energy Export 31,827 MJ Annual Net Electrical Energy Import 136,440 MJ Hours of Operation 5,158.5 Hours Heating Hours Not Met 2,773 Hours Cooling Hours Not Met 2,986 Hours Regeneration Hours Not Met 3,184 Hours Total Energy Used Total Fuel Consumption Total Fuel Energy Consumption Average Annual Efficiency 834,821 9,025 1,228,845 68% • Operates for ~5,000 hours annually. MJ Gallons MJ • Has overall highest efficiency • Has large number of hours unmet as most of the year the IW loads are less than 25% of the CHP systems capacity. • System turndown ratio is not small enough. 55 IWESS Mode Two Results Mode Two Results: Regeneration Load Follow Annual Net Energy Export 390,334,042 MJ Annual Net Thermal Energy Import 389,883,120 MJ Annual Net Electrical Energy Import 450,922 MJ Hours of Operation 1,042.0 Hours Heating Hours Not Met 5,486 Hours Cooling Hours Not Met 2,927 Hours Regeneration Hours Not Met 7,136 Hours Total Energy Used 71,217 MJ Total Fuel Consumption Total Fuel Energy Consumption Average Annual Efficiency 800 108,900 65% • Operates for ~1,000 hours annually. Gallons MJ • Most of the loads were not met as the majority of the time the regeneration load is below 25% of the engines operating capacity. • Again, the turndown ratio of the CHP system is not small enough. 56 BAPP Mode Zero Results Mode Zero Results: Design Operation at 200 kWe Annual Net Energy Export 38,543 MJ Annual Net Thermal Energy Import 3,165,375 MJ Annual Net Electrical Energy Export 3,203,918 MJ Hours of Operation 8,760 Hours Heating Hours Not Met 3,531 Hours Cooling Hours Not Met 2,050 Hours Regeneration Hours Not Met 2,956 Hours Total Energy Used Total Fuel Consumption Total Fuel Energy Consumption Average Annual Efficiency 13,006,500 119,965 16,333,612 80% MJ Gallons MJ • Achieves the highest efficiency, however is undersized for the estimated BAPP loads. • The undersized system allows for more utilization of the coolant energy, driving up the efficiency. 57 BAPP Mode Two Results Mode Two Results: Regeneration Load Follow Annual Net Energy Import 7,008,961 MJ Annual Net Thermal Energy Import 4,146,361 MJ Annual Net Electrical Energy Import 2,862,600 MJ Hours of Operation 1,042 Hours Heating Hours Not Met 5,653 Hours Cooling Hours Not Met 2,942 Hours Regeneration Hours Not Met 7,283 Hours Total Energy Used Total Fuel Consumption Total Fuel Energy Consumption Average Annual Efficiency 504,924 4,706 640,713 MJ Gallons MJ • Most of the loads were not met as the majority of the time the regeneration load is below 25% of the engines operating capacity. • Again, the turndown ratio of the CHP system is not small enough. 79% • Operates for ~1,000 hours annually. 58 Steam Generate T-Q Diagram 1000 900 Temperature (oF) 800 700 Exhaust at 25 kWe 600 500 Exhaust at 6 kWe 400 Saturated Steam (87psig) 300 Condensate 200 Domestic Hot Water 100 0 0 5 10 15 Heat Transfer (kWt) 20 25 59 Coolant Heat Exchanger T-Q Diagram at 25kWe 210 Temperature (oF) Coolant (12 GPM) 190 Summer Operation Water (12 GPM) 170 150 130 Coolant (2 GPM) 110 Water (4 GPM) Winter Operation 90 0 5 10 Heat Transfer (kWt) 15 20 60 High Performance Building Guidelines • High performance building guidelines require that the entire energy supply process from fuel to terminal units is understood and integrated. – Separating heating and cooling from ventilation allows for the use of desiccant regeneration providing an additional load for a CHP system. – Using low temperature heating systems influences the control and the design of the heat recovery systems and the operation of the engine. – Understanding the entire energy supply system informs the design process and the energy cascade. 61 CHP Results • Plant overall efficiency through winter: 77% • Engine brake efficiency: – 6kWe = 6.8 kWm = 26% – 12kWe = 13.6 kWm = 32% – 18kWe = 20.5 kWm = 36% – 25kWe = 28.4 kWm = 37% 62 Definitions • Distributed Generation (DG) – An electrical power source with a capacity of less than 5 MW electrical • Combined Cooling – Heating and Power (CCHP) – Burning a single source of fuel to generate electrical and thermal energy. – Commonly electricity and heating and/or cooling. 63 Standard Electricity Generation 2002 Electricity Flow, in Quadrillion Btu (1015 Btu) (Conversion: 1 quadrillion Btu = 293 billion kWh) Total energy consumed to generate electricity in 2002 is 39.56 quadrillion Btu = 11.59 trillion kWh Source: EIA, Annual Energy Review 2002, Diagram 5. 64 DG & CCHP Generation 2002 Electricity Flow, in Quadrillion Btu (1015 Btu) (Conversion: 1 quadrillion Btu = 293 billion kWh) Total energy consumed to generate electricity in 2002 is 39.56 quadrillion Btu = 11.59 trillion kWh Source: EIA, Annual Energy Review 2002, Diagram 5. 65 CHP vs. Conventional Power & Heat 66 Ref: www.microturbine.com