GROUND RESPONSE TEST (GRT) AND Paolo CONTI, Ph.D University of Pisa -DESTEC HEAT PUMP DESIGN Italian Geothermal Union
SUMMARY 1. Heat pumps: basic concepts and fundamentals 2. Thermal sources: types, pros & cons 3. GSHP – Ground Source Heat Pump systems 4. Ground source modeling 5. Ground source characterization: site-investigation methods a) Thermal response test / Ground response test b) Pumping test P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
MAIN TOPICS Influence of thermal sources characteristics on HP performances Ground source modelling and main parameters Ground source characterization: in-situ test methods Standard/handbook design procedures for: • Vertical boreholes • Horizontal ground heat exchangers • Water wells for open-loop systems P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1.HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS What is an heat pump? Heat to Heat pumps is a device able to transfer heat from a hot source cold source to an hot source, against the natural Q H direction of flow. To do that, driven energy is Gradient of temperature required (heat or work) Driven energy Coefficient of performance ( Heat or Work ) Heating mode 𝐷𝑃𝑄 = 𝑅 𝐼 𝑅 𝐼 𝑋 = 𝑅 𝐼 − 𝑅 𝐷 Q C Cooling mode 𝐹𝐹𝑆 = 𝑅 𝐷 𝑅 𝐼 Heat from 𝑋 = 𝑅 𝐼 − 𝑅 𝐷 cold source P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Why heat pumps? Traditional Boiler 𝑅 𝑗𝑜 𝑅 𝑝𝑣𝑢 Primary Energy Useful energy (fossil fuels) 100 90 ÷ 115 η gen 𝜃 𝑓𝑜 = 𝑅 𝑝𝑣𝑢 ≈ 1 𝑅 𝑗𝑜 5 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Why heat pumps? Electrically-driven HPs – Heating & DHW mode Electricity 25 National system of COP Useful Energy electricity generation 100 𝜃 𝑓𝑜 ≈ 0.4 Primary Energy 62.5 ! Primary Energy Energy from cold source saving: ≈ 40% 75 6 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Why heat pumps? Adsorption HPs – Heating & DHW mode Primary Energy GUE Useful Energy (fossil fuels) 100 60 ! Primary Energy Energy from cold source saving: ≈ 40% 40 7 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Why heat pumps? Electrically-driven HPs – Cooling mode Electricity 25 National system of EER Useful energy electricity generation 100 𝜃 𝑓𝑜 ≈ 0.4 Primary Energy Energy to hot source 62.5 125 8 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Why heat pumps? (if properly sized and managed) Energy HPs are remarkable energy-saving devices for both heating and cooling, resulting in notable primary energy savings Environment HPs reduce fossil fuels consumption in favor of RES utilization Economy According to local economy context (energy and equipment prices), HPs result in a profitable investment P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS How does it works? Reference thermodynamic cycle Four main processes: A – B Evaporation B – C Compression C – D Condensation D – A Lamination Suitable working fluids Liquid Vapor-compression cylce Vapor R134a, R410a, !R22 R-744 (C02), Liquid + Vapor Adsorption NH3-H20; LiBr-H20 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND PRINCIPLES OF WORK Components diagram Thermodynamic reference cycle Saturation curve T – Temperature [K] C D C Condenser Vapor Saturated liquid D Expansion valve Compressor B A Liquid + Vapor Evaporator A B s – Entropy [J/kg] P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND PRINCIPLES OF WORK 5 Components 2 4 1. Compressor 4 2. 4-way valve 2 3. Condenser 4. Lamination valve 3 3 5. Evaporator 1 1 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND PRINCIPLES OF WORK Primary Energy Compressor is replaced by a generator/absorber system containing a refrigerant/absorbant mixture Heat (primary energy) is used to “generate” refrigerant from mixture Refrigerant follows the typical thermodynamic processes of inverse cycles (i.e. evaporation, condensation, lamination) Energy from Useful Energy cold source Useful heat is removed from absorber and condenser P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Maximum theoretical performances 𝑈 𝐼 Carnot cycle 𝑅 𝐼 𝑗𝑒 = 𝑅 𝐼 𝑅 𝐼 𝑈 𝐼 𝐷𝑃𝑄 𝑋 = = 𝑋 𝑅 𝐼 − 𝑅 𝐷 𝑈 𝐼 − 𝑈 𝐷 Ideal 𝐹𝐹𝑆 𝑗𝑒 = 𝑅 𝐼 𝑅 𝐼 𝑈 𝐷 HP 𝑋 = = 𝑅 𝐼 − 𝑅 𝐷 𝑈 𝐼 − 𝑈 𝐷 𝑅 𝐷 ! Energy conversion efficiency depends on temperature lift between thermal sources 𝑈 𝐷 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Performances of real units 𝑅 𝑑𝑝𝑜𝑒 𝑅 𝑑𝑝𝑜𝑒 𝐷𝑃𝑄 = = 𝑅 𝑑𝑝𝑜𝑒 − 𝑋 𝑅 𝑓𝑤𝑏 Saturation curve T – Temperature [K] C 𝑅 𝑓𝑤𝑏 𝑅 𝑓𝑤𝑏 𝐹𝐹𝑆 = = Vapor Saturated liquid 𝑅 𝑑𝑝𝑜𝑒 − 𝑋 𝑅 𝑓𝑤𝑏 D Equivalent Carnot Temperature 𝑅 𝑑𝑝𝑜𝑒 𝑅 𝑓𝑤𝑏 𝑈 𝑑𝑝𝑜𝑒 = 𝑈 𝑓𝑤𝑏 = A B 𝑡 𝐷 −𝑡 𝐸 𝑡 𝐷 −𝑡 𝐸 𝑈 𝑑𝑝𝑜𝑒 𝑈 Liquid + Vapor 𝑓𝑤𝑏 𝐷𝑃𝑄 = 𝑓𝑤𝑏 EER = 𝑈 𝑑𝑝𝑜𝑒 − 𝑈 𝑑𝑝𝑜𝑒 − 𝑈 𝑈 𝑓𝑤𝑏 s – Entropy [J/kg] P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Performances of real units 16 T H – 35°C 14 Thermal capacity - kW 12 T H – 45°C ∆Q T /∆T f ~0.3 [kW/°C] 10 8 T H – 35°C COP 6 ∆COP/∆T f ~0.1 [1/°C] 4 T H – 45°C 2 0 -10 -5 0 5 10 15 20 25 30 T C – [°C] 16 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Performance evaluation: Reference temperatures for real units Nominal data refer to standard rating condition of thermal sources (e.g. UNI EN 14511-2:2013) Nominal performances Heating capacity – kW 15.1 Total power input – kW 3.6 COP 4.2 Secondary fluid (Evaporator): Inlet 10°C / Outlet 7°C Secondary fluid (Condenser): Inlet 30°C / Outlet 35°C 17 P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND FUNDAMENTALS Performance evaluation: Reference temperatures for real units P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
1. HEAT PUMPS: BASIC CONCEPTS AND PRINCIPLES OF WORK Performances of real units: second-law efficiency P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
2. THERMAL SOURCES: TYPES, PROS & CONS Which source should I use? Ground Can I use more than one source? Alternative Water Technologies Which are selection and design criteria? Air P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
2. THERMAL SOURCES: TYPES, PROS & CONS Air Temp -0.25 m -0.5 m -1m - 2.5 m - 5 m - 10 m 35 30 TEMPERATURE - °C 25 20 15 10 5 0 -5 -10 0 1000 2000 3000 4000 5000 6000 7000 8000 TIME - H P. Conti: Ground response test (GRT) and heat pump design . International school on geothermal development. Miramare (TR), Italy, 7 – 12 Dec 2015.
Recommend
More recommend
