Transcript Document
Commercial / Residential Applications Why Water? • Most efficient • 5,1 cm water pipe = 61 cm air duct • Less space • Higher mass and thermal conductivity • Benefit of thermal storage Why WSHP? • COP ~ 5 Efficiency 500% • Boilers/fossil fuel furnaces < 100% • More compact than Air cooled • Linked to outdoor WB or deep earth temperatures ----->Higher efficiencies and longer service life Why Geothermal? • Less dependency on Temperature variations ~ Constant Ground temperature • Utilizes the natural thermal properties of earth. • Eliminates boiler and heat rejecter installation. • Eliminates all outdoor equipment • Reduces mechanical room space • Single zone applications • Higher efficiency Open Loop Applications • Open Vertical loop with a recharge well Well ----->Heat Pump ----->Separate recharge well • Open Vertical loop with a Surface discharge Well ----->Heat Pump ----->Pond , Stream or River • Open Loop surface water system Pond,Stream,river ----->Heat Pump ----->Water body Open Loop-Thumb rules • Water well which can produce 2,0 to 2,6 l/m per kW • Water quality must be good to prevent fouling and clogging of pipes • Ground water from a fresh water aquifer better than surface water – constant temperature – thermodynamic advantage – Surface water - organic materials Open Loop-Thumb rules • Shut off valves for ease of servicing • Boiler drains - tee’d for acid flushing • P/T plugs to measure temperature and pressure • Cu HX recommended • Cu-Ni HX -Heavy scale • Expansion tank to minimize mineral formation by air exposure • Water control valve(Slow closing) on discharge line to prevent mineral precipitation Closed Loop Applications • Vertical Borehole loop – – – – Least land space High excavation/drilling costs Holes drilled 45-180 m Typical hole 10 cm diameter for each 3 to 4 kW of cooling capacity – Minimal spacing is about 3 m – U-shaped pipe (HDPE) – Computer model determines exact length. Closed Loop Applications • Horizontal trenched or bored loop – – – – More land space Low excavation costs Less expensive installation Straight length U-tube laid flat in wide trenches – Typical depth is 1,5 m – Polyethylene coil tube (flat Slinky) Cost Comparison for decision Vertical, Horizontal straight tube, Horizontal Slinky • Parameters – – – – Land Cost of pipe Cost of trenching Cost of Excavation • Example • Vertical 122 m deep BHE requires 21 sq m SA with wells separated by 5 m=HHE 2.5 m trench will have to be 183 m in length with 5m separation = 848 m of land/40 times land area • Straight pipe - Higher trenching cost • Slinky - Higher pipe costs Soil/Rock Conditions • • Open Loops – Simple – Can the aquifer support the volume extraction and injection? Closed Loops – Large soil categories • Dry soil • wet soil • saturated soil – Solid rocks (granite, igneous rocks) - Highest thermal conductivity – Dry sands and clay - Lowest thermal conductivity Grouting • Why Grout? – Drilling geothermal boreholes • Surface water penetrates downward into the aquifer • Hydraulic characteristics of aquifer degraded – Bentonite (Clay) + Water ---> Swells 10 to 20 times volume – forms a gel with low viscosity and semi-rigid when set – Good seal between upper and lower aquifers Geothermal and Hydronics • Most acceptable indoor climate Floor temperature: 19 and 29°C Air temp at head level: 20 and 24°C • Air convection methods - Warm, buoyant air rises wastefully to the ceiling in convection-heated rooms, warming the upper body • A simple heating element is installed beneath the flooring • Warms the lower part of both the room and the body - convects from the radiant floor surface Geothermal and Hydronics • • Radiant floor heating with water- water heat pumps Buffer tank – control flow rates through the unit – Typically 13 litres/kW – Electric water heaters Hybrid Systems • Cost not justified for a GHP with uneven demands • Cooling demand >> Heating demand – Cooling tower • Heating demand >> Cooling demand – Boiler • First cost low Benefits • • • • • • • • • • Year round individual control Tenant metering Quiet operation Minimizes downtime – Failure affects the single zone served Low overall Life cycle cost Low operational costs Higher comfort Health and safety – eliminates the need for onsite fossil fuel combustion Low maintenance Longer service life Benefits • • • • Hedge against Fuel Savings Space/Structural savings Higher comfort Reduced emissions – eliminates the need for onsite fossil fuel combustion • Simpler to design • Simpler to control • Simpler to commission Green/Sustainable design • Certification programs/Incentives – – – – – Energy efficiency Geothermal Enhanced refrigerant management Functionality, flexibility, maintainability Lower operational environmental impacts • • • • USGBC - LEED BREEAM in UK VROM in Netherlands DENA in Germany, Austria and 11 Euro Nations Thank You Arun Shenoy ClimateMaster Inc [email protected]