Geothermal Heat Pump Systems 1
Earth is a Vast Solar Collector 2
U.S. Underground Temperatures 3
The Earth is a Source of Heat in Winter Outdoor air temperature: 5 F 72 F Geothermal heat pumps transfer underground d heat into 62 F the building to provide heating 4
and an Efficient Place to Reject Heat in the Summer Outdoor air temperature: 100 F 72 F Geothermal heat pumps transfer heat from the building to the earth to provide cooling 62 F 5
using Heat Pump Technology Geothermal heat pumps circulate water through a sealed underground piping loop where it is naturally warmed (or cooled) by the earth 6
Geothermal is not new technology 7
Geothermal is not new technology 8
Geothermal is not new technology Ground loop development using iron and copper loops in the 1940 s. PB and PE pp pipe made viable in late 1970 s. Oklahoma State University began involvement in late 1970s driven by J. Bose, J. Partin, and G. Parker 9
Heat Pumps Heat pumps move energy from one location to another, instead of creating heat by burning fossil fuels, such as a gas furnace does. -- (like your refrigerator). Geothermal Heat Pumps use the earth or well water to provide heating, cooling and hot water for your home. A geothermal heat pump moves energy to/from the ground, eliminating the outdoor equipment associated with ordinary heat pumps or air conditioners. 10
Heat Pump Operation Geothermal heat pumps consist of four circuits: Distribution circuit The system that distributes the conditioned air or water solution throughout the home or building and returns it to the unit. Refrigerant circuit it A sealed and pressurized circuit of refrigerant including compressor, expansion valve, water-to- refrigerant heat exchanger(s), air coil, reversing valve. The refrigerant is either R-22 or R-410A. 11
Heat Pump Operation Geothermal heat pumps consist of four circuits: it Ground loop circuit The piping system buried in the ground has fluid that is circulated by pumps to and from the geothermal unit. Hot water circuit Domestic water can be heated in a geothermal unit with a device called a desuperheater. A piping connection is made from the geothermal unit to the water heater. 12
Heat Pump Operation The Four Circuits in a Geothermal Heat Pump Distribution Circuit = Flow of Energy (Heat) Refrigeration Circuit Earth Loop Circuit Hot Water Circuit 13
Heat Pump Operation Each of these circuits is closed and sealed from the others there there is no direct mixing. However, heat energy does transfer from the refrigeration circuit to the other three circuits. The refrigerant flow will change direction when the unit changes modes (heating or cooling). 14
Heating Mode Operation 15
Cooling Mode Operation 16
The Basic Refrigeration Cycle Compressor Low Pressure Vapor State High Pressure Vapor State Evaporator Condenser Low Pressure Liquid State High Pressure Liquid State TXV 17
The Refrigeration Cycle Heating Mode Operation 18
The Refrigeration Cycle Cooling Mode Operation 19
Free Energy Geothermal Heat Pumps use only a small amount of energy to capture a large amount of FREE energy from the earth. 20
Equipment Performance Ratings ARI has designated the efficiency ratings for water-to-air heat pumps as: Energy Efficiency Ratio (EER) EER = BTU output divided by power watt input For cooling operation under steady state test conditions Coefficient of Performance (COP) COP = BTU output divided by BTU input For heating operation under steady state test conditions 21
Geothermal Performance Comparison Cooling Efficiency (EER) 30 25 New Geothermal Unit 20 Previous Geothermal Unit 15 High Efficiency AC or Heat Pump 10Ordinary Air Conditioner or Heat Pump 5 0 22
Geothermal Performance Comparison Heating Efficiency (COP) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 New Geothermal Unit Previous Geothermal Unit Heat Pump High Efficiency Gas/Propane Furnace Ordinary Gas/Propane Furnace 1.0 0.5 0.0 23
Loop Types Closed Loop (w/ antifreeze) Horizontal Vertical Pond Open Loop Well Water 24
Well Water (Open Loop) Uses existing well Requires 1.5 gpm/ton 25
Horizontal Loop 26
2- Pipe Horizontal 3 feet 5-6 feet 2 feet 10 ft. 2 feet Typically 3-4 trenches, 250 feet long each 27
4- Pipe Horizontal 3 feet 5-6 feet 2 feet 2 feet 10 ft. Typically 2 trenches, 180 feet long each 28
6- Pipe Horizontal 3 feet 5-6 feet 2 feet 10 ft. 2-3 feet 1 foot Typically 1 or 2 trenches, 120 feet long each 29
Horizontal 4 & 6 Pipe Loops 30
Slinky 5-6 feet 10 ft. 2-3 feet Typically 3 or 4 trenches, 100-150 feet long each 31
Horizontal Slinky Loops 32
Horizontal Bore Loops Typically 3-4 bores, 200 feet long each 33
Vertical Loop 34
Side View Vertical Loop 5-6 feet Typically 3 to 5 bore holes, 130 feet deep each 120 150 feet 10 15 feet 35
Vertical bore without backfill 36
Vertical Loop/Grouted Geothermal pipe Bentonite Grout backfill 37
U-Bend used for Vertical Loops 38
Vertical Loop Drilling Use drilling rig like ones used for water well drilling. 39
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Pond Loop Minimum ½ acre, 8 ft. deep 42
Spacers allow for more circulation around pipes 43
Top View Side View Typically 3 to 5 coils Typically 3 to 5 coils, 300 feet long each 44
Horizontal Pond/Lake Loops Slim Jim Lake Plate Heat Exchanger 45
Racked Loops 46
Position, Fill & Submerge 47
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Applications Forced air heating and cooling Supplemental water heating Forced Air Zoned Systems Dedicated water heating (radiant floor, snow melt, domestic purposes, pools) Add-on splits to fossil fuel furnaces 49
Typical Commercial System 50
Zoning Methods Duct Zoning Equipment Zoning 51
Duct Zoning Pros Low first cost Only one unit Cons Design air flow must match unit requirement Complexity of controls Requires es additional a safeties es to protect unit Cannot heat one zone while cooling another 52
Equipment Zoning Pros Can heat/cool simultaneously Unit is matched to zone load Unit is matched to air flow Cons Cost 53
Typical Commercial Vertical Loop System Zone HP Ground HX 54
Lake / Pond Loop (surface water) System 55
Surface Water System Zone HP Submerged Heat Exchanger 56
Ground-Water Heat Pump System Zone HP Plate HX Supply and Injection Wells 57
Geothermal Dubuque Co. Courthouse Historics 58
Questions? 59