geothermal design software
GEO® Hourly
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   Geothermal Loop Design-Vertical-Horizontal-Hybrid


GEO®Hourly Advantages:
  • Unique Zone Hourly Analysis
  • Realistic Heat Pump Operation
  • Proper Size Zone Heat Pumps
  • Energy Model - Zones
  • Intelligent Triple Hourly Zone Analysis
  • Lower the First Cost
  • Easy Analysis Optimization
  • Hybrid Design Integration
  • Patents No. 9,443,043 and No.9,852,243

Geothermal Loop Design for GSHP

 ◦   In a geothermal loop design-vertical-horizontal-hybrid geothermal design software ground Loop design (Ground Source Heat Pumps) utilizes water to cool and heat the refrigerant instead of air. Water (fluid) is circulated in a closed loop heat exchanger located in the earth where the earth's temperature at 28 feet below the surface is constant all year and doesn't fluctuate to extremes like the air temperatures above the surface. Ground Loop heat exchangers consist of a borehole about 5 inches in diameter vertically drilled in the earth. U-tube pipe about 1 inch in diameter is inserted in the borehole and sealed with a bentonite-sand-graphite slurry grout. GEO®Hourly simulates the design length of the closed loop heat exchanger for the heating system and a separate design length for the cooling systems.

Vertical Bore Closed Loop

 ◦  Vertical bore closed loop in-ground heat exchangers can be designed with good accuracy because the earths temperature below 28 feet is constant all year. Vertical systems are the most universally applicable ground source system configuration for commercial applications. Vertical systems need less pipe and require less land area than do Horizontal systems, and do not require water-bearing formations.

Horizontal Closed Loop

Horizontal - Directional Borehole

 ◦  Horizontal bore closed loop heat exchangers are directionally drilled at an angle to a depth then levels off into a horizontal plain. The angle portion of this horizontal bore will be closer to the earth's surface requiring extra pipe to offset the seasonal extremes in soil temperature and soil drying near the surface. Horizontal bore systems are not normally as energy efficient as Vertical bore systems because of the extra pipe required and have limited use on large buildings because of the land area requirement.

Horizontal - Trench

 ◦  Horizontal trench closed loop heat exchangers can have a single straight pipe or multiple pipes installed in a trench. Multiple pipes in a trench can reduce the trench length when in a compact area. The coiled (slinky) arrangement is a substituted for the multiple pipe installation laying in a trench and being closer to the earth's surface require extra pipe to offset the seasonal extremes in soil temperature and soil drying near the surface. Horizontal trench systems are not normally as energy efficient as Vertical bore systems because of the extra pipe required and have limited use on large buildings because of the land area requirement.

Soil Thermal Conductivity

 ◦   Soil Thermal Conducitivity is a heat property and a measurment of soils or rocks ability to conduct heat. Soil Conductivity is a key element in the design length of an in-ground heat exchanger. The conduction rate to the rate of thermal storage in the ground is used to calculate the grounds thermal resistance. By analyzing the heat flow resistance of the ground surrounding the borehole and the resistance of the borehole a heat transfer equation can represent the variable heat rate in an in-ground heat exchanger.

Borehole Resistance

 ◦   Borehole Thermal Resistance is a heat property and a measurment of the combined heat flow resistance of the U-bend heat exchanger pipe, the U-bend heat exchanger pipe configuration, and the grout in the borehole. Borehole Thermal Resistance is a key element in the design length of an in-ground heat exchanger. Research has shown that by combining several elements into a single variable heat rate a heat transfer equation can determine the length of an in-ground heat exchanger.
 ◦   Borehole Resistance is based on rigorous detailed designs following reports by IGSHPA in 2012, and US DOE research reported in 2013.

U-Bend Pipe and Configuration Layout

 ◦   In a borehole, water circulates in pipes forming a closed loop between the heat pump and the in-ground heat exchanger. The U-bend heat exchanger pipe size and the U-bend heat exchanger pipe configuration layout in the borehole are corresponding elements of thermal resistance in the borehole.
 ◦   In a single U-bend heat exchanger pipe circulating fluid flows down one leg of the U-bend and flows up the other. Double U-bend heat exchanger pipes divide the flow between the two U-bend in parallel flow. Recent research sponsored by the DOE shows that double U-bend heat exchanger pipes have lower Borehole Resistance resulting in a significant length reduction in the in-ground heat exchanger compared to a single U-bend pipe.
 ◦  The proximity of the U-bend heat exchanger pipe layout in the borehole between the pipe and the borehole wall contribute to thermal resistance in the borehole. Single or double U-bend heat exchanger pipe with a spacer that holds the pipe near the borehole wall results in the lowest thermal resistance.

Grout Conductivity

 ◦   Grout Conducitivity is a heat property and a measurment of grouts ability to conduct heat. The environmentally safe method to seal a borehole is to install a bentonite slurry. Bentonite swells and forms a good seal of the borehole but the conductivity of the bentonite slurry alone will insulate the borehole yielding a very poor conductivity. Silica sand or graphite can be added to the bentonite slurry to raise the conductivity to an acceptable value making an Enhanced grout.
 ◦   Enhanced grout is always recommented because it provides better heat transfer in the borehole compared to just plain bentonite. Grout, U-bend pipe, and U-bend pipe configuration are corresponding elements of borehole resistance and are combined into a single variable heat rate in a heat transfer equation used to determine the length of an in-ground heat exchanger.