Geothermal System Design Principles Flashcards

What is the primary purpose of a geothermal heat pump system?

Answer: To transfer heat between the building and the ground

The primary purpose of a geothermal heat pump system is to efficiently transfer heat between a building and the stable temperature of the earth. In winter, it extracts heat from the ground to warm the building, and in summer, it moves heat from the building into the cooler ground. This process provides highly energy-efficient heating and cooling.

Which component circulates fluid through the geothermal loop system?

Answer: Circulating pump

The circulating pump is the component responsible for moving the heat transfer fluid (typically water or an antifreeze solution) through the geothermal loop system. This continuous circulation is essential for efficiently exchanging thermal energy between the ground and the heat pump, enabling the system to provide heating or cooling.

What is the difference between open loop and closed loop geothermal systems?

Answer: Open loop uses groundwater; closed loop uses buried pipes

Open-loop geothermal systems directly use groundwater from an aquifer for heat exchange before returning it, while closed-loop systems circulate a fluid through a sealed network of buried pipes. The key difference lies in the direct interaction with groundwater in open-loop systems versus the contained, indirect heat exchange in closed-loop systems.

Why is soil thermal conductivity important in geothermal design?

Answer: It impacts the system's heating and cooling efficiency

Soil thermal conductivity is crucial in geothermal design because it dictates how effectively heat can move between the ground loop pipes and the surrounding earth. A higher conductivity allows for more efficient heat transfer, directly impacting the size of the ground loop required and the overall heating and cooling efficiency of the system.

Which factor is critical when sizing a geothermal system?

Answer: Load calculation

Load calculation is a critical factor when sizing a geothermal system because it accurately determines the specific heating and cooling requirements of a building. A precise calculation ensures the system is neither undersized (leading to inadequate comfort) nor oversized (resulting in higher costs and reduced efficiency), optimizing performance for the specific property.

What is a common antifreeze used in closed-loop geothermal systems?

Answer: Propylene glycol

Propylene glycol is a common antifreeze used in closed-loop geothermal systems because it lowers the freezing point of the circulating fluid, preventing damage to the pipes in cold conditions. It is preferred over ethylene glycol due to its lower toxicity, making it a safer and more environmentally friendly option for residential applications.

Which loop configuration is typically used when ground space is limited?

Answer: Vertical loop

A vertical loop configuration is typically used when ground space is limited because it involves drilling boreholes deep into the earth, allowing the pipes to extend vertically rather than horizontally across a large area. This design minimizes the surface footprint required for the ground heat exchanger while still providing effective heat transfer.

What is the function of the expansion valve in a geothermal heat pump?

Answer: Regulates refrigerant flow and pressure

The expansion valve in a geothermal heat pump regulates the flow of refrigerant into the evaporator coil, reducing its pressure and temperature. This controlled expansion allows the refrigerant to efficiently absorb heat from the circulating fluid, which is a critical step in the refrigeration cycle that enables the heat pump to transfer thermal energy.

Why is proper system commissioning important?

Answer: To ensure system meets performance standards

Proper system commissioning is important to ensure the geothermal system meets performance standards and operates as designed. This process involves verifying correct installation, testing all components, and making necessary adjustments to optimize efficiency, reliability, and comfort for the homeowner.