Solar Thermal System Design & Components Flashcards

What is the primary function of a solar collector in a thermal system?

Answer: Absorb sunlight and convert to heat

The primary function of a solar collector in a thermal system is to capture solar radiation from the sun. It is specifically designed to absorb this sunlight and efficiently convert the light energy into thermal energy, or heat. This collected heat is then transferred to a fluid, which circulates through the system to provide hot water or space heating.

Which component stores heat energy in a solar thermal system?

Answer: Storage tank

In a solar thermal system, the storage tank is the dedicated component responsible for holding and maintaining the temperature of the heated fluid, typically water. This allows the system to store the thermal energy collected during sunny periods. The stored heat can then be used later, ensuring a continuous supply of hot water or heating even when the sun is not shining.

What is the role of a heat exchanger?

Answer: Transfer heat between fluids

A heat exchanger is a device engineered to efficiently transfer thermal energy from one fluid to another without the two fluids physically mixing. In solar thermal systems, it typically transfers heat from the solar collector's heat-transfer fluid (e.g., glycol) to the potable water or space heating fluid. This separation prevents contamination and allows for optimal fluid selection in each loop.

Which fluid is commonly used in solar thermal systems?

Answer: Propylene glycol

Propylene glycol is a commonly used heat transfer fluid in solar thermal systems, particularly in climates where freezing temperatures are a concern. It acts as an antifreeze, preventing the fluid in the collector loop from freezing and potentially damaging pipes or collectors. Additionally, it is non-toxic, making it a safer choice for systems that might interact with domestic hot water.

What type of collector is best for high-temperature applications?

Answer: Evacuated tube collector

Evacuated tube collectors are highly efficient and are particularly well-suited for high-temperature applications or colder climates. The vacuum between the glass tubes significantly reduces heat loss through convection and conduction, allowing these collectors to achieve and maintain much higher operating temperatures compared to traditional flat plate collectors. This makes them ideal for demanding heating needs.

What component circulates fluid in an active solar thermal system?

Answer: Pump

In an active solar thermal system, a pump is a critical mechanical component responsible for circulating the heat transfer fluid. It actively moves the fluid through the solar collector to absorb heat, then through the heat exchanger, and finally to the storage tank. This forced circulation ensures continuous and efficient heat collection and delivery throughout the system.

Which system does not require electrical components?

Answer: Passive system

A passive solar thermal system is designed to operate without the need for electrical components like pumps or controllers. Instead, it relies on natural physical principles such as convection and thermosiphoning to circulate the heat transfer fluid or air. This design makes passive systems simpler, more reliable, and independent of external power sources for operation.

What is the purpose of an expansion tank?

Answer: Regulate fluid pressure due to thermal expansion

An expansion tank is an essential component in closed-loop solar thermal systems, designed to manage changes in fluid volume. As the heat transfer fluid heats up, it expands, increasing pressure within the system. The expansion tank provides a compressible space to accommodate this increased volume, preventing excessive pressure buildup that could damage pipes, collectors, or other system components.

Why is system insulation important in solar thermal installations?

Answer: Minimizes heat loss and boosts efficiency

System insulation is critically important in solar thermal installations to prevent the loss of collected heat from pipes, storage tanks, and other components. By minimizing heat transfer to the surrounding environment, insulation ensures that more of the solar energy absorbed is delivered to its intended use. This directly boosts the overall efficiency and performance of the system, leading to greater energy savings.