Solar Thermal Energy Systems Flashcards

What is the primary function of a solar thermal collector?

Answer: Convert sunlight into heat

Solar thermal collectors are designed to harness the sun's energy specifically for heating purposes, rather than electricity generation. They absorb solar radiation and convert it into thermal energy, which is then used to heat water or air for various applications. This technology is commonly employed for domestic hot water, space heating, or industrial processes.

Which type of solar thermal system is commonly used for residential water heating?

Answer: Active solar water heating

Active solar water heating systems use pumps to circulate a heat-transfer fluid (like water or an antifreeze solution) between the solar collector and a storage tank. This mechanical circulation allows for efficient collection and distribution of heat, making it a highly effective and common choice for residential hot water needs. Passive systems rely on natural convection, which is less efficient for continuous hot water supply.

What is the main advantage of an evacuated tube solar collector over a flat-plate collector?

Answer: More efficient in cold climates

Evacuated tube collectors consist of glass tubes with a vacuum between two layers of glass, which acts as an excellent insulator. This vacuum significantly reduces heat loss to the ambient air, making them much more efficient than flat-plate collectors, especially in colder temperatures or when there's a large difference between the collector temperature and the outside air. Their superior insulation allows them to achieve higher temperatures and perform better in challenging conditions.

Which working fluid is commonly used in solar thermal power plants?

Answer: Molten salts

In large-scale concentrated solar power (CSP) plants, molten salts (typically a mixture of sodium and potassium nitrates) are widely used as a heat transfer and thermal energy storage fluid. They can absorb and retain heat at very high temperatures (up to 565°C), allowing for efficient electricity generation through steam turbines and enabling energy storage to provide power even after sunset. This high thermal capacity and stability make them ideal for continuous power production.

What is the role of a heat exchanger in a solar thermal system?

Answer: Transfer heat from the solar fluid to water

A heat exchanger in a solar thermal system is crucial for safely transferring thermal energy. It takes the heat absorbed by the solar fluid in the collectors and transfers it to the potable water or heating system. This process ensures that the two fluids do not mix, preventing contamination while efficiently delivering hot water for various uses.

Which component in a solar thermal system helps store heat for use when sunlight is not available?

Answer: Thermal storage tank

The thermal storage tank is an essential component in a solar thermal system, designed to store the heat collected by the solar panels. This allows the system to provide hot water or space heating even when sunlight is not available, such as during the night or on cloudy days. By storing heat, it ensures a continuous and reliable supply of thermal energy, maximizing the system's utility.