Which system relies on natural convection to move the heat-transfer fluid between the solar collector and storage tank without using a pump?

Which system relies on natural convection to move the heat-transfer fluid between the solar collector and storage tank without using a pump?

• A. Forced circulation system
• B. Centrifugal circulation
• C. Hydronic looping
• D. Thermosiphon system

Answer: (D)

Natural convection moves heat-transfer fluid through a solar loop when heated fluid becomes less dense and rises, while cooler fluid sinks, creating a passive flow driven by gravity and buoyancy. In a thermosiphon system, the solar collector is placed above the storage tank. As the fluid in the collector heats up, it rises into the storage tank; cooler fluid from the bottom of the tank then flows back down toward the collector, and the cycle continues without any pump. This passive circulation depends on the height difference and the temperature-induced density changes, making it distinct from systems that require a pump to move the fluid.

Natural convection moves heat-transfer fluid through a solar loop when heated fluid becomes less dense and rises, while cooler fluid sinks, creating a passive flow driven by gravity and buoyancy. In a thermosiphon system, the solar collector is placed above the storage tank. As the fluid in the collector heats up, it rises into the storage tank; cooler fluid from the bottom of the tank then flows back down toward the collector, and the cycle continues without any pump. This passive circulation depends on the height difference and the temperature-induced density changes, making it distinct from systems that require a pump to move the fluid.