Fabrication and performance study of a new design of passive thermosyphon type solar water heater

The work presents an example of a passive solar heating system, which utilizes direct solar energy to heat the water for domestic use. A passive thermosyphon heating system was designed, fabricated, and tested for its thermal performance in the semi-arid and four-season climate of the Faisalabad district of Pakistan. The heating system design was based on two-stage storage and natural thermosyphon circulation of water. An enhancement of the thermal performance of the thermosyphon systems by using a semicircular steel pot collector (covered with water carrying copper coil), two-step water storage, and side mirror reflectors was investigated. The experiments were conducted from April to July, $2014$ when the ambient temperature was reported approximately between $30$ to $45^{\circ}$C. For the cited time duration, the cold-water temperature remained in the range of $18$ to $25^{\circ}$C. The maximum water temperature, during the intermittent flow mode operation of the system, remained between $48$ and $88^{\circ}$C. In continuous flow mode operation, the hot water temperature remained between $46$ and $78^{\circ}$C. Since water temperature in the range of $45$ to $50^{\circ}$C is considered suitable for domestic use, the presented design is acceptable for domestic use.