Abstract
Laboratory and field experiments were carried out, to assess the efficiency of palm-based insulators for storage water tanks under variable ambient temperatures. Palm fronds, palm leaves and their composite were used to wrap pilot water tanks and examine their thermal insulation efficiency. Four arrangements were tested including: double layer of fronds and an inner air gap, double layer of fronds separated by an intermediate air gap, palm leaves and composite of palm leaves sandwiched between two layers of fronds. The insulation efficiency was assessed in laboratory setting under heating-up and cooling-down conditions using the time constant,
, and compared to a reference unwrapped tank. The insulators were also tested in the field under variable ambient air temperatures. In this case, their efficiencies were assessed considering the relative amplitude ratio of the stored water and ambient air temperatures, in addition to the phase shift between the times of temperature extremes of air and water in the different tanks. The results indicate that the fronds–leaves composite provides better insulation efficiency under heating-up, cooling-down and variable ambient air temperatures.