Optimal location of a single horizontal pipeline in a rectangular, horizontal air-filled enclosure to achieve maximum thermal insulation

An experimental investigation into the effect of the displacement ratio of a heated horizontal pipeline within an atmospheric pressure air-filled, relatively cold, horizontal rectangular cavity was made. The optimal position of the pipeline to achieve maximum energy thrift occurred at a displacement ratio approximately equal to 0·7, i.e. in the upper region of the cavity. This result is of significance with respect to the reduction of distribution heat losses from underground district-heating pipelines.