Predicted Thermal Performance of Transparent Bubble Structures

This paper presents the thermal performance of transparent structures that incorporate super thermal insulation via a bubble technology. The transparent structure is a cavity formed by transparent interior and exterior membranes and filled with liquid bubbles. The liquid bubbles in the cavity transmit daylight while providing a thick blanket of insulation, which reduces heat losses in winter and solar gains in summer. Such structures are extremely energy efficient and could be used as transparent building envelopes in place of conventional glazing for facades and/or atrium roofs as well as greenhouses. CFD has been used to assess the thermal performance of two structures of semicircular and pitch-roof configurations. The effects of bubbe diameter, density and distribution as well as cavity width on the insulation level in terms of cavity convective heat transfer coefficient have been determined numerically. It has been found that the cavity convective heat transfer coefficient of a bubble structure increases with bubble diameter and porosity but decreases with the increase in cavity width and bubble filling depth. The cavity heat transfer coefficient also increases with the temperature difference between indoors and outdoors.