Reduction Of Heat Conductivity Research Articles

Energy Adaptive Glass Matter

The critical aims of glass envelope design and development must be to enable measures upon glass buildings to prevent uncontrolled heating of the building surfaces, increase emissivity and the impacts of this heat conduction into the building interior spaces. Current glass envelopes depend upon hybrid facades, double skin glass facades; solar shading; passive solar energy systems (transparent insulation materials, solar glazing balconies) to reduce solar temperature gains upon this surface. The envelope performance is based upon measures in the reduction of heat conduction via the material that form its surface, to resolve the conflicts between services and fabric provisions (such as heating systems fighting cooling systems). New materials have been developed of increased performance to resolve this issue by product and component development. For example the integration of solar active elements within the glass panels. However glass building envelopes constructed in hot locations (where temperature are over 40 degrees) have the poorest lighting levels, as the needs to control thermal conduction and high energy consumption needs, to cool the building. These buildings are dependent upon artificial lighting and the reliance of HVAC systems. The current technological development strategies for the building envelope is a static one, by this understanding materials are used without the ability to react to differing climatic zones or recognition of its global positioning. This is in contrast to the nature’s adaptive functions, an adaptive bio-system in constant change to the influence of ambient temperature, solar radiation gain, exposure to wind and changing micro climatic variations. This reactive system is not transposed or reflected into the building envelope systems currently deployed. This non-reactive envelope gives little recognition of the response to climatic change or strategy variation to meet changing environmental situation. This approach is not reflected in nature, as these biosystems have the ability to adapt and control material composition. Could the innovation and direction of a nature-inspired intelligent control of glass matter enable a new paradigm that will lead us in a direction to discover more adaptive systems in a dynamic response to our climate. To use the frontiers of science, in materials, in chemistry and physics, at a nanotechnology and biotechnology scale for greater control of thermal conduction. Could the essence of nature forge evolution, in the creation of climatic responsive skins, by the principles of: material thermal facade behavior and thermal material temperature management. The employment of these objectives is to create material matter that is reactive in real-time to climatic change to enable thermal material management and regulation of its own material temperature. A dynamic skin that is responsive to the influence of ambient temperature, solar regulation gain as a adaptive biosystem.

Carbon nanostructures as thermal field emitters for waste heat recovery

Traditional vacuum-based thermal energy conversion (VTEC) devices with “flat” metal emitters have been compromised by high working temperature mainly due to high work function and electron space charge effect. However, a VTEC system is inherently efficient due to unimpeded flow of electrons through vacuum and reduction of heat conduction by the vacuum medium. Consequently, VTEC devices are attractive in terms of space, weight and energy efficiency for waste heat recovery in a TEC system. Carbon nanostructured emitters including multiwalled carbon nanotubes (CNTs) and “ridge” nanodiamond thin films have shown relatively low threshold fields for electron field emission mainly due to their nanoscaled, high aspect ratio, emitting surfaces. In this study, the field-enhancing features of carbon nanostructures were investigated as thermal-field emitters for waste heat recovery. The turn-on field of CNTs was found to decrease from ~ 1.9 V/μm at room temperature to ~ 0.9 V/μm at 400 °C. A high emission current of ~ 26 μA was achieved at relatively low field of ~ 1.5 V/μm and low temperature of 400 °C. The maximum efficiency of the VTEC device is estimated to be ~ 15% at 300 °C with a current density of 54 mA/cm 2.