Developments in organic solid–liquid phase change materials and their applications in thermal energy storage

Conventional impervious pavements have dark surface and large thermal inertia. During summertime they tend to absorb and store solar radiation but negate the evaporative cooling, contributing to the development of urban heat island (UHI). The idea of using cool pavements to mitigate the UHI has gained momentum recently. This review synthesizes the existing definition, physical mechanism, and typical cooling techniques of cool pavements, presenting the influence of cool pavements on the urban thermal environment. Benefits, penalties, costs and policies for the applications of cool pavements are presented with special emphasis on reflective pavements and evaporative pavements. The review suggests that the definition of cool pavements remain incomplete; that the influence of cool pavements on the air temperature in the urban canopy layer is unknown; and that the impact of cool pavements on the thermal conditions of adjacent buildings and pedestrians remains unknown. Many speculations of using cool pavements to battle the UHI effect need refinements and validations. Heat-harvesting pavements seem interesting because they not only stay cool but harness renewable energy. However, the results from the heat-harvesting pavement prototype require scrutiny on the power output, durability, and lifetime of the pavement system. Future studies are expected to understanding the impacts of cool pavements on pedestrian thermal stress, on adjacent building’s energy loads, and on the air temperature in the urban canopy layer.

A review on the development of cool pavements to mitigate urban heat island effect

In recent years, the major factors that determine commercialization of perovskite photovoltaic technology have been shifting from solar cell performance to stability, reproducibility, device upscaling and the prevention of lead (Pb) leakage from the module over the device service life. Here we simulate a realistic scenario in which perovskite modules with different encapsulation methods are mechanically damaged by a hail impact (modified FM 44787 standard) and quantitatively measure the Pb leakage rates under a variety of weather conditions. We demonstrate that the encapsulation method based on an epoxy resin reduces the Pb leakage rate by a factor of 375 compared with the encapsulation method based on a glass cover with an ultraviolet-cured resin at the module edges. The greater Pb leakage reduction of the epoxy resin encapsulation is associated with its optimal self-healing characteristics under the operating conditions and with its increased mechanical strength. These findings strongly suggest that perovskite photovoltaic products can be deployed with minimal Pb leakage if appropriate encapsulation is employed. Lead leakage from damaged perovskite solar cells poses a challenge to the deployment of such technology. Here, Jiang, Qiu and co-workers quantify lead leakage caused by a simulated hail impact under a number of weather conditions and show that self-healing encapsulations can effectively reduce it.

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Reduction of lead leakage from damaged lead halide perovskite solar modules using self-healing polymer-based encapsulation

A novel paraffin/expanded perlite composite phase change material for prevention of PCM leakage in cementitious composites

Understanding pavement-surface energy balance and its implications on cool pavement development

Preparation of composite shape-stabilized phase change materials for highway pavements

The mechanism of different thermoregulation types of composite shape-stabilized phase change materials used in asphalt pavement

Reliability-based assessment of deteriorating performance to asphalt pavement under freeze–thaw cycles in cold regions

Preparation and analysis of composite phase change material used in asphalt mixture by sol–gel method

The application of Phase Change Material (PCM) to asphalt mixture can lighten the temperature-dependent disease of the asphalt pavement and improve the usability as well as extend the operating life of it. We choose agreeable PCM with comprehensive consideration to the technical requirement of its application in the construction industry and the characteristic of asphalt mixture. Through simulating temperature experiment, we make a conclusion that incorporate the carrier accompanied PCM into asphalt mixture can reduce the increasing rate and cooling rate of the mixture, which shows that PCM can put into use of adjusting the asphalt mixture operating temperature, softening the negative influence of ambient temperature variation on asphalt mixture.

Biao Ma

Papers

Preparation of composite shape-stabilized phase change materials for highway pavements

The mechanism of different thermoregulation types of composite shape-stabilized phase change materials used in asphalt pavement

Reliability-based assessment of deteriorating performance to asphalt pavement under freeze–thaw cycles in cold regions

Preparation and analysis of composite phase change material used in asphalt mixture by sol–gel method

Study on Application of PCM in Asphalt Mixture