Dynamic modelling of the solar radiation exposure effects on the thermal performance of a PCMs-integrated wall

The authors present a dynamic simulation of the thermal behavior of a multilayer plane wall, integrated with Phase Change Materials (PCMs), exposed to solar radiation in summer conditions, in a Mediterranean site. PCMs are a promising kind of heat storage materials that are particularly good in some climatic conditions: if properly placed, they can decrease heat flux through the walls, thus reducing cooling loads in buildings. Due to their strong non-linearity in thermal behavior, PCMs must be carefully modeled, possibly in transient conditions. The dynamic model consists of two main distinct parts. First, a solar radiation model is implemented, based on the daily evolution of the solar angles. This solution uses the results of a novel simple model for splitting the diffuse and the direct solar radiation starting from data on total radiation on a horizontal surface only. Then, solar radiation is used as a boundary condition for the dynamic modeling of a typical multilayer lightweight wall provided with one insulation layer integrated by PCMs. The calculated of solar effect and cooling loads are studied for three different melting temperatures of the PCMs

Phase Change Material for Thermotherapy of Buruli Ulcer: A Prospective Observational Single Centre Proof-of-Principle Trial

Buruli ulcer is an infection of the subcutaneous tissue leading to chronic necrotizing skin ulcers. The causative pathogen, Mycobacterium ulcerans, grows best at 30°C–33°C and not above 37°C, and this property makes the application of heat a treatment option. We achieved a breakthrough in heat treatment of Buruli ulcer by employing the phase change material sodium acetate trihydrate as a heat application system for thermotherapy, which is widely used in commercial pocket heat pads. It is easy to apply, rechargeable in hot water, non-toxic and non-hazardous to the environment. Six laboratory reconfirmed patients with ulcerative Buruli lesions were included in the proof-of-principle study and treated for four to six weeks. In patients with small ulcers, wounds healed completely without further intervention. Patients with large defects had skin grafting after successful heat treatment. Heat treatment was not associated with marked increases in local inflammation or the development of ectopic lymphoid tissue. One and a half years after completion of treatment, all patients are relapse-free. The reusable phase change material–based heat application device appears perfectly suited for use in remote Buruli ulcer–endemic areas of countries with limited resources and infrastructure

Numerical and experimental investigation of an insulation layer with phase change materials (PCMs)

Phase change materials (PCMs) are used in novel thermal insulating materials in order to exploit their high apparent thermal capacity, which is particularly interesting for buildings with moderate thermal inertia because PCMs have a high potential for CO2 reduction in lightweight buildings and their energy consumption as well as for increasing the thermal comfort of the inhabitants. In addition, one of the most promising applications of PCMs is embedding them directly in the insulation layers of a lightweight wall. In fact, due to their apparent thermal capacity, light insulators with embedded PCM particles have good performances in smoothing and shaving of thermal peak loads. Furthermore, in some climatic conditions, they can act as thermal storages by reducing thermal loads in buildings. Many sectors of evidence in the literature indicate that it is necessary to use a hysteresis model with two different curves of specific heat versus melting and solidification to assess the transient thermal performance of PCMs embedded precisely in an insulation layer. The main aim of this research is to develop a detailed dynamic model in order to calculate the effects of PCMs in insulation layers of lightweight walls. In this paper, the results of some actions, used to improve the effectiveness of the models, are investigated. In particular they are the adoption of two distinct cp curves, which improves the accuracy of dynamic simulations and, hence, allows the development of the model using a smaller number of points and a larger time step. Several experimental tests validate the numerical model. Furthermore, this paper presents the way in which the position of the PCM insulation layer, in a typical wallboard, affects the temperature and heat flux, inside each layer, in transient conditions. The results show that, in the case evaluated, the maximum reduction of heat consumption, of about 15%, was obtained when PCMs are located in positions three and four, which are approximately in the middle of the wall. In addition, this specific kind of insulation layer generates a delay of the maximum heat flux that is of about two hours