Critical review of latent heat storage systems for free cooling in buildings

Abstract

Buildings have a major contribution to the global energy consumption. Heating, ventilating and air conditioning systems (HVAC) are responsible for most of the energy use in buildings. Thus, clean and sustainable alternatives such as free cooling of buildings have recently gained much attention as means to reduce the operation hours and capacity of the conventional cooling and heating systems. The free cooling could be provided by collecting the natural cold energy during night time in appropriate thermal storage form and this could be retrieved when needed. Phase change materials are exploited by a number of investigators as a storage medium in free cooling applications, as these substances possess high energy densities, and absorb and release heat at a narrow temperature range, hence, the comfort temperature can be maintained day and night. The objectives of this article are to provide a comprehensive review on recent development on free cooling technologies incorporating latent heat storage and to shit lights on the most significant parameters affecting the performance of these materials in free cooling strategy. The outcomes of this review would be helpful in providing clear insight information on potential improvements that can be applied to the storage materials. All the reviewed studies demonstrated that the night cooling strategy using PCMs has the capacity to maintain the indoor temperature well within the comfort zone whilst providing a considerable reduction in cooling loads in all considered climates.

Improving Thermal Performance of Dwelling Single Glass Windows Using Secondary Glazing in the UK

“…Although windows are not the only one cause of heat losses, around the globe, its glazing is responsible for around 40% of heat losses in the building [5], [6], which in turn increases the fossil fuel need and hence leads to environmental damage and climate change [7], [8].…”

Improving the performance of air conditioning systems by using phase change materials: A review

“…PCMs can be classified into solid‐liquid, solid‐gas, liquid‐gas, and solid‐solid according to their phase change . The phase change, including gas phase, is not appropriated in light of the huge volumes or high pressures required to store thermal energy; meanwhile, solid‐solid PCMs typically have a very slow phase change and low heat of transition . Therefore, solid‐liquid PCMs are considered the most appropriate materials for storing thermal energy in structures.…”

Phase Change Materials for Textile Application

“…The phase changes required for this type of storage are first-order transitions. However, only solid-solid and solid-liquid transitions are used [17]. Indeed, the liquid-gas transition is technologically unusable since it leads to too high a variation in volume, and the liquid-liquid transition is vigorously too weak to generate any interest.…”