Studies on free cooling potential and PCM based heat exchanger for thermal management of buildings

Abstract

The rapid growth of energy use around the world has already raised newlineconcerns over supply difficulties, exhaustion of energy resources and heavy newlineenvironmental impacts such as ozone layer depletion, global warming, newlineclimate change, etc. The global contribution from buildings towards energy newlineconsumption, both residential and commercial, has steadily increased, newlinereaching figures between 20% and 40% in developed countries. The growth newlinein population, increasing demand for building services and comfort levels, newlinetogether with the rise in the time spent inside buildings, ensure the upward newlinetrend in energy demand, which will continue in the future. For this reason, newlineenergy efficiency in buildings is, today, the prime objective of the energy newlinepolicy at the regional, national and international levels. Among building newlineservices, the growth in Heating, Ventilation and Air Conditioning (HVAC) newlinesystem s energy use is particularly significant. newlineFree cooling is one of the novel methods of energy saving in building newlineair-conditioning systems. Free cooling is the process of storing the cool newlineenergy available in the nighttime ambient air in a storage device, and newlineretrieving this energy in order to cool the building during the daytime. newlineA Thermal Energy Storage system using the free cooling concept is an economical energy storage technique, where the energy stored during its free newlineavailability in the environment is used during the demand period. Latent heat newlinestorage with Phase Change Materials (PCMs) provides a high-energy storage newlinedensity and has the capability of storing a large amount of energy during the newlinephase change process with a small variation in the PCM volume and newlinetemperature. Compared with other energy storage systems, phase change newlinethermal storage offers a number of advantages, such as low temperature newlinevariation during the charging and discharging cycles, small unit size and low newlineweight per unit storage capacity.