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PCM emulsions have attracted considerable interest as the media for thermal energy storage (TES) owing to their high thermal storage capacity, desirable fluidity and thermal conductivity. However, the direct transportation of PCM emulsions in TES systems for both charging and discharging is rarely reported. In this work, a PCM-in-water nano-emulsion was prepared with n-hexadecane and suitable surfactants for cooling energy storage at a charging and discharging temperature range of 20–5 °C and 5–15 °C, respectively. It was applied to a tubular heat exchanger system to evaluate its TES performance for a cooling panel of 0.2 m2 total surface area. The thermal storage performance was notably increased with the flow rate of emulsion through the exchanger tube. The volumetric thermal storage capacity of charging was 50% higher than that of water. The cooling energy could be rapidly released in the discharging process, 79% of the stored energy at averaging 25 W during most of the discharging period. The emulsion remained stable throughout the test period. Overall, the results demonstrated that the PCM nano-emulsion has the unique characteristics of high static stability, and high energy releasing efficiency and the promising potential for air-conditioning application in buildings.

This study aims to evaluate thermal performance of a new ventilated Trombe wall integrated with phase change materials (PCMs-VTW). Double PCM wallboards are embedded in the building facade for different purposes, i.e. exterior PCM wallboard is to store natural cooling energy via night-time ventilation, and interior active PCM wallboard is for radiant cooling. Melting temperature and latent heat of PCM have been discussed for PCMs-VTW system from 1st August to 7th August in Changsha, China. Also, high-reflective coating is coated on the exterior PCM wallboard for reflecting solar radiation, thus ameliorating daytime overheating. Nighttime ventilation is for natural cooling energy storage via regenerating solid exterior PCM wallboard. The obtained result shows that under the weather condition in Changsha, melting temperature 22 °C for interior PCM and the latent heat 176 kJ/kg for exterior PCM show considerable benefit for cooling energy release. Compared with the classical Trombe wall system, annual cooling energy consumption is decreased by 20.8% and by 18.6% in the PCMs-VTW system when indoor air temperature is kept at 22 °C and 24 °C respectively. Our research has provided scientific evidences for potentials provided by PCMs-VTW system in reducing building energy consumption and improving indoor thermal comfort via exploiting natural cooling energy, mitigating overheating at summer condition and utilizing cold sources in high temperature. [ABSTRACT FROM AUTHOR]

The recently built school building has adopted a novel heat recovery air conditioning system. Heat recovery efficiency of the heat recovery facility and energy conservation ratio of the air conditioning unit were analytically modeled, taking the ventilation networks into account. Following that, school classroom displacement ventilation and its thermal stratification have been numerically investigated concerning the effects of the heat flow flux of passive cooling within the ceiling concrete in the classroom due to night ventilation in summer which could result in cooling energy storage. Numerical results indicate that the promotion of passive cooling can simultaneously decrease the volume averaged indoor temperatures and the non-uniformity of indoor thermal distributions. Subsequent energy performance analysis demonstrates that classroom energy demands for ventilation and cooling could be reduced with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air-cooling unit decreases with the increasing temperatures of exhaust air and the heat flux value for passive cooling within the classroom ceiling concrete. Fitting correlations of heat recovery ventilation and cooling energy conservation have been presented. [ABSTRACT FROM AUTHOR]

• Swimming pool as a seasonal, cooling, thermal energy storage solution. • Case study in Phoenix, Arizona, USA. • The pool is used for heating in the winter and cooling in the summer. • An average pool stores 3500 kWh of cooling energy at 0oC. • Cooling energy storage cost of 0.078 US$ kWhe−1. The rise in distributed renewable energy generation creates a growing need to find viable solutions for energy storage to match energy demand and supply at any time. This paper evaluates the possibility of using swimming pools as a long-term cooling energy storage solution, i.e., Swimming Pool Thermal Energy Storage (SPTES). This technology allows a small building to store solar energy for cooling purposes in a yearly cycle, by filling the pool with ice slurry in winter and using that ice to cool the house in the summertime. Additionally, the pool can be used as a heat sink for a heat pump to heat the house during the winter. Results show that the energy storage cost of 0.078 US$ kWhe−1 is substantially smaller when compared with batteries (125 US$ kWhe−1). This makes SPTES a good alternative to support the development of 100% renewable energy systems in locations where the climate has a highly seasonal variation in temperature and the cooling demand is high in summer. [ABSTRACT FROM AUTHOR]