During peak shine hour, the thermal energy storage absorbs heat energy and supplies it for heating of food products during absence of solar power. Solar dryer assisted with thermal energy storage are studied numerically, experimentally and theoretically by many researchers.
Solar heat storage technology is urgently needed to harness intermittent solar energy to directly drive widespread heat-related applications. However, achieving high-efficiency solar heat storage remains elusive due to the loss of heat to the surroundings, especially through radiative processes.
Energy storage systems can be charged during peak sunlight hours, enabling the utilization of stored energy during the night to facilitate continuous drying processes. Based on solar radiation, solar dryers are broadly categorized as direct, indirect, or blended solar dryers (refer to Fig. 3).
A possible method is based on sensible heat storage, (7,25) by heating (in the charging stage, at the expense of solar energy) and then cooling (in the discharging stage that yields energy back again) of a liquid or a solid.
As a result, in a LAS-integrated solar heat storage system, the LAS governs the incident and dissipated radiation, suppresses the radiative heat dissipation by 20 times, and achieves high-efficiency solar heat storage with a near-zero net radiative heat dissipation.
Latent heat solar-thermal energy storage (STES) offers a promising cost-effective solution to overcome intermittency of solar irradiation and provide stable heating supply owing to narrow heat storage/release temperature range, high energy density, and abundance of heat storage phase change materials (PCMs) (5 – 8).