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This study proposes a novel combined cooling, dehumidification and power system based on internal combustion engine (ICE) for high temperature and humidity regions. In the proposed system, the electricity demand is mainly provided by ICE while the cooling and dehumidification demands are totally satisfied by absorption chiller (AC) and liquid desiccant dehumidification (LDD) units driven by waste heat of engine exhaust and jacket water. In addition, the electricity demand can be supplemented by battery and Organic Rankine Cycle (ORC) units driven by abundant waste heat of ICE. The aim of this system is designed to succeed the highly efficient utilization of ICE waste heat among AC, LDD and ORC units, and satisfy the multi-energy demands of users by optimizing the operation strategy. Firstly, a case study based on the actual power, cooling and dehumidification demands of a hotel building in Singapore is conducted to assess the performance of the proposed system. The parametric study of prominent design parameters in this system is investigated first to explore their effects on the system performance. Next, considering annual total cost and CO2 emissions as evaluation objectives, augmented e-constraint method combined with improved Mutation particle swarm optimization (M-PSO) algorithm is used to conduct the multi-objective optimization of equipment capacity and operation. Finally, a sensitivity analysis of significant uncertainty factors is researched. The optimal results show that, compared to the traditional energy supply system, the annual carbon dioxide emission reduction ratio and total cost saving ratio can reach 35.91% and 25.46%, respectively.

The previous studies focus on the heat storage process of shell-and-tube latent thermal energy storage (LTES) under steady heat sources, without considering the fluctuating and intermittent characteristics of the most available heat sources in real applications. The effect of different fin sizes and locations on the charging performance of shell-and-tube LTES still keeps unclear under fluctuating heat source, and it is critical to improve the heat storage rate and density due to the low thermal conductivity of phase change materials (PCM). Consequently, this study aims to investigate the charging performance of a shell-and-tube LTES considering different fin layouts. Firstly, the effects of different fin number and configurations on heat storage process are performed under fluctuating heat sources. The case with comprehensive performance of high melting rate and large heat storage capacity is obtained. Then the effects of critical parameters on the charging process, including the fin angle, fin thickness, fin height and deviation distance of tube under fluctuating heat sources are further analyzed based on this case, and the results are compared with that of steady heat source. Results indicate that the fin height is the dominant factor influencing the heat storage rate and density under both steady and fluctuating heat source conditions, while the total melting time is shorter and the heat storage capacity is smaller, and the heat storage capacity is less obvious with the variation of fin parameters under the fluctuating heat source. In addition, the effect of downward deviation distance of tube on heat storage capacity is much obvious under fluctuating heat source than that of steady heat source.

Thermal energy storage (TES) technology is considered to have the greatest potential to balance the demand and supply overcoming the intermittency and fluctuation nature of real-world heat sources, making a more flexible, highly efficient and reliable thermal energy system. This article provides a comprehensive state-of-the-art review of latent thermal energy storage (LTES) technology with a particular focus on medium-high temperature phase change materials for heat recovery, storage and utilisation. This review aims to identify potential methods to design and optimise LTES heat exchangers for heat recovery and storage, bridging the knowledge gap between the present studies and future technological developments. The key focuses of current work can be described as follows: (1) Insight into moderate-high temperature phase change materials and thermal conductivity enhancement methods. (2) Various configurations of latent thermal energy storage heat exchangers and relevant heat transfer enhancement techniques (3) Applications of latent thermal energy storage heat exchangers with different thermal sources, including solar energy, industrial waste heat and engine waste heat, are discussed in detail.

The intermittent and fluctuating nature of thermal sources such as solar, geothermal, industrial processes and waste heat from internal combustion engines is one of the most challenging research areas and currently limits the implementation of heat recovery systems such as Organic Rankine Cycle (ORC) technology. Latent Thermal Energy Storage (LTES) using Phase Change Material (PCM) is a promising solution to mitigate fluctuations of thermal sources and maintaining the heat recovery systems under designed conditions. However, the melting process significantly affects the energy storage performance, as well as the design and optimisation of the LTES system under fluctuating thermal conditions. In this study, the melting process of a shell-and-tube LTES unit, under a sinusoidal heat source, is numerically investigated in order to consider the effects of period and amplitude. Then, the effects of PCM thermal conductivity, with and without nanoparticles, were simulated and the heat transfer coefficient of sinusoidal heat source on the melting process is separately analysed under the sinusoidal heat source condition. The parametric study of thermal conductivity and heat transfer coefficient is conducted to evaluate whether these parameters affect the period and amplitude of sinusoidal heat sources on the melting process of LTES. The results indicate an overall trend of the total melting time and heat storage capacity of LTES decreasing whilst there is an increase of period and amplitude of the fluctuating heat source.