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Photovoltaic technology plays a crucial role in harnessing renewable energy. While photovoltaic panels directly convert solar energy into electricity, more than 50% of solar radiation is lost as waste heat, diminishing the overall efficiency of the panels. This study reviews various cooling technologies for photovoltaic systems, focusing on the use of phase change materials for cooling in photovoltaic systems. Phase change materials, known for their high latent heat capacity, are extensively used in thermal energy storage applications. Incorporating phase change materials in photovoltaic systems can increase thermal storage potential by 30–50% compared to conventional systems, leading to a 70% extension in heat storage duration and various levels of enhanced power output. The main purpose of the article is to review the advantages and disadvantages of various technologies, determine the research direction of phase change materials for cooling systems in photovoltaics, and ensure the reliability of this technology. [ABSTRACT FROM AUTHOR]

The adsorption desalination and cooling system (ADCS), a promising technology for alleviating water scarcity, requires adsorbents with high performance, low cost, and low energy consumption. Enhancing the operating efficiency and minimizing the energy consumption of the system entails improving the adsorption performance and thermal conductivity of adsorbents. In this study, nanoparticles (NP) embedded silica gel (SG) composite adsorbents with CaCl2 were synthesized for use in ADCS. The effects of nano-Fe, nano-Cu and carbon nanotubes (CNT) as SG thermal conductivity enhancers were thoroughly compared through microscopic properties, thermal properties and adsorption properties. The experimental results show that SG/CNT/CaCl2 composite performs the largest specific surface area and pore volume of 180.72 m2 g−1 and 0.13 cm3 g−1. Scanning electron microscopy (SEM), accelerated surface area and porosimetry (ASAP) and constant thermal analyzer (TCA) were used to characterize the various performance of the enhanced adsorbents comprehensively. SG/CNT/CaCl2 sample exhibits high thermal conductivity and thermal diffusion coefficient, measuring as high as 0.664 W m−1 K−1 and 0.701 × 10−6 m2 s−1, respectively. Based on dynamic water adsorption performance tests, the SG/CNT/CaCl2 composite had an adsorption capacity of 0.665 g g−1, five times higher than SG. The composite's adsorption capacity and thermal conductivity did not decline significantly during cycling, indicating a high degree of sustainability. Therefore, these results imply that the nanoparticles-embedded SG/CaCl2 adsorbent with excellent integrated properties has promising prospects in adsorption desalination systems. Highlights: The silica gel/nanoparticles composites adsorbent with CaCl2 are synthesized. The thermal conductivity of silica gel/CNT/CaCl2 composite is 0.664 W m−1 K−1. The adsorption capacity for composite with CNT/CaCl2 is five times higher than silica gel. [ABSTRACT FROM AUTHOR]

In order to solve the phase separation problem of Na2S2O3·5H2O–CH3COONa·3H2O PCM (phase change material), sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), xanthan gum (XG), sodium polyacrylate (PAAS) and polyacrylamide (PAM) were selected as additives. The effects of different proportions of the above thickeners on the supercooling degree, phase separation, phase change temperature and latent heat of Na2S2O3·5H2O–CH3COONa·3H2O system were studied by using the cooling curve and DSC, so as to screen the best thickener for eutectic PCM. The experimental results show that CMC, XG and PAAS can eliminate the phase separation of Na2S2O3·5H2O–CH3COONa·3H2O. Among them, the optimal ratio of CMC, XG and PAAS is 3 mass%, 3 mass% and 1 mass%, respectively. From the perspective of heat storage performance, PAAS is the optimal thickener for Na2S2O3·5H2O–CH3COONa·3H2O. The phase change temperature is 40.5 °C. The subcooling degree is about 14.7 °C, and the latent heat is about 221 J g−1. The melting time is 15 min. Only PAAS can make Na2S2O3·5H2O–CH3COONa·3H2O eutectic PCM completely exothermic at room temperature, which can not only play the role of thickener to eliminate phase separation, but also is a nucleating agent. After 100 melting-solidification cycles, the change rate of latent heat value was only 5%, and the change rate of phase transition temperature was less than 1%. Considering heat storage performance and cyclic stability, PAAS is the optimal thickener for Na2S2O3·5H2O–CH3COONa·3H2O PCM. [ABSTRACT FROM AUTHOR]

Summary: In order to find phase change materials that can be better applied in the field of solar collectors, the phase change heat storage properties of urea (U) and ammonium bromide (AB) were studied. The eutectic ratio of UAB was found by the Edison method, and different additives were added to UAB by dipping and mixing. The structure and property of the composites were characterized by X‐ray powder diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC), and TG/TGA, respectively. The results showed that the eutectic ratio of UAB was 6:3; it was weakly acidic after melting not layered. When 6‐wt% EG and 1‐wt% nanometer titanium dioxide (TiO2) were added, the thermal conductivity of the material increased by 3.62 times; the thermal diffusivity was increased by 6.77 times. When the mass fraction of EG is between 1% and 6%, the larger the mass fraction of EG, the greater the thermal conductivity of the material. After 1000 cycles, the composite material performance was stable; at the same time, the used materials can be used as fertilizers to solve the problem of material pollution, which indicated that the prepared UAB/TiO2/EG composite PCMs had great application prospect in the field of solar collectors. [ABSTRACT FROM AUTHOR]

Summary: Composite expended graphite (EG)/Ba(OH)2·8H2O form‐stable phase change material (PCM) is prepared with porous adsorption method in this study to solve the problem of the leakage risk in the application process based on barium hydroxide octahydrate. In addition, the thermal properties and stability have been measured and verified. Thermal conductivity of each group composite material was enhanced by about two to four times, while the addition has little negative effect on the other properties. With microscopic features being characterized by scanning electron microscope (SEM), the experimental result demonstrates that the composite material with 7 wt% of EG is optimal to be a saturated state between two phases. After the thermal cyclings of 100, 300, and 500 times, thermal properties did not change dramatically, which can be used as an ideal material for solar thermal storage system within finite thermal cyclings. In order to simulate the operating condition of solar energy or waste heat storage, the composite material was encapsulated in the heat storage unit with pipe bundle, and heat storage/release experiences were performed to test the performance of the material and hot water supply. The results indicate that the composite material is qualified to storage and release sufficient heat. The experimental data can provide necessary technical reference for engineering design and effect prediction in practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PCM used to control the chip temperature is summarized. • The research methods and results of PCM being encapsulated in chip modules are reviewed. • The standard for selecting chip-level PCM is proposed. • A structure to solve the PCM leakage problem and a theory of selecting PCM on the micro-scale are introduced. With the rapid development of integrated circuits, chips are gradually miniaturized, but the number of transistors inside them increases exponentially, which increases the complexity and power density of the chip. The increase in power density makes the peak temperature of the chip higher, which reduces the chip's performance and shortens its life. Heat management using the latent heat storage(LHS) technique is nowadays employed to reduce the chip's temperature peak. This paper reviews the theoretical basis of phase change materials(PCMs) applied to chip thermal management technology and summarizes the application progress of PCMs in electric chip thermal management through the research of recent related literature. This paper is composed of three parts. The first part introduces different types of PCMs used in the field of chip thermal management, especially composite PCMs. The second part discusses non-embedded cooling solutions, focusing on analyzing the effect of using thermal conductivity enhancers (TCE) to improve the thermal performance of the PCM heat sink. The third part is a pioneering review of the research methods and conclusions of embedded cooling, showing that the application of PCM on the micro-scale has an important effect on suppressing the temperature peak of electronic chips. [ABSTRACT FROM AUTHOR]

Calcium ions can react with polyethylene glycol (PEG) to form a form-stable phase change material, but the low thermal conductivity hinders its practical application. In this paper, hydroxylated multi-walled carbon nanotubes (MWCNTs) with different mass are introduced into PEG1500·CaCl2 form-stable phase change material to prepare a new type of energy storage material. Carbon nanotubes increased the mean free path (MFP) of phonons and effectively reduced the interfacial thermal resistance between pure PEG and PEG1500·CaCl2 3D skeleton structure. Thermal conductivity was significant improved after increasing MWCNTs mass, while the latent heat decreases. At 1.5 wt%, composite material shows the highest phase change temperature of 42 °C, and its thermal conductivity is 291.30% higher than pure PEG1500·CaCl2. This article can provide some suggestions for the preparation and application of high thermal conductivity form-stable phase change materials. [ABSTRACT FROM AUTHOR]

In order to solve undercooling and phase separation of sodium acetate trihydrate (SAT), experimental screening method was used to select nucleating agents and thickeners that are suitable for SAT, and the optimal ratio was identified. Through screening experiments of nucleating agents, it is found that disodium hydrogen phosphate can be used as an effective nucleating agent for SAT. When the weight content of disodium hydrogen phosphate in SAT is 2%, the degree of undercooling was reduced to approximately 2 K. The addition of 1–1.5% (weight) of xanthan gum (XG) to SAT can effectively inhibit the phase separation. Since the properties of SAT changes after the modification, the corresponding comparison analysis was performed. The results showed that XG has a significant influence on the SAT performance of SAT. With the addition of 1.5 wt % of XG in pure SAT, the latent heat of fusion and solid/liquid volume expansion reduce by 5.2% and 5.4% respectively, and the thermal conductivity and solid/liquid density also decreases accordingly. [ABSTRACT FROM AUTHOR]