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Thermochemical energy storage using salt hydrates is a promising method for the efficient use of energy. In this study, three host matrices, expanded vermiculite, expanded clay, and expanded natural graphite were impregnated with a eutectic mixture of CaCl2·6H2O and bischofite (MgCl2·6H2O). These composites were subjected to various humidity conditions (30–70% relative humidity) at 20 °C over an extended hydration period to investigate their cyclability. It was shown that only expanded natural graphite could contain the deliquescent salt at high humidity over 50 cycles. Hence, the expanded natural graphite composites containing either CaCl2·6H2O or CaCl2·6H2O/bischofite eutectic mixture were placed in a lab-scale open packed bed reactor, providing energy densities of 150 and 120 kWh/m3 over 20 h, respectively. The eutectic composite showed slightly lower temperature lift, water uptake rate, and power output but at reduced cost. Using the eutectic mixture also decreased the composite's dehydration temperature at which the maximum mass loss rate occurred around 16.2 °C to 62.3 °C, allowing recharge using less energy-intensive heating methods. The cost of storing 1 kWh of energy with expanded natural graphite composites is only USD 0.08 due to its stability. This research leveraging cost-effective composites with enhanced stability, reaction kinetics, and high thermal energy storage capabilities benefits renewable energy, power generation, and the building construction research communities and industries by providing a competitive alternative to sensible heat storage technologies. [ABSTRACT FROM AUTHOR]

In view of the battery thermal management system, a novel type of thermal management system based on the coupling of supercooled phase change material calcium chloride hexahydrate and thermal switch was proposed. The thermal switch device was applied to 18650 lithium-ion battery and the cooling and heat preservation effects of the device were studied based on numerical method. The device provides power for thermal switch based on the significant change of the volume of the phase change material. Besides, it combines with the characteristics of the supercooled of the phase change material to further improve the temperature control capability. The results show that, compared with the thermal management system without thermal switch, the supercooled phase change thermal switch device can reduce the battery temperature by 1.61 ℃ at the end of 5C high-rate discharge. Moreover, when the external environment temperature is -20 ℃, the supercooled phase change thermal switch system extends the battery temperature management time by 660 s.

Radiant cooling panel systems are now popular solution for low carbon buildings, so has received great attention of researchers. Current development, however, is that radiant cooling panel systems have low cooling efficiency and cause high pressure on national energy supply during peak energy consumption periods. This study, therefore, has developed a novel composite phase change material (CPCM) coupled with a typical radiant cooling panel system, providing longer indoor comfort duration and less temperature fluctuation, while also alleviating the pressure on national energy supply during peak energy consumption. In this study, eutectic hydration salt of CaCl 2 ·6H 2 O and mannitol have been combined with SiO 2 to prepare a shape-stabilized CPCM. It has been placed in a test room to justify the impact of the new material. Experimental results have demonstrated some major properties of this material, namely, a melting point of 20.7 °C, a high latent heat value of 119.8 J/g, and a supercooling degree of 1.3 °C, as well as good stability and thermal reliability. Therefore, it can be used as a good solution for radiant cooling panel systems. Comparing the results with another test room with ordinary radiant cooling panels, the room with the new CPCM panel showed less indoor temperature fluctuation and 73 % longer indoor comfort duration. This work provides further development of using hydrated salts and CPCMs with different phase change temperatures in radiant cooling panel systems. [ABSTRACT FROM AUTHOR]

CaCl2·6H2O is selected as the original substrate for research, and a new composite phase change material (CPCM) suitable for air-conditioning was developed through experiments. The new modified CaCl2·6H2O CPCM uses glycerol as a temperature regulator and barium hydroxide octahydrate as a nucleating agent. The experimental results show that when the mass ratio of CaCl2·6H2O to glycerol is 85:15, the melting temperature of the CPCM is 11.8 °C and the enthalpy of phase change is 112.86 J/g. The chemical composition of the CPCM was characterized by Fourier transform infrared spectroscopy, which confirmed that the material was successfully developed. When the amount of barium hydroxide octahydrate nucleating agent was 1.0 wt.%, the supercooling of the CPCM decreased to 1.22 °C. CPCM still show good stability after 50 thermal cycles and can be used in practical production.

Highlights • A new CaCl 2 ·6H 2 O-Mg(NO 3 ) 2 ·6H 2 O/EG eutectic hydrate salt composite PCM is prepared. • The composite PCM has little supercooling and good thermal reliability. • A room containing two kinds of PCM for year-round energy management is proposed. • The room containing two kinds of PCM performs better than the one containing only one PCM. Abstract To explore phase change materials (PCMs) with different melting points for building energy saving in different seasons, Mg(NO 3 ) 2 ·6H 2 O was mixed with CaCl 2 ·6H 2 O at different mass fractions to prepare eutectics. And the obtained two eutectics were selected as the two appropriate PCMs to combine with expanded graphite (EG), one of which is CaCl 2 ·6H 2 O-8wt%Mg(NO 3 ) 2 ·6H 2 O/EG (PCM1), exhibiting a onset point and melting peak temperature of 21.17 and 27.87 °C and latent heat of 105.4 J/g, and the other one is CaCl 2 ·6H 2 O-15wt%Mg(NO 3 ) 2 ·6H 2 O/EG (PCM2), having a onset point and melting peak temperatures of 14.23 and 23.17 °C and latent heat of 80.19 J/g. Then, two EG-based composites were formed into PCM panels by vacuum compression, respectively, and a kind of double-layer panel was fabricated by integrating the single-layer one together. The experimental investigation on the thermal performance of the chamber equipped with PCM panels was carried out, and the obtained results were used to validate a numerical simulation method. Finally, by employing the validated numerical model, the thermal performance of the concrete room containing PCM1, PCM2 and double-layer panels were investigated, respectively. It is shown that the better energy saving potential of the room can be achieved by placing PCM1 and PCM2 on the roof and southern wall, respectively. The wall panels fabricated from the CaCl 2 ·6H 2 O-Mg(NO 3 ) 2 ·6H 2 O/EG composites with suitable phase change temperatures show potentials in practical applications. [ABSTRACT FROM AUTHOR]

The inorganic salt hydrate PCM, CaCl 2 ·6H 2 O, has a promising potential for thermal energy storage. However, this salt hydrate has tremendous issues of supercooling (the supercooling degree was 25.5 °C as found in this research) which restricts its utilization in practical applications. The present study aimed to reduce the supercooling degree of CaCl 2 ·6H 2 O through the innovative use of hydrophilic graphene oxide (GO) nano-sheets and SrCl 2 ·6H 2 O as nucleating agents. The percentages of these nucleating agents in PCM were 0.005, 0.01, 0.02, 0.05 and 0.08 wt% for GO and 0.2, 0.5 and 0.8 wt% for SrCl 2 ·6H 2 O, respectively. Based on the synergistic/additive effects, a novel composite PCM based on CaCl 2 ·6H 2 O, GO and SrCl 2 ·6H 2 O was proposed and developed. The test results showed that the composite PCM containing 0.02 wt% GO nano-sheets and 0.8 wt% SrCl 2 ·6H 2 O effectively lowered the supercooling degree of CaCl 2 ·6H 2 O from 25.5 °C to as low as 0.2 °C (approximately 99.2% supercooling degree of CaCl 2 ·6H 2 O was reduced). To the best of authors' knowledge, it was the first time that the combination of GO and SrCl 2 ·6H 2 O was found effective in reducing supercooling degree of CaCl 2 ·6H 2 O. Moreover, 99.2% supercooling reduction of CaCl 2 ·6H 2 O is considered the best achievement so far when compared to other studies related to supercooling reduction of CaCl 2 ·6H 2 O. Finally, the solidification enthalpy of the composite PCMs was found to be as high as 207.90 J/g. Therefore, the developed composite PCM is an excellent candidate for thermal energy storage applications in buildings. [ABSTRACT FROM AUTHOR]

Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl2·2H2O/CaCl2 Salt hydrates have issues of supercooling when they are utilized as phase change materials (PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM system to reduce the supercooling phenomenon existing in CaCl2·2H2O/CaCl2. Six samples with different compositions of CaCl2 were prepared. The relationship between the performance and the proportion of calcium chloride dihydrate (CaCl2·2H2O/CaCl2) and calcium chloride anhydrous (CaCl2) was also investigated. The supercooling degree of the final PCM reduced with the increase in volume of CaCl2·2H2O/CaCl2 during its preparation. The PCM obtained with 66.21 wt %CaCl2·2H2O/CaCl2 reduced the supercooling degree by about 96.8%. All six samples, whose ratio of CaCl2·2H2O/CaCl2 to (CaCl2 plus CaCl2·2H2O/CaCl2) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings for thermal energy storage purposes. Hence, CaCl2·2H2O plays an important role in reducing supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of adding different percentages of Nano-SiO2 (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling degree of some PCM samples was investigated. The test results showed that the supercooling of the salt hydrate PCM in Samples 6 and 5 reduced to 0.2 °C and 0.4 °C respectively. Finally, the effect of the different cooling conditions, including frozen storage (-20 °C) and cold storage (5 °C), that were used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of the two materials, the performance and properties of the newly developed PCM systems were better especially in terms of reducing the supercooling degree of the PCM. The novel composite PCMs are promising candidates for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl2·2H2O/CaCl2 Salt hydrates have issues of supercooling when they are utilized as phase change materials (PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM system to reduce the supercooling phenomenon existing in CaCl2·2H2O/CaCl2. Six samples with different compositions of CaCl2 were prepared. The relationship between the performance and the proportion of calcium chloride dihydrate (CaCl2·2H2O/CaCl2) and calcium chloride anhydrous (CaCl2) was also investigated. The supercooling degree of the final PCM reduced with the increase in volume of CaCl2·2H2O/CaCl2 during its preparation. The PCM obtained with 66.21 wt %CaCl2·2H2O/CaCl2 reduced the supercooling degree by about 96.8%. All six samples, whose ratio of CaCl2·2H2O/CaCl2 to (CaCl2 plus CaCl2·2H2O/CaCl2) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings for thermal energy storage purposes. Hence, CaCl2·2H2O plays an important role in reducing supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of adding different percentages of Nano-SiO2 (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling degree of some PCM samples was investigated. The test results showed that the supercooling of the salt hydrate PCM in Samples 6 and 5 reduced to 0.2 °C and 0.4 °C respectively. Finally, the effect of the different cooling conditions, including frozen storage (-20 °C) and cold storage (5 °C), that were used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of the two materials, the performance and properties of the newly developed PCM systems were better especially in terms of reducing the supercooling degree of the PCM. The novel composite PCMs are promising candidates for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

CaCl 2 ·6H 2 O/expanded graphite (EG) composite phase change material (PCM) with melting and freezing points of 27.11 °C and 21.67 °C and corresponding latent heat values of 118.7 J/g and 115.7 J/g was employed to fabricate the PCM panels for building application. The thermal performance of the test room equipped with the PCM panels at each position was evaluated by placing the room in an artificial climatic chamber. Compared with the reference one without the PCM panels, the test room equipped with the PCM panels exhibited much lower maximum temperature, higher minimum temperature, and reduced temperature amplitude, revealing the function of the PCM panels for reducing indoor temperature fluctuation. Furthermore, the investigation on the effect of the position of the PCM panels indicated that, the more inside position the PCM panels were placed at, the better thermal performance the obtained test room had. Moreover, numerical modeling was carried out to study the thermal performance of the PCM panels containing the CaCl 2 ·6H 2 O/EG composite. It was found that the results from the numerical modeling agreed well with those from the experimental investigations. Base on the numerical modeling, it was found that the optimum thickness of the PCM panel was about 8–10 mm, and the thermal performance of the CaCl 2 ·6H 2 O/EG panels was better than that of the RT27/EG. It is revealed that the CaCl 2 ·6H 2 O/expanded graphite composite PCM shows great promise in building energy saving. [ABSTRACT FROM AUTHOR]

• A novel composite PCM using CaCl 2 ·6H 2 O as PCM and silica aerogels as carrier was prepared. • The addition of silica aerogels could significantly reduce thermal conductivity, prevent leakage and lessened subcooling. • The form-stabilized composite PCM had high phase change enthalpy and low supercooling degree. • The composite PCM has a great potential application in building energy storage. To meet the national demand for energy conservation and emission reduction, a shape-stable CaCl 2 ·6H 2 O /silica aerogel composite phase change material (CPCM) for building energy storage was successfully developed. The CPCM was formed by using modified CaCl 2 ·6H 2 O composed of CaCl 2 ·6H 2 O (main PCM) and SrCl 2 ·6H 2 O (nucleating agent) as PCM, and silica aerogel as carrier via physical blending method. The structure and properties of the CPCM were investigated by various techniques. The results showed that compositing of modified CaCl 2 ·6H 2 O with silica aerogel could significantly reduce the thermal conductivity, effectively prevent leakage as well as lessen supercooling. The obtained CPCM with 75 wt% modified CaCl 2 ·6H 2 O had suitable phase transition temperature (27.0 °C) with high latent heat (110.9 J·g−1), acceptable supercooling degree (1.6 °C), low thermal conductivity (0.1954 W/(m·K)) as well as excellent thermal reliability. The results obtained make the CPCM in this work promising for use in building thermal insulation materials. [ABSTRACT FROM AUTHOR]

This paper thermo-physically characterizes salt hydrate, paraffin wax and milk fat as phase change materials (PCMs). The three PCMs are compared in terms of improving heat sink (HS) performance for cooling electronic packaging. An experimental study is carried out on commercially available finned HS with and without PCM under natural ventilation (NV) and forced ventilation (FV) at different heat loads (4 W to 10 W). The results indicate that integration of all of the PCMs into the HS improves its cooling performance; however, milk fat lags behind the other two PCMs in terms of cooling produced. A three-dimensional pressure-based conjugate heat transfer model has been developed and validated with experimental results. The model predicts the parametric influence of PCM melting range, thermal conductivity and density on HS thermal management performance. The HS cooling performance improves with increased density and conductivity while it deteriorates with the wider melting range of the PCMs. [ABSTRACT FROM AUTHOR]

This communication presents the thermal performance and economic evaluation of the thermal management system (TMS) for cooling applications using calcium chloride hexahydrate as a phase change material. This experimental work was done to shift the peak time cool energy demand for off peak time. The PCM was selected for TMS on the basis of availability in the desired temperature range and long term thermal behavior. The designed system was tested with air conditioning system for cool energy storage and discharged with three heating loads (1 kW, 2 kW and 3 kW) for the real life application. The energetic and exergetic efficiencies were also calculated and found to be highest for 1 kW and lowest for 3 kW heating load. The economic evaluation of the TMS has been carried with respect of per unit cost of electricity generated by coal, diesel and solar energy and found that payback time is low for solar based generation in comparison to electricity generation by other sources. The results of this study were also compared with those of the theoretical values and are found in good agreement with each other. [ABSTRACT FROM AUTHOR]

This paper thermo-physically characterizes salt hydrate, paraffin wax and milk fat as phase change materials (PCMs). The three PCMs are compared in terms of improving heat sink (HS) performance for cooling electronic packaging. An experimental study is carried out on commercially available finned HS with and without PCM under natural ventilation (NV) and forced ventilation (FV) at different heat loads (4 W to 10 W). The results indicate that integration of all of the PCMs into the HS improves its cooling performance; however, milk fat lags behind the other two PCMs in terms of cooling produced. A three-dimensional pressure-based conjugate heat transfer model has been developed and validated with experimental results. The model predicts the parametric influence of PCM melting range, thermal conductivity and density on HS thermal management performance. The HS cooling performance improves with increased density and conductivity while it deteriorates with the wider melting range of the PCMs.

CaCl2·6H2O is selected as the original substrate for research, and a new composite phase change material (CPCM) suitable for air-conditioning was developed through experiments. The new modified CaCl2·6H2O CPCM uses glycerol as a temperature regulator and barium hydroxide octahydrate as a nucleating agent. The experimental results show that when the mass ratio of CaCl2·6H2O to glycerol is 85:15, the melting temperature of the CPCM is 11.8 °C and the enthalpy of phase change is 112.86 J/g. The chemical composition of the CPCM was characterized by Fourier transform infrared spectroscopy, which confirmed that the material was successfully developed. When the amount of barium hydroxide octahydrate nucleating agent was 1.0 wt.%, the supercooling of the CPCM decreased to 1.22 °C. CPCM still show good stability after 50 thermal cycles and can be used in practical production. [ABSTRACT FROM AUTHOR]