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As a kind of low temperature bulk heat storage material, calcium chloride hexahydrate has a great application prospect in heat storage and energy saving. However, the single calcium chloride hexahydrate phase change heat storage material has the disadvantages of low thermal conductivity and easy leakage when melting. Mesoporous silicon dioxide with large inner core and interpenetrating mesoporous channel structure can solve the above problems. Mesoporous silicon dioxide has the advantages of low density, low thermal expansion coefficient, low refractive index and large specific surface area. However, it has low thermal conductivity and needs to be combined with other materials with good thermal properties to enhance its thermal conductivity. MXene was used as the thermal conductivity enhancement material, mesoporous silicon dioxide was grown on its surface, and then the phase change material calcium chloride hexahydrate was loaded into it. By means of synchronous thermal analyzer and infrared thermal imager, it is proved that the heat storage performance, thermal stability and heat transfer rate of the composite phase change materials are significantly improved. The leakage of calcium chloride hexahydrate in the oven was also obviously inhibited by the carrier material. A kind of composite phase change heat storage material with excellent thermal properties and stability was successfully prepared. [ABSTRACT FROM AUTHOR]

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.

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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.

In order to obtain a low-cost, high latent heat and thermostable phase change material with a phase change temperature between 18 and 25 °C as a room temperature phase change material, a novel solid-liquid calcium-based composite named as PCM-Ca of 44.6% CaCl2, 6.9% Ca(NO3)2, 1.2% SrCl2 and 47.3% H2O with a phase change temperature of 21.8 °C and latent heat of 155.5 J g−1 was developed. The determination of thermal performances of PCM-Ca indicated that the thermal conductivities in liquid and solid state are of 0.6429 and 0.8256 W m−1 K−1, and the thermal conductivity in the phase change point is 1.2401 W m−1 K−1; the specific heat capacities at the temperature range of 5.5-26.5 °C and 31.5-38.5 °C were fitted as y = 0.0001x4 − 0.0042x3 + 0.0707x2 − 0.4151x + 3.9526 (r = 0.9999) and y = −0.0001x4 + 0.0208x3 − 1.1155x2 + 26.477x + 231.57 (r = 0.9984), respectively. The stability analysis demonstrated that PCM-Ca is stable at the temperatures less than 130 °C, and no phase separation and the obvious supercooling phenomenon were presented after thirty times cycle use. This material PCM-Ca has a potential for energy storage application. [ABSTRACT FROM AUTHOR]

Highlights • Co-integration of two composite phase change materials in building was explored. • A CaCl 2 ·6H 2 O-NH 4 Cl-SrCl 2 ·6H 2 O mixture was developed to prepare composites. • The composites were based on two matrices with different thermal conductivities. • A test room composed of a main room and a ventilation system was constructed. • The test room containing two types of composite panels has better thermal comfort. Abstract Herein the co-integration of two composite phase change materials into building envelopes and ventilation systems was first explored for reducing indoor temperature fluctuation. Specifically, a ternary mixture consisting CaCl 2 ·6H 2 O, NH 4 Cl and SrCl 2 ·6H 2 O was combined with expanded perlite and expanded graphite to prepare two composites with different thermal conductivities, followed by fabricating them into two kinds of panels. A test room composed of a main room and a ventilation system was constructed, in which the expanded perlite-based composite panels were placed at the insides of the four walls, floor and roof of the main room, while the other expanded graphite-based composite ones were incorporated into the ventilation system. It is shown that the ternary mixture consisting of 95 wt% CaCl 2 ·6H 2 O-4 wt% NH 4 Cl-1 wt% SrCl 2 ·6H 2 O exhibits a melting point of 23.46 °C, lower than that of CaCl 2 ·6H 2 O, making it more suitable for use in buildings. Its melting enthalpy is as high as 173.2 kJ/kg. The thermal conductivities of the expanded perlite- and expanded graphite-based composites have been measured to be 0.1170 and 9.720 W/(m·K), respectively. Compared with the room equipped with the expanded perlite-based composite panels at the envelopes, the one containing the two composite phase change panels at the envelopes and the ventilation system simultaneously exhibits a reduced indoor temperature fluctuation (22.29–28.69 °C) and a higher frequency of thermal comfort (78.3%). This work paves the way to the exploitation of hydrated salts as well as the applications of the phase change composites with different thermal conductivity in buildings envelopes and ventilation systems. [ABSTRACT FROM AUTHOR]

Abstract Peritectic transformation of pure CaCl 2 ·6H 2 O during its phase-change process limits its application as a phase change material (PCM). After modification by adding other salts, it may turn into eutectic material. In this work, the possibility of CaCl 2 ·6H 2 O + NH 4 Cl + KCl as eutectic phase change material is studied by experiment combining computer simulation. At first, solubility isotherms of the quaternary system CaCl 2 + NH 4 Cl + KCl + H 2 O was experimentally determined at T = 293.15 K. Secondly, phase diagrams of the quaternary system and its sub-system were simulated by a Pitzer-Simonson-Clegg model. The predicted solubility isotherms was found in good agreement with the experimental data at 293.15 K, which shows the model is reliable for this system. The solubility behavior of the system at other temperatures was predicted with the model, and an eutectic point (46.68 wt% CaCl 2 , 4.65 wt% NH 4 Cl, 2.70 wt% KCl and 45.97 wt% H 2 O) with melting temperature at 297.35 K was found existing in this system which is a promising PCM. At last, a heat storing and releasing experiment of 80 g PCM was carried out to check the possibility of the predicted material as PCM, it was found that the predicted material is an excellent PCM with latent heat of 149.6 J/g. Graphical abstract fx1 Highlights • Solubility isotherms of the titled system were measured at 293.15 K. • A PSC model was applied to simulate and predict the solubility of the system. • The predicted isotherms agree with the experimental ones very well. • A eutectic phase change material (PCM) has been predicted by the PSC model. • The phase change behaviors of the predicted PCM were testified by experiments. [ABSTRACT FROM AUTHOR]

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]

A porous supporting matrix, expanded perlite (EP) is composited with a salt hydrate mixture of CaCl 2 ·6H 2 O and SrCl 2 ·6H 2 O (98:2 in mass ratio), to develop a nonflammable thermal storage material for building use. The salt hydrate is uniformly adsorbed on sheets of EP, and a maximum absorption capacity test shows EP can contain as high as 55 wt% the salt hydrate and keep the stable form. It is shown that the melting temperature of the composite PCM is 27.38 °C, close to that of CaCl 2 ·6H 2 O, and its latent heat is 87.44 J/g, equivalent to the calculated value based on the mass fraction of CaCl 2 ·6H 2 O in the composite. EP further reduces the salt hydrate thermal conductivity by over 70% to enhance its thermal insulation, and suppresses the supercooling. A 1000 heating-cooling cycles test verifies the CaCl 2 ·6H 2 O/EP composite possesses good thermal reliability. The CaCl 2 ·6H 2 O/EP composite is then fabricated into a board for replacing the foam board employed as the core in a commercial foam insulating brick to obtain a PCM brick. It is found that, when applied as the roof of a test room, the PCM brick has the function of decreasing the indoor peak temperature and causing the hysteresis in the indoor temperature rise, compared with the foam insulation brick. The nonflammability along with good thermal storage and insulation properties makes the CaCl 2 ·6H 2 O/EP composite PCM show great promises for use in building energy conservation. [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]

Thermal energy storage (TES) using a phase change material (PCM) has been proposed as a supplemental cooling system to improve the performance of power plant air-cooled condensers (ACCs). In this proposed system, frozen PCM would remove heat from plant's condensing steam during the day, which would melt the PCM. The PCM would be frozen at night as its stored heat is rejected to the cooler atmosphere. Calcium chloride hexahydrate (CaCl2 · 6H2O) is an attractive material to serve as a PCM in this innovative system due to its appropriate melting temperature, low price, and relatively high latent heat of fusion. The corrosion of container materials is a major challenge in using CaCl2 · 6H2O. Any material used needs to survive constant exposure to the salt for several years to ensure a long operational life for the system. In this study, the corrosion behavior of four metals in contact with CaCl2 · 6H2O was experimentally investigated. Three different temperature conditions and two pH level conditions were considered under static metal exposure conditions. [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]

Deep eutectic solvents (DESs) are gaining interest in various applications due to their tuneable properties and affordable preparation cost. Developing low cost new DESs is vital for some potential industrial applications. This work introduces a new type III DESs based on choline chloride as a quaternary ammonium salt (QAS) and calcium chloride hexahydrate as a hydrated salt. The prepared DESs were characterized by measuring some of their important physical and chemical properties. Furthermore, the applicability of the new DESs as a possible phase change material (PCM) that can be used for building applications was investigated. The experimental results manifested that the DESs in the molar ratios of 1:6 and 1:8 (QAS: hydrated salt) have the potential to be utilized as PCMs in building applications with large latent heat (127.2–135.2 kJ Kg −1 ) and suitable phase change temperature (20.65–23.05 °C), However, they suffered from supercooling and phase segregation. In order to overcome these problems, 2 wt% of SrCI 2 ·6H 2 O as nucleating agent and fumed silica as thickener were used during the 100 thermal cycling test. The cycling results showed the degree of supercooling of the DESs was significantly reduced and the phase change temperatures of the DESs remained unchanged. [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.

Abstract: Phase change behaviour of pure and some chemically modified calcium chloride hexahydrate materials suggested in the literature as suitable heat storage media was studied in storage systems with a low degree of mixing in order to evaluate their long-term reversibility. The influence of gravitation on the phase change properties of the pure system was elaborated by determining local salt concentrations in the liquid phase and changes in the volume of the system during repeated melting and crystallization, whereby the amounts of the different phases being present could be assessed. It was found that thermo gravitational effects are of minor importance in generating salt concentration gradients in the liquid phase when compared to the concentration gradients resulting from the sedimentation of the formed tetrahydrate and the hexahydrate during the phase change reactions. Due to these effects it was not possible to prevent irreversible tetrahydrate formation and deterioration in heat storage capability by adding a surplus of water to the hexahydrate materials, if seeds for the tetrahydrate were present during repeated melting and crystallization. Upon addition of SrCl2 ·6H2O a solid solution of the two hexahydrates is formed and as a result the formation of the tetrahydrate is suppressed. Due to irreversible formation of SrCl2 ·2H2O a state of true congruent melting seems, however, not possible to reach. Phase segregation effects also in this case lead to irreversible calcium chloride tetrahydrate formation if seeds for the latter are added during repeated melting and crystallization. If Ca(OH)2 is also added, the tetrahydrate formation can be further suppressed. But, even in this case, irreversible tetrahydrate formation can not be prevented if the composition of the liquid phase corresponds to the hexahydrate. On addition of 5wt% KCl or 5wt% KCl+2wt% SrCl2 ·6H2O or 5wt% KCl+0.4wt% NaCl, repeated melting and crystallization in the presence of seeds of the tetrahydrate can, however, be carried out without irreversible formation of the latter occurs. In the heat storage system CaCl2 ·6H2O+5wt% KCl, formation of tetrahydrate is observed but its rate of dissolution is found considerably faster than in the pure hexahydrate system. It was concluded that with those modified calcium chloride hexahydrate systems reversible phase change cycling can be performed and therefore there is for example no the need for thickener agents to be added to avoid irreversible tetrahydrate formation successively reducing heat storage capability of systems in those cases. [Copyright &y& Elsevier]

In this study, experiments are conducted to investigate melting and solidification characteristics of calcium chloride hexahydrate (CaCl2.6H2O) as a phase change material (PCM). In the present study, some parameters that affect the melting and the solidification time of PCM used to store low temperature energy have been observed experimentally. These parameters are inlet temperature and mass flow rate of water used as a heat transfer fluid (m = 2.51, 3.75, and 4.95 kg min-1), fin numbers inside the PCM. For this purpose, PCM has been stored constantly between the coaxial pipes and water adjusted to 45°C for the melting process and to 5°C for the solidification process, and was circulated by a pump through the inner pipe at the experimental setup. During the experiments, when the water mass flow rate is increased to 49 and 97% with respect to the starting mass flow rate (m = 2.51 kg min-1), a rate of 5 and 15% decrease at the melting time is obtained, respectively. As a result, it has been observed that the effect of the fins placed inside the PCM to the melting and solidification time is much more than the effects obtained by the flow rate and the swirling generators. [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. [ABSTRACT FROM AUTHOR]

Novel eutectic mixtures have been produced using calcium chloride hexahydrate as the hydrogen bond acceptor, together with ethylene glycol as the hydrogen bond donor. The liquids are found to have increased conductivity, decreased viscosity and a lower glass transition temperature compared to most deep eutectic solvents produced using quaternary ammonium salts. Additionally, metal speciation was found to be almost the same as in a commonly-used choline chloride: ethylene glycol DES, despite the difference in water content. Calcium chloride is an interesting component as it is a waste product from the Solvay process hence it is inexpensive, and also has low toxicity. The electrochemical properties of four different metals in these eutectic mixtures were investigated, and critically, it was shown that metallic iron, cobalt and nickel could be electrodeposited at ambient temperatures without the need for additives. [ABSTRACT FROM AUTHOR]

• CaCl 2 ·6H 2 O-Mg(NO 3) 2 ·6H 2 O/EG is integrated into the room for year-round energy management. • The performance of the room containing two kinds of PCMs is studied numerically. • The smaller energy demand can be obtained by placing PCM panels inside the room. • Changes of the PCM layer thickness do not affect the choice of the phase change temperature. • PCM panels perform better in area with large temperature different between day and night. A new type of a phase change material (PCM) room containing CaCl 2 ·6H 2 O-Mg(NO 3) 2 ·6H 2 O/expanded graphite (EG) with different phase transition temperatures was proposed. PCM panels with a lower phase transition temperature were active in heating seasons, and PCM panels with a higher phase transition temperature were active in cooling seasons. The effects of the PCM panels and different parameters on the thermal behavior of concrete rooms used for annual energy management were investigated by using the validated numerical model. The energy demand was used as an evaluation index. The results indicated that a smaller energy demand could be obtained by placing the PCM panels inside the room. The energy demand was affected by the phase transition temperature. The PCM panels suitable for the roof and south wall were CaCl 2 ·6H 2 O-2wt%Mg(NO 3) 2 ·6H 2 O/EG and CaCl 2 ·6H 2 O-15wt%Mg(NO 3) 2 ·6H 2 O/EG, respectively. As the thickness of the PCM panels increased, the energy demand decreased, but the optimal types of PCM panels for the roof and south wall remained the same. Different climate regions influenced the choice of PCM panels. A climate region with large temperature differences between day and night minimized the energy demand. It is revealed that the PCM rooms exhibited better thermal behavior in both cooling and heating seasons. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) with excellent energy conservation performance have been extensively utilized in solar energy storage system. In this study, a novel kind of thermal storage composite material based on calcium chloride hexahydrate (CaCl 2 ·6H 2 O) salt hydrate as core PCM and cesium tungsten bronze (Cs x WO 3) nanoparticles as near-infrared (NIR) light absorbent additives is fabricated. The effect of Cs x WO 3 nanoparticles on crystalline morphology, thermal physical behaviors and light transmittance of CaCl 2 ·6H 2 O are investigated. Additionally, thermal cycle tests are conducted for stability examination. Furthermore, thermal regulating performance of double layer glass window filled with the PCM composite is tested in small chambers by being sunlight irradiated under a solar simulator. All results manifest that with the incorporation of Cs x WO 3 nanoparticles, the salt hydrate PCM composite exhibits large latent heat, low supercooling degree and high NIR light shielding ability as well as good thermal stability. When employed as the glazing window of a test room, the PCM panel has functions of reducing indoor temperature fluctuations and increasing thermal inertia. Hence, the salt hydrate/nano Cs x WO 3 PCM design in this work shows great potentials for the development of solar energy storage products in energy conservation fields. • Cs x WO 3 nanoparticles were added to CaCl 2 ·6H 2 O for enhancing the utilization of near infrared region (NIR) light. • The melting enthalpy of the CaCl 2 ·6H 2 O/Cs x WO 3 composite was 138.6J/g at 29.66 °C with little supercooling degree. • CaCl 2 ·6H 2 O/Cs x WO 3 nanoparticles composite PCM showed high NIR absorbing rate (~92%). • The composite PCM glazing panelscan effectively decrease temperature fluctuation in a test chamber. [ABSTRACT FROM AUTHOR]