Transition Temperatures of the Hydrates of Na2SO4, Na2HPO4, and KF as Fixed Points in Biomedical Thermometry

Magin, Richard L.; Mangum, B. W.; Statler, John A.; Thornton, D. D.

doi:10.6028/jres.086.007

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…Suzuki et al(2010a) reported the latent heat transportation system with this hydrate slurry. Disodium hydrogen phosphate has several hydration structures as reported by Telkes (1980), Magin et al (1981) and Kenisarin and Mahvkamov (2016). In this study, the concentration of disodium hydrogen phosphate in water was set at 30 wt% as dodecahydrates of disodium hydrogen phosphate was obtained even in the cooling process.…”

Section: Materials and Experimental Details 21 Materialsmentioning

confidence: 60%

Fabrication of hard-shell microcapsules containing inorganic materials

Tamaru

Suzuki

Hidema

et al. 2017

International Journal of Refrigeration

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The fabrication method of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate (Na 2 HPO 4 ･12H 2 O) has been developed. The effects of the mixing rates for the emulsification, of the volume ratios of solutions and of surfactant concentrations on the size of hollow microcapsules have been also studied. From the results, it was confirmed that silica hard shell microcapsules can contains Na 2 HPO 4 ･12H 2 O with the present method using hollow microcapsules. The present micro-encapsulated Na 2 HPO 4 ･ 12H 2 O was also found to cause the supercooling depression effect. As the fabricated microcapsules have no flammability, the present microcapsule was concluded to be a promising item not only for latent heat transportation media but also for the static thermal storage materials for architectural structures. From the studies on the fabrication parameters, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule.

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Section: Materials and Experimental Details 21 Materialsmentioning

confidence: 60%

Fabrication of hard-shell microcapsules containing inorganic materials

Tamaru

Suzuki

Hidema

et al. 2017

International Journal of Refrigeration

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“…In this regard, the K 2 (H 2 O) 0,2,4 B 12 F 12 system resembles the K(H 2 O) 0,2,4 F system (i.e., KF·(H 2 O) 0,2,4 ) . The KF dihydrate crystallizes from aqueous solutions in the temperature range 19−41 °C, the tetrahydrate crystallizes at lower temperatures, and anhydrous KF crystallizes at temperatures above 41.4 °C . As we will discuss below, crystalline K 2 B 12 F 12 does not absorb water vapor to any extent above 52 °C.…”

Section: Resultsmentioning

confidence: 98%

“…86 The KF dihydrate crystallizes from aqueous solutions in the temperature range 19-41 °C, the tetrahydrate crystallizes at lower temperatures, and anhydrous KF crystallizes at temperatures above 41.4 °C. 87 As we will discuss below, crystalline K 2 B 12 F 12 does not absorb water vapor to any extent above 52 °C. DSC experiments revealed that the dehydration of crystalline K 2 (H 2 O) 2 B 12 F 12 in a stream of dry nitrogen was endothermic, with ∆H 298 ) 111(1) kJ mol -1 (the initial temperature was 25.0(5) °C).…”

Section: B Rapid and Irreversible Dehydration Of K 2 (H 2 O) 4 B 12 F 12mentioning

confidence: 93%

Latent Porosity in Potassium Dodecafluoro-closo-dodecaborate(2−). Structures and Rapid Room Temperature Interconversions of Crystalline K₂B₁₂F₁₂, K₂(H₂O)₂B₁₂F₁₂, and K₂(H₂O)₄B₁₂F₁₂ in the Presence of Water Vapor

2010

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Structures of K(2)(H(2)O)(2)B(12)F(12) and K(2)(H(2)O)(4)B(12)F(12) were determined by X-ray diffraction. They contain [K(μ-H(2)O)(2)K](2+) and [(H(2)O)K(μ-H(2)O)(2)K(H(2)O)](2+) dimers, respectively, which interact with superweak B(12)F(12)(2-) anions via multiple K···F(B) interactions and (O)H···F(B) hydrogen bonds (the dimers in K(2)(H(2)O)(4)B(12)F(12) are also linked by (O)H···O hydrogen bonds). DFT calculations show that both dimers are thermodynamically stabilized by the lattice of anions: the predicted ΔE values for the gas-phase dimerization of two K(H(2)O)(+) or K(H(2)O)(2)(+) cations into [K(μ-H(2)O)(2)K](2+) or [(H(2)O)K(μ-H(2)O)(2)K(H(2)O)](2+) are +232 and +205 kJ mol(-1), respectively. The calculations also predict that ΔE for the gas-phase reaction 2 K(+) + 2 H(2)O → [K(μ-H(2)O)(2)K](2+) is +81.0 kJ mol, whereas ΔH for the reversible reaction K(2)B(12)F(12 (s)) + 2 H(2)O((g)) → K(2)(H(2)O)(2)B(12)F(12 (s)) was found to be -111 kJ mol(-1) by differential scanning calorimetry. The K(2)(H(2)O)(0,2,4)B(12)F(12) system is unusual in how rapidly the three crystalline phases (the K(2)B(12)F(12) structure was reported recently) are interconverted, two of them reversibly. Isothermal gravimetric and DSC measurements showed that the reaction K(2)B(12)F(12 (s)) + 2 H(2)O((g)) → K(2)(H(2)O)(2)B(12)F(12 (s)) was complete in as little as 4 min at 25 °C when the sample was exposed to a stream of He or N(2) containing 21 Torr H(2)O((g)). The endothermic reverse reaction required as little as 18 min when K(2)(H(2)O)(2)B(12)F(12) at 25 °C was exposed to a stream of dry He. The products of hydration and dehydration were shown to be crystalline K(2)(H(2)O)(2)B(12)F(12) and K(2)B(12)F(12), respectively, by PXRD, and therefore these reactions are reconstructive solid-state reactions (there is also evidence that they may be single-crystal-to-single-crystal transformations when carried out very slowly). The hydration and dehydration reaction times were both particle-size dependent and carrier-gas flow rate dependent and continued to decrease up to the maximum carrier-gas flow rate of the TGA instrument that was used, demonstrating that the hydration and dehydration reactions were limited by the rate at which H(2)O((g)) was delivered to or swept away from the microcrystal surfaces. Therefore, the rates of absorption and desorption of H(2)O from unit cells at the surface of the microcrystals, and the rate of diffusion of H(2)O across the moving K(2)(H(2)O)(2)B(12)F(12 (s))/K(2)B(12)F(12 (s)) phase boundary, are even faster than the fastest rates of change in sample mass due to hydration and dehydration that were measured. The exchange of 21 Torr H(2)O((g)) with either D(2)O or H(2)(18)O in microcrystalline K(2)(D(2)O)(2)B(12)F(12) or K(2)(H(2)(18)O)(2)B(12)F(12) at 25 °C was also facile and required as little as 45 min to go to completion (H(2)O((g)) replaced both types of isotopically labeled water at the same rate for a given starting sample of K(2)B(12)F(12), demonstrating that water molecules were exchanging, not proton...

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“…Non organic-Salt hydrates and metallic iii. Eutectics-it's a mixture of two or more component [71] There are lots of PCM available now days but its selection is very crucial thing [72]. It depends on the availability and applicability of the PCM of the selected purpose.…”

Section: Materials For Storage (Pcm)mentioning

confidence: 99%

Comparative study of heat storage and transfer system for solar cooking

Gawande

Ingole

2019

SN Appl. Sci.

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To run the Solar energy appliances, the continuous availability of solar energy is an essential. The Solar appliances are run by using solar energy either from PV cell or solar collector. Both of these devices require continuous solar rays. In order to use the solar energy after sunshine, it requires being stored first and then can be transferred to the appliances. One of the focused applications by using solar energy is the solar cooking. A Lot of research is going on the use of solar energy for cooking. But still, some extensive technique needs develop for easily usable systems. The various solar cookers are discussed to insist the need for development of solar storage systems for efficient cooking. This paper presents the comparative study of heat storage and transfer systems for solar cooking. The key aspects like, methodology to develop the heat storage system, requirements and properties of heat storage materials, need of insulations and their types are addressed. Some most usable materials are also analyzed. Keywords Heat storage system • PCM • Solar cooking List of symbols PCM Phase change material HTF Heat transfer fluid x Fraction melted Cp Specific heat (kJ/kg K) Csp Average specific heat between T1 and Tm (kJ/ kg K) Clp Average specific heat between Tm and T 2 (kJ/ kg K) dt Change in temperature in °C m Mass of heat storage medium (kg) Q Quantity of heat stored (kJ) T 2 Final temperature (°C) T 1 Initial temperature (°C) Tm Melting temperature (°C) hm Heat of fusion per unit mass (kJ/kg) VSI Vacuum super insulation VIM Vacuum insulation material VIP Vacuum insulation panel NIM Nano insulation material

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Transition Temperatures of the Hydrates of Na2SO4, Na2HPO4, and KF as Fixed Points in Biomedical Thermometry

Cited by 15 publications

References 28 publications

Fabrication of hard-shell microcapsules containing inorganic materials

Fabrication of hard-shell microcapsules containing inorganic materials

Latent Porosity in Potassium Dodecafluoro-closo-dodecaborate(2−). Structures and Rapid Room Temperature Interconversions of Crystalline K₂B₁₂F₁₂, K₂(H₂O)₂B₁₂F₁₂, and K₂(H₂O)₄B₁₂F₁₂ in the Presence of Water Vapor

Comparative study of heat storage and transfer system for solar cooking

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Transition Temperatures of the Hydrates of Na2SO4, Na2HPO4, and KF as Fixed Points in Biomedical Thermometry

Cited by 15 publications

References 28 publications

Fabrication of hard-shell microcapsules containing inorganic materials

Fabrication of hard-shell microcapsules containing inorganic materials

Latent Porosity in Potassium Dodecafluoro-closo-dodecaborate(2−). Structures and Rapid Room Temperature Interconversions of Crystalline K2B12F12, K2(H2O)2B12F12, and K2(H2O)4B12F12 in the Presence of Water Vapor

Comparative study of heat storage and transfer system for solar cooking

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Resources

About

Latent Porosity in Potassium Dodecafluoro-closo-dodecaborate(2−). Structures and Rapid Room Temperature Interconversions of Crystalline K₂B₁₂F₁₂, K₂(H₂O)₂B₁₂F₁₂, and K₂(H₂O)₄B₁₂F₁₂ in the Presence of Water Vapor