Thermal Properties Of Paraffin Research Articles

Investigation of behavior of heat storage system including paraffin with involving MWCNT nanoparticles

To create new system for heat saving and producing required cool air for building, new air conditioning system has been offered with involving several circular pipes containing paraffin. The thermal properties of paraffin have been upgraded with scattering MWCNT nano-powders and to apply the efficacy in modeling, the new material properties have been changed according to formulations based on homogeneous mixture assumption. Unsteady laminar flows have been considered in both zones and relevant source terms of melting process have been added in equations of paraffin zone. With incorporation of finite volume method, the outputs of current suggested system have been achieved and various values for size of pipe (DR) and fraction of MWCNT (ϕ) were considered. With adding nanoparticles, the conduction increases and higher heat can be absorbed by paraffin, thus, the required time for charging declines around 3.86 %. As size of pipe reduces (with considering same volume of paraffin) the melting process has been expedited. With change of DR from 0.16 to 0.12 and 0.08, the melting time reduces around 30.04 % and 12.48 %, respectively.

Molecular dynamics study on the adsorption and thermal properties of paraffin in graphene

Graphene is a promising filler to solve the low thermal conductivity and the leakage of phase change materials (PCM). Understanding the adsorbing process of PCM in porous graphene nanosheets and thermal property of composites is essential for practical application. The simulations reveal that the maximum adsorption range is 15 Å. The final structures of composites look like a spherical structure. The maximum adsorbing percentage of paraffin is 81.72% with the density of graphene at 0.3 g/cm3, which has a storage efficiency of 75.88%. With the increasing density, the total diffusion coefficients of composites slightly decrease in the range of 4∼5 × 10−10 m2/s. A dense phase around graphene affects the phase change behavior of paraffin. By analyzing the interaction energy and the phonon vibration coupling, the thermal conductivity of composites is found to increase with the increasing density of graphene. Due to the coactions of small calculated size and interfacial thermal resistance between graphene and paraffin, the current values of thermal conductivity are lower than the expected ones. In this paper, the optimum density of graphene is 0.5 g/cm3, at which latent heat and thermal conductivity of composites are 84.17 J/g and 0.51 W/m·K, respectively.

Evaluation of α-AL2O3-PW nanocomposites for thermal energy storage in the agro-products solar dryer

Abstract The shortage of fossil fuels and environmental pollution is one of the main issues of the recent century. One of the optimal ways to save energy resources is to use phase change materials for storing thermal energy. In this research, three types of AL2O3-PW nanocomposites were used to store solar thermal energy and use it in a solar dryer. Nanoparticles of AL2O3 were combined in three levels of 0.5, 1 and 1.5% w / w with paraffin wax. Synthesized nano-composites were poured into steel pipes and were used to store solar energy. The results showed that by adding nanoparticles to paraffin, the thermal properties of paraffin are improved, and its thermal energy storage potential is increased. The maximum amount of absorbed thermal energy was 3393, 6109, 6445, and 6089 kJ, for composites with 0, 0.5, 1, and 1.5 (wt%) nanoparticles of AL2O3, respectively. Also, the results showed that the time required to reach agro-products with equilibrium moisture is reduced by increasing the amount of AL2O3 in the nanocomposite. Considering the cost-benefit economic discussion, the use of nanocomposites with 1 wt% nano-particles of AL2O3 is recommended.

Time-dependent heat transfer simulation for NEPCM solidification inside a channel

The aim of current investigation is to model NEPCM behavior in an air heat exchanger storage unit by means of FVM. Unsteady governing equations are obtained including single-phase model for NEPCM. Thermal properties of paraffin are enhanced with dispersing CuO nanoparticles. The geometry was symmetric, and so there is no need to simulate the whole domain. Converting liquid to solid makes the air flow warmer and helps the ventilation of building. Wavy wall was employed to accelerate the discharging rate. Outputs reveal that dispersing nanoparticles leads to propagation of solid front. Discharging rate enhances with augmenting amplitude of inner wall.

The effects of various carbon derivative additives on the thermal properties of paraffin as a phase change material

Summary The storage of thermal energy in phase change materials (PCMs) has found wide applications that enable energy conservation and management. Paraffin is a major PCM with its low cost, wide availability, and relatively high latent heat, yet its low thermal conductivity may become a drawback in high-power applications. In this study, composites of paraffin were prepared with multiwalled carbon nanotubes and activated carbon by a dispersion technique to overcome these drawbacks. Thermal, chemical, and physical influences of incorporating carbon additives with varying structures in paraffin composites on thermal storage capacity were determined. Results indicated that the thermal conductivities of paraffin-activated carbon composites (PACC) and paraffin multiwalled carbon nanotube composites (PCNC) were improved by a factor of 39.1 and 34.1%, respectively, compared with the conductivity of pure paraffin. As a bonus, the thermal energy storage capacities of PCNCs were enhanced by 9.6%, whereas this remained unchanged for PACCs. Copyright © 2015 John Wiley & Sons, Ltd.

Influence of layered zinc hydroxide nitrate on thermal properties of paraffin/intumescent flame retardant as a phase change material

The thermal properties of paraffin as phase change material (PCM), combined with layered zinc hydroxide nitrate (LZHN) and intumescent flame retardant (IFR), have been studied by thermogravimetric analysis (TG), TG-Fourier transform infrared spectrometry (TG-FTIR), cone calorimeter (CONE),and differential scanning calorimetry (DSC). The TG results indicated that the thermal stabilities of the paraffin and paraffin/IFR composites could be improved when dodecyl sodium sulfate-modified LZHN (ds-LZHN) was incorporated. The TG-FTIR results indicated that ds-LZHN could reduce the release of combustible gases for paraffin and paraffin/IFR. The CONE results showed that the flame-retardant efficiency of IFR could be improved in the paraffin/IFR system owing to ds-LZHN. DSC results presented that the phase change temperatures and latent heats of the composites were determined by the dispersed paraffin with their mass percentage.

Preparation and thermal properties of expanded graphite/paraffin/organic montmorillonite composite phase change material

Expanded graphite (EG)/paraffin/organic montmorillonite (OMMT) composite phase change material (PCM) was prepared by using melt intercalation method. The microstructure of EG/paraffin/OMMT is observed by scanning electron microscope (SEM). The thermal properties are investigated by differential scanning calorimetry (DSC). The mass loss of EG/paraffin/OMMT after 50 heating cycles was measured for investigating the influence of EG and OMMT on the thermal properties of paraffin. The results show that EG and OMMT have the ability of adsorption and shape-stability. The melting point EG/paraffin/OMMT is decreased slightly with an addition of paraffin and the latent heat of EG/paraffin/OMMT is determined by the mass ratio of paraffin. The heat transfer efficiency of EG/paraffin/OMMT is strengthened and the heating time is decreased to one-sixth of that of paraffin by addition of EG and OMMT. The thermal stability of EG/paraffin/OMMT is improved by addition of OMMT.

Determining thermal properties of heat storage materials using the twin bath method

The thermal properties of paraffin, high density polyethylene, zinc nitrate tetrahydrate, ethylene glycol, and brick are determined using the twin bath method. The heat storage capacities of the materials with and without the effect of container are measured. The heating and cooling curve for zinc nitrate tetrahydrate is obtained to detect its supercooling tendency.