Yanlai Zhang

Thermal Management with Phase Change Material for a Power Battery under Cold Temperatures

A 3-D module of power battery thermal management unit with phase change material is formulated. The cold start-up time of air heating is 4.2 times of phase change material heating from 243.15 to 283.15 K. The temperature difference decreases from 9.9 to 4.6°C when the thermal conductivity of the phase change material increases to five times. The heat transports from the domain near an electrode can reheat the domain away from the electrode and make the thermal energy distributing more even inside the battery. A well-designed thermal management system with phase change material is positive for power battery applying under cold temperature.

Simulation of heat dissipation with phase change material for cylindrical power battery

AbstractIn order to better understand the heat dissipation performance of power battery for electrical vehicles, a three-dimensional model based on phase change material (PCM) cooling for individual cylindrical battery cell has been developed. The model takes into account the effects of unsteady heat generation, internal conduction and external natural convection to investigate the temperature response and distribution. The simulation results showed that the PCM with thermal conductivity higher than 0·8 W m−1 K−1 can be used for keeping the maximum temperature below 50°C in a battery cell under a constant heat generation rate of 170 000 W m−3. The unsteady discharge simulated results demonstrated that the heat transfer coefficient was another important factor for heat transfer enhancement. The PCM based power battery thermal management system indicated effective cycle application because the PCM can store most of the thermal energy during discharge and release it to the outer air during charge or non-star...

Molecular dynamics simulations of phase transition of n-nonadecane under high pressure

The phase transition behavior of n-nonadecane under high pressure was investigated with molecular dynamics (MD) simulations method. A simplified model with amorphous structure and periodic boundary conditions in constant-temperature, constant-pressure ensemble was used in this study. The results showed that the whirling and molecules motion of n-nonadecane chains were restrained by the high pressure. The simulated phase transition temperature of n-nonadecane under high pressure is higher than that under atmospheric pressure. The order parameter of n-nonadecane decreases with the increase in temperature. The simulations reveal that MD is an effective method to understand the phase transition of alkane-based phase change materials on molecular and atomic scale.

Thermal Storage Technology on Solar Energy Wood Drying in China

The article mainly discusses the application situation on the solar energy wood drying in China, and summarizes its advantages and problems in the real application. Because solar energy is low in thermal density, intermittent, and it is affected by weather, these have very big limitation to use solar energy in the actual production process. Based on these, it is introduced that the advantages of thermal energy storage technology in wood drying process of solar energy, the main application modes and the actual application status. It summarizes the major thermal energy storage materials and their basic characteristics, discusses the application prospect and the importance on the latent heat storage technology in wood drying.

Physical Property and Thermal Physical Property of Microencapsulated Phase Change Material Slurry

Microencapsulated phase change material (PCM) slurry is a kind of novel heat transfer fluid called latent functionally thermal fluid. Unlike conventional (sensible) materials, when the PCM reach the temperature at which they begin phase change (its melting point), they absorb large amounts of heat with little or no temperature change. Due to this, the heat transfer ability and energy transport ability can be obviously improved. Therefore, they have many potentially important applications in some fields such as energy storage, thermal conditioning of buildings, waste heat recovery, off peak power utilization, heat pump systems, space applications. In present study, the core materials are encapsulated with membrane of synthetic material. And the core materials are composed of several kinds of n-paraffin waxes (mainly nonadecane) and the membrane is a type of melamine resin. The range of diameter of the PCM particles is distributed from 0 μm to 4.5 μm, and its average diameter is 0.74 μm. The thickness of melamine resin is about 11nm. The melting point of the PCM is about 304K. Physical properties, such as density, diameter and its distribution of microencapsulated PCM slurry are investigated. Meanwhile, the thermal physical property, apparent specific heat, is determined by a Differential Scanning Calorimeter (DSC). Also, the influence of mass concentration has been discussed.

Characterization and Thermal Properties of the Microencapsulated PCM Slurry

The microencapsulated phase change material (PCM) slurry is a kind of mixture with the PCM microcapsule particles and water. The actual PCM in the microcapsule is composed of several kinds of paraffin waxes (mainly nonadecane), and the membrane is a type of melamine resin. This study is focused on preparation, characterization, and thermal properties of the microencapsulated (PCM) slurry. The microencapsulated PCM particles are prepared by in-situ polymerization method. Four different levels of mass concentration Cm of the PCM will be used such as Cm=10%, 20%, 30% and 40%, respectively. The diameter of the particles is distributed in the range of 0µm~4.5µm, and most (61%) of them occur in the range of 0.5µm~1.5µm. The average volumetric diameter of the PCM microcapsule particle is about 0.78µm. And the average membrane thickness is about 11nm.Thermal properties of the microencapsulated PCM slurry are determined using differential scanning calorimeter (DSC). From DSC analysis, the melting and freezing temperatures and the latent heats of Cm=30% are measured as 38°C and 25°C, and 37.9 kJ/kg, respectively. The rheological properties are measured by a rotating cylinder type of rheometer, which the slurry shows the pseudo plastic non-Newtonian fluid behavior with the power-law fluid index n.

Numerical Simulation for Heat Storage Study of the Microencapsulated Phase Change Material Slurry in a Horizontal Rectangular Enclosure

Two-dimensional numerical simulation of heat storage characteristics in a horizontal rectangular enclosure heated from below by natural convection has been investigated with the microencapsulated phase change material (PCM) slurry. Effects of PCM on heat storage and heat transfer are discussed, in which PCM slurry exhibits the pseudoplastic non-Newtonian fluid behavior and a peak value in the specific heat capacity with latent heat in phase temperature range. And their characteristics between the slurries with and without phase change of PCM are compared in the phase change temperature range. And vertical temperature distributions at the middle position are given. This paper shows streamlines and isotherms in the enclosure for phase change process.

Stability of 4,4,4-Trifluoro-3-(indole-3-)butyric Acid Dissolved in Water on Growth of Rice Roots

The stability of 4,4,4-trifluoro-3-(indole-3-) butyric acid (TFIBA) were examined. Elongation of rice seminal root was promoted approximately 80% by continuous supply of 10-5 molL-1 TFIBA. Such promotion effect on root elongation is not found in IAA or IBA. The promotive effect of TFIBA on root elongation was not reduced by either direct heating in a microwave oven or autoclaving at 121°C for 15 min and root elongation was promoted by 70 - 80% at the concentration of 10-5 mol L-1. The effect of TFIBA was not lost by heat of microwave oven or autoclave. Although the effect of TFIBA dissolved in water was gradually lost at 30°C in the light, it was maintained at 4°C in the light and at 30°C in the dark. Consequently, aqueous solution of TFIBA can be stored at room temperature for at least 1 month when it is kept in the dark.

Preparation of the Microencapsulated Phase Change Material

The microencapsulated phase change material is a kind of functional material with latent heat. It may be used applied heat storage and energy transport systems. Methods of the microcapsule production and four kinds of production process are introduced.

Comparison of 4,4,4-Trifluoro-3-(indole-3-)butyric Acid Dissolved in Water and Dimethyl Sulfoxide as a Solvent on Root Growth of Rice

The effective dissolution method of 4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA) to rice plant growth was examined. Elongation of rice seminal root was promoted approximately 80% by continuous supply of 10-5 mol L-1 TFIBA dissolved in water. The primitive effect of TFIBA dissolved in DMSO on root elongation was greater than that of TFIBA dissolved in water, and the length of root was significantly increased by 233% by treatment with TFIBA at 10-5 mol L-1, compared with that in untreated control seedlings. However, DMSO occurred increase of root weight and showed somewhat disadvantage about reproducibility of TFIBA effect. In contrast, the reproducibility of TFIBA effect was high in the solution prepared with water.