Control Characteristics And Heat Transfer In Thermal Storage With Ring Space By Using PCM

The energy which sent out from automobile fuel burning only about a third is used effectively, others release into the atmosphere, not only creates the energy waste, but also brings the poor environmental influence. Therefore, the new energy vehicles and energy-efficient vehicle is an important development direction, adopting effective methods to fully utilize the waste heat discharged by automobiles has to be an important research topic in automobile economy. As the effective way to recovery the automobile waste heat, thermal phase change storage is Green Technology of energy-saving. At present, in our country, the technology research in this field has just started, a series of problems are to be solved urgently.This article has classified the methods of automobile waste heat utilization and thermal storage with PCM which have been proposed currently, designed the thermal storage device with Ring Space by using PCM and thermal insulation structure. The system uses the heat carried by the engine coolant as the main energy and carried for a long time, in order to preheat the engine, improve the hot atmosphere and the comfort when starting a cold engine. By introducing modern design optimization software CFD, this article focuses on the simulation and depth analysis of the heat transfer and coupling, brings great effect on optimized design of thermal storage device.The author elaborated and designed the system of waste heat-storing with PCM and ascertained the place where the thermal storage with Ring Space was fixed. Then the writer filtrated Ba(OH)2·8H2O as the materials and made sure the heat capability of the case, finished the design of configuration and size of the heat storage device. Using enthalpy method, the author analyzed the characteristics of phase change and got some main points in simulation。Then the author established the model of Ring Space and made the simplified analysis, set material properties and the solving condition.In the simulation study about the process of thermal storage, the author simulated the main factors which influence the efficiency of energy storage such as the structure of the regenerator, void ratio, inlet temperature, entrance flow, the number of regenerator, environment temperature, physical parameter of PCM. Under certain conditions and given thermal storage device, Results showed that the thermal conductivity of PCM, inlet temperature and entrance flow which had great influence on heat storage time and heat power. In standard conditions, in order to obtain shorter thermal storage time and larger heat power, it should take the thermal conductivity for 1.2W/(m·K), take the inlet temperature for 368.15K and take the entrance flow for 19.23L/min,and the influence of environmental temperature is relatively small. Especially, the affect of combination of more heat-storage containers on the characteristics of thermal energy storage was investigated. Results showed that the heat storage capacity increased exponentially, but heat storage time was linear increasing, it can satisfy the different requirements. By changing the structure of regenerative heat exchanger, the author obtained that the number and length of the haplont had great influence on heat storage time and heat power. The void ratio had great influence on heat storage time, but little influence on heat storage power.In the simulation study about the process of thermal release, the author simulated the main factors which influence the efficiency of energy storage such as the structure of the regenerator, void ratio, inlet temperature, entrance flow, the number of regenerator, environment temperature, physical parameter of PCM. Under certain conditions and given thermal storage device, results showed that the thermal conductivity of PCM and entrance flow had great influence on heat storage time and heat power. In standard conditions, in order to obtain shorter exothermic time and larger exothermic chemical power it should take the thermal conductivity for 1.2W/(m·K), and take the entrance flow for 10.2L/min, the influence of environmental temperature and inlet temperature was relatively small. Especially, the affect of combination of more heat-storage containers on the characteristics of thermal energy discharge was investigated. Results showed that the capacity heat storage discharge increased exponentially, but thermal release time was linear increasing, it can satisfy the different requirements. By changing the structure of regenerative heat exchanger, the author obtained that the number and length of the haplont had great influence on thermal release time and heat discharge power. The void ratio had great influence on thermal release time, but little influence on heat discharge power.In addition, when calculated the performance of heat preservation, the author chose polyurethane as the insulation medium and simulated the factors which influence the insulation performance such as thermal conductivity of heat preservation material, insulation thickness and environmental temperature. Under certain conditions, results showed that they had great influence on insulation performance. Heat loss increases with the thermal conductivity increasing, and decreases with the environmental temperature rising and the thickness of insulating layer increasing.Throughout the characteristics of heat transfer in thermal storage with PCM, the regenerator with Ring Space can keep the energy consistent for a long time and release quickly to preheat the engine, improve the hot atmosphere, which can provide the foundation to further explore automobile waste heat utilization. Through analyzing the factors which influence the heat transfer, it can bring further research and optimize the structure.