Research on Rates Discharge Characteristics of High Energy Density Ternary Lithium Battery

In order to study the effect of rates discharge on characteristics of ternary lithium batteries, a new type of high rate ternary lithium battery from a unit is used as the research object. The discharge test is carried out at the discharge rates of 1C, 4C, 7C, 12C and 15C on this ternary lithium battery at room temperature with high and low temperature charge/discharge test system. The test results show that the energy density under 1C rate discharge is 202.62wh/kg. Correspondingly, the energy density under 4C, 7C and 12C rate discharge is 95.17%, 93.83% and 91.79% of the value under 1C rate discharge respectively. Even for 15C rate discharge, its energy density can reach 87.15% of 1C rate discharge. During the discharge process, the temperature of the battery increased with the increase of discharge rate, and the temperature rise at 15C rate by 26 °C.

Rack-Level Thermosyphon Cooling and Vapor-Compression Driven Heat Recovery: Compressor Model

This paper introduces a novel thermal management solution coupling in-rack cooling and heat recovery system. System-level modeling capabilities are the key to design and analyze thermal performance for different applications. In this study, a semi-empirical model for a hermetically sealed scroll compressor is developed and applied to different scroll geometries. The model parameters are tuned and validated such that the model is applicable to a variety of working fluids. The identified parameters are split into two groups: one group is dependent on the compressor geometry and independent of working fluid, whereas the other group is fluid dependent. By modifying the fluid-dependent parameters using the specific heat ratios of two refrigerants, the model shows promise in predicting the refrigerant mass flow rate, discharge temperature and compressor shaft power of a third refrigerant. Here, the approach has been applied using data for two refrigerants (R22 and R134a) to achieve predictions for a third refrigerant’s (R407c) mass flow rate, discharge temperature, and compressor shaft power, with normalized root mean square errors of 0.01, 0.04 and 0.020, respectively. The normalization is performed based on the minimum and maximum values of the measured variable data. The technique thus presented in this study can be used to accurately predict the primary variables of interest for a scroll compressor running on a given refrigerant for which data may be limited, enabling component-level design or analysis for different operating conditions and system requirements.