Experimental and analytical investigation of thermal energy storage system for automotive applications.

A latent heat energy storage device has been designed, constructed and tested to investigate the reduction of engine warm-up time by using phase change materials (PCMs) as a thermal energy storage (TES) medium. The aim of this work was to test the TES performance under low ambient temperatures well below 0 °C, which are often encountered in winter in many countries. A new TES device with vacuum insulation was designed to contain 1.43 kg of paraffin wax in small sealed aluminum cans, and 2.2 kg of an engine coolant which was circulated between the TES device and a 15 kg aluminum block simulating an engine block. Heat discharging tests were then conducted with all the components placed in a freezer set at -15 °C. The experiments showed that the TES device initially at 60 °C was able to heat up the aluminum block from -15 °C to about +10 °C in five minutes. An analytical model was also developed to simulate the heat transport process during the TES discharging experiment. The model predictions were compared with the experimental data to validate the model and optimize the model parameters. A sensitivity study was also performed using the simulation model to investigate the effects of various parameters such as the mass of engine block, fluid flow rate, and amount of paraffin wax contained in the TES device. Both the experimental and model simulation results demonstrated the promising potential of the latent heat-based TES device for cold engine warm-up during winter.