Energy and Exergy Analysis of Pebble Bed Energy Storage System

A short Increasing gap between demand and supply of energy has resulted in raised prices of conventional energy sources, and concern for clean environment has led to increase in use of renewable energy sources and focus on increased energy efficiency. In context of increased energy efficiency, waste heat recovery plays an important role as it improves overall efficiency of various systems. However, time-lag between energy demand and waste heat recovery poses a challenge in useful implementation of the same. Hence, thermal energy storage comes into picture as it allows available excess thermal energy to be stored for later use. This work presents energy and exergy analysis of a designed pebble bed energy storage system (PBESS), which is designed to store waste heat from engine exhaust of a 4.4 kW single cylinder stationary CI engine. Experimental investigation is carried out and simple thermodynamic relations are used for energy and exergy analysis.