ABSTRACT
Storage of both energy and exergy in the packed beds is experimentally
investigated. Experiments are carried out to measure the time dependent temperature
distributions inside two vertically oriented packed beds constructed from PVC cylinders
with 0.15 and 0.25 m inside diameters, respectively. Rock grains of two irregular sizes
ranging between 15 to 20 mm and between 30 to 35 mm, respectively, are packed inside
the beds at different aspect ratios ranging from 1.0 to 4.5. For each bed, temperatures at
different axial and radial positions as well as the axial pressure distribution are measured
at different operating parameters. The stored energy, exergy and the bed efficiencies
based on both the 1st and the 2nd laws of thermodynamics are calculated utilizing the
present measurements.
The influence of bed diameter, bed aspect ratio, packing grains size, air flow rate,
and the inlet air temperature on the system storage characteristics are investigated. The
present results for the stored energy, exergy per unit storage volume, system efficiencies
and the charging duration are correlated as functions of the different operating and
design parameters.