'Periodica Polytechnica Budapest University of Technology and Economics'
Abstract
The latent heat storing materials are capable of storing the energy of the solid/liquid
phase-change in a significant amount. In this paper, a special application of this storage
is discussed, namely the utilization of the waste heat of vehicles for facilitating the re-
starting of engines.
With Diesel engines, the friction losses considerably increase at a temperature of
about 0 °C, and due to this, a higher engine power should be provided for starting, and
at the same time, the compression pressure is also reduced, which - in turn - results in
the aggravation of starting the engine. On the other hand, in the course of operation a
considerable amount of heat will be dissipated into the environment, apart of which can
be utilized for cold starting.
With the latent heat stores used for pre-heating the vehicle engines, a great storage
capacity should be ensured, as well as a high density of energy should be provided for
the discharge of the store. In addition, the mass of the store should be possibly small as
compared to that of the vehicle.
According to the examinations, the used mixture of Ba(OH)2 · 8H2O and water can
be considered as a suitable heat storing material.
With the applied hybrid heat storage construction, the coolant establishes a good
heat transfer between the storing material and the exhaust gases, as well as the engine to
be heated up and the storage material, respectively.
The metal ribs inserted into the tube stores result in more favourable heat transfer
conditions for the solidification of the phase change material.
With the ribs amounting to 2,5 volume-flow-rate of the storage material, nearly
twice as much thermal power was yielded, and due to it, the mass of the store could be
reduced
