ENTWICKLUNG VON STATISCHEN LATENTWÄRMESPEICHERN FÜR NUTZKRAFTFAHRZEUGE

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.