EXPERIMENTAL AND SIMULATIVE CHARACTERIZATIONOF A FIN AND TUBES HEAT EXCHANGER WITH PCMFOR PROCESS HEAT APPLICATIONS

摘要

Thermal storage is one option to make solar or conventional process heat applications more efficient. Phasernchange material (PCM) storages offer the potential to keep constant temperatures for different time periods. Inrnthis paper a fin and tubes heat exchanger filled with the sugar alcohol D-mannitol was characterized regardingrnits usability as PCM storage in the temperature range between 100 and 250 °C. D-mannitol melts at ca. 166 °C.rnDifferent heating and cooling experiments were carried out. The specific heat capacity of the PCM as well asrnthe latent heat was determined. The heat flow into the storage was determined at different mass flow rates forrnheating and cooling processes. During the measurements thermal losses to the ambient were very high leadingrnto high uncertainties. Due to the viscosity of D-mannitol natural convection between the fins seems to have nornsignificant influence on heat transfer during melting of the PCM. Some results led to the assumption that thernheat distribution in the heat exchanger was not even. A simulation model was created and a first validation wasrncarried out. Geometry improvement with the aim of more even heat distribution and higher charge andrndischarge power will be carried out by using the simulation model and further measurements.