Abstract:
I
n this study, micro-cogeneration application is used to increase the efficiency of Proton
Exchange Membrane Fuel Cell (PEMFC) systems and effect of different operation temperatures on system performance is observed. For this reason, two different PEMFC systems
were comparatively studied operating at 70o
C and 160o
C, respectively. Micro-cogeneration
system design has done considering experimentally determined current density, power and
temperature values. Since the amount of heat extracted from each PEMFC system is different related to the operating temperatures, different heat transfer fluids have been used for
the cooling systems. These systems are designed for utilization of electricity and hot water
for Atılım University Hydrogen Energy Laboratory. Heat loss calculation is made for the
laboratory and thermal energy needed for heating the laboratory is calculated. Parallel to the
design calculations, simple payback times for PEMFCs with micro-cogeneration applications
were determined. LT-PEMFC and HT-PEMFC systems have 402 W and 456 W thermal
powers respectively and 87.4 % and 92.8 % total cogeneration efficiencies were calculated
for each system respectively. For each system maximum water temperatures and flow rates
are calculated as a result of micro-cogeneration application. HT-PEMFC system has found to
be capable of higher amount of heating. Even LT-PEMFC system has a lower thermal power
and efficiency; it is determined to be more economical and has a lower pay pack time then
HT-PEMFC system. For both systems, necessary number of stacks to be used for laboratory
heating is calculated as four.
