integration of solid oxide fuel cells and ... - Ea Energianalyse

2.3. Micro Combined Heat and Power (µCHP)
2.3 Micro Combined Heat and Power (µCHP)
2.3.1 Micro CHP - Air condition
If a SOFC is installed in private homes to generate electrical power,
the waste heat can be utilized for domestic hot water as well as space
heating. The space heating, however, is not so relevant during summer
in hot climates, although hot water is still necessary for showering etc.
Many places (e.g. the US or in most asian countries) air conditioners are
employed during most of the summer. So it would be beneficial if the
excessive heat from the SOFC could be used in an absorption cooling
unit to create air conditioning.
By contacting the majority of the producers of ABS units it was
discovered that the smallest available heat driven air conditioning unit
had a cooling power of 4kW, which is in the right range for cooling a
one family house 2 . But the heat demand of the absorption unit was
12.5kW 3 which was far more than the maximum approximately 1kW
heat which would in average be supplied by the SOFC for a 1kW of
electricity production 4 .
Of course the absorption cooling unit could be run at part load, but
the low COP combined with fact that some of the waste heat was to
be used to heat up the hot water, and that some part of the waste heat
can not be extracted due to heat exchanger efficiency below 1, made the
absorption unit a very bad match for the SOFC. Furthermore the small
absorption chillers are fairly expensive per kW, so they have to have a lot
of full load hours in order to make for a reasonable pay back time.
Conclusion
This all meant that there seems not to be a potential for using an
absorption air conditioning unit together with SOFCs in private homes.
2 Assuming a well insulated house or that the climate is not too hot.
3 the small 4kW absorption unit had a COP of only 0,4 whereas most of the larger
single cycle units experienced COPs of around 0,7
4 assuming an electrical efficiency of the SOFC of approximately 0,5 and an expected
electrical power consumption of a single family house of 1kW [32]
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