Patent Application
20110117464
The invention relates to a fuel cell system comprising at least one component generating heat and at least one component using process air.
The invention relates furthermore to a method for managing the temperature of a fuel cell system.
Fuel cell systems serve to generate electrical energy and thermal energy, it being the primary feed of fossile fuels that is increasingly gaining significance. In the mobile sector, i.e. particularly in motor vehicles preference is given to using the fuels as normal for motor vehicles whilst in the non-mobile sector, i.e. particularly in domestic applications, natural gas and fuel oil are used.
Needed to process these fuels is a reforming process which, at least partly, is strongly exothermic. Likewise finding application are afterburners capable of converting the exhaust gases of the fuel cell or also the primary feed fuel in exothermic reactions. The waste heat generated by the fuel cells themselves in the fuel cell system which, particularly in the case of the solid oxide fuel cell (SOFC), can be quite considerable, need to be taken into account. Thus temperatures ranging from 500 to 1000° C. are involved in the fuel cell system depending on the operating condition and design.
To reduce the heat losses from the fuel cell system due to heat transfer to the environment, components of the fuel cell system are sited within an insulation means. But it is natural that such an insulation means cannot fully prevent heat losses. Apart from this, heat losses may occur particularly in the region of leadthroughs needed especially for supplying or discharging the flow media involving, for instance, fuel feed, air feed or removal, or exhaust gases. The waste heat generated by a DC/DC or an DC/AC converter can be considered as a power loss of the fuel cell system.
This excessive waste heat whilst reducing the efficiency of the system, on the one hand, may also be a nuisance, on the other hand, for instance when operating a fuel cell system for air conditioning on hot days.
The invention is based on the object of providing a fuel cell system having reduced heat losses and an improved temperature management.
This object is achieved by the features of the independent claim.
Advantageous embodiments of the invention read from the dependent claims.
The invention is based on the generic fuel cell system in that the heat generating component can now receive a supply of ambient air for heating by means of the heat generating component and that the thus heated air can be supplied as process air to the component using the process air. Thus, the heat absorbed by the feed of ambient air can now be returned to the system in this way via the chemical and electrochemical processes occurring in the fuel cell system in it thus being recovered.
It is expediently provided for that the heat generating component is accommodated in a housing, to an inner portion of which the ambient air can be supplied. The housing permits accommodating several heat generating components and channeling of the supplied ambient air such that the heat given off by all heat generating components can now contribute towards heating the supplied ambient air.
It is likewise just as possible that a heat generating component is sited outside of a housing in which the further heat generating components are accommodated. For example, it may be expedient to site a DC/DC or a DC/AC converter some distance away from the substantially hotter other components of the fuel cell system. It may thus prove useful not to provide the housing intended for the feed of ambient air for accommodating the converter. If so, applying ambient air to the converter would need to be provided separately, or to do away with making use of the waste heat of the converter.
In another particularly preferred embodiment it may be provided for that the housing is a thermal insulation means which may either be that as provided in any case surrounding heat generating components of the fuel cell system or an additional insulation means surrounding that as provided in any case. In the latter case the air flow is guided between the conventional insulation means and the additional insulation means.
In accordance with another preferred embodiment of the invention it is provided for that the at least one heat generating component is a reformer and/or an afterburner and/or a fuel cell stack and/or a media conduit and/or a DC/DC converter.
It is expediently provided for that the supply of ambient air is fed to the first heat generating components at a first temperature and to subsequent heat generating components at a second temperature, the first temperature being lower than the second temperature. Since the rate of heat transfer depends on the difference in temperature of the media involved, it is usual to first apply colder ambient air to the cooler components to provide a relatively large difference in temperature here too. Air which is already heated can then be supplied to the hotter components, here too a corresponding large difference in temperature existing. In this way all components can be included in managing the temperature of the fuel cell system.
It is particularly useful that the ambient air can be supplied by the delivery of a blower assigned to the component using process air in thus not requiring an additional blower for introducing ambient air into the system.
It may be provided for that the component using process air is a reformer and/or an afterburner and/or a fuel cell stack.
The invention also relates to a method for managing the temperature of a fuel cell system in accordance with the invention.
The invention will now be detailed by way of particularly preferred embodiments with reference to the attached drawings in which:
The reference numerals in the following description of the FIGS. in the drawings identify components which are the same or comparable.
Referring now to
Problematic in such fuel cell systems 10 is the loss of heat as is, on the one hand, natural via the insulation means 38 as indicated by the arrows 48, 50 and, on the other, particularly in the region of leadthroughs through the insulation means 38, for example in the region of the media feeders as indicated by arrow 52. Further heat losses occur at the converter 32 indicated by the arrow 54.
Referring now to
By means of the aspects as described above, it is now possible to reduce the heat given off by the system as a whole, i.e. the heat emerging from the housing 36 due to the intake ambient air 34 forming so-to-speak a second skin enclosing the insulation means 38 which is continually renewed and the thermal energy communicated by the skin is returned to the fuel cell system 10 via the process air.
Referring now to
It is understood that the features of the invention as disclosed in the above description, in the drawings and as claimed may be essential to achieving the invention both by themselves or in any combination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 031 866.8 | Jul 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2007/001003 | 6/5/2007 | WO | 00 | 12/19/2008 |
